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Amyloid-beta peptide degradation in cell cultures by mycoplasma contaminants
Haitian Zhao1, Ute Dreses-Werringloer, Peter Davies
1Litwin-Zucker Research Center for the Study of Alzheimer Disease, The Feinstein Institute for Medical Research, North Shore-LIJ, Manhasset, NY, USA. hzhao@nshs.edu
Background:
Cell cultures have become an indispensable tool in Alzheimer's disease research for studying amyloid-beta (Abeta) metabolism. It is estimated that up to 35% of cell cultures in current use are infected with various mycoplasma species. In contrast with common bacterial and fungal infections, contaminations of cell cultures with mycoplasmas represent a challenging issue in terms of detectability and prevention. Mycoplasmas are the smallest and simplest self-replicating bacteria and the consequences of an infection for the host cells are variable, ranging from no apparent effect to induction of apoptosis.
Findings:
Here we present evidence that mycoplasmas from a cell culture contamination are able to efficiently and rapidly degrade extracellular Abeta. As a result, we observed no accumulation of Abeta in the conditioned medium of mycoplasma-positive cells stably transfected with the amyloid-beta precursor protein (APP). Importantly, eradication of the mycoplasma contaminant - identified as M. hyorhinis - by treatments with a quinolone-based antibiotic, restored extracellular Abeta accumulation in the APP-transfected cells.
Conclusion:
These data show that mycoplasmas degrade Abeta and thus may represent a significant source of variability when comparing extracellular Abeta levels in different cell lines. On the basis of these results, we recommend assessment of mycoplasma contaminations prior to extracellular Abeta level measurements in cultured cells.
Insights
Mycoplasma contamination in cell cultures degrades amyloid-beta (Abeta), leading to inaccurate Alzheimer's research. Removing mycoplasma restored Abeta accumulation, highlighting the need for contamination checks.
Area of Science:
- Cell biology
- Microbiology
- Neuroscience research
Background:
- Cell cultures are vital for Alzheimer's disease (AD) research, particularly for studying amyloid-beta (Abeta) metabolism.
- Mycoplasma contamination affects up to 35% of cell cultures, posing detection and prevention challenges.
- Mycoplasma infections can range from asymptomatic to inducing apoptosis in host cells.
Purpose of the Study:
- To investigate the impact of mycoplasma contamination on extracellular amyloid-beta (Abeta) metabolism in cell cultures.
- To determine if mycoplasma influences Abeta accumulation in cells engineered to produce it.
Main Methods:
- Utilized cell cultures stably transfected with the amyloid-beta precursor protein (APP).
- Monitored extracellular Abeta levels in mycoplasma-infected and subsequently treated cell cultures.
- Identified the mycoplasma contaminant as Mycoplasma hyorhinis.
Main Results:
- Mycoplasmas efficiently degraded extracellular Abeta, preventing its accumulation in APP-transfected cells.
- Eradication of M. hyorhinis using a quinolone-based antibiotic restored extracellular Abeta accumulation.
- Mycoplasma-positive cultures showed no extracellular Abeta buildup.
Conclusions:
- Mycoplasmas actively degrade Abeta, introducing significant variability in research findings.
- Recommend routine mycoplasma testing before measuring extracellular Abeta levels in cell cultures.
- Mycoplasma contamination can confound Alzheimer's disease research by altering Abeta levels.
