Kazushi Tsuruga

Retinoic acid-inducible gene-I is induced by double-stranded RNA and regulates the expression of CC chemokine ligand (CCL) 5 in human mesangial cells

BACKGROUND Retinoic acid-inducible gene-I (RIG-I) is a putative RNA helicase involved in immune reactions against RNA viruses and various inflammatory and autoimmune diseases. The purpose of the present study was to investigate the role of RIG-I in glomerular diseases. METHODS We treated human mesangial cells in culture with polyinosinic-polycytidylic acid (poly IC), which is an authentic double-stranded RNA, and analysed the expression of RIG-I, CC chemokine ligand 5 (CCL5) and interferon (IFN)-β by western blotting, reverse transcriptase-polymerase chain reaction (RT-PCR) or enzyme-linked immunosorbent assay (ELISA). To elucidate the poly IC-signalling pathway, we subjected the cells to RNA interference (RNAi) against RIG-I, IFN-β or Toll-like receptor (TLR) 3. Furthermore, we studied the effects of IFN-β receptor blocking and IFN-β overexpression. RESULTS Poly IC induced the expression of RIG-I and CCL5 in human mesangial cells, and RNAi against RIG-I inhibited this poly IC-induced CCL5 expression. Poly IC-induced RIG-I expression was also inhibited by RNAi against IFN-β and by an antibody against the IFN-β receptor. IFN-β overexpression induced the expression of both RIG-I and CCL5. The knockdown of TLR3 abolished poly IC-induced RIG-I expression. CONCLUSIONS The TLR3/IFN-β/RIG-I/CCL5 signalling pathway may mediate immune and inflammatory responses against viral infection in mesangial cells, suggesting the role of this pathway in the aggravation of glomerulonephritis due to viral infection.

IFN-γ and TNF-α Synergistically Induce microRNA-155 Which Regulates TAB2/IP-10 Expression in Human Mesangial Cells

Background/Aims: MicroRNAs are noncoding small RNA molecules that posttranscriptionally regulate gene expression. microRNA-155 (miR-155), one of the microRNAs, is involved in the control of various genes. However, the role of miR-155 in inflammatory responses in mesangial cells is not known. In the present study, we examined the expression of miR-155 in mesangial cells. Methods: The expression of miR-155 in cultured normal human mesangial cells treated with interferon-γ (IFN-γ) and/or tumor-necrosis factor-α (TNF-α) was examined. The cells were transfected with miR-155 mimic, siRNA against transforming growth factor-β-activated kinase-1 (TAK1)-binding protein 2 (TAB2) or siRNA against nuclear factor-ĸB (NF-ĸB). Results: IFN-γ and TNF-α synergistically induced the expression of miR-155. Transfection of cells with miR-155 mimic inhibited the expression of TAB2 and IFN-γ-inducible protein of 10 kDa (IP-10). The expression of IP-10 was suppressed by knockdown of TAB2. Induction of miR-155 was inhibited by RNA interference against TAB2 or NF-ĸB. Conclusion: Combined stimulation with IFN-γ and TNF-α induces miR-155 via TAB2 and NF-ĸB. miR-155 negatively regulates TAB2, as a negative feedback system, to lower IP-10 expression. miR-155 may play a role in the regulation of inflammatory and immune reactions in the kidney.

Combined therapy of enalapril and losartan attenuates histologic progression in immunoglobulin A nephropathy

Abstract Background : It has been reported that combined therapy of angiotensin converting enzyme inhibitor and angiotensin receptor blocker significantly decreases proteinuria in immunoglobulin A (IgA) nephropathy. However, histologic alterations following the therapy have not been reported.

Carnosic acid attenuates apoptosis induced by amyloid-β 1-42 or 1-43 in SH-SY5Y human neuroblastoma cells.

Amyloid-beta (Aβ) peptides, Aβ 1-42 (Aβ42) and Aβ43 in particular, cause neurotoxicity and cell death in the brain of Alzheimers disease (AD) at higher concentrations. Carnosic acid (CA), a phenolic diterpene compound in the labiate herbs rosemary and sage, serves as an activator for neuroprotective and neurotrophic functions in brain cells. We investigated the effect of CA on apoptosis induced by Aβ42 or Aβ43 in cultured SH-SY5Y human neuroblastoma cells. Treatment of the cells with Aβ42 or Aβ43 (monomer, 10 μM each) induced apoptosis, which was confirmed by the cleavage of poly-(ADP-ribose) polymerase (PARP) and apoptosis-inducing factor (AIF). Concurrently, the Aβ treatment induced the activation of caspase (Casp) cascades including an effector Casp (Casp3) and initiator Casps (Casp4, Casp8 and Casp9). Pretreatment of the cells with CA (10 μM) partially attenuated the apoptosis induced by Aβ42 or Aβ43. CA pretreatment also reduced the cellular oligomers of Aβ42 and Aβ43. These results suggest that CA suppressed the activation of Casp cascades by reducing the intracellular oligomerization of exogenous Aβ42/43 monomer. The ingestion of an adequate amount of CA may have a potential in the prevention of Aβ-mediated diseases, particularly AD.

Retinoic acid-inducible gene-I (RIG-I) is induced by IFN-γ in human mesangial cells in culture: possible involvement of RIG-I in the inflammation in lupus nephritis

Interferon-γ is a potent Th1-type cytokine and a key molecule in the pathogenesis of autoimmune diseases including lupus nephritis. Retinoic acid-inducible gene-I is a putative RNA helicase that plays an important role in immune and inflammatory reactions. We previously demonstrated the increased expression of the retinoic acid-inducible gene-I protein in the kidney tissue of patients with lupus nephritis, and the presence of a significant amount of retinoic acid-inducible gene-I mRNA in the urinary sediment of patients with this inflammatory renal disease. In the present study, interferon-γ was found to induce the expression of retinoic acid-inducible gene-I in human mesangial cells in culture. Knockdown of retinoic acid-inducible gene-I inhibited the interferon-γ-induced upregulation of interferon regulatory factor 7, a transcriptional factor involved in immune and inflammatory reactions. These findings suggest that retinoic acid-inducible gene-I produced by mesangial cells may be involved in the pathogenesis of lupus nephritis.

Mizoribine Treatment of Young Patients with Severe Lupus Nephritis: A Clinicopathologic Study by the Tohoku Pediatric Study Group

Background: A novel purine synthesis inhibitor, mizoribine (MZR), with a similar activity to that of mycophenolate mofetil, was developed in Japan. We suspected that long-term oral MZR intermittent pulse therapy (MZR-P) might be more effective than the conventional daily MZR regimen due to the higher peak serum MZR levels that are achieved. Here, we examined the clinicopathologic efficacy of MZR-P treatment in 10 young patients with diffuse proliferative lupus nephritis (DPLN), including 3 patients who received MZR-P as their primary cytotoxic therapy. Methods: After their most recent renal flare-ups, all the patients were treated using MZR-P combined with oral prednisolone (PDN). MZR was administered as a single daily dose of 6–10 mg/kg per day (maximum dose of 500 mg) on 2 days of the week (Monday and Thursday) for at least 12 months or longer. The concomitantly administered PDN dose was gradually reduced. Results: The baseline characteristics of the patients were as follows: mean age 15 years; urinary protein/creatinine (Up/cr) ratio 1.57 ± 1.05 mg/mg; serum C3 level 50.3 ± 19.7 mg/dl; serum complement hemolytic activity (CH50) 18.1 ± 9.9 U/ml; serum anti-dsDNA antibody titer 177.5 ± 152.7 IU/ml; serum creatinine 0.6 ± 0.1 mg/dl, and European Consensus Lupus Activity Measurement (ECLAM) index 4.9 ± 2.6. Despite the gradual tapering of the PDN dose, marked improvements compared with the baseline values were observed at the last observation, mean interval of 29 months after the start of treatment: Up/cr ratio 0.19 ± 0.14; ECLAM index 1.3 ± 0.7 (p < 0.01); serum C3 level 76.5 ± 22.1 mg/dl; serum CH50 value 31.9 ± 8.7 U/ml, and anti-dsDNA antibody titer 34.2 ± 20.5 IU/ml (p < 0.05). The serum creatinine level remained within the normal range in all study participants. Post-treatment renal biopsies were performed in 5 of the patients; histology showed a marked attenuation of lesion progression. No serious adverse effects were observed. Conclusion: We believe that long-term MZR-P may prove to be a treatment of choice for young patients with DPLN. However, confirmation is needed as this preliminary study is limited by the small number of subjects, lack of controls, and its retrospective nature.

Mizoribine for the treatment of lupus nephritis in children and adolescents.

AIM The optimal treatment for lupus nephritis in the pubertal age group is still unclear. We therefore retrospectively evaluated the efficacy and safety of mizoribine (MZR), a novel selective inhibitor of inosine monophosphatase dehydrogenase, developed in Japan for the treatment of lupus nephritis in pubertal patients, because MZR has been reported to have relatively less clinically toxicity than conventionally used drugs. METHODS Over the past 12 years, we have treated 20 children with newly diagnosed, biopsy-proven lupus nephritis at our hospital. Of these, 10 patients who received a 2-year course of MZR in combination with prednisolone (PSL) as initial maintenance therapy and who could be observed for at least two years after the commencement of the MZR treatment, were enrolled in this study. MZR was given orally at the dose of 4 - 5 mg/kg per day in two divided doses. Changes in the clinical parameters, such as the urinary protein excretion, serum anti-dsDNA antibody titer, serum hemolytic complement activity (CH50) and serum creatinine, and in the frequency of disease flares defined as persistent worsening of those clinical parameters, were examined pre- and posttreatment for comparison, and the steroid-sparing effect of MZR was analyzed. RESULTS As induction therapy, all the patients had received high-dose oral PSL or intravenous methylprednisolone pulse therapy. Five female patients who were diagnosed to have proliferative lupus nephritis (WHO class III or IV) were scheduled to receive an 8-week course of oral cyclophosphamide (CPA) combined with high-dose steroids prior to the commencement of MZR, but CPA needed to be discontinued in four of these patients because of clinical drug toxicity. The clinical parameters showed significant improvement after the 2-year treatment with MZR combined with PSL, as compared to the pretreatment values (mean urinary protein excretion: 1.6+/-1.9 g/day vs.0.1 +/-0.1 g/day, serum CH50 value: 12.6+/-5.4 U/ml vs. 34.5+/-7.7 U/ml, serum anti-dsDNA antibody titer: 141.8+/-128.2 IU/ml vs. 18.5+/-17.7 IU/ml, respectively (p <0.01)). The serum creatinine remained normal. Although the daily dose of the concomitantly administered PSL to maintain clinical remission could be decreased significantly in all the study participants (39.5+/-1.6 mg/day vs. 6.8+/-5.1 mg/day, p < 0.01), two patients developed flares while on treatment, which were successfully treated by transiently increasing the dose of PSL. The MZR therapy could be completed in all of the patients without significant clinical toxicity being reported. At their most recent follow-up (mean 4.3 years), none of the 10 patients had renal insufficiency, and complete remission without any need for further medication had been achieved in two patients. CONCLUSION Although this case series is without controls, maintenance therapy with MZR administered in combination with PSL may be beneficial and clinically less toxic in at least a proportion of pubertal patients with lupus nephritis.

Toll-like receptor 3 signaling contributes to the expression of a neutrophil chemoattractant, CXCL1 in human mesangial cells

BackgroundMesangial proinflammatory chemokine/cytokine expressions via innate immunity play a pivotal role in the pathogenesis of glomerulonephritis. CXCL1/GROα is a strong neutrophil chemoattractant cytokine and reportedly plays an important role in regional inflammatory reactions. However, detailed signaling of mesangial CXCL1 expression induced by viral or “pseudoviral” immunity remains to be determined.MethodsWe treated normal human mesangial cells (MCs) in culture with polyinosinic-polycytidylic acid (poly IC), an authentic double-stranded RNA, and analyzed the expression of CXCL1 by reverse transcription-polymerase chain reaction (RT-PCR), real-time quantitative RT-PCR and enzyme-linked immunosorbent assay. To elucidate the poly IC-induced signaling pathway for CXCL1 expression, we subjected the cells to RNA interference against Toll-like receptor (TLR) 3, retinoic acid-inducible gene-I (RIG-I), melanoma differentiation-associated gene 5 (MDA5), interferon (IFN)-β, nuclear factor (NF)-κB p65 and IFN regulatory factor (IRF) 3. We also conducted an immunofluorescence study to examine mesangial CXCL1 expression in biopsy specimens from patients with lupus nephritis (LN) and IgA nephropathy (IgAN).ResultsWe found that activation of TLR3 signaling could induce the expression of CXCL1 in MCs. NF-κB, IRF3 and IFN-β, but neither RIG-I nor MDA5, were found to be involved in mesangial CXCL1 expression in this setting. Induction of CXCL1 by poly IC was inhibited by pretreatment of cells with dexamethasone. Intense glomerular CXCL1 expression was observed in biopsy specimens from patients with LN, whereas only a trace staining occurred in specimens from patients with IgAN.ConclusionTLR3 signaling also contributes to the CXCL1 expression in MCs. These observations further support the implication of viral and “pseudoviral” immunity in the pathogenesis of inflammatory renal diseases, especially in LN.

Carnosic acid suppresses the production of amyloid-β 1-42 and 1-43 by inducing an α-secretase TACE/ADAM17 in U373MG human astrocytoma cells

Amyloid beta (Aβ) peptides are key molecules in the pathogenesis of Alzheimers disease (AD). The sequential cleavage of amyloid precursor protein (APP) by the β- and γ-secretases generates Aβ peptides; however, the alternate cleavage of APP by the α- and γ-secretases decreases Aβ production. We previously reported that carnosic acid (CA), a phenolic diterpene compound found in the labiate herbs rosemary and sage, suppresses Aβ (1-40 and 1-42) production by activating α-secretase in cultured SH-SY5Y human neuroblastoma cells (Neurosci. Res. 2013; 75: 94-102). Here, we investigated the effect of CA on the production of Aβ peptides (1-40, 1-42 and 1-43) in U373MG human astrocytoma cells. The treatment of cells with CA suppressed Aβ40/42/43 release (55-71% decrease at 50μM). CA treatment enhanced the mRNA expressions of an α-secretase TACE (tumor necrosis factor-α-converting enzyme, also called a disintegrin and metalloproteinase-17, ADAM17); however, the β-secretase BACE1 (β-site APP-cleaving enzyme-1) was not increased by CA. Knockdown of TACE by siRNA reduced soluble-APPα release enhanced by CA and partially recovered the CA-suppressed Aβ40/42/43 release. These results suggest that CA reduces Aβ production, at least partially, by activating TACE in human astroglial cells. The use of CA may have a potential in the prevention of Aβ-mediated diseases.

Mizoribine attenuates renal injury and macrophage infiltration in patients with severe lupus nephritis.

The purine synthesis inhibitor mizoribine (MZR) has been successfully used without serious adverse effects in the treatment of several renal diseases including lupus nephritis. Besides its immunosuppressive effects, MZR has recently been reported to ameliorate tubulointerstitial fibrosis in rats via suppression of macrophage infiltration. However, there has been little information regarding the beneficial effects of MZR from the histologic standpoint in human lupus nephritis. Pre- and posttreatment renal biopsy specimens obtained from nine patients with diffuse proliferative lupus nephritis (DPLN) were divided into two groups (group A, five patients who received immunosuppressive treatment with MZR and group B, four patients who received immunosuppressive treatment without MZR) and histologically evaluated. Grading was done according to the 2003 classification system for lupus nephritis developed by the International Society of Nephrology/Renal Pathology Society, which considers the activity and chronicity indices, an immunohistologic study to assess intraglomerular and interstitial infiltration by macrophages, and the expression of osteopontin. Although in all the patients the posttreatment renal biopsy showed improvement of histologic grading and activity indices, group A patients showed a significant decrease of the chronicity indices and of intraglomerular infiltration by macrophages when compared to group B patients (2.6 ± 0.5 vs 4.0 ± 1.4 and 0.5 ± 0.2 vs 2.4 ± 1.9 cells per glomerulus, respectively; p < 0.05). Although this was a preliminary study in a small number of subjects, these histological observations may further confirm the beneficial effects of MZR for selected patients with DPLN.