Idiopathic pulmonary fibrosis (IPF) is a progressive disease lacking effective therapy. Metformin, an antidiabetic medication, has shown promising therapeutic properties in preclinical fibrosis models; however, its precise cellular targets and associated mechanisms in fibrosis resolution remain incompletely defined. Most research on metformin's effects has focused on mesenchymal and inflammatory responses with limited attention to epithelial cells. In this study, we utilized Sftpc lineage-traced and Fgfr2b conditional knockout mice, along with BMP2/PPARγ and AMPK inhibitors, to explore metformin's impact on alveolar epithelial cells in a bleomycin-induced pulmonary fibrosis model and cell culture. We found that metformin increased the proliferation and differentiation of alveolar type 2 (AT2) cells, particularly the recently identified injury-activated alveolar progenitors (IAAPs)-a subpopulation characterized by low SFTPC expression but enriched for PD-L1. Single-cell RNA sequencing revealed a reduction in apoptosis among mature AT2 cells. Interestingly, metformin's therapeutic effects were not significantly affected by BMP2 or PPARγ inhibition, which blocked the lipogenic differentiation of myofibroblasts. However, Fgfr2b deletion in Sftpc lineage cells significantly impaired metformin's ability to promote fibrosis resolution, a process linked to AMPK signaling. In conclusion, metformin alleviates fibrosis by directly activating AT2 cells, especially the IAAPs, through a mechanism that involves AMPK and FGFR2b signaling, but is largely independent of BMP2/PPARγ pathways.

Objective To establish different sleep deprivation models in zebrafish to provide reproducible and practical modeling reference solutions for basic research on insomnia.Methods Zebrafish insomnia models were induced by two interventions:continuous light(150 Lux)and light plus caffeine.The zebrafish were divided randomly into control,light,caffeine(100 μmol/L),and combined light and caffeine groups.The locomotor ability of zebrafish in each group was observed using open field and circadian rhythm behavioral experiments.The expression and secretion of related sleep genes and the neurotransmitter 5-hydroxytryptamine(serotonin;5-HT)were detected using quantitative polymerase chain reaction and enzyme-linked immunosorbent assay,respectively.Results Sleep time,resting time(during the day),and sleep rounds were significantly reduced(P＜0.01 or P=0.01)and the distance traveled was significantly increased in the light group compared with the control group(P＜0.01).The resting time(daytime)and sleep rounds were increased in the combined and caffeine groups(P＜0.01)compared with the control group.There was no significant difference in the activity distance between the combined and caffeine groups(P＞0.05).The percentages of swimming distance and swimming time in the central area were decreased in the light group compared with the control group(P＜0.05),and were both decreased in the caffeine group compared with the light group(P＜0.01).HT receptor 1Aa(HTR1aa)mRNA expression at 6:00.and 12:00 was up-regulated in the light group compared with the control group(P＜0.05),but there was no significant difference in HTR1ab mRNA levels between the light group and the combined group(P＞0.05).5-HT secretion was decreased in the light group at 6:00(P＜0.01)and at 12:00 compared with the control group.5-HT levels were reduced in both the light and combined groups(P＜0.01),and secretion levels in the light and combined groups were still lower than in the control group at 18:00.(P＜0.01).Conclusions Light alone is the best intervention for modeling long-lasting insomnia in zebrafish larvae.The responsible mechanisms may be related to the HTR1aa gene as well as biological factors such as 5-HT.

Objective To establish different sleep deprivation models in zebrafish to provide reproducible and practical modeling reference solutions for basic research on insomnia.Methods Zebrafish insomnia models were induced by two interventions:continuous light(150 Lux)and light plus caffeine.The zebrafish were divided randomly into control,light,caffeine(100 μmol/L),and combined light and caffeine groups.The locomotor ability of zebrafish in each group was observed using open field and circadian rhythm behavioral experiments.The expression and secretion of related sleep genes and the neurotransmitter 5-hydroxytryptamine(serotonin;5-HT)were detected using quantitative polymerase chain reaction and enzyme-linked immunosorbent assay,respectively.Results Sleep time,resting time(during the day),and sleep rounds were significantly reduced(P＜0.01 or P=0.01)and the distance traveled was significantly increased in the light group compared with the control group(P＜0.01).The resting time(daytime)and sleep rounds were increased in the combined and caffeine groups(P＜0.01)compared with the control group.There was no significant difference in the activity distance between the combined and caffeine groups(P＞0.05).The percentages of swimming distance and swimming time in the central area were decreased in the light group compared with the control group(P＜0.05),and were both decreased in the caffeine group compared with the light group(P＜0.01).HT receptor 1Aa(HTR1aa)mRNA expression at 6:00.and 12:00 was up-regulated in the light group compared with the control group(P＜0.05),but there was no significant difference in HTR1ab mRNA levels between the light group and the combined group(P＞0.05).5-HT secretion was decreased in the light group at 6:00(P＜0.01)and at 12:00 compared with the control group.5-HT levels were reduced in both the light and combined groups(P＜0.01),and secretion levels in the light and combined groups were still lower than in the control group at 18:00.(P＜0.01).Conclusions Light alone is the best intervention for modeling long-lasting insomnia in zebrafish larvae.The responsible mechanisms may be related to the HTR1aa gene as well as biological factors such as 5-HT.