Aquaporin-2 Promoter Is Synergistically Regulated by Nitric Oxide and Nuclear Factor of Activated T Cells

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2020-05-22 DAILY UNM GLOBAL HEALTH COVID-19 BRIEFING

Executive Summary: NM Highlights: 12 positive cases at NMSU. Short-term rentals restrictions. Dine-in reopening. US Highlights: Models to forecast COVID-19 deaths. Places of worship reopening. Contact tracing at University of Alabama. International Highlights: More deaths among poor. Mortality data in Italy. High death toll in Brazil. Global vaccines fall behind. Italy cases drop. Vaccines to go through India. Epidemiology Highlights: Children not pandemic drivers. Healthcare Policy Recommendations: Burnout of HCWs. NYC surgeons’ response. Foggy glasses tips. Practice Guidelines: Recommendations are provided on surgical strategies during COVID-19, management of hypertension, anesthesia practice, avoiding drug-induced cardiovascular impairments, arrhythmia management, elective surgery reboot, nutritional management, stroke care, neurointerventional surgery, blood management. Testing: Unregulated tests identified. Interpreting test results. Drugs, Vaccines, Therapies, Clinical Trials: Vaccine trials results. Vaccine moves to trials. Monoclonal antibody identified. Hydroxychloroquine no benefit. Adjuvant corticosteroid therapy. Old drugs may benefit. Vaccines inducing antibodies. Other Science: Mortality and CKD/liver disease. Transmission in pregnancy. Pathophysiology insights. Readmission characteristics. Sodium and severity. Simulated sunlight disinfects

Knocking out COL5A1 from smooth muscle does not impact chronic hypoxia-induced pulmonary hypertension

To determine the role of Col5a1 in CH-induced PH, we developed an inducible smooth muscle-specific col5a1 knockout mouse model (SMC-col5a1 KO). We found no significant differences in PH indexes between the control and SMC-col5a1 KO mice, while col V seems to be decreased in pulmonary arteries validating the mouse model. It is possible that Col5a2, which was also upregulated following CH in control pulmonary arteries, compensated for the lack of Col5a1. However, our results can also suggest Col5a1 is not the only self-antigen that plays a role in CH-induced PH.  </p

<strong>NFATc3 regulation of collagen V expression contributes to cellular immunity to collagen type V and hypoxic pulmonary hypertension</strong>

 Chronic hypoxia (CH)-induced pulmonary hypertension (PH) results, in part, from T helper-17 (TH17) cell-mediated perivascular inflammation. However, the antigen(s) involved is unknown. Cellular immunity to collagen type V (col V) develops after ischemia-reperfusion injury during lung transplant and is mediated by naturally occurring (n)TH17 cells. Col5a1 gene codifies for the α1-helix of col V, which is normally hidden from the immune system within type I collagen in the extracellular matrix. COL5A1 promoter analysis revealed nuclear factor of activated T cells, cytoplasmic 3 (NFATc3) binding sites. Therefore, we hypothesized that smooth muscle NFATc3 upregulates col V expression, leading to nTH17 cell-mediated autoimmunity to col V in response to CH, representing an upstream mechanism in PH development. To test our hypothesis, we measured indexes of PH in inducible smooth muscle cell (SMC)-specific NFATc3 knockout (KO) mice exposed to either CH (380 mmHg) or normoxia and compared them with wild-type (WT) mice. KO mice did not develop PH. In addition, COL5A1 was one of the 1,792 genes differentially affected by both CH and SMC NFATc3 in isolated intrapulmonary arteries, which was confirmed by RT-PCR and immunostaining. Cellular immunity to col V was determined using a trans vivo delayed-type hypersensitivity assay (Tv-DTH). Tv-DTH response was evident only when splenocytes were used from control mice exposed to CH but not from KO mice, and mediated by nTH17 cells. Our results suggest that SMC NFATc3 is important for CH-induced PH in adult mice, in part, by regulating the expression of the lung self-antigen COL5A1 protein contributing to col V-reactive nTH17-mediated inflammation and hypertension. </p

Col5a1 expression increases following hypoxia in mouse pulmonary arterial smooth muscle cells

We reported that chronic hypoxia increases Col5a1 in the perivascular region of mouse pulmonary arteries (Sheak J. AJP LCMP 2020, 319(6):L968-L980). To determine whether this phenomenon occurs ex vivo, we cultured cells from the media layer of pulmonary arteries and exposed them to ex vivo hypoxia (2% O2, 5% CO2) or normoxia (21% O2, 5% CO2) for 72 hours. We analyzed Col5a1 fluorescence intensity in both SM22+ (smooth muscle cell marker) and SM22- cells. We found an increase in the number and area of Col5a1+ objects in SM22+ cells in response to hypoxia. Interestingly, the shape of the objects significantly changed to a more fiber shape, and there was less overlap between SM22 and Col5a1 following hypoxia, suggesting that col V was secreted out of the cells. The mechanisms causing hypoxia-induced Col5a1 secretion are unknown. </p

Role of Cholesterol in the Regulation of Hydrogen Sulfide Signaling within the Vascular Endothelium

H2S is a gaseous signaling molecule enzymatically produced in mammals and H2S-producing enzymes are expressed throughout the vascular wall. We previously reported that H2S-induced vasodilation is mediated through transient receptor potential cation channel subfamily V member 4 (TRPV4) and large conductance (BKCa) potassium channels; however, regulators of this pathway have not been defined. Previous reports have shown that membrane cholesterol limits activity of TRPV4 and BKCa potassium channels. The current study examined the ability of endothelial cell (EC) plasma membrane (PM) cholesterol to regulate H2S-induced vasodilation. We hypothesized that EC PM cholesterol hinders H2S-mediated vasodilation in large mesenteric arteries. In pressurized, U46619 pre-constricted mesenteric arteries, decreasing EC PM cholesterol in large arteries using methyl-β-cyclodextrin (MBCD, 100 µM) increased H2S-induced dilation (NaHS 10, 100 µM) but MBCD treatment had no effect in small arteries. Enface fluorescence showed EC PM cholesterol content is higher in large mesenteric arteries than in smaller arteries. The NaHS-induced vasodilation following MBCD treatment in large arteries was blocked by TRPV4 and BKCa channel inhibitors (GSK219384A, 300 nM and iberiotoxin, 100 nM, respectively). Immunohistochemistry of mesenteric artery cross-sections show that TRPV4 and BKCa are both present in EC of large and small arteries. Cholesterol supplementation into EC PM of small arteries abolished NaHS-induced vasodilation but the cholesterol enantiomer, epicholesterol, had no effect. Proximity ligation assay studies did not show a correlation between EC PM cholesterol content and the association of TRPV4 and BK. Collectively, these results demonstrate that EC PM cholesterol limits H2S-induced vasodilation through effects on EC TRPV4 and BKCa channels