In this study the researcher studied about Cromolyn which is belong to a class of medications called mast cell stabilizers,and is approved for treatment of asthma and for other allergic indications. Cromolyn, in a new redesigned dry powder formulation, is being tested in a pivotal clinical trial in combination with low dose ibuprofen to treat early Alzheimer’s Disease (AD) subjects. To better understand the mechanistic effect cromolyn has in slowing down or halting the neuroinflammatory response associated with AD progression, we tested the effect of cromolyn to dampen the inflammatory response in the human HMC3 microglia cell line.
Fig: Inflammatory activation of HMC3 human microglia cell line by TNF-α and IFN-γ. (a) Flow cytometric analyses demonstrate the increased protein expression of inflammatory microglia biomarkers (IBA-1, CD40, MHC-II, CD68, CD14, and CD86) in the HMC3 cells treated with IFN-γ (0.3 µg/mL, 24 h) (red), but no alteration in the expression of the anti-inflammatory microglia biomarkers CD163 and CD206. TNF-α (0.3 µg/mL, 24 h) (blue) also increases the expression of inflammatory microglia biomarkers (IBA-1, CD40, and CD14). (b) q-PCR analysis revealed increased CD11b and TMEM119 expression by HMC3 microglia after addition of 0.3 µg/mL TNF-α or 0.3 µg/mL IFN-γ for 24 h. Fold change is normalized to untreated control. GAPDH was used as an internal control to normalize mRNA level of the gene of measurement in each sample (n = 5 independent experiments). Quantitative analysis (c) and representative fluorescence micrographs (d, displayed at ×10 and ×4 magnification) of the cell viability assay show that both TNF-α and IFN-γ induce cell death in a concentration-dependent manner (0, 0.01, 0.03, 0.1, 0.3 µg/mL) for 24 h in the HMC3 human microglial cells. Fluorescent green features are AO stains of live cells and fluorescent red features are PI stains of dying cells. *p < 0.1, **p < 0.01, ***p < 0.001, and NS (no significant difference).
The direct effect of cromolyn on HMC3 microglia is on cytokines and chemokines production following their activation by the inflammatory cytokine TNF-α. Cromolyn and a new fluorinated analog dramatically reduced the secretion of a wide spectrum of inflammatory mediators, which included cytokines such as IL-1β, IL-6, IL-8 and IFN-γ, and chemokines such as CXCL10, CCL2, CCL3 and CCL4. These results bolster our understanding of how our cromolyn platform modulates toxic microglia behavior as a dynamic future treatment option for neurodegenerative disorders.
Wang, YJ., Monteagudo, A., Downey, M.A. et al. Cromolyn inhibits the secretion of inflammatory cytokines by human microglia (HMC3). Sci Rep 11, 8054 (2021). https://doi.org/10.1038/s41598-021-85702-8