Intervention with VG1177, a MHC Class II Invariant Peptide Chain (CLIP) Antagonist, Restores Afferent Arteriolar Autoregulatory Behavior during Chronic 14 Day Lipopolysaccharide Treatment
Authors: Van Beusecum Justin Pieter , Cook Anthony K , Zhang Shali , Tobin Richard P , Newell‐Rogers Karen , Inscho Edward W 
Published: November 2023

Lipopolysaccharide (LPS) is a cell wall component of gram‐negative bacteria that is a known ligand for toll‐like receptor 4, which, in turn, activates the innate immune system. MHC Class II‐associated invariant peptide (CLIP) is critically linked to antigen processing, presentation, and adaptive immune system activation. Chronic immune system activation and inflammation are linked to blunted afferent arteriolar autoregulatory behavior and kidney injury. Previous work established that afferent arteriolar autoregulatory behavior is impaired following 7 days of LPS treatment by osmotic minipump, while simultaneous co‐treatment with VG1177 preserved autoregulatory capability. Accordingly, we postulated that competitive CLIP antagonist (VG177) treatment could rescue autoregulatory behavior impaired by chronic low‐dose LPS exposure. Osmotic minipumps were implanted (day 0) for infusion of LPS (0.01mg/kg/day) or saline (0.9% NaCl) for 14 days and then kidneys were harvested for juxtamedullary nephron studies. Three groups (n=6/group) were studied: saline, LPS, and LPS + VG1177. LPS + VG1177 group received LPS infusion from day 0 through day 14 and then daily VG1177 treatment (3mg/kg/day; i.p.) was added on LPS‐infusion days 7–14. Systolic blood pressures were similar in all three on day 14 (124 ± 1 mmHg, 124 ± 2 mmHg, and 125 ± 2 mmHg, respectively). Afferent arteriole autoregulatory behavior was assessed in these groups by increasing perfusion pressure from 65 to 170 mmHg in 15 mmHg increments. Starting diameters were similar across all three groups (15.1 ± 1.2 μm; 14.5 ± 1.1 μm and 14.7 ± 1.6 μm, respectively). When perfusion pressure was increased from 65 to 170 mmHg, arteriolar diameter in the saline group decreased by 25 ± 1% (P<0.05; n=6), exhibiting normal pressure‐induced autoregulatory vasoconstriction. Afferent arteriolar diameters in LPS treated kidneys decreased by just 4.5 ± 2% over the same pressure range, indicating significant (P<0.05 vs. saline) loss of autoregulatory behavior. In the LPS + VG1177 intervention group, afferent arteriolar diameter decreased by 15.2 ± 1% (P<0.05 vs. LPS) over the same pressure range, signifying partial restoration of afferent arteriolar autoregulatory behavior. Plasma endotoxin was measured on day 14 by Pierce LAL chromogenic endotoxin quantitation kit in the saline, LPS, and LPS + VG1177 groups. Plasma endotoxin concentration in the saline group averaged 5.5 ± 0.6 EU/mL compared to 67.7 ± 10.4 EU/mL; (P<0.05; n=6) in the 14 day LPS alone group. In 14 day LPS + 7 days of VG1177 intervention, plasma endotoxin concentration was significantly lower (29.8 ± 3.5 EU/mL; P<0.05; n=6) compared with LPS alone. Collectively, these data support the hypothesis that CLIP antagonism with VG1177 restores afferent arteriolar autoregulatory behavior during chronic 14 day low dose LPS treatment and may reduce the plasma endotoxin load. CLIP antagonism may open novel therapeutic targets for inflammatory kidney disease.

Support or Funding Information

This study was funded by a Pre‐doctoral Fellowship from the AHA Greater Southeast Affiliate: 14PRE20460061 and NIH: DK44628, HL098135.