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. 2019 Oct 1;317(4):F957-F966.
doi: 10.1152/ajprenal.00164.2019. Epub 2019 Aug 21.

Antagonism of major histocompatibility complex class II invariant chain peptide during chronic lipopolysaccharide treatment rescues autoregulatory behavior

Justin P Van Beusecum  1 , Shali Zhang  1 , Estevan Beltran  2 , Anthony K Cook  1 , Richard P Tobin  3 , M Karen Newell-Rogers  4 , Edward W Inscho  1
Affiliations

Antagonism of major histocompatibility complex class II invariant chain peptide during chronic lipopolysaccharide treatment rescues autoregulatory behavior

Justin P Van Beusecum et al. Am J Physiol Renal Physiol. .

Abstract

Toll-like receptor 4 (TLR4) activation contributes to vascular dysfunction in pathological conditions such as hypertension and diabetes, but the role of chronic TLR4 activation on renal autoregulatory behavior is unknown. We hypothesized that subclinical TLR4 stimulation with low-dose lipopolysaccharide (LPS) infusion increases TLR4 activation and blunts renal autoregulatory behavior. We assessed afferent arteriolar autoregulatory behavior in male Sprague-Dawley rats after prolonged LPS (0.1 mg·kg-1·day-1 sq) infusion via osmotic minipump for 8 or 14 days. Some rats also received daily cotreatment with either anti-TLR4 antibody (1 μg ip), competitive antagonist peptide (CAP; 3 mg/kg ip) or tempol (2 mmol/l, drinking water) throughout the 8-day LPS treatment period. Autoregulatory behavior was assessed using the in vitro blood-perfused juxtamedullary nephron preparation. Selected physiological measures, systolic blood pressure and baseline diameters were normal and similar across groups. Pressure-dependent vasoconstriction averaged 72 ± 2% of baseline in sham rats, indicating intact autoregulatory behavior. Eight-day LPS-treated rats exhibited significantly impaired pressure-mediated vasoconstriction (96 ± 1% of baseline), whereas it was preserved in rats that received anti-TLR4 antibody (75 ± 3%), CAP (84 ± 2%), or tempol (82 ± 2%). Using a 14-day LPS (0.1 mg·kg-1·day-1 sq) intervention protocol, CAP treatment started on day 7, where autoregulatory behavior is already impaired. Systolic blood pressures were normal across all treatment groups. Fourteen-day LPS treatment retained the autoregulatory impairment (95 ± 2% of baseline). CAP intervention starting on day 7 rescued pressure-mediated vasoconstriction with diameters decreasing to 85 ± 1% of baseline. These data demonstrate that chronic subclinical TLR4 activation impairs afferent arteriolar autoregulatory behavior through mechanisms involving reactive oxygen species and major histocompatibility complex class II activation.

Keywords: Toll-like receptor 4; inflammation; major histocompatibility complex class II; oxidative stress; renal microcirculation.

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Conflict of interest statement

M. K. Newell-Rogers and R. P. Tobin have a financial interest in the work. M. K. Newell-Rogers and R. P. Tobin are inventors on patents related to CAP and the use of the peptide. The peptide has been licensed to BCell Solutions Incorporated and VG Life Sciences Incorporated.

Figures

Fig. 1.
Fig. 1.
Example images of an afferent arteriole in the in vitro blood-perfused juxtamedullary nephron preparation before (left) and during (right) exposure to a vasoconstrictor stimulus.
Fig. 2.
Fig. 2.
Eight-day lipopolysaccharide (LPS) treatment impairs afferent arteriolar autoregulatory behavior. A: effect of renal perfusion pressure changes on afferent arteriolar diameter in kidneys from saline- and LPS (0.1 mg·kg−1·day−1 sq)-treated male rats. B: data are expressed as percentages of baseline diameter at 100 mmHg. Each data point represents the mean ± SE of n = 6 rats/group. *P < 0.05 vs. baseline diameter in the same group; †P < 0.05 vs. the-treated saline group at the same perfusion pressure. Within-group analysis was conducted using one-way ANOVA for repeated measures with post hoc analysis using Dunnett’s multiple-comparisons test. Differences between groups were determined using a Student’s t-test.
Fig. 3.
Fig. 3.
Cotreatment with anti-Toll-like receptor 4 (TLR4) antibody preserves afferent arteriolar autoregulatory behavior during lipopolysaccharide (LPS) treatment. A: effect of perfusion pressure changes on afferent arteriolar diameter in kidneys from saline-, LPS (0.1 mg·kg−1·day−1 sq)-, LPS + anti-TLR4 (1 μg ip)-, and saline + anti-TLR4-treated male rats. B: data are expressed as percentages of baseline diameter at 100 mmHg during the equilibration period. Saline and LPS data are included from Fig. 1 for reference. Each data point represents the mean ± SE of n = 5–6 rats/group. *P < 0.05 vs. baseline diameter in the same group; †P < 0.05 vs. the saline-treated group at the same perfusion pressure; #P < 0.05 vs. the LPS + anti-TLR4 antibody-treated group at the same perfusion pressure; &P < 0.05 vs. the saline + anti-TLR4 antibody-treated group at the same perfusion pressure. Within-group analysis was conducted using one-way ANOVA for repeated measures with post hoc analysis using Dunnett’s multiple-comparisons test. Differences between groups were determined using one-way ANOVA with post hoc analysis using Dunnett’s multiple-comparisons test.
Fig. 4.
Fig. 4.
Major histocompatibility complex class II-associated invariant peptide antagonism by competitive antagonist peptide (CAP) preserves afferent arteriolar autoregulatory behavior during 8-day lipopolysaccharide (LPS) treatment. A: effect of renal perfusion pressure changes on afferent arteriolar diameter in kidneys from saline (0.9% NaCl sq)-, LPS (0.1 mg·kg−1·day−1 sq)-, LPS + CAP (3 mg/kg ip daily)-, and saline + CAP-treated male rats. B: data are expressed as percentages of baseline diameter at 100 mmHg. Saline and LPS data are included from Fig. 1 for reference. Each data point represents the mean ± SE of n = 6 rats/group. *P < 0.05 vs. baseline diameter in the same group; †P < 0.05 vs. the saline-treated group at the same perfusion pressure; #P < 0.05 vs. the LPS + CAP-treated group at the same perfusion pressure; &P < 0.05 vs. the saline + CAP-treated group at the same perfusion pressure. Within-group analysis was conducted using one-way ANOVA for repeated measures with post hoc analysis using Dunnett’s multiple-comparisons test. Differences between groups were determined using one-way ANOVA with post hoc analysis using Dunnett’s multiple-comparisons test.
Fig. 5.
Fig. 5.
Cotreatment with tempol preserves afferent arteriolar autoregulatory behavior. A: effect of renal perfusion pressure changes on afferent arteriolar diameter in saline (0.9% NaCl sq)-, lipopolysaccharide (LPS; 0.1 mg·kg−1·day−1 sq)-, and LPS + tempol (2 mmol/l, drinking water)-treated male rats. Saline and LPS-treated groups are the same as those shown in Fig. 1. B: data are expressed as percentages of baseline diameter at 100 mmHg during the equilibration period. Each data point represents the mean ± SE of n = 6 rats/group. *P < 0.05 vs. baseline diameter in the same group; †P < 0.05 vs. the saline-treated group at the same perfusion pressure; #P < 0.05 vs. the LPS + tempol-treated group at the same perfusion pressure. Within-group analysis was conducted using one-way ANOVA for repeated measures with post hoc analysis using Dunnett’s multiple-comparisons test. Differences between groups were determined using one-way ANOVA with post hoc analysis using Dunnett’s multiple-comparisons test.
Fig. 6.
Fig. 6.
Competitive antagonist peptide (CAP) intervention rescues afferent arteriolar autoregulatory behavior during chronic 14-day lipopolysaccharide (LPS) treatment. Intervention with CAP, a major histocompatibility complex class II-associated invariant chain peptide antagonist, rescued renal autoregulatory behavior during 14-day LPS administration. A: effect of perfusion pressure changes on afferent arteriolar diameter in kidneys from saline (0.9% NaCl sq)-, LPS (0.1 mg·kg−1·day−1 sq)-, and LPS + CAP (3 mg/kg ip daily)-treated male rats. B: data are expressed as percentages of baseline diameter at 100 mmHg. Each data point represents the mean ± SE of n = 6 rats/group. *P < 0.05 vs. baseline diameter in the same group; †P < 0.05 vs. the saline-treated group at the same perfusion pressure; #P < 0.05 vs. the LPS + CAP-treated group at the same perfusion pressure. Within-group analysis was conducted using one-way ANOVA for repeated measures with post hoc analysis using Dunnett’s multiple-comparisons test. Differences between groups were determined using one-way ANOVA with post hoc analysis using Dunnett’s multiple-comparisons test.
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