OBJECTIVETo determine the effects of transient receptor potential vanilloid type 1 (TRPV1) channel ablation and a chemokine receptor 2 (CCR2) antagonist on salt-sensitive hypertension-induced renal injury.

METHODSWild-type (WT) and TRPV1-null mutant (TRPV1(-/-)) mice were subjected to uninephrectomy and deoxycorticosterone acetate (DOCA)-salt treatment for 4 weeks with or without a CCR2 antagonist, RS504393 (n=8 for all the 4 groups). Sham WT and TRPV1(-/-) mice (both n=7) underwent uninephrectomy without receiving DOCA and saline. Systolic blood pressure, urinary excretion of albumin, 8-isoprostane and creatinine clearance for 24 hours were assayed during the experimental period and at the end of the 4-week treatment. The morphological analysis was performed in renal histological sections, including glomerulosclerosis, tubulointerstitial injury, and monocyte/macrophage infiltration.

RESULTSCompared to the corresponding control mice, DOCA-salt treatment in both WT and TRPV1(-/-) mice led to increased systolic blood pressure (SBP), enhanced urinary excretion of albumin and 8-isoprostane, decreased creatinine clearance, increased glomerulosclerosis and tubulointerstitial injury associated with enhanced monocyte/macrophage infiltration (all P<0.05), all of which were much more severe in TRPV1(-/-) mice compared to WT mice with the exception of blood pressure (all P<0.05). RS5043943 attenuated DOCA-salt-induced changes in renal function and morphology in WT and TRPV1(-/-) mice (all P<0.05). There was no difference in blood pressure among DOCA-salt WT and TRPV1(-/-) mice with or without RS505393 with the exception of sham WT and TRPV1(-/-) mice (all P>0.05).

CONCLUSIONSCCR2 antagonist inhibits DOCA-salt-induced renal injury and monocyte/macrophage infiltration in WT and TRPV1(-/-) mice with the greater in the latter strain. Activation of TRPV1 attenuates salt-sensitive hypertension-induced renal injury possibly via inhibition of CCR2-induced monocyte/macrophage infiltration.