Metformin alleviates LTA-induced inflammatory response through PPARγ/MAPK/NF-κB signaling pathway in bovine mammary epithelial cells

[摘要] Mastitis is a common inflammatory cow mammary infection; that causes significant economic loss in dairyindustry. Given the interesting connection between metformin’s anti-inflammatory function and mastitis modelinduced by LTA in pbMECs, our objective was to prove that metformin was beneficial in suppressingproinflammatory response induced by LTA through modulation of mitogen-activated protein kinase (MAPK) andnuclear factor kappa B (NF-κB) signaling pathways and activation of peroxisome proliferator-activated receptor-γ(PPARγ) in pbMECs. The proliferation of cells and mRNA expression were measured using EdU assay andquantitative reverse transcriptase-polymerase chain reaction (qRT-PCR). Immunoblotting and immunofluorescenceanalysis were conducted to evaluate the expression of target proteins in inflammatory and anti-inflammatoryresponses to metformin and LTA. Finally, pbMECs were allowed to treat with the PPAR antagonist GW9662, andinflammatory markers were detected in the cells. Our results showed that LTA concentration at 100 µg/mLsignificantly stimulated the MAPK14, IL-6 and IL-1β mRNA expressions compared to the control cells (P < 0.05) indose-dependent tests for LTA. Metformin suppressed the phosphorylation expressions of MAPK (ERK1/2, p38, andJNK) in LTA-stimulated pbMECs. Metformin also reduced the protein expression of NF-κB, interleukin-8 (IL-8),interleukin-1β (IL-1β) and interleukin-6 (IL-6) in pbMECs pretreated with LTA. Metformin administration activatedPPARγ phosphorylation by up-regulating the expression of PPARγ in LTA-stimulated pbMECs. Treatment withGW9662 resulted in increased IL-6 expression, which was reversed by metformin. These findings collectivelyindicated that metformin act to attenuate LTA-stimulated inflammatory response in pbMECs by suppressing MAPKand NF-κB activation via a mechanism partially dependent on PPARγ activation. These results suggested thatmetformin could function as an anti-inflammatory drug.

[学科分类] 仪器

[关键词] Metformin;LTA;Primary bovine mammary epithelial cell;Anti-inflammatory effect;PPARγ;Nuclear factor-κB;Mitogen-activated protein kinase