Fig 2: BMP10 inhibited LPS-induced in vitro human pulmonary endothelial apoptosis. A TUNEL staining showed that BMP10 treatment effectively suppressed apoptosis of HPMECs induced by 24 h of LPS stimulation; scale bars, 100 µm. B IF staining of HPMECs demonstrated that BMP10 treatment inhibited the downregulation of MCL-1 expression caused by 24 h of LPS incubation; scale bars, 100 µm; Green, MCL-1; Blue, DAPI. C Western blot analysis of HPMECs showed an elevation in cleaved caspase 3 protein levels after 6 h of LPS stimulation, and treatment with BMP10 effectively inhibited caspase 3 cleavage (*p < 0.05, n = 4 mouse per group); Data were presented as mean ± standard error of mean, and groups were analyzed by two-tailed non-parametric test (Mann–Whitney U test). TUNEL terminal deoxynucleotidyl transferase dUTP nick end labeling, BMP10 bone morphogenetic protein 10, LPS lipopolysaccharide, IF immunofluorescence, HPMEC human pulmonary microvascular endovascular cell, MCL-1 myeloid cell leukemia sequence 1

Fig 3: BMP10 alleviated LPS-induced endothelial dysfunction both in vitro and in vivo through the canonical signaling pathway. HPMECs were cultured with 100 ng/ml of BMP10 for 24 h, followed by exposure to 10 μg/ml of LPS for a predetermined duration based on the study design. A Western blot analysis showed that 24 h of LPS stimulation significantly increased the protein expression levels of ICAM-1 and VCAM-1 in HPMECs. However, these changes were reversed by BMP10 treatment (*p < 0.05, n = 4 per group); Data are presented as mean ± standard error of the mean, and group comparisons were analyzed using a two-tailed non-parametric test (Mann–Whitney U test). B IF staining of HPMECs demonstrated that BMP10 prevented the LPS-induced reduction in the expression of VE-cadherin and pSmad1/5/8, a marker of the BMP10-activated canonical signaling pathway, following 2 h of LPS stimulation; scale bars, 100 µm; Green, VE-cadherin; Red, pSmad1/5/8; Blue, DAPI. C Western blot analysis of lung homogenates revealed that 24 h of LPS stimulation significantly increased pSmad1/5/8 protein levels, but BMP10 treatment reversed these effects (*p < 0.05, n = 4 per group); Data are presented as mean ± standard error of the mean, and group comparisons were analyzed using a two-tailed non-parametric test (Mann–Whitney U test). D Western blot analysis of HPMECs showed that 6 h of LPS stimulation significantly increased pSmad1/5/8 protein expression, which was similarly reversed by BMP10 pretreatment (*p < 0.05, n = 4 per group); Data are presented as mean ± standard error of the mean, and groups were analyzed using a two-tailed non-parametric test (Mann–Whitney U test). HPMEC human pulmonary microvascular endothelial cell, LPS lipopolysaccharide, BMP10 bone morphogenetic protein 10, ICAM-1 intercellular adhesion molecule 1, VCAM-1 vascular cell adhesion protein 1, VE-cadherin vascular endothelial cadherin, pSmad1/5/8 phosphorylated small mother against decapentaplegic 1/5/8

Fig 4: BMP10 is a biomarker for predicting mortality in ICU patients diagnosed with pneumonia-related acute respiratory failure requiring invasive mechanical ventilation. A Plasma levels of BMP10 on the day of recruitment and B on day 2 after recruitment were significantly higher in patients who died in the hospital than in those who survived; Data were presented as medians with interquartile ranges (IQR) and groups were analyzed by Mann–Whitney U test; BMP10 bone morphogenetic protein 10

Fig 5: BMP10 mitigated LPS-induced increasing murine pulmonary endothelial permeability. A TEM of murine lung sections revealed that BMP10 treatment improved the LPS-induced disruption of pulmonary endothelial integrity and continuity, as well as reduced interstitial edema; Scale bar, 5 μm. B Quantitative IHC analysis of pulmonary VE-cadherin expression demonstrated that BMP10 treatment significantly inhibited the LPS-induced downregulation of VE-cadherin expression (*p < 0.05, n = 3 mice per group); Scale bar, 100 μm; Data were presented as mean ± standard error of mean, and groups were analyzed by two-tailed non-parametric test (Mann–Whitney U test). C The total protein levels in the BALF were significantly lower in BMP10-treated, LPS-stimulated mice than in LPS-stimulated mice (*p < 0.05, n = 4 mice per group); Data were presented as mean ± standard error of mean, and groups were analyzed by two-tailed non-parametric test (Mann–Whitney U test). TEM transmission electron microscopy, BMP10 bone morphogenetic protein 10, LPS lipopolysaccharide, IHC immunohistochemistry, BALF bronchoalveolar lavage fluid, VE-cadherin vascular endothelial cadherin