Phenobarbital (PB) promotes liver tumorigenesis in rodents, in part through activation of the constitutive androstane receptor (CAR) and the consequent changes in hepatic gene expression and increases in hepatocyte proliferation. A typical effect of CAR activation by PB is a marked induction of Cyp2b10 expression in the liver; the latter has been suspected to be vital for PB-induced hepatocellular proliferation. This hypothesis was tested here by using a Cyp2a(4/5)bgs-null (null) mouse model in which all Cyp2b genes are deleted. Adult male and female wild-type (WT) and null mice were treated intraperitoneally with PB at 50 mg/kg once daily for 5 successive days and tested on day 6. The liver-to-body weight ratio, an indicator of liver hypertrophy, was increased by 47% in male WT mice, but by only 22% in male Cyp2a(4/5)bgs-null mice, by the PB treatment. The fractions of bromodeoxyuridine-positive hepatocyte nuclei, assessed as a measure of the rate of hepatocyte proliferation, were also significantly lower in PB-treated male null mice compared with PB-treated male WT mice. However, whereas few proliferating hepatocytes were detected in saline-treated mice, many proliferating hepatocytes were still detected in PB-treated male null mice. In contrast, female WT mice were much less sensitive than male WT mice to PB-induced hepatocyte proliferation, and PB-treated female WT and PB-treated female null mice did not show significant difference in rates of hepatocyte proliferation. These results indicate that CYP2B induction plays a significant, but partial, role in PB-induced hepatocyte proliferation in male mice.

Statins, which are 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase competitive inhibitors, not only lower blood cholesterol, but also exert pleiotropic and beneficial effects in various diseases. However, the effects of statins on acute lung injury (ALI) induced by hyperbaric oxygen (HBO) have not been investigated. The present study is the first to investigate the effects of simvastatin in ALI induced by HBO in 8 - 9 week old C57BL/6 mice exposed to 0.23 MPa (= 2.3 atmosphere absolute (ATA)) hyperoxia ( 95% O2) for 6 hrs. Mice were either given simvastatin (20 mg/kg/day) in saline or a saline vehicle for 3 days before oxygen exposure. Lung tissue, serum, and bronchoalveolar lavage fluid (BALF) were collected for analysis of pro-apoptotic proteins, low-density lipoprotein cholesterol (LDL-C) levels, and lung inflammation. Simvastatin treatment significantly reduced lung permeability, serum LDL-C levels, tissue apoptosis, and inflammation. However, simvastatin treatment had no effect on antioxidant enzyme activity, nicotinamide adenine dinucleotide phosphate oxidase 4 (NADPH4) expression, and Akt phosphorylation levels. Furthermore, we investigated the role of endothelial nitric oxide synthase (eNOS) in simvastatin protection through inhibiting eNOS activity with NG-Nitro-L-arginine methyl ester (L-NAME; 20 mg/kg). Results showed that the beneficial effects of simvastatin on ALI induced by HBO (anti-inflammatory, anti-apoptotic, lipid-lowering, and reduction in lung permeability) were reversed. These results showed that simvastatin curbs HBO-induced lung edema, permeability, inflammation, and apoptosis via upregulating eNOS expression, and that simvastatin could be an effective therapy to treat prolonged HBO exposure.

In murine allogeneic transplantation models, ICOS gene-transduced bone marrow-derived mesenchymal stem cells (MSCs^ICOS-EGFP) were evaluated for their effects on GvHD severity and long-term survival. Lethally irradiated BALB/c or first filial generation of BALB/c and C57BL/6 (CB6F1) mice were transplanted with bone marrow cells and splenocytes from C57BL/6 mice to establish acute GvHD models. Recipient mice were injected with MSCs^ICOS-EGFP, MSCs, MSCs^EGFP, ICOS-Ig fusion protein, MSCs + ICOS-Ig, or PBS (control group). Long-term survival, GvHD rates and severity, CD4⁺T-cell apoptosis and proliferation, and Th1/Th2/ Th17 effecter cell polarization were evaluated. In the C57BL/6 → CB6F1 HSCT model, the long-term survival in the MSC^ICOS-EGFPgroup was higher than that in the GvHD group (74.29 ± 7.39% vs. 0, p < 0.01), and this survival rate was also higher than that in the MSC, ICOS-Ig, or MSC + ICOS-Ig groups (42.86 ± 8.36%, p = 0.004; 48.57 ± 8.45%, p = 0.03; or 50.43 ± 8.45% p = 0.04, respectively). The survival advantages of MSC^ICOS-EGFP-treated group were confirmed in the C57BL/6 → BALB/c HSCT model. In both HSCT models, the low mortality in the MSC^ICOS-EGFPgroup was associated with lower incidence and severity of acute GvHD. Treatment with MSCs^ICOS-EGFPinduced more CD4⁺T-cell apoptosis compared with that in the GvHD group. The effect on CD4⁺T cells was shown as early as day 2 and maintained until day 14 ( p < 0.05 on days 2, 3, 7, and 14). Furthermore, we demonstrated that MSCs^ICOS-EGFPwere able to suppress Th1 and Th17 polarization and promote Th2 polarization on both protein expression and gene transcription levels. Higher serum levels of IL-4, IL-10, and lower levels of IFN-γ, IL-2, IL-12, and IL-17A were detected in the MSC^ICOS-EGFPgroup. The MSCs^ICOS-EGFPcould also induce GATA-3, STAT6 expression and inhibit T-bet, STAT4, ROR-gt expression. Our results showed that injection of MSCs^ICOS-EGFPis a promising strategy for acute GvHD prevention and treatment. It provides synergistic benefits of MSC immune modulation and ICOS-B7h pathway blockage.

Oxygen is an essential substance for the maintenance of human life. It is also widely used in clinical and diving medicine. Although oxygen is crucial for survival, too much oxygen can be harmful. Excessive oxygen inhalation in a short period of time can lead to injury, and the lung is one of the main target organs. Acute lung injury (ALI) induced by hyperbaric oxygen (HBO) is notably more severe than that caused by normobaric oxygen, yet systematic research on such injury and its regression is scarce. In this study, two independent experiments were designed. In the first experiment, mice were exposed to 2 atmospheres absolute (ATA), ≥95% oxygen for 2, 4, 6, and 8 h. Changes in lung histopathology, inflammation and expression of chemokines, alveolar-capillary barrier, and 8-OHdG were detected before and after the exposure. In the second experiment, these parameters were measured at 0 h, 12 h, and 24 h following 6 h of exposure to 2 ATA of ≥95% oxygen. Research indicates that ALI induced by HBO is characterized histologically by alveolar expansion, atelectasis, inflammatory cell infiltration, and hemorrhage. At 2 ATA, significant changes in the alveolar-capillary barrier were observed after more than 95% oxygen exposure for 4 h, as evidenced by increased Evans blue (EB) extravasation (p = 0.0200). After 6 h of HBO exposure, lung tissue pathology scores, 8-OHdG levels, and inflammatory and chemotactic factors (such as Il6, CCL2, CCL3, CXCL5, and CXCL10), intercellular adhesion molecule 1 (ICAM1), and vascular cell adhesion molecule 1 (VCAM1) were significantly elevated. Compared to lung injury caused by normobaric oxygen, the onset time of injury was significantly shortened. Additionally, it was observed that these markers continued to increase after leaving the HBO environment, peaking at 12 h and starting to recover at 24 h, indicating that the peak of inflammatory lung injury occurs within 12 h post-exposure, with recovery beginning at 24 h. This contradicts the common belief that lung injury is alleviated upon removal from a high-oxygen environment. However, EB levels, which reflect damage to the alveolar-capillary barrier, and VE-Cadherin (VE-Cad), tight junction protein 1 (ZO-1), ICAM1, and VCAM1 remained significantly altered 24 h after leaving the HBO environment. This suggests that the alveolar-capillary barrier is the most sensitive and slowest recovering part of the lung injury induced by HBO. These findings can provide insights into the pathogenesis and progression of lung injury caused by HBO and offer references for identifying corresponding intervention targets.

Decompression illness (DCI) is a multi-system pathological syndrome triggered by rapid environmental pressure reduction, leading to multi-organ damage, including pulmonary injury. Through integrated transcriptomic and proteomic analyses, this study reveals that P-selectin activates neutrophil NADPH oxidase 2 (NOX2) and peptidylarginine deiminase 4 (PAD4) via its receptor PSGL-1, forming a cascade signaling network that regulates neutrophil extravasation and extracellular trap (NETosis) formation, playing a pivotal role in DCI-induced lung injury. By pioneering a human lung organoid-on-a-chip (OOC)-based bionic DCI in vitro model, we dynamically simulated the pathological progression of DCI and systematically validated, for the first time in a human-derived experimental system, the central role of endothelial barrier injury-mediated neutrophil transendothelial extravasation and NETosis in DCI-related pulmonary damage. Furthermore, in vivo pharmacological interventions confirmed the therapeutic potential of targeting P-selectin/PSGL-1 interactions or inhibiting the NOX2/PAD4 signaling axis in mitigating DCI lung injury. These findings not only provide an innovative theoretical framework for elucidating the molecular pathology of DCI-induced pulmonary injury, but also establish a translational foundation for developing precision therapies based on neutrophil extravasation regulation and NETosis balance strategies.

Although hyperbaric oxygen (HBO) therapy is an established medical intervention effective for various conditions, prolonged or excessive exposure can induce acute lung injury (ALI), the mechanisms of which remain poorly understood. In this study, we show that expression of CYP1A1 and CYP1A2, two isoforms of the cytochrome P450 (CYP) 1A subfamily, is significantly upregulated in mouse lung tissues and primary mouse lung microvascular endothelial cells (MLVECs) following HBO exposure. Global double knockout of CYP1A1 and CYP1A2 (referred to as CYP1A-deficient mice) exacerbated pulmonary endothelial dysfunction and ALI in response to HBO, whereas CYP1A inducer β-naphthoflavone (BNF) ameliorated these pathological changes. Mechanistically, activation of the heat shock factor 1 (HSF1) signaling pathway mediates the protective effects of CYP1A induction against HBO-induced mitochondrial oxidative stress, mitochondrial dysfunction, and endothelial cell apoptosis. Critically, HSF1 inhibition abolished BNF-induced HSF1 recruitment to the succinate dehydrogenase subunit C (SDHC) promoter, thereby suppressing SDHC transcription in HBO-exposed pulmonary endothelial cells. Furthermore, the HSF1-mediated protection is dependent on succinate dehydrogenase C (SDHC), thereby linking CYP1A upregulation to the preservation of pulmonary endothelial barrier integrity. CYP1A deficiency leads to reduced SDHC expression, resulting in enhanced mitochondrial oxidative stress, impaired mitochondrial function, and increased apoptosis in lung tissues under HBO conditions. Our findings reveal a previously unrecognized protective mechanism in which upregulation of CYP1A serves as an adaptive response against HBO-induced pulmonary endothelial injury by attenuating mitochondrial oxidative stress and restoring mitochondrial homeostasis via the HSF1/SDHC signaling axis.