Kohsuke Masutani

Suppressor of cytokine signaling-1 is essential for suppressing dendritic cell activation and systemic autoimmunity.

Suppressor of cytokine signaling-1 (SOCS1/JAB) negatively regulates not only the cytokine-signaling pathway but also lipopolysaccharide (LPS)-induced macrophage activation. We found that SOCS1-deficient dendritic cells (DCs) were also hyperresponsive to interferon-gamma and interleukin-4. To define the role of SOCS1-deficient DCs in vivo, we generated mice in which the SOCS1 expression was restored in T and B cells on a SOCS1(-/-) background. In these mice, DCs were accumulated in the thymus and spleen and produced high levels of BAFF/BLyS and APRIL, resulting in the aberrant expansion of B cells and autoreactive antibody production. SOCS1-deficient DCs efficiently stimulated B cell proliferation in vitro and autoantibody production in vivo. These results indicate that SOCS1 plays an essential role in the normal DC functions and suppression of systemic autoimmunity.

Predominance of Th1 Immune Response in Diffuse Proliferative Lupus Nephritis

OBJECTIVE Lupus nephritis, which shows various histologic patterns, is a serious complication of systemic lupus erythematosus (SLE). We previously demonstrated the importance of Thl cell-mediated immune response in patients with diffuse proliferative lupus nephritis (DPLN). The aim of this study was to examine the relationship between the peripheral blood Th1/Th2 balance and the intrarenal immune response. METHODS The Th1:Th2 ratio in peripheral blood was measured by intracellular staining for cytokines with flow cytometry. Immunohistochemical analysis of renal biopsy specimens was performed to clarify the characterization of local infiltrating cells in 3 groups of subjects: SLE patients with World Health Organization (WHO) class IV nephritis (DPLN) (group I; n = 13), SLE patients with WHO class V nephritis (group II; n = 9), and patients with minor glomerular lesions (group III; n = 7). In addition, the histologic activity index and chronicity index were evaluated and correlated with the Th1:Th2 ratio. RESULTS Immunohistochemical studies showed higher numbers of CD68+ macrophages, CD3 + T cells, and interferon-gamma-positive cells in group I than in groups II or III. Renal tissues from patients in group I also showed up-regulation of expression of osteopontin and CD40, with a small number of infiltrating T cells expressing interleukin-4. Overall, the Thl:Th2 ratio in group I patients (SLE with DPLN) was high and correlated significantly with the histologic activity index, but not with the chronicity index. CONCLUSION We have identified a predominance of Thl-type response in both peripheral and renal tissues of patients with DPLN, suggesting that the peripheral blood Thl:Th2 ratio directly reflects the local histopathologic findings. In patients with lupus nephritis, the peripheral blood Th1:Th2 ratio could be useful as a parameter that reflects the renal histologic activity or the strength of the local Thl response.

Controlled, prospective trial of steroid treatment in IgA nephropathy: a limitation of low-dose prednisolone therapy

BACKGROUND No accepted therapy has been established for progressive immunoglobulin A (IgA) nephropathy. METHODS A prospective, randomized, controlled trial of low-dose prednisolone therapy was performed in patients with IgA nephropathy with moderate histological characteristics. Forty-three patients in the steroid group and 47 patients in the control group were included in the study. The initial dose of prednisolone was 20 mg/d, gradually tapered to 5 mg/d during 2 years. RESULTS Baseline urine protein-creatinine ratio (UP-UCR) was significantly greater in the steroid group than in controls. Follow-up duration was 65 +/- 25 months in the steroid group and 64 +/- 23 months in controls. Changes in UP-UCR from baseline, ie, UP-UCR at last follow-up minus UP-UCR at baseline, were significantly lower in the steroid group than in controls (steroid group, -0.84 +/- 1.78; controls, 0.26 +/- 1.65; P = 0.0034). Kidney survival was similar in both groups. Patients were divided into two subgroups according to clinical course. There were 28 improved patients and 15 unimproved patients in the steroid group and 27 improved patients and 20 unimproved patients in the control group. In the steroid group, UP-UCR was significantly greater in the unimproved than improved subgroup (3.1 +/- 2.6 versus 1.8 +/- 1.5). CONCLUSION These data suggest that our protocol had an antiproteinuric effect, but could not improve kidney survival. Because the effect of steroid therapy to prevent the progression of IgA nephropathy is believed to be linked closely to reduction in urinary protein, an insufficient dose of prednisolone in our protocol may be the reason for the discrepancy between the effect on proteinuria and kidney survival.

The mTOR pathway is highly activated in diabetic nephropathy and rapamycin has a strong therapeutic potential.

Diabetic nephropathy (DN) associated with type 2 diabetes is the most common cause of end-stage renal disease (ESRD) and a serious health issue in the world. Currently, molecular basis for DN has not been established and only limited clinical treatments are effective in abating the progression to ESRD associated with DN. Here we found that diabetic db/db mice which lack the leptin receptor signaling can be used as a model of ESRD associated with DN. We demonstrated that p70S6-kinase was highly activated in mesangial cells in diabetic obese db/db mice. Furthermore, systemic administration of rapamycin, a specific and potent inhibitor of mTOR, markedly ameliorated pathological changes and renal dysfunctions. Moreover, rapamycin treatment shows a significant reduction in fat deposits and attenuates hyperinsulinemia with few side effects. These results indicate that mTOR activation plays a pivotal role in the development of ESRD and that rapamycin could be an effective therapeutic agent for DN.

Membranous Glomerulonephritis Development with Th2-Type Immune Deviations in MRL/lpr Mice Deficient for IL-27 Receptor (WSX-1)

MRL/lpr mice develop spontaneous glomerulonephritis that is essentially identical with diffuse proliferative glomerulonephritis (World Health Organization class IV) in human lupus nephritis. Lupus nephritis is one of the most serious complications of systemic lupus erythematosus. Diffuse proliferative glomerulonephritis is associated with autoimmune responses dominated by Th1 cells producing high levels of IFN-γ. The initial mounting of Th1 responses depends on the function of the WSX-1 gene, which encodes a subunit of the IL-27R with homology to IL-12R. In mice deficient for the WSX-1 gene, proper Th1 differentiation was impaired and abnormal Th2 skewing was observed during infection with some intracellular pathogens. Disruption of the WSX-1 gene dramatically changed the pathophysiology of glomerulonephritis developing in MRL/lpr mice. WSX-1−/− MRL/lpr mice developed disease resembling human membranous glomerulonephritis (World Health Organization class V) with a predominance of IgG1 in glomerular deposits, accompanied by increased IgG1 and IgE in the sera. T cells in WSX-1−/− MRL/lpr mice displayed significantly reduced IFN-γ production along with elevated IL-4 expression. Loss of WSX-1 thus favors Th2-type autoimmune responses, suggesting that the Th1/Th2 balance may be a pivotal determinant of human lupus nephritis development.

Phosphate overload directly induces systemic inflammation and malnutrition as well as vascular calcification in uremia

Hyperphosphatemia contributes to increased cardiovascular mortality through vascular calcification (VC) in patients with chronic kidney disease (CKD). Malnutrition and inflammation are also closely linked to an increased risk of cardiovascular death in CKD. However, the effects of Pi overload on inflammation and malnutrition remain to be elucidated. The aim of the present study was to investigate the effects of dietary Pi loading on the interactions among inflammation, malnutrition, and VC in CKD. We used control rats fed normal diets and adenine-induced CKD rats fed diets with different Pi concentrations ranging from 0.3% to 1.2% for 8 wk. CKD rats showed dietary Pi concentration-dependent increases in serum and tissue levels of TNF-α and urinary and tissue levels of oxidative stress markers and developed malnutrition (decrease in body weight, serum albumin, and urinary creatinine excretion), VC, and premature death without affecting kidney function. Treatment with 6% lanthanum carbonate blunted almost all changes induced by Pi overload. Regression analysis showed that serum Pi levels closely correlated with the extent of inflammation, malnutrition, and VC. Also, in cultured human vascular smooth muscle cells, high-Pi medium directly increased the expression of TNF-α in advance of the increase in osteochondrogenic markers. Our data suggest that dietary Pi overload induces systemic inflammation and malnutrition, accompanied by VC and premature death in CKD, and that inhibition of Pi loading through dietary or pharmacological interventions or anti-inflammatory therapy may be a promising treatment for the prevention of malnutrition-inflammation-atherosclerosis syndrome.

Amelioration of human lupus-like phenotypes in MRL/lpr mice by overexpression of interleukin 27 receptor α (WSX-1)

Objective: In the present work, we investigate the role of interleukin (IL)27/IL27 receptor α (Rα) (WSX-1) in the development of autoimmune disorders in the MRL/lpr mouse, which is considered as an experimental model of systemic lupus erythaematosus (SLE) in humans. Methods: We generated two strains of WSX-1 transgenic mice in the MRL/lpr background with different expression levels of WSX-1, and investigated the effect of WSX-1 overexpression on survival, glomerulonephritis and immunological properties. Results: In comparison with wild type (WT) MRL/lpr and transgenic (Tg) low (TgL) mice, Tg high (TgH) mice exhibited a prolonged lifespan and no apparent development of autoimmune nephritis. Production of anti-dsDNA antibody and total IgG and IgG2a were significantly lower in TgH mice than those of TgL and WT mice. The expressed amounts of interferon (IFN)γ and IL4 mRNA by CD4+ T cells from Tg mice decreased in a dose-dependent fashion. CD4+ splenic lymphocytes in TgH mice were more subject to the IL27-mediated suppression of cytokine production. In vitro stimulation of CD4+ T cells by IL27 resulted in over phosphorylation of STAT3 in TgH cells than in WT cells. Conclusion: WSX-1 overexpression in the MRL/lpr background rendered the autoimmune prone mice protected from the development of autoimmune diseases. Our results suggest that IL27 signalling may be a therapeutic target against autoimmune diseases, including human SLE.

Amelioration of human lupus-like phenotypes in MRL/lpr mice by overexpression of IL-27Rα (WSX-1)

Objective: In the present work, we investigate the role of interleukin (IL)27/IL27 receptor α (Rα) (WSX-1) in the development of autoimmune disorders in the MRL/lpr mouse, which is considered as an experimental model of systemic lupus erythaematosus (SLE) in humans. Methods: We generated two strains of WSX-1 transgenic mice in the MRL/lpr background with different expression levels of WSX-1, and investigated the effect of WSX-1 overexpression on survival, glomerulonephritis and immunological properties. Results: In comparison with wild type (WT) MRL/lpr and transgenic (Tg) low (TgL) mice, Tg high (TgH) mice exhibited a prolonged lifespan and no apparent development of autoimmune nephritis. Production of anti-dsDNA antibody and total IgG and IgG2a were significantly lower in TgH mice than those of TgL and WT mice. The expressed amounts of interferon (IFN)γ and IL4 mRNA by CD4+ T cells from Tg mice decreased in a dose-dependent fashion. CD4+ splenic lymphocytes in TgH mice were more subject to the IL27-mediated suppression of cytokine production. In vitro stimulation of CD4+ T cells by IL27 resulted in over phosphorylation of STAT3 in TgH cells than in WT cells. Conclusion: WSX-1 overexpression in the MRL/lpr background rendered the autoimmune prone mice protected from the development of autoimmune diseases. Our results suggest that IL27 signalling may be a therapeutic target against autoimmune diseases, including human SLE.

Spironolactone suppresses inflammation and prevents L-NAME-induced renal injury in rats

Chronic inhibition of nitric oxide synthase by N(omega)-nitro- L-arginine methyl ester (L-NAME) causes progressive renal injury with systemic hypertension and interstitial macrophage infiltration. We have previously shown that there is local activation of the renin-angiotensin-aldosterone system in the renal cortex as a major pathogenic feature of macrophage infiltration. In this study, we measured the effects of the aldosterone antagonist, spironolactone, on renal injury in L-NAME-treated male Wistar rats. After 12 weeks of L-NAME-treatment, rats had increased systolic blood pressure, urinary protein excretion, and serum creatinine and histological analysis showed glomerulosclerosis, interstitial fibrosis, and macrophage infiltration. Treatment with spironolactone significantly prevented these renal changes, whereas treatment with hydralazine had no effect. The cortical expression of osteopontin was significantly elevated in L-NAME-treated rats, and expression of its mRNA significantly correlated with the number of infiltrating macrophages and degree of interstitial fibrosis. Spironolactone treatment markedly suppressed osteopontin expression. Our results suggest that reduced nitric oxide bioavailability caused renal inflammation and fibrosis through an aldosterone receptor-dependent mechanism associated with osteopontin expression independent of its systemic hemodynamic effects.

Deficiency in EBV-induced gene 3 (EBI3) in MRL/lpr mice results in pathological alteration of autoimmune glomerulonephritis and sialadenitis

MRL/lpr mice develop a systemic autoimmune disease that is reminiscent of systemic lupus erythematosus (SLE) and Sjögren’s syndrome in humans. To investigate the role of IL-27 in the development of autoimmune disorders in MRL/lpr mice, we disrupted the EBV-induced gene 3 (EBI3), which is a subunit of IL-27. Consequently, the pathophysiology of glomerulonephritis and sialadenitis, which develops in MRL/lpr mice, was drastically changed. EBI3−/− MRL/lpr mice developed disease that resembles human membranous glomerulonephritis (MGN), not diffuse proliferative glomerulonephritis (DPGN), with a predominance of IgG1 in glomerular deposits, and different type sialadenitis from Sjögren’s syndrome, with IgG1 producing plasma cell infiltration in salivary glands, accompanied by increased IgG1 and IgE in the sera. T cells in these mice displayed significantly reduced IFN-γ production along with elevated IL-4 expression. Loss of EBI3 thus favors Th2-type autoimmune responses, suggesting that the Th1/Th2 balance may be a pivotal determinant of phenotypes of human autoimmune diseases.