Method of detecting cleaved SNAP25 in tissue samples
10527620 ยท 2020-01-07
Assignee
Inventors
- Ron S. Broide (San Marcos, CA, US)
- Brian Cai (Irvine, CA, US)
- Ester Fernandez-Salas (Ann Arbor, MI)
- Joseph Francis (Laguna Niguel, CA, US)
- Catherine Rheaume (Irvine, CA, US)
Cpc classification
C07K2317/72
CHEMISTRY; METALLURGY
C07K2317/34
CHEMISTRY; METALLURGY
International classification
Abstract
Methods and compositions for detecting BoNT/A enzymatic activity in tissues or a tissue sample are described herein. The invention encompasses antibodies that bind preferentially to BoNT/A cleaved SNAP25 and is able to preferentially detect BoNT/A cleaved SNAP25, as compared to intact (non-cleaved) SNAP25, in a tissue sample.
Claims
1. A recombinant anti-SNAP25 (synaptosomal-associated protein, 25 kDa) antibody, wherein the antibody binds preferentially to BoNT/A (botulinum neurotoxin serotype A) cleaved SNAP25; and wherein the antibody is a recombinant murine antibody and comprises the heavy chain sequence of SEQ ID NO: 3 and the light chain sequence of SEQ ID NO:1; or wherein the antibody is a recombinant human antibody and comprises the heavy chain sequence of SEQ ID NO:7 and the light chain sequence of SEQ ID NO:5.
2. The anti-SNAP25 antibody of claim 1, wherein the antibody binds BoNT/A cleaved SNAP25 in a tissue sample.
3. The anti-SNAP25 antibody of claim 2, wherein the tissue sample is a biopsy sample.
4. The anti-SNAP25 antibody of claim 1, wherein the antibody does not bind to full length SNAP25.
5. A method of determining if a tissue has been exposed to BoNT/A enzymatic activity comprising contacting a tissue sample suspected of having been exposed to BoNT/A (botulinum neurotoxin serotype A) enzymatic activity with an anti-SNAP25 antibody wherein the antibody binds preferentially to BoNT/A cleaved SNAP25; wherein the antibody is a recombinant murine antibody and comprises the heavy chain sequence of SEQ ID NO: 3 and the light chain sequence of SEQ ID NO: 1, or wherein the antibody is a recombinant human antibody and comprises the heavy chain sequence of SEQ ID NO:7 and the light chain sequence of SEQ ID NO:5; and detecting the presence of anti-SNAP25 antibody bound to the tissue sample, wherein the presence of the anti-SNAP25 antibody bound to the tissue sample indicates that the tissue sample has been exposed to BoNT/A activity.
6. The method of claim 5, wherein the antibody binds BoNT/A cleaved SNAP25 in a tissue sample.
7. The method of claim 6, wherein the tissue sample is a biopsy sample.
8. The method of claim 5, wherein the antibody does not bind to full length SNAP25.
9. A kit for determining if a tissue sample has been exposed to BoNT/A enzymatic activity comprising a recombinant anti-SNAP25 antibody of claim 1.
10. The kit of claim 9, wherein the tissue sample is a biopsy sample.
11. The kit of claim 9, wherein the antibody does not bind to full length SNAP25.
Description
BRIEF DESCRIPTION OF THE DRAWINGS
(1) The patent or application file contains at least one drawing executed in color. Copies of this patent or patent application publication with color drawing(s) will be provided by the office upon request and payment of the necessary fee.
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DETAILED DESCRIPTION OF THE INVENTION
I. Definitions
(12) Unless defined otherwise, all technical and scientific terms used herein have the meaning commonly understood by a person skilled in the art to which this invention belongs. As used herein, the following terms have the meanings ascribed to them unless specified otherwise.
(13) BoNT/A refers to botulinum toxin serotype A produced by Clostridium botulinum.
(14) OnabotulinumtoxinA refers to the trade name of BOTOX, which is an FDA-approved formulation of the 900 kDa botulinum neurotoxin serotype A complex.
(15) An epitope that specifically binds or preferentially binds (used interchangeably herein) to an antibody or a polypeptide is a term that is well understood in the art, and methods to determine such specific or preferential binding are also well known in the art. A molecule is said to exhibit specific binding or preferential binding if it reacts or associates more frequently, more rapidly, with greater duration and with greater affinity with a particular cell or substance than it does with alternative cells or substances. An antibody specific binding or preferential binding to a target if it binds with greater affinity, avidity, more readily, more exclusively and/or with greater duration than it binds to other substances. It is understood by reading this definition that, for an example, an antibody (or moiety or epitope) that specifically or preferentially binds to a first target may or may not specifically or preferentially bind to a second target. As such, specific binding or preferential binding does not necessarily require (although it can include) exclusive binding. Generally, but not necessarily, reference to binding herein means preferential binding.
(16) SNAP25.sub.197 as used herein refers to the 197 amino acid fragment of synaptosomal-associated protein, 25 kDa (SNAP25) that is produced when full-length SNAP25 protein is cleaved by botulinum toxin serotype A or a recombinant botulinum toxin with enzymatic (light chain) activity of botulinum toxin serotype A.
(17) SNAP25.sub.206 as used herein refers to the full length SNAP25 protein containing 206 amino acids.
(18) It is to be understood that this invention is not limited to particularly exemplified antibodies, formulations, or methods of using such antibodies, which as such, may vary. It is also to be understood that the technical terminology used herein is for the purpose of describing particular embodiments of the invention only, and is not intended to be limiting.
II. Antibodies that Bind to SNAP25197
(19) BoNT/A molecular targets, including synaptic vesicle glycoprotein 2C (SV2C), fibroblast growth factor receptor 3 (FGFR3) and SNAP25.sub.206, are broadly expressed and co-localized in autonomic and sensory nerve fibers throughout the body, including rat and primate urinary bladder and glabrous skin. Consequently, the nerve endings are likely equally susceptible to the inhibitory effects of BoNT/A. Although antibodies exist against various molecular targets of BoNT/A, there has not been an optimal antibody identified that is useful for detecting cleaved (i.e., BoNT/A activity) SNAP25 (e.g., SNAP25.sub.197 fragment) in both Western blotting technique and also in tissue samples (e.g., using immunofluorescence).
(20) Aspects of the present disclosure comprise, in part, an anti-SNAP25 antibody that is specific for the BoNT/A SNAP25 cleavage product that can be used in ELISA assays, Western blot applications, in cell culture assays and in tissue samples to detect BoNT/A activity. Another aspect of the present invention is an anti-SNAP25 antibody with an epitope to the carboxy terminus of the SNAP25.sub.197 fragment that does not substantially bind to full length SNAP25 (SNAP25.sub.206).
(21) Methods for making antibodies (monoclonal or polyclonal) are known in the art. One method which may be employed is the method of Kohler and Milstein, Nature 256:495-497 (1975) or a modification thereof. Typically, monoclonal antibodies are developed in non-human species such as mice. In general, a mouse or rat is used for immunization but other animals may also be used. Also, once an antibody is identified to have the binding characteristics that are desired, the antigen-binding site including their complementarity determining regions (CDRs) can be fused to the constant domains or supporting framework region of antibodies of other species including human. In some instances, producing these recombinant monoclonal antibodies can minimize unwanted immunological response in patients or host animals that these antibodies are injected into. In other instances, producing these recombinant monoclonal antibodies can expand the utility of a specific antibody with certain binding characteristics for diagnostic or use for detecting BoNT/A activity in tissues of different species of animals. In some instances, recombinant monoclonal antibodies may have an advantage of minimal off target signal because of the selectively of not only the CDR, but also due to the recombinant IgG backbone, which can be very different than the endogenous IgG of the tissue of interest.
(22) Anti-SNAP25.sub.197 antibodies were generated and described in US Patent Publication No. US2012/0225436A1, hereby incorporated by reference. The CDRs of one of these monoclonal antibodies, selected for its superior performance in immunohistochemical (IHC) assays, were sequenced and recombinantly engineered into immunoglobulin backbones from either human (IgG1) or murine (IgG2A) origin. These antibodies were further characterized along with commercially available antibodies for their specificity to cleaved SNAP25 (SNAP25.sub.197) in both Western blot assays and for use in tissue samples (either rat tissue or human tissue) using immunofluorescence. Table 1 below includes a list of anti-SNAP25 that were used in this comparison.
(23) TABLE-US-00001 TABLE 1 List of anti-SNAP25 antibodies Species/ IgG- SNAP25.sub.197 Antibody Specificity Vendor Type isotype antigen SMI-81R SNAP25.sub.206/197 Covance, Murine/ IgG1 Uncleaved Princeton, mAb SNAP25 NJ MC-6050 SNAP25.sub.206/197 R&D Abs, Murine/ n/a 15-mer, LV, NV mAb C.sub.OOH-term MC-6053 SNAP25.sub.197 R&D Abs, Murine/ n/a 15-mer, LV, NV mAb C.sub.OOH-term Ab507 SNAP25.sub.197 Allergan Murine/ n/a 12-mer, mAb C.sub.OOH-term Ab632 SNAP25.sub.197 Allergan rHuman/ IgG1 12-mer, rMAb C.sub.OOH-term Ab635 SNAP25.sub.197 Allergan rMurine/ IgG2A 12-mer, rMAb C.sub.OOH-term RGT-1092 SNAP25.sub.197 Allergan Rabbit/ IgG 7-mer, pAb C.sub.OOH-term n/a = not available; mAb = mouse monoclonal antibody; rMAb = recombinant monoclonal antibody; pAb = rabbit polyclonal antibody
III. Characterization of Anti-SNAP25197 Antibodies
(24) Several methods can be used to characterize anti-SNAP25 antibodies. One method is to identify the epitope to which it binds. Epitope mapping is commercially available from various sources, for example, Pepscan Systems (Edelhertweg 15, 8219 PH Lelystad, The Netherlands). Epitope mapping can be used to determine the sequence to which an anti-SNAP25 antibody binds. The epitope can be a linear epitope, i.e., contained in a single stretch of amino acids, or a conformational epitope formed by a three-dimensional interaction of amino acids that may not necessarily be contained in a single stretch. Peptides of varying lengths (e.g., at least 4-6 amino acids long) can be isolated or synthesized (e.g., recombinantly) and used for binding assays with anti-SNAP25 antibodies. The epitope to which anti-SNAP25 antibody binds can be determined in a systematic screening by using overlapping peptides derived from the extracellular sequence and determining binding by an anti-SNAP25 antibody.
(25) Another method that can be used to characterize an anti-SNAP25 antibody is to use competition assays with other antibodies that bind to the same antigen or even the same epitope on the same antigen. Competition assays are well known to those skilled in the art.
(26) Another method of characterizing anti-SNAP25 antibodies is by the antigen to which it binds. Anti-SNAP25 antibodies can be used in Western blots. Specifically, in some embodiments, anti-SNAP25 antibodies were used in Western blot assays to determine its specificity to BoNT/A cleaved SNAP25 (SNAP25.sub.197). Anti-SNAP25 antibodies that preferentially bind to SNAP25.sub.197 and not full-length (i.e., uncleaved) SNAP25 in Western blot assays are preferred embodiments of the present disclosure. Characterization of anti-SNAP25 antibodies in Western blot assays are detailed in the Examples below.
IV. Methods of Diagnosing BoNT/A Activity in Tissue Samples
(27) Antibodies that binds to BoNT/A cleaved SNAP25 (SNAP25.sub.197) may be used to identify the presence or absence of BoNT/A activity in a variety of tissues. Such tissues may include skin, including but not limited to, glabrous or hairy, muscle, including but not limited to skeletal muscle and smooth muscle, bladder, glandular tissues, including but not limited to prostate, lacrimal gland, endocrine glands, and exocrine glands, blood vessels, spinal cord and brain, including nerve fibers within any and all of these tissues. Such tissues may be procured as part of a biopsy or skin punch.
(28) An antibody that is suitable for use to detect BoNT/A activity in tissues would need to (1) be specific to binding to SNAP25.sub.197 and not to full-length or uncleaved SNAP 25 (SNAP25.sub.206); and (2) be able to detect SNAP25.sub.197 preferentially (and not full-length or uncleaved SNAP25) in tissue samples. Another characteristic that would be desirable is that the antibody would preferentially bind to BoNT/A cleaved SNAP25 (SNAP25.sub.197) in tissue samples without substantially binding to non-specific antigens (i.e., low or no background, non-specific binding).
(29) Determining the absence or presence of BoNT/A, or BoNT/A-like compound activity in a particular tissue sample may be important for a variety of clinical and non-clinical diagnostic purposes including, but not limited to: 1) understanding the mechanism of action for BoNT/A in a particular tissue or clinical indication; 2) assessment of BoNT/A activity and/or spread beyond the site of injection; 3) assessment of suspected immunity to BoNT/A; 4) assessment and understanding of local diffusion of BoNT/A (e.g., from an injected muscle to a neighboring muscle or tissue); 5) assessment of potential exposure to BoNT/A in the setting of human botulism performed by biopsy; and 6) clinical pharmacological studies.
(30) In one embodiment, the use can involve the formation of a complex between SNAP25.sub.197 and an antibody that specifically binds to SNAP25.sub.197. In one embodiment of the diagnostic methods of this invention, the anti-SNAP25.sub.197 antibody can bear a detectable label. Examples of labels may be used include a radioactive agent, a fluorophore, chemical label, a biological agent such as but not limited to, biotin/streptavidin detection, or an enzymatic substrate label. In other embodiments, a secondary antibody of another species that can bear a detectable label can be used to detect the anti-SNAP25.sub.197 antibody. The use of a secondary antibody may in some cases, boost the signal of the primary anti-SNAP25.sub.197 antibody, thereby detecting low/lower levels of BoNT/A activity in tissue samples.
V. Compositions of this Invention
(31) This invention also encompasses compositions comprising an anti-SNAP25.sub.197 antibody that can preferentially detect BoNT/A cleaved SNAP25 without detecting uncleaved SNAP25 (SNAP25.sub.206) in ELISA, Western blot assays and in tissue samples. In some embodiments, the anti-SNAP25.sub.197 antibody is a recombinant monoclonal antibody where the CDR has been fused with the supporting framework of an antibody of a different species. In other embodiments, the anti-SNAP25.sub.197 antibody is a recombinant monoclonal antibody where the CDR has been fused with the supporting framework of an antibody of the same species. In some embodiments, the anti-SNAP25.sub.197 antibody is a recombinant monoclonal antibody where the CDR has been fused with the supporting framework of a human antibody. In some embodiments, the anti-SNAP25.sub.197 antibody is a recombinant monoclonal antibody where the CDR has been fused with the supporting framework of a mouse antibody.
(32) It was found that one antibody, 3C1A5, that has been previously preliminarily described in US2012/0225436 was especially useful in the present invention because of its inherent ability to detect SNAP25.sub.197 in BoNT/A-treated tissues. It was known that 3C1A5 preferentially bound to SNAP25.sub.197 in an immuno-based (e.g., ELISA) assay and/or in a cell-based assay.
(33) In some cases, the antibody of the present invention is 3C1A5. In other cases, the antibody of the present invention is a recombinant antibody comprising the antigen binding site of 3C1A5, but has been fused with the framework regions of another antibody from the same or different species.
(34) In one embodiment, the light chain/heavy chain of the anti-SNAP25.sub.197 antibody comprises one or more of the sequences listed below in Table 2.
(35) TABLE-US-00002 TABLE2 Ab635and632AntibodySequence Murine-3C1A5(Ab635)Sequence-(pOptiVec/pcDNA3) SEQIDNO:1LightChainMurine3C1A5(Ab635) DVVMTQTPLTLSVTIGQPASISCKSSQSLLNTNGKTYLTWLIQRPGQSPQRLIYLVSKL DSGVPDRFSGSGSGTDFTLKISRVEAEDLGVYYCLQSSHFPFTFGSGTKLEIKRADAA PTVSIFPPSSEQLTSGGASVVCFLNNFYPKDINVKWKIDGSERQNGVLNSWTDQDSK DSTYSMSSTLTLTKDEYERHNSYTCEATHKTSTSPIVKSFNRNEC SEQIDNO:2LightChainVariableDomainMurine3C1A5 (Ab635) DVVMTQTPLTLSVTIGQPASISCKSSQSLLNTNGKTYLTWLIQRPGQSPQRLIYLVSKL DSGVPDRFSGSGSGTDFTLKISRVEAEDLGVYYCLQSSHFPFTFGSGTKLEIK SEQIDNO:3HeavyChainMurine3C1A5(Ab635) QVKLQESGAELVKPGASVKISCKASGYTFTDHSIHWVKQKPGQGLEWIGYLFPGNG NFEYNEKFKGKATLTADKSSSTVYMYLNSLTSEDSAVYFCKRMGYWGQGTTVTVS SAKTTPPSVYPLAPGSAAQTNSMVTLGCLVKGYFPEPVTVTWNSGSLSSGVHTFPAV LESDLYTLSSSVTVPSSPRPSETVTCNVAHPASSTKVDKKIVPRDCGCKPCICTVPEVS SVFIFPPKPKDVLTITLTPKVTCVVVDISKDDPEVQFSWFVDDVEVHTAQTQPREEQF NSTFRSVSELPIMHQDWLNGKEFKCRVNSAAFPAPIEKTISKTKGRPKAPQVYTIPPPK EQMAKDKVSLTCMITDFFPEDITVEWQWNGQPAENYKNTQPIMNTNGSYFVYSKLN VQKSNWEAGNTFTCSVLHEGLHNHHTEKSLSHSPGK SEQIDNO:4HeavyChainVariableDomainMurine 3C1A5(Ab635) QVKLQESGAELVKPGASVKISCKASGYTFTDHSIHWVKQKPGQGLEWIGYLFPGNG NFEYNEKFKGKATLTADKSSSTVYMYLNSLTSEDSAVYFCKRMGYWGQGTTVTVS S Human-3C1A5(Ab632)Sequence-(pOptiVec/pcDNA3) SEQIDNO:5LightChainHuman3C1A5(Ab632) DVVMTQTPLTLSVTIGQPASISCKSSQSLLNTNGKTYLTWLIQRPGQSPQRLIYLVSKL DSGVPDRFSGSGSGTDFTLKISRVEAEDLGVYYCLQSSHFPFTFGSGTKLEIKRTVAA PSVFIFPPSDEQLKSGTASVVCLLNNFYPREAKVQWKVDNALQSGNSQESVTEQDSK DSTYSLSSTLTLSKADYEKHKVYACEVTHQGLSSPVTKSFNRGEC SEQIDNO:6LightChainVariableDomainHuman 3C1A5(Ab632) DVVMTQTPLTLSVTIGQPASISCKSSQSLLNTNGKTYLTWLIQRPGQSPQRLIYLVSKL DSGVPDRFSGSGSGTDFTLKISRVEAEDLGVYYCLQSSHFPFTFGSGTKLEIK SEQIDNO:7HeavyChainHuman3C1A5(Ab632) QVKLQESGAELVKPGASVKISCKASGYTFTDHSIHWVKQKPGQGLEWIGYLFPGNG NFEYNEKFKGKATLTADKSSSTVYMYLNSLTSEDSAVYFCKRMGYWGQGTTVTVS SASTKGPSVFPLAPSSKSTSGGTAALGCLVKDYFPEPVTVSWNSGALTSGVHTFPAVL QSSGLYSLSSVVTVPSSSLGTQTYICNVNHKPSNTKVDKKVEPKSCDKTHTCPPCPAP ELLGGPSVFLFPPKPKDTLMISRTPEVTCVVVDVSHEDPEVKFNWYVDGVEVHNAK TKPREEQYNSTYRVVSVLTVLHQDWLNGKEYKCKVSNKALPAPIEKTISKAKGQPRE PQVYTLPPSRDELTKNQVSLTCLVKGFYPSDIAVEWESNGQPENNYKTTPPVLDSDG SFFLYSKLTVDKSRWQQGNVFSCSVMHEALHNHYTQKSLSLSPGK SEQIDNO:8HeavyChainVariableDomainHuman 3C1A5(Ab632) QVKLQESGAELVKPGASVKISCKASGYTFTDHSIHWVKQKPGQGLEWIGYLFPGNG NFEYNEKFKGKATLTADKSSSTVYMYLNSLTSEDSAVYFCKRMGYWGQGTTVTVS S
(36) In some cases, the antibodies of the invention comprises a light chain sequence of SEQID NO:1 or SEQ ID NO:2 and is a recombinant murine antibody. In other cases, the antibodies of the invention comprises a heavy chain sequence of SEQID NO:3 or SEQID NO:4 and is a recombinant murine antibody. In other cases, the antibodies of the invention comprises a light chain sequence of SEQID NO: 5 or SEQID NO: 6 and is a recombinant human antibody. In other cases, the antibodies of the invention comprises a heavy chain sequence of SEQID NO:7 or SEQID NO:8 and is a recombinant human antibody.
(37) Still in other embodiments the antibodies of the invention can be an antibody that binds to the same epitope of an antibody with a heavy chain and/or light chain comprising one or more sequences of SEQID NOs:1-8. In some cases, the antibodies of the invention can be an antibody that will compete for binding to the same epitope of an antibody with a heavy chain and/or light chain comprising one or more sequences of SEQID NOs:1-8.
(38) The following Examples are provided to illustrate, but not to limit the invention.
IV. Examples
Example 1. Western Blot Comparison
(39) SNAP25 antibodies (listed in Table 1) were first compared by Western blot analysis in their ability to recognize the full-length (206) or BoNT/A-cleaved (197) forms of SNAP25 from rat embryonic cortical cell lysates and in SiMa cell lysates treated with and without BoNT/A. (See
(40) Rat cortical neurons were harvested from embryonic pups (E18) and digested in a papain dissociation system (Worthington Biochemical Corp., Lakewood, N.J.) at 37 C. for 15 minutes to obtain individual cells. Cortical cells were then transferred to Neurobasal medium (Life Technologies, Carlsbad, Calif.) containing B-27 supplements, 0.5 mM L-glutamine and penicillin/streptomycin. Rat dorsal root ganglia (DRG) harvested from neonatal pups (P7-P14) were pooled and digested in papain-containing HBSS (final concentration of 20 units of papain per ml in 1 mM L-cysteine) at 37 C. for 15 minutes. Ganglia were washed and subsequently digested in Ca2+/Mg2+-free HBSS containing Type 1 collagenase (1.7 mg/ml, Sigma, St Louis, Mo.) and incubated at 37 C. for an additional 15 minutes. The ganglia were then washed in Neurobasal-A media (Life Technologies, Carlsbad, Calif.) containing B-27 supplements, 0.5 mM L-glutamine, penicillin/streptomycin and 20 ng/ml 2.5S nerve growth factor (NGF) and gently triturated through Pasteur pipettes. Cortical and DRG cells were homogenously dispersed, plated onto poly-D-lysine/laminin-coated 12-mm coverslips (BD Biosciences, San Jose, Calif.) placed in 100-mm culture dishes and grown for 6 to 7-DIV prior to treatment. All animal protocols and procedures were approved by the Allergan Institutional Animal Care and Use Committee and performed in accordance with NIH guidelines.
(41) On select days, cultures were treated with or without 3 nM BoNT/A (150 kDa; Metabiologics, Madison, Wis.) for 3 hr at 37 C. Following treatment, cells were rinsed with and then incubated in fresh culture medium overnight. Cortical cells were then washed with PBS, lysed in freshly prepared Lysis Buffer (20 mM Tris pH 7.5, 0.15 M sodium chloride, 1 nM EDTA, 1 mM EGTA, 10% Triton X-100 and one tablet of EDTA-free protease inhibitors) for 20 min on ice and then centrifuged at 4000 rpm for 20 min to eliminate debris prior to Western blot (WB) analysis. DRG cells were washed, fixed with 4% paraformaldehyde for 10-15 min and processed for immunocytochemistry according to the protocol below.
(42) SiMa cells (DSMZ, Germany) were cultured in BD Biosciences brand Collagen IV flasks (VWR, Radnor, Pa.) with vented caps (Marini, P., MacLeod, R. A., Treuner, C., Bruchelt, G., Bohm, W., Wolburg, H., Schweizer, P., and Girgert, R., 1999. SiMa, a new neuroblastoma cell line combining poor prognostic cytogenetic markers with high adrenergic differentiation. Cancer Genet. Cytogenet. 112, 161-164.). Growth media consisted of RPMI 1640, 0.1 mM Non-Essential Amino-Acids, 10 mM HEPES, 1 mM Sodium Pyruvate, 100 U/mL Penicillin, 100 g/mL Streptomycin, and 10% Fetal Bovine Serum. Cells were treated with or without BoNT/A (0.01 nM) for 24 hrs at 37 C. Following treatment, SiMa cells were washed with PBS, lysed in freshly prepared Lysis Buffer for 20 min on ice and then centrifuged at 4000 rpm for 20 min to eliminate debris prior to WB analysis.
(43) For WB assays, we employed rat embryonic cortical neurons as well as a human neuroblastoma cell line (SiMa), which is known for its sensitivity to BoNT/A-mediated SNAP25 cleavage (Fernandez-Salas, E., Wang, J., Molina, Y., Nelson, J. B., Jacky, B. P., and Aoki, K. R., 2012. Botulinum neurotoxin serotype A specific cell-based potency assay to replace the mouse bioassay. PLoS. One. 7, e49516.). Total cell lysates from these cultures were separated by electrophoresis (Biorad TGX Any Kd gel) and the gel was transferred onto a PVDF membrane. Blots were blocked in buffer (5% dry milk in 1TBS-0.1% Tween-20) for 1 hr at room temperature and then incubated overnight at 4 C. with primary antibodies in blocking buffer. Following washes, blots were incubated with HRP-conjugated secondary antibodies (Bio Rad, Hercules, Calif.) and developed by ECL Plus (GE Healthcare, Pittsburgh, Pa.). A separate control blot was probed for glyceraldehyde 3-phosphate dehydrogenase (GAPDH) to show equal loading of cell lysate samples. Western blots were scanned using a variable mode GE Typhoon 9410 imager and analyzed with ImageQuant TL v.2005 software (GE Healthcare, Pittsburgh, Pa.).
(44) First a commercially available and widely-used monoclonal antibody (SMI-81R) directed against all forms of the SNAP25 protein recognized both SNAP25.sub.206 and SNAP25.sub.197 (
(45) The human (Ab632) and murine (Ab635) rMAbs directed against BoNT/A-cleaved SNAP25 were very specific for SNAP25.sub.197; only a single band was detected in toxin-treated lysates, while no bands were detected in the untreated, control lanes (
(46) A separate WB analysis was performed to examine the epitope specificity of our rMAbs using BoNT/C- and BoNT/E-treated SiMa cell lysates compared to the BoNT/A-treated lysate. It is well established that BoNT/C cleaves SNAP25 at amino acid (aa) residue 198, while BoNT/E cleaves SNAP25 at aa residue 180 [11]. While the SMI-81R mAb recognized both full length and BoNT-cleaved forms of SNAP25 (
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Example 2. Immunohistochemical ComparisonRat Tissue
(50) The specificity of the antibodies was then tested using immunohistochemistry (IHC) in rat bladder and glabrous skin that had been treated with either onabotulinumtoxinA or saline and then harvested 2-days post-injection. Throughout these IHC studies, adjacent sections processed without primary antibodies showed only background staining (data not shown).
(51) Male Sprague-Dawley rats (Charles River Laboratories, Wilmington, Mass.) were used for this study. Rats were pair-housed in the RD3 vivarium with free access to food and water on a 12 hour light-dark cycle. All procedures were approved by the Allergan Institutional Animal Care and Use Committee and adhered to NIH guidelines.
(52) Working solutions of onabotulinumtoxinA (BOTOX, Allergan, Inc., Irvine, Calif.) and BoNT/A (150 kDa; Metabiologics, Madison, Wis.) were prepared in either 0.9% saline or 0.5% BSA/0.9% saline, respectively. For bladder injections, rats were first anesthetized and prepped for surgery. A lower midline abdominal incision was made, exposing the urinary bladder, seminal vesicles, and prostate gland. The urinary bladder wall was then injected at four equidistant sites along the midline circumference with 10 l of onabotulinumtoxinA (2.5 U/kg) yielding a final toxin load of 10 U/kg. Control animals received 10 l injections of vehicle (0.9% saline) into comparable target sites. For glabrous skin injections, onabotulinumtoxinA (30 U/kg) or vehicle was administered as a single intradermal (ID) injection (25 l) into the center of the right hindlimb paw between the footpads.
(53) Rats were sacrificed at 2-days post-injection and bladders or the central portion of the planter surface of the hindpaws were harvested and fixed overnight at 4 C. in Zamboni's fixative (American MasterTech, Lodi, Calif.). Tissues were washed and cryoprotected in 30% sucrose/PBS solution overnight at 4 C. Bladder and skin samples were hemisected along the midline, embedded in O.C.T. (Tissue-Tek) and stored frozen at 80 C. until sectioning. Tissue blocks were cryostat-sectioned (14 m-thick), slide-mounted and slides were kept at 20 C. until use.
(54) Slide-mounted tissue sections and cell culture coverslips were first blocked for non-specific signal in blocking buffer (1PBS+0.1% Triton X-100+10% Normal Donkey Serum) and then incubated with primary antibodies at the desired concentrations in blocking buffer overnight at 4 C. Following several washes, sections and coverslips were incubated with secondary antibodies (Jackson ImmunoResearch, West Grove, Pa.) diluted in blocking buffer for 2 hr at 4 C. and then washed again. Coverslips with cultures were inverted and mounted onto microscope slides using Fluoromount-G (EM Sciences, Hatfield, Pa.) containing 1.5 g/ml DAPI. Slide-mounted sections were coversliped using the same mounting media. Adjacent sections processed without primary antibodies served as negative controls to show background signal. Alternate sections were stained with hematoxylin & eosin for better anatomical identification.
(55) Images were captured and analyzed using either a Zeiss LSM-710 confocal microscope with ZEN software (Carl Zeiss, Thornwood, N.Y.) or an Olympus FV1000 confocal microscope (Olympus, Center Valley, Pa.). Imaris (Bitplane, South Windsor, Conn.) software was utilized for qualitative analysis of nerve fibers. Nerve fiber-types were identified on the basis of their morphology and neurochemistry.
(56) In the rat bladder, the SMI-81R antibody directed against SNAP25 showed IR-signal in nerve fibers throughout the detrusor muscle. The SNAP25-IR pattern was identical in both onabotulinumtoxinA and saline-treated bladders, as expected (
(57) In the rat glabrous skin, the SMI-81R antibody exhibited IR-signal in nerve fibers surrounding blood vessels (among other skin regions). As expected for this antibody, the SNAP25-IR pattern was identical in both onabotulinumtoxinA and saline-treated skin (
(58) Our samples of rat glabrous skin often contain underlying skeletal muscle, providing an excellent opportunity to validate our rMAbs on their ability to recognize BoNT/A-cleaved SNAP25 within motor nerve terminals (MNT). Similar results for antibody specificity were observed in MNTs as in other skin nerve fiber-types (
(59) To further exemplify the Ab632-rMAb's superior specificity for SNAP25.sub.197 in tissues, we compared the immuno-reactive signal of Ab632 and Ab635 to an initial batch lot of the human rMAb (May 2, 2011), the original, native 3C1A5 mAb purified from ascites and the 2E2A6 (Ab507) mAb used for Allergan's cell-based potency assay for BOTOX (Fernandez-Salas, E., Wang, J., Molina, Y., Nelson, J. B., Jacky, B. P., and Aoki, K. R., 2012. Botulinum neurotoxin serotype A specific cell-based potency assay to replace the mouse bioassay. PLoS. One. 7, e49516.). The IR signal for these antibodies was compared in rat glabrous skin and bladder tissues following treatment with onabotulinumtoxinA.
(60) In rat glabrous skin, both Ab632 and Ab635 showed strong IR-signal for SNAP25.sub.197 in nerve fibers surrounding blood vessels (
(61) Comparable results were demonstrated in the rat bladder following BOTOX treatment. All three rMAbs (Ab632, Ab635 and the older human batch lot) showed specific IR-signal for SNAP25.sub.197 in nerve fibers throughout the detrusor muscle of the bladder (
(62)
(63)
(64)
(65)
Example 3. Immunohistochemical ComparisonHuman Tissue
(66) Among the commercially available antibodies against SNAP25, the MC-6053 monoclonal antibody targeting SNAP25.sub.197 is most similar to our murine Ab635-rMAb with regard to the type and species of antibody (Table 1). We therefore performed a head-to-head comparison of the SNAP25-IR expression patterns between our Ab635-rMAb and the MC-6053 mAb in biopsy samples of onabotulinumtoxinA and saline-treated human back skin. The presumption was that since this was a probe of human tissue using a mouse antibody, the non-specific IR-signal (regardless of the source) would be minimal.
(67) Human skin biopsy samples were obtained through a Phase 1 Allergan clinical study. The study was conducted in accordance with the guidelines and regulations for Good Clinical Practice and all relevant local and country privacy guidelines. The study protocol, informed consent, and all appropriate study-related documents were approved by the Institutional Review Board/Ethics Committee.
(68) Adult human back skin was injected ID with either 10 U of onabotulinumtoxinA or vehicle. Punch biopsy samples from back skin were harvested 14-days post-treatment and fixed overnight in the same fixative. Tissues were washed and cryoprotected in 30% sucrose/PBS solution overnight at 4 C. Skin samples were hemisected along the midline, embedded in O.C.T. (Tissue-Tek) and stored frozen at 80 C. until sectioning. Tissue blocks were cryostat-sectioned (14 m-thick), slide-mounted and slides were kept at 20 C. until use. IHC and data analysis was performed as outlined above.
(69) In the human back skin, the IR-signal for both antibodies was observed in nerve fibers surrounding blood vessels and sweat glands within the skin (
(70)
(71) Given the difficulty in detecting BoNT/A location and movement within cells, the proprietary recombinant humanized a-SNAP25.sub.197 and proprietary recombinant murine a-SNAP25.sub.197 can be used to cross detect SNAP25.sub.197 in the other species. While other a-SNAP25 antibodies are capable of detection, using recombinant murine a-SNAP25.sub.197 to detect SNAP25.sub.197 in human tissue or using recombinant humanized a-SNAP25.sub.197 to detect SNAP25.sub.197 in murine allows for in-depth analysis of BoNT/A mechanism of action not possible with other available antibodies.
Example 4. Immunocytochemical Comparison
(72) Some antibodies may work better for one assay/indication over another. Therefore, in order to complete our analysis, we compared the IR-signal from several of the antibodies in DRG cell cultures that were treated with either BoNT/A (3 nM) or saline.
(73) DRG cell cultures were prepared and treated as outlined above. Immunocytochemistry and data analysis was performed as detailed above.
(74) As in the tissues, the SMI-81R antibody showed strong IR-signal in both BoNT/A and saline-treated cultures (
(75)
(76) The presence of active BoNT/A in cells expressing SNAP25 can often be determined by using a selective antibody against the cleaved substrate (SNAP25.sub.197). In the present study, we introduce several rMAbs that were developed in-house against SNAP25.sub.197 and compared their immuno-reactive signal against that of commercial antibodies using a variety of different methods (Table 3). Both our human and murine rMAbs consistently detected SNAP25.sub.197 in all assays and on different tissues, and as expected, did not detect full-length SNAP25 (SNAP25.sub.206). This was not the case with other purportedly SNAP25.sub.197-selective antibodies, which displayed variable assay-dependent specificity. These results confirm that the BoNT/A-cleaved SNAP25 epitope is difficult to target specifically with an antibody without also recognizing the intact SNAP25 protein, which could lead to potential misinterpretation of results if the proper controls are not in place. Therefore, any given SNAP25.sub.197 antibody should be tested under multiple conditions and tissue types to ensure its fidelity in detecting the presence of BoNT/A-cleaved SNAP25.
(77) Site-specific antibodies are increasingly being used for both in vitro and in vivo analysis. These antibodies can detect sites of phosphorylation or sites of enzymatic cleavage and are invaluable tools for our understanding of the maturation, activity and degradation of proteins (Mort, J. S. and Buttle, D. J., 1999. The use of cleavage site specific antibodies to delineate protein processing and breakdown pathways. Mol. Pathol. 52, 11-18.; Mort, J. S., Flannery, C. R., Makkerh, J., Krupa, J. C., and Lee, E. R., 2003. Use of anti-neoepitope antibodies for the analysis of degradative events in cartilage and the molecular basis for neoepitope specificity. Biochem. Soc. Symp. 107-114.; Nagata, K., Izawa, I., and Inagaki, M., 2001. A decade of site- and phosphorylation state-specific antibodies: recent advances in studies of spatiotemporal protein phosphorylation. Genes Cells 6, 653-664.). Within the field of botulinum neurotoxins, cleavage site-specific antibodies can help detect the activity of minute quantities of BoNT light-chain that may otherwise be very difficult to perceive. To that end, the use of polyclonal antibodies may be of limited value because a mixed immunoglobulin population could be produced, not all of which would have the required specificity for the cleavage epitope (Mort, J. S. and Buttle, D. J., 1999. The use of cleavage site specific antibodies to delineate protein processing and breakdown pathways. Mol. Pathol. 52, 11-18.). Furthermore, the peptide antigen should be relatively short in order to reduce the possibility of generating antibodies that bind to a part of the sequence remote from the target epitope.
(78) The anti-SNAP25.sub.197 mAb presented in the current study was initially screened and selected for its superior performance in IHC assays. The rMAbs (Ab632 and Ab635) that were subsequently generated from this antibody demonstrated superb specificity to BoNT/A-cleaved SNAP25 in several different assays, including IHC. Furthermore, these rMAbs showed superior SNAP25.sub.197 specificity compared to other antibodies tested (Table 3). Accordingly, our rMAbs represent effective new tools for the detection of BoNT/A activity within cells and in clinical samples, and will be utilized in future studies to characterize the efficacy of BoNT/A in tissues of interest. The specific sequences for these antibodies are presented in Table 2 above.
(79) Overall, the antibodies tested in Western blot assays, immunohistochemistry on tissues and immunocytochemistry on cells showed various specificity to BoNT/A cleaved SNAP25 (SNAP25.sub.197) and uncleaved SNAP25 (SNAP25.sub.206). A summary of the results are shown in Table 3 below.
(80) TABLE-US-00003 TABLE 3 Summarized Results of Antibody Specificity to full length SNAP25 (206) or BoNT/A-cleaved SNAP25 (197). Rat DRG Antibody Specificity Western Blot Rat bladder Rat skin Human skin culture SMI-81R SNAP25.sub.206/197 206 + 197 206 + 197 206 + 197 n/t 206 + 197 MC-6050 SNAP25.sub.206/197 197 197 206 + 197 + b n/t n/t MC-6053 SNAP25.sub.197 197 197 206 + 197 + b 206 + 197 197 + b Ab632 SNAP25.sub.197 197 197 197 n/t 197 Ab635 SNAP25.sub.197 197 197 n/t 197 n/t RGT-1092 SNAP25.sub.197 197 206 + 197 206 + 197 n/t n/t n/t = not tested; b = background
(81) It is understood that the examples and embodiments described herein are for illustrative purposes only and that various modifications or changes in light thereof will be suggested to persons skilled in the art and are to be included within the spirit and purview of this application. All publications, patents and patent applications cited herein are hereby incorporated by reference in their entirety for all purposes to the same extent as if each individual publication, patent or patent application were specifically and individually indicated to be so incorporated by reference.