Objective To investigate the expression profile of cell adhesion molecular 3(CADM3)on pulmonary endothelial cells,analyze its role in mediating specific adhesion to monocyte,and explore a new mechanism of hypoxia inducing peripheral monocyte infiltration in pulmonary vessels.Methods Human umbilical vein endothelial cells(HUVEC),rat pulmonary vascular endothelial cells(rPEC),and rat aortic endothelial cells(rAEC)were subjected,and divided into normoxic(21%O2)control group and hypoxic(1%O2 or 5%O2)treatment group.Analyzing the transcriptome data of HUVEC exposure to hypoxia for 8 h screened a differentially expressed molecule,CADM3.Cell adhesion experiments,siRNA interference,immunohistochemical assay,Western blotting,and flow cytometry were used to study the role of CADM3 in hypoxia specific high adhesion of HUVEC monocytes.Iron chelator deferoxamine(DFX)and shRNA interference were employed to enhance the expression of HIF-1α,and the effect of HIF-1 transcriptional activity on CADM3 expression was analyzed.Results Hypoxic treatment resulted in enhanced expression of CADM3 in HUVEC,and the expression level reached the peak at 6-8 h after hypoxia,and then decreased.Transfection with siRNA targeting CADM3 decreased the expression of CADM3,and significantly reduced the adhesion rate of hypoxic HUVEC-U937 cells when compared with the negative control group(P<0.05).Compared with the solvent control group,the protein levels of HIF-1α and its target protein STC2 in HUVEC treated with DFX(100 μmol/L)were increased.Transfection with shRNA targeting HIF-1α led the protein levels of HIF-1α and its target protein STC2 decreased,but had no effect on the protein expression of CADM3 in comparison to the negative control group.The protein level and distribution of CADM3 on the cell membrane were increased in hypoxic rPEC.No expression of CADM3 protein was found in the rAEC when compared with rPEC.After treatment with 5 μg/mL LPS,there were no significant changes in HIF-1α,STC2 and CADM3 in rPEC cultured under normoxia or hypoxia.The adhesion rate between hypoxia rPEC with CD11b+cells was the highest,with statistical significance(P<0.01).After incubation with anti-CADM3 antibody,the adhesion of hypoxic rPEC-U937 was significantly decreased compared with the solvent control group(P<0.05).Conclusion Hypoxia specifically induces the expression of CADM3 in pulmonary vascular endothelial cells in a HIF-1-independent manner,and promotes the specific adhesion of pulmonary vascular endothelial cells and monocytes induced by hypoxia.

Objective To investigate the protective effects and underlying mechanisms of sodium butyrate on rats exposed to hypoxia and cold conditions.Methods Fifty-eight male SD rats (aged 7～8 weeks,weighing 240～260 g ) were randomly divided into normoxia normothermia saline control (NNC ) group (n=10),normoxia normothermia sodium butyrate(NNB)group(n=10),hypoxia cold saline control (HCC) group (n=19),and hypoxia cold sodium butyrate (HCB)group (n=19).The intragastric dose of sodium butyrate was 200 mg/kg for the NNB and HCB groups,while the NNC and HCC groups were given normal saline of 5 mL/kg.①After continuous intragastric administration for 7 d,the rats in the HCC and HCB groups were placed in a low-pressure hypoxic chamber to simulate an altitude of 5000 m and exposed to a temperature of 8 ℃ for 7 d.Subsequently,blood samples were collected from the abdominal aorta for blood gas analysis,blood routine test,and detection for serum biochemical indicators.ELISA was used to determine serum inflammatory cytokines and endocrine hormones.The rats in the NNC and NNB groups(n=10)were fed outside the chamber and underwent the same tests in 7 d later to evaluate the protective effects of sodium butyrate on the body.②Core body temperature monitoring was conducted to assess the impact of sodium butyrate on the rmoregulation in rats exposed to hypoxia and cold(n=3).③Hypoxia exercise tolerance of the HCC group and HCB group in a hypoxic chamber (11％O2 )was evaluated for their hypoxia resistance (n=6).Results Compared to the NNC group,the rats in the HCC group exhibited significant decreases in arterial oxygen saturation (SaO2 )and arterial oxygen partial pressure (PaO2 ),serum levels of IL-4,estradiol (E2)and cortisol (F),core temperature,and exercise duration (P<0.05),and had notably increased levels of red blood cell (RBC)count,hemoglobin (HGB),hematocrit (HCT),cardiac troponin (CRDAC-T),uric acid (UA),alanine aminotransferase (ALT),total cholesterol (TC),low-density lipoprotein (LDL),IL-6 and granulocyte-macrophage colony-stimulating factor (GM-CSF)(P<0.05).Compared to the HCC group,the rats in the HCB group exhibited significant increases in SaO2,PaO2,IL-4,E2,F,corticotropin releasing hormone (CRH)and adrenocorticotropic hormone (ACTH)(P<0.05),remarkably longer exercise duration under hypoxic exposure (P<0.05 ),but decreases in RBC count,serum levels of HGB,HCT,CRDAC-T,UA,ALT,TC,LDL,IL-6,GM-CSF and free thyroxine (FT4 ),and core temperature (P<0.05).Conclusion Sodium butyrate exhibits protective effects on rats exposed to hypoxia and cold conditions,and it is helpful in their adaptation to these hypoxia and cold environments.