Methods are provided for the prognosis, diagnosis and treatment of various pathological states, including cancer, chemotherapy resistance and dementia associated with Alzheimer's disease. The methods provided herein are based on the discovery that various proteins with a high level of sialylation are shown herein to be associated with disease states, such as, cancer, chemotherapy resistance and dementia associated with Alzheimer's disease. Such methods provide a lysosomal exocytosis activity profile comprising one or more values representing lysosomal exocytosis activity. Also provided herein, is the discovery that low lysosomal sialidase activity is associated with various pathological states. Thus, the methods also provide a lysosomal sialidase activity profile, comprising one or more values representing lysosomal sialidase activity. A lysosomal sialidase activity profile is one example of a lysosomal exocytosis activity profile.

The invention relates a method for producing a stable recombinant protein, comprising growing a non-naturally occurring host cell in a culture medium to produce a recombinant protein, and making a composition comprising the recombinant protein and a polysorbate. The production of endogenous lipoprotein lipase by the host cell is reduced. The endogenous lipoprotein lipase is present in the composition in a small amount, and is capable of degrading the polysorbate. The invention also relates to the relevant host cells and compositions, and preparation thereof.

The invention relates a method for producing a stable recombinant protein, comprising growing a non-naturally occurring host cell in a culture medium to produce a recombinant protein, and making a composition comprising the recombinant protein and a polysorbate. The production of endogenous lipoprotein lipase by the host cell is reduced. The endogenous lipoprotein lipase is present in the composition in a small amount, and is capable of degrading the polysorbate. The invention also relates to the relevant host cells and compositions, and preparation thereof.

The invention relates a method for producing a stable recombinant protein, comprising growing a non-naturally occurring host cell in a culture medium to produce a recombinant protein, and making a composition comprising the recombinant protein and a polysorbate. The production of endogenous lipoprotein lipase by the host cell is reduced. The endogenous lipoprotein lipase is present in the composition in a small amount, and is capable of degrading the polysorbate. The invention also relates to the relevant host cells and compositions, and preparation thereof.

Methods are provided for the prognosis, diagnosis and treatment of various pathological states, including cancer, chemotherapy resistance and dementia associated with Alzheimer's disease. The methods provided herein are based on the discovery that various proteins with a high level of sialylation are shown herein to be associated with disease states, such as, cancer, chemotherapy resistance and dementia associated with Alzheimer's disease. Such methods provide a lysosomal exocytosis activity profile comprising one or more values representing lysosomal exocytosis activity. Also provided herein, is the discovery that low lysosomal sialidase activity is associated with various pathological states. Thus, the methods also provide a lysosomal sialidase activity profile, comprising one or more values representing lysosomal sialidase activity. A lysosomal sialidase activity profile is one example of a lysosomal exocytosis activity profile.

In some aspects the disclosure provides compositions and methods for promoting expression of functional NEU1 protein in a subject. In other aspects, the disclosure provides compositions and methods for treating sialidosis, galactosialidosis, and/or Alzheimer's Disease in a subject having or suspected of having sialidosis, galactosialidosis, and/or Alzheimer's Disease.