CD1d deficiency limits tolerogenic properties of peritoneal macrophages.

Invariant natural killer T (iNKT) cells are involved in various autoimmune diseases. Although iNKT cells are arthritogenic, transforming growth factor beta (TGFß)-treated tolerogenic peritoneal macrophages (Tol-pMφ) from wild-type (WT) mice are more tolerogenic than those from CD1d knock-out iNKT cell-deficient mice in a collagen-induced arthritis (CIA) model. The underlying mechanism by which pMφ can act as tolerogenic antigen presenting cells (APCs) is currently unclear. To determine cellular mechanisms underlying CD1d-dependent tolerogenicity of pMφ, in vitro and in vivo characteristics of pMφ were investigated. Unlike dendritic cells or splenic Mφ, pMφ from CD1d+/- mice showed lower expression levels of costimulatory molecule CD86 and produced lower amounts of inflammatory cytokines upon lipopolysaccharide (LPS) stimulation compared to pMφ from CD1d-deficient mice. In a CIA model of CD1d-deficient mice, adoptively transferred pMφ from WT mice reduced the severity of arthritis. However, pMφ from CD1d-deficient mice were unable to reduce the severity of arthritis. Hence, the tolerogenicity of pMφ is a cell-intrinsic property that is probably conferred by iNKT cells during pMφ development rather than by interactions of pMφ with iNKT cells during antigen presentation to cognate T cells. [BMB Reports 2021; 54(4): 209-214].

GV1001 immunotherapy ameliorates joint inflammation in a murine model of rheumatoid arthritis by modifying collagen-specific T-cell responses and downregulating antigen-presenting cells.

This study investigated whether GV1001 may be useful for treating rheumatoid arthritis (RA). Two collagen-induced arthritis (CIA) experiments showed that therapeutic, but not preventive, GV1001 treatment reduced the severity of joint inflammation in CIA. The third CIA experiment indicated that, compared to vehicle treatment, therapeutic GV1001 treatment was associated with a significantly smaller area under the curve for the overall clinical joint score over the 98day observation period (p<0.05). GV1001 treatment was also associated with lower Day 98 serum IL-6 levels (p<0.01) and histological joint scores (p<0.05). Moreover, splenocytes harvested from the GV1001-treated mice exhibited lower basal and collagen-stimulated production of IFN-γ and IL-6 on Days 49 and 98 than the splenocytes from vehicle-treated mice. The fourth and fifth experiments indicated that earlier treatment resulted in a better response. In addition, human (THP-1) and murine (RAW 264.7) macrophages and fibroblast-like synoviocytes (FLS) from RA patients were used for in vitro analyses. GV1001 treatment of lipopolysaccharide-stimulated macrophages derived from THP-1 and RAW 264.7 monocytes significantly reduced TNF-α and IL-6 secretion (THP-1: all p<0.05; RAW 264.7: all p<0.01). However, GV1001 treatment did not affect IL-6 expression in TNFα-stimulated RA FLS. GV1001 reduced the clinical joint scores, serum IL-6 levels, and histological joint scores of mice with CIA. In addition, GV1001 lowered the collagen-stimulated IFN-γ and IL-6 production of murine T-cells and reduced the TNF-α and IL-6 production of macrophages in vitro. Thus, GV1001 may ameliorate joint inflammation by modifying T-cell reactions to the triggering autoantigen and by reducing macrophage cytokine production.

Effect of renal sympathetic nerve on adrenergically and angiotensin II-induced renal vasoconstriction in normal Wistar-Kyoto rats.

BACKGROUND: This study examined the effect of renal sympathetic innervation on adrenergically and angiotensin II (Ang II)-induced renal vasoconstriction in Wistar-Kyoto (WKY) rats. METHODS: Forty-eight WKY rats were treated with either losartan (10 mg/kg/day p.o.) or carvedilol (5 mg/kg/day p.o.) or a combination of them (10 mg/kg/day + 5 mg/kg/day p.o.) for 7 days. On day 8, the rats were anaesthetized, and renal vasoconstrictor experiments were carried out. A group of rats was subjected to acute unilateral renal denervation during the acute study. Changes in the renal vasoconstrictor responses were determined in terms of reductions in renal blood flow caused by Ang II, noradrenaline (NA), and methoxamine (ME). RESULTS: In normal animals, losartan decreased (P < 0.05) the renal vasoconstrictor response to Ang II but not to NA or ME. Carvedilol treatment, however, blunted (P < 0.05) the renal vasoconstrictor responses to Ang II and adrenergic agonists. Combination of losartan and carvedilol blunted (P < 0.05) the renal vasoconstrictor response to Ang II but augmented the responses to NA and ME (all P < 0.05). Interestingly, when denervated rats were treated with the same combination, there was a reduction (P < 0.05) in the renal vasoconstrictor responses to Ang II and adrenergic agonists. CONCLUSIONS: Data suggest that the renal sympathetic nerve contributes to adrenergic agonist-mediated renal vasoconstrictions in normal rats. The data further indicate an interactive relationship between renin-angiotensin and sympathetic nervous systems in modulating adrenergically and Ang II-induced renal vasoconstriction in WKY rats.

Role of renal sympathetic nervous system in the control of renal potassium handling.

BACKGROUND: It is well established that renal sympathetic nerves are primarily involved in renal sodium and water regulation. However, the relationship between renal sympathetic nerve activity (RSNA) and renal potassium handling is not extensively known. The present study was performed to investigate the role of the renal sympathetic nervous system in the regulation of tubular potassium reabsorption and secretion. METHODS: Male Sprague Dawley (SD) rats (each group, n=6) were fasted overnight, anesthetized with pentobarbital sodium (60 mg/kg intraperitoneal), denervated by application of phenol to the left renal artery and maintained on an intravenous infusion of saline for 2 hours. During this period, 6 urine and plasma samples were collected at 20-minute intervals to study kidney function parameters. RESULTS: In denervated rats, there were significantly higher (all p<0.05 vs. innervated control) urine flow rate (UFR), glomerular filtration rate (GFR), absolute sodium excretion (U(Na)V), fractional sodium excretion (FE(N)a), absolute potassium excretion (U(K)V), fractional potassium excretion (FE(K)) and urinary sodium to urinary potassium ratio (U(Na)/U(K)). No appreciable differences were seen in the mean arterial pressure (MAP) and plasma sodium (P(Na)) between denervated and innervated SD rats. However, plasma potassium (P(K)) levels were significantly lower (p<0.05) in denervated rats as compared with innervated counterparts. CONCLUSIONS: There is a possible involvement of renal nerves in the regulation of renal potassium handling. This effect is largely attributable to a direct action of renal sympathetic nerves on the renal tubular segments.

Functional subtypes of renal alpha1-adrenoceptor in spontaneously hypertensive rats with streptozotocin-induced experimental diabetic nephropathy.

AIM: This study investigated the impact of hypertension combined with diabetic nephropathy on rat renal alpha(1)-adrenoceptor subtype composition. METHODS: In streptozotocin-induced diabetic spontaneously hypertensive rats (SHR), diabetic nephropathy developed as reflected by increased kidney index, plasma creatinine, albumin excretion, creatinine clearance and fractional excretion of Na(+) (all p < 0.05). Renal vasoconstrictions caused by electrical stimulation of renal nerves and intrarenally administered noradrenaline (alpha-adrenoceptor agonist), phenylephrine (alpha(1)-adrenoceptor agonist) and methoxamine (alpha(1A)-adrenoceptor agonist) were determined in the presence and absence of intrarenally administered amlodipine (Ca(2+) channel blocker), 5-methylurapidil (alpha(1A)-adrenoceptor antagonist), chloroethylclonidine (alpha(1B)-adrenoceptor antagonist) and BMY 7378 (alpha(1D)-adrenoceptor antagonist). RESULTS: In diabetic nephropathy SHR, there was a significant (all p < 0.05) attenuation of all adrenergically induced vasoconstrictor responses in the antagonists, except chloroethylclonidine, which caused a significant (all p < 0.05) enhancement of the responses. CONCLUSION: The data demonstrated that there was a functional coexistence of alpha(1A)- and alpha(1D)-adrenoceptors in the renal vasculature of SHR irrespective of the presence of diabetic nephropathy. However, there was a minor contribution of pre-synaptic alpha-adrenoceptors to the adrenergically mediated vasoconstrictor responses in the diabetic nephropathy SHR.