MAZ51

Pulmonary fibrosis (PF) is a serious, chronic, and progressive disease with increased collagen deposition and the collapse of lung structures. Currently, the antifibrotic drugs for PF treatment, nintedanib and pirfenidone, have been proven to reduce the decline of pulmonary function in PF, but both have side effects, and to date, there is no significantly effective treatment to halt the progression of PF. The aim of this study was to investigate the molecular mechanism of pregranuloprotein (PGRN) in pulmonary fibrosis through in vitro and in vivo experiments.

PF models was induced in animals using bleomycin (BLM) and treated MRC-5 cells with TGF-β1. The mRNA expression of PGRN in fasting peripheral blood samples was measured via RT-qPCR and ELSA. PGRN siRNAs were synthesized and transfected into MRC-5 cells. MAZ51, an activator of the Akt/GSK3β pathway, was applied in recovery experiment. The proliferation and apoptosis of MRC-5 cells were determined using the CCK8 kit, MTT kit, and Muse® Cell Analyzer. H&E and Masson staining were applied to evaluate the inflammatory and fibrosis in mouse lung tissue. Levels of PGRN, inflammatory factors (IL-6 and IL-1β), fibrosis markers (α-SMA, COL-I and COL-III), and Akt/GSK3β pathway-related proteins (AKT, GSK-3β and β-catenin) were determined in tissues or cells by ELISA, RT-qPCR, western blot, or Immunofluorescence.

PGRN mRNA expression was elevated in the plasma of PF patients. In TGF-β1 induced MRC-5 cells, PGRN knockdown reduced the levels of IL-6, IL-1β, α-SMA, COL-I and COL-III, and suppressed the phosphorylation of AKT and GSK-β. Treatment with MAZ51 partially reversed the effect of PGRN knockdown on TGF-β1-induced PF. Moreover, PGRN knockdown mitigated BLM-induced alveolar destruction and wall thickening, inflammatory cell infiltration, and collagen deposition in mice. It also reduced the expression of α-SMA, TGF-β1, COL-I, COL-III, β-catenin, and the phosphorylation of AKT and GSK-3β in BLM-treated mice.

PGRN knockdown alleviates PF in vitro and in vivo by modulating the Akt/GSK3β signaling pathway, proposing that PGRN could serve as a potential therapy or adjuvant therapy for lung fibrosis.

Background: The role of meningeal lymphatic vessels (mLVs) in neurodegenerative diseases has been increasingly recognized. However, their involvement in lipopolysaccharide (LPS)‐induced neuroinflammation and associated depression‐like behaviors remains poorly understood. Given that impaired clearance of neurotoxic substances can prolong central nervous system (CNS) inflammation, investigating the function of mLVs in this context may offer new insights into the mechanisms underlying acute neuroinflammation and provide potential therapeutic targets.Methods: First, the impact of intracerebral injection of LPS on the function of mLVs was investigated. Subsequently, the MAZ51, a VEGFR3 antagonist, was administered via intraperitoneal injection for 1 month to inhibit the development and function of mLVs, and to evaluate whether the impaired drainage function of mLVs exacerbates inflammation in the CNS caused by LPS. Finally, VEGFR3 ligand VEGF‐C was administered preemptively to assess whether enhancing the function of mLVs mitigates LPS‐induced inflammation and depression‐like behavior.Results: The mice with intracerebral injection of LPS demonstrated a substantial reduction in the transport of OVA‐647 to the deep cervical lymph nodes (dCLNs) and in the coverage of Lyve‐1 within the mLVs, suggesting LPS impaired the development and drainage of mLVs. Pretreatment with MAZ51 further damages the drainage function of mLVs and intensify LPS‐induced activation of microglia and astrocytes. Additionally, MAZ51 led to a decrease in the protein levels of PSD95 as well in the hippocampus, which was paralleled by an elevation in TNF‐α and IL‐6 levels, and aggravated depression‐like behavior. On the contrary, pretreatment with VEGFR3 ligand VEGF‐C attenuated LPS‐induced neuroinflammation, as indicated by a decrease in TNF‐α, IL‐6, Iba1, and GFAP expression in the hippocampus. VEGF‐C treatment also significantly increased the level of PSD95 and improved depression‐like behavior.Conclusion: The drainage function of mLVs is pivotal in inflammation of the CNS. Enhancing meningeal lymphatic improves the development of neuroinflammation and inflammation‐induced depression‐like behaviors. VEGFR3 could serve as a potential therapeutic target for CNS inflammation.