Acute ischemic stroke is a disastrous disease characterized by damaging blood flow in the brain, leading to acute brain injury. Acute brain ischemia elicits severe inflammation, thus in turn, aggravates neural injury. Interferon-Induced Protein 35 (IFP35), is a 35 kDa protein, a novel type of DAMP that trigger inflammatory responses, exacerbating acute and chronic inflammatory disease. This study aimed to investigate the potential neuroinflammation role of IFP35 in acute ischemic stroke in a mouse model of MCAO. C57BL/6 male mice were subjected to middle cerebral artery occlusion (MCAO) to establish an animal model of acute ischemic stroke. Leveraging serum from stroke patients, serum and brain tissue after MCAO mice, IFP35 was released. Immunofluorescence assay was used to investigated the cell sources of IFP35 expression after MCAO. The impact of IFP35 on neuroinflammation and neural injury was assessed by siRNA-mediated cerebral IFP35 knockdown. Behavioral tests, and brain tissues were harvested for histological analysis and biochemical assays. TUNEL assays were used to evaluate neuronal damage. TTC staining was performed to assess infarction volumes. Additionally, using western blotting and immunofluorescence assays, we further assessed the contribution of TLR4/NF-κB/NLRP3 signaling in MCAO mice and BV2 cells. IFP35 was accumulated in peripheral blood of cerebral ischaemia patients, ischemia mice serum, as well as peri-infarct regions in focal cerebral ischemia mice. Although endothelial cells, microglia, and astrocytes are capable of expressing IFP35, cerebral neural cells seem to express and release more IFP35 compare to other cell types. Knockdown of IFP35 alleviated the production of neuroinflammatory cytokines, decreased neuronal death, and minimized infarct volumes, ultimately leading to improved neurological outcomes. Importantly, IFP35 triggered the activation of NF-κΒ and NLRP3 signaling, exacerbating neuroinflammation and brain injury by binding its receptor TLR4. This study revealed IFP35 as a novel DAMP released during cerebral ischemia that promotes neuroinflammation and injury, expanding the current understanding of inflammatory networks following stroke.

Background: Acute exacerbation of idiopathic pulmonary fibrosis (AE-IPF) is a severe condition with high morbidity and mortality, characterized by increased inflammation, oxidative stress, apoptosis and epithelial barrier damage. However, there are a few drugs available for the treatment of AE-IPF. Although sivelestat sodium (SIV) has been shown to be an effective agent for acute lung injury (ALI) and acute respiratory distress syndrome (ARDS) through various mechanisms, including reduction of inflammation and oxidative stress, the therapeutic potential of SIV in managing AE-IPF remains limited. This study aims to investigate the protective potential of SIV in AE-IPF mouse model through multiple mechanisms. Methods: Male C57BL/6J mice were used to establish the acute exacerbation of pulmonary fibrosis (AE-PF) mouse model through intratracheal instillation of bleomycin (BLM) followed by lipopolysaccharide (LPS). SIV was administered intraperitoneally at a dose of 100 mg/kg daily for 3 or 7 days post-LPS challenge. The therapeutic efficacy was assessed through micro-computed tomographic (Micro-CT), histopathological analysis, immunohistochemistry, immunofluorescence, enzyme-linked immunosorbent assay (ELISA) and Western blotting. Results: SIV significantly alleviated AE-PF symptoms in mice, as demonstrated by reductions in inflammation, structural damage, and collagen formation. Additionally, SIV reduced neutrophil elastase (NE) activity, highlighting its pharmacological effectiveness. Importantly, SIV reduced oxidative stress in AE-PF mice by activating the nuclear factor erythroid 2-related factor 2 (Nrf2)/heme oxygenase-1 (HO-1) signaling pathway, leading to increased superoxide dismutase (SOD) activity and decreased reactive oxygen species (ROS) levels. Furthermore, SIV significantly reduced lung inflammation, as evidenced by decreased interleukin-6 (IL-6) and interleukin-1 beta (IL-1β) levels in bronchoalveolar lavage fluid (BALF), possibly mediated by the inhibition of the Toll-like receptor 4 (TLR4)/nuclear factor kappa B (NF-κB) signaling. Moreover, SIV exhibited anti-apoptotic properties by modulating the B-cell lymphoma 2 (Bcl-2)/BCL2-associated X protein (Bax)/cleaved caspase-3 pathway. Meanwhile, SIV improved epithelial barrier integrity, as shown by enhanced expression of tight junction proteins and adherens junction protein. Conclusions: SIV demonstrates significant protective effects in AE-PF mice by mitigating inflammation, oxidative stress, apoptosis, and preserving epithelial barrier integrity. These findings suggest that SIV is a promising therapeutic candidate for the treatment of AE-IPF.