IFNG induces NKCC2 phosphorylation only in Thick Ascending Limbs of hypertensive rats

Hypertension is recognized to be a state of chronic inflammation, with elevated levels of inflammatory cytokines and with activation of the immune system. Genetic deletion, inhibition or receptor deletion of IL-6, IL-1 or TNF-a, blunt experimental hypertension. Mice deficient in IFNg have a blunted blood pressure response to Angiotensin II infusion. However, it is not clear how IFNg modulates sodium cotransporters or its downstream mediators in the nephron to blunt pressure natriuresis. We hypothesize IFNg, acting in TALs increases the phosphorylation of the apical Na/K/2Cl cotransporter (NKCC2) at thr96,101 in the thick ascending limb (TAL), in part due to the activation of SPAK kinase. First, we tested the effect of acute treatment of IFNg in outer medullary TALs isolated from Sprague Dawley rats. TALs were isolated from the renal outer medulla and treated with IFNg 300 ng/ml for 30 min. We did not find a significant change in NKCC2 phosphorylation compared to the control (C= 100% vs IFNg 84.7 ± 14.6%, n=3). Then, we tested the effect of IFNg on Dahl Salt Sensitive rats. TALs were treated with IFNg or the SPAK inhibitor ZT1a. IFNg increased NKCC2 phosphorylation by 121 ± 48% (n=4, p<0.05). The SPAK inhibitor did not affect baseline phosphorylation of NKCC2 but blunted the stimulatory effect of IFNg (n=4). RNAseq in isolated rat TALs indicate the presence of IFNg receptors IFNGR1 and IFNGR2, JAK1, JAK2 and STAT2. These data suggested that IFNg stimulates NKCC2 phosphorylation in TALs from genetically hypertensive rats but not in normal rats suggesting that a “second hit” or additional pro-inflammatory conditions are required for IFNg to stimulate NKCC2 phosphorylation. Our data could help directly link inflammatory mediators and increased tubular NaCl reabsorption in hypertension.

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This abstract was presented at the American Physiology Summit 2025 and is only available in HTML format. There is no downloadable file or PDF version. The Physiology editorial board was not involved in the peer review process.