A-71915

Social isolation (ISO) is associated with an increased risk and poor outcomes of ischemic stroke. However, the roles and mechanisms of ISO in stroke-associated pneumonia (SAP) remain unclear. Adult male mice were single- or pair-housed with an ovariectomized female mouse and then subjected to transient middle cerebral artery occlusion. Isolated mice were treated with the natriuretic peptide receptor A antagonist A71915 or anti-gamma-delta (γδ) TCR monoclonal antibody, whereas pair-housed mice were treated with recombinant human atrial natriuretic peptide (rhANP). Subdiaphragmatic vagotomy (SDV) was performed 14 days before single- or pair-housed conditions. We found that ISO significantly worsened brain and lung injuries relative to pair housing, which was partially mediated by elevated interleukin (IL)-17A levels and the migration of small intestine-derived inflammatory γδ T-cells into the brain and lung. However, rhANP treatment or SDV could ameliorate ISO-exacerbated post-stroke brain and lung damage by reducing IL-17A levels and inhibiting the migration of inflammatory γδ T-cells into the brain and lung. Our results suggest that rhANP mitigated ISO-induced exacerbation of SAP and ischemic cerebral injury by inhibiting small intestine-derived γδ T-cell migration into the lung and brain, which could be mediated by the subdiaphragmatic vagus nerve.

Cell‐cycle regulatory proteins (p21 Cip1 /p27 Kip1 ) inhibit cyclin and cyclin‐dependent kinase (CDK) complex that promotes fibrosis and hypertrophy. The present study examined the role of CDK blockers, p21 Cip1 /p27 Kip1 in the progression of renal fibrosis and dysfunction using Npr1 (encoding guanylyl cyclase/natriuretic peptide receptor‐A, GC‐A/NPRA) gene‐knockout (0‐copy; Npr1 −/− ), 2‐copy ( Npr1 +/+ ), and 4‐copy ( Npr1 ++/++ ) mice treated with GC inhibitor, A71915 and cGMP‐dependent protein kinase (cGK) inhibitor, (Rp‐8‐Br‐cGMPS). A significant decrease in renal cGMP levels and cGK activity was observed in 0‐copy mice and A71915‐ and Rp‐treated 2‐copy and 4‐copy mice compared with controls. An increased phosphorylation of Erk1/2, p38, p21 Cip1 , and p27 Kip1 occurred in 0‐copy and A71915‐treated 2‐copy and 4‐copy mice, while Rp treatment caused minimal changes than controls. Pro‐inflammatory (TNF‐α, IL‐6) and pro‐fibrotic (TGF‐β1) cytokines were significantly increased in plasma and kidneys of 0‐copy and A71915‐treated 2‐copy mice, but to lesser extent in 4‐copy mice. Progressive renal pathologies, including fibrosis, mesangial matrix expansion, and tubular hypertrophy were observed in 0‐copy and A71915‐treated 2‐copy and 4‐copy mice, but minimally occurred in Rp‐treated mice compared with controls. These results indicate that Npr1 has pivotal roles in inhibiting renal fibrosis and hypertrophy and exerts protective effects involving cGMP/cGK axis by repressing CDK blockers p21 Cip1 and p27 Kip1 .