Fibrinogen regulates microglial function through the JAK2/STAT3 signaling pathway

Neuroinflammation, a defining feature of numerous neurological disorders, arises predominantly from activating immune cells such as microglia, which play a critical role in maintaining homeostasis within the central nervous system. Microglial activation and polarization exhibit a dual nature, mediating both neuroprotective and neurotoxic effects. Fibrinogen, as a potent pro-inflammatory mediator, interacts with microglia and is implicated in the progression of various neurological conditions. This study investigates the effects of fibrinogen and the exogenous STAT3 inhibitor cryptotanshinone on primary microglial function.

Primary microglial cells were isolated from neonatal C57BL/6 mice and subsequently treated with fibrinogen and the STAT3 inhibitor cryptotanshinone. Inflammatory marker expression was quantified by quantitative polymerase chain reaction, while protein levels of JAK2 and STAT3 were determined using immunofluorescence and Western blot analysis.

Fibrinogen exposure upregulated STAT3 and JAK2 phosphorylation in primary microglial cells. Cryptotanshinone treatment effectively attenuated STAT3 phosphorylation while concurrently downregulating JAK2 activation. Furthermore, fibrinogen significantly enhanced the release of pro-inflammatory cytokines, such as IL-6 and IL-1β, while the transcription levels of TGF-β remained unchanged.

This study demonstrates that fibrinogen stimulates the production of pro-inflammatory cytokines in primary microglial cells by activating the JAK2/STAT3 signaling pathway. These findings provide mechanistic insights into fibrinogen-induced neuroinflammation and suggest potential therapeutic targets for neurological diseases.