Yohei Ikezumi

BACKGROUND: The immunosuppressant mizoribine (Miz) can reduce progression of childhood IgA nephropathy (IgAN). This study examined whether Miz affects CD163+ M2-type macrophages which are associated with kidney fibrosis in childhood IgAN. METHODS: A retrospective cohort of 90 children with IgAN were divided into groups treated with prednisolone (PSL) alone (P group; n = 42) or PSL plus Miz (PM group; n = 48) for a 2-year period. Normal human monocyte-derived macrophages were stimulated with dexamethasone (Dex), or Dex plus Miz, and analyzed by DNA microarray. RESULTS: Clinical and histological findings at first biopsy were equivalent between patients entering the P and PM groups. Both treatments improved proteinuria and haematuria, and maintained normal kidney function over the 2-year course. The P group exhibited increased mesangial matrix expansion, increased glomerular segmental or global sclerosis, and increased interstitial fibrosis at 2-year biopsy; however, the PM group showed no progression of kidney fibrosis. These protective effects were associated with reduced numbers of glomerular and interstitial CD163+ macrophages in the PM versus P group. In cultured human macrophages, Dex induced upregulation of cytokines and growth factors, which was prevented by Miz. Miz also inhibited Dex-induced expression of CD300E, an activating receptor which can prevent monocyte apoptosis. CD300e expression by CD163+ macrophages was evident in the P group, which was reduced by Miz treatment. CONCLUSION: Miz halted the progression of kidney fibrosis in PSL-treated pediatric IgAN. This was associated with reduced CD163+ and CD163+CD300e+ macrophage populations, plus in vitro findings that Miz can suppress steroid-induced macrophage expression of pro-fibrotic molecules. A higher resolution version of the Graphical abstract is available as Supplementary information.

Background <p>Rituximab is the standard therapy for childhood-onset complicated frequently relapsing or steroid-dependent nephrotic syndrome (FRNS/SDNS). However, most patients redevelop FRNS/SDNS after peripheral B cell recovery. </p>Methods <p>We conducted a multicenter, randomized, double-blind, placebo-controlled trial to examine whether mycophenolate mofetil (MMF) administration after rituximab can prevent treatment failure (FRNS, SDNS, steroid resistance, or use of immunosuppressive agents or rituximab). In total, 39 patients (per group) were treated with rituximab, followed by either MMF or placebo until day 505 (treatment period). The primary outcome was time to treatment failure (TTF) throughout the treatment and follow-up periods (until day 505 for the last enrolled patient). </p>Results <p>TTFs were clinically but not statistically significantly longer among patients given MMF after rituximab than among patients receiving rituximab monotherapy (median, 784.0 versus 472.5 days, hazard ratio [HR], 0.59; 95% confidence interval [95% CI], 0.34 to 1.05, log-rank test: P=0.07). Because most patients in the MMF group presented with treatment failure after MMF discontinuation, we performed a post-hoc analysis limited to the treatment period and found that MMF after rituximab prolonged the TTF and decreased the risk of treatment failure by 80% (HR, 0.20; 95% CI, 0.08 to 0.50). Moreover, MMF after rituximab reduced the relapse rate and daily steroid dose during the treatment period by 74% and 57%, respectively. The frequency and severity of adverse events were similar in both groups. </p>Conclusions <p>Administration of MMF after rituximab may sufficiently prevent the development of treatment failure and is well tolerated, although the relapse-preventing effect disappears after MMF discontinuation. </p>

BACKGROUND: Several immunosuppressants have been used to treat children with steroid-dependent nephrotic syndrome (SDNS). Mizoribine (MZR) is an immunosuppressant used to maintain remission in children with SDNS, although its effectiveness for treating SDNS remains controversial. Therefore, in this study, we assessed the clinical factors associated with children having SDNS who were successfully treated with MZR. METHODS: A total of 47 children with SDNS who underwent MZR treatment were retrospectively evaluated. Clinical features including pharmacokinetics after MZR administration were compared between MZR responders and non-responders. RESULTS: The comparison of the two groups revealed no significant differences in age, body weight (BW), daily dose of MZR per BW, serum concentration 2 h after administration (C2), peak serum concentration (Cmax), and area under the concentration curve 0-4 h after administration (AUC0-4). C2/(single dose/BW), Cmax/(single dose/BW), and AUC0-4/(single dose/BW) were significantly higher in the MZR responders than in the non-responders (all p < 0.01). Receiver operating characteristic analysis revealed that the cutoff values of C2 (single dose/kg), Cmax/(single dose/BW), and AUC0-4/(single dose/BW) were 0.55, 0.58, and 1.37, respectively. CONCLUSIONS: MZR is a useful immunosuppressant for treating frequent-relapse NS in children who are susceptible to the drug. The efficacy of MZR may be associated with not only serum concentrations defined by the dosage or absorption efficiency through MZR transporters, but also the susceptibility defined by the expression level and performance of MZR transporters on the target cells.

Prevention of chronic kidney allograft injury (CAI) is a major goal in improving kidney allograft survival; however, the mechanisms of CAI are not clearly understood. The current study investigated whether alternatively activated M2-type macrophages are involved in the development of CAI. A retrospective study examined kidney allograft protocol biopsies (at 1 h and at years 1, 5, and 10-a total of 41 biopsies) obtained from 13 children undergoing transplantation between 1991 and 2008 who were diagnosed with CAI: interstitial fibrosis and tubular atrophy (IF/TA) not otherwise specified (IF/TA-NOS). Immunostaining identified a significant increase in interstitial fibrosis with accumulation of CD68 + CD163+ M2-type macrophages. CD163+ cells were frequently localized to areas of interstitial fibrosis exhibiting collagen I deposition and accumulation of alpha-smooth muscle actin (SMA) + myofibroblasts. There was a significant correlation between interstitial CD163+ cells and the parameters of interstitial fibrosis (p &lt; 0.0001), and kidney function (r =-0.82, p &lt; 0.0001). The number of interstitial CD163+ cells at years 1 and 5 also correlated with parameters of interstitial fibrosis at years 5 and 10 respectively. Notably, urine CD163 levels correlated with interstitial CD163+ cells (r = 0.79, p &lt; 0.01) and parameters of interstitial fibrosis (p &lt; 0.0001). However, CD3+ T lymphocytic infiltration did not correlate with macrophage accumulation or fibrosis. In vitro, dexamethasone up-regulated expression of CD163 and cytokines (TGF-beta 1, FGF-2, CTGF) in human monocyte-derived macrophages, indicating a pro-fibrotic phenotype. Our findings identify a major population of M2-type macrophages in patients with CAI, and suggest that these M2-type macrophages might promote the development of interstitial fibrosis in IF/TA-NOS.

Aims: New onset of the clinical symptoms of immunoglobulin A (IgA) nephropathy (IgAN) manifests with proliferative glomerular lesions in children, whereas adults exhibit mesangial matrix expansion and interstitial fibrosis. Alternatively, activated (M2) macrophages have been implicated in promoting tissue fibrosis in some settings. Therefore, the aim of this study was to investigate whether M2 macrophages are present in new-onset IgAN and if they are related to pathological differences between paediatric and adult disease. Methods and results: Biopsy specimens from paediatric (&lt; 10 years, n = 14; &gt; 12 years, n = 15) and adult (n = 27) IgAN showed a significant infiltrate of CD68+ macrophages. M2 macrophages, identified by CD163 or CD204 expression, were detected in glomeruli and the interstitium, being more prominent in adults versus young children. CD163+ and CD204+ macrophages were present in areas of fibrosis containing myofibroblasts, and double staining showed that CD163+ cells produced the profibrotic molecule, connective tissue growth factor. In young children, total CD68+ macrophages, but not M2 macrophages, correlated with glomerular hypercellularity. In contrast, in adults and older children, mesangial matrix expansion correlated with M2 macrophages but not with the total CD68+ macrophage infiltrate. Conclusions: Alternatively activated M2 macrophages are present in new-onset paediatric and adult IgAN, and this population may promote the development of fibrotic lesions.

The development of proteinuria and glomerulosclerosis in kidney disease is associated with podocyte damage, including down-regulation of nephrin and podocin. Macrophages are known to induce renal injury, but the mechanisms involved are not fully understood. This study examined macrophage-mediated podocyte damage. Conditioned media (CM) from activated macrophages caused a 50-60% reduction in nephrin and podocin nnRNA and protein expression in cultured mouse podocytes and rat glomeruli. This was abolished by a neutralizing anti-TNF alpha antibody. The addition of recombinant TNF alpha to podocytes OF glomeruli caused a comparable reduction in podocyte nephrin and podocin expression to that of macrophage CM. Inhibition of c-Jun amino terminal kinase (JNK) or p38 kinase abolished the TNF alpha-induced reduction in nephrin and podocin expression. This study demonstrates that activated macrophages can induce podocyte injury via a TNF alpha-JNK/p38-dependent mechanism. This may explain, in part, the protective effects of JNK and p38 blockade in experimental kidney disease. (C) 2008 Elsevier Inc. All rights reserved.

Recent clinical trials have shown a beneficial effect of mizoribine (Miz), an immunosuppressive drug, in the treatment of new-onset pediatric IgA nephropathy (IgAN). In this study, we evaluated the efficacy of Miz treatment in three children with established steroid-resistant IgAN. The patients had IgAN featuring persistent proteinuria and diffuse mesangial proliferation and had failed to respond to 2 years of treatment with prednisolone. Based upon the second biopsy results, patients were given methylprednisolone (mPSL) pulse therapy that induced a transient reduction in proteinuria, which was reversed when the mPSL dose was tapered. Miz therapy was then instigated in place of pulse mPSL. All three patients showed a substantial reduction in proteinuria and resolution of hematuria within 5 months. A follow-up biopsy in two of the patients showed a substantial reduction in the severity of glomerular lesions and a decrease in the number of activated macrophages. In conclusion, Miz therapy was found to be a safe and effective therapy in three cases of steroid-resistant pediatric IgAN. The ability of Miz to reduce the number of activated macrophages may be an important mechanism by which this drug ameliorated renal disease in these patients.

Background. It is suggested that IgA nephropathy (IgAN) manifests differently in children vs adults on the basis of biopsy findings. However, this has been difficult to establish owing to the uncertainty of the timing of disease onset in adult IgAN. We addressed this question by comparing both histology and leucocyte accumulation in biopsies of recently diagnosed childhood and adult IgAN. Methods. Biopsies taken within 2 years from the onset of renal abnormalities in 33 childhood (10 +/- 3 years of age) and 38 adult (35 +/- 6 years) cases of IgAN were examined for histological changes (cellularity in mesangial, endocapillary and extracapillary areas, matrix expansion, adhesions/crescents and interstitial damage), glomerular deposition of immunoglobulin and complement, and the presence of macrophages, activated macrophages and T cells by immunohistochemistry. Results. Glomerular hypercellularity owing to increased cells in mesangial area was prominent in paediatric IgAN and significantly greater than in adult IgAN. In contrast, glomerular matrix expansion, crescent formation and interstitial damage were more severe in adults compared to paediatric IgAN. Indeed, glomerular hypercellularity correlated with proteinuria in paediatric but not in adult IgAN, whereas glomerular matrix correlated with proteinuria and renal function in adult but not in paediatric IgAN. The degree of C3c deposition was significantly greater in paediatric IgAN, while deposition of fibrinogen was greater in adult IgAN. Glomerular and interstitial CD68+ macrophages and a subset of sialoadhesin (Sn)+ activated macrophages were identified in both paediatric and adult IgAN, being significantly greater in number in adult IgAN. Glomerular leucocyte infiltration correlated with proteinuria while interstitial leucocyte infiltration correlated with interstitial damage in both groups. However, only the subset of Sn+ macrophages gave a significant correlation with renal function, glomerular hypercellularity and glomerular matrix. Conclusions. This study has demonstrated significant differences in the early glomerular lesions of IgAN in children vs adults. Furthermore, Sn+ activated macrophages are implicated in the pathogenesis of IgAN in both patient groups. The prognostic significance of these findings warrants further study.

Background. Sialoadhesin ( Sn; CD169) is a lectin-like receptor whose expression is restricted to subsets of tissue and inflammatory macrophages. We have previously identified accumulation of Sn+ macrophages as an important marker of disease progression versus remission in rat mesangial proliferative nephritis. The current study examined the significance of Sn+ macrophages in human proliferative glomerulonephritis. Methods. Frozen kidney sections from normal adult human kidney ( n = 4) and pediatric nephropathy ( n 40) were stained for total macrophages ( CD68+ cells), Sn+ macrophages, CD3+ T-cells and collagen type I by immunofluorescence. Leukocyte infiltration and the severity of glomerular lesions and interstitial damage were scored. A second protocol biopsy was performed in 27 cases and clinical and biopsy-based data obtained. Results. Sn+ macrophages were absent from glomeruli in normal adult human kidney and in thin basement membrane disease ( n = 4), but were detected in 4 of 9 cases of purpura nephritis; 7 of 17 IgA nephropathy; 5 of 5 membranoproliferative glomerulonephritis, and 5 of 5 lupus nephritis. Sn+ macrophages were localized in areas of focal glomerular and interstitial damage. Two-colour immunostaining confirmed that Sn+ cells are a subset of total CD68+ macrophages. The number of glomerular Sn+ macrophages correlated with the degree of proteinuria and glomerular lesions ( r = 0.44, P = 0.0045 and r = 0.82, P &lt; 0.0001; respectively), while interstitial Sn+ macrophages correlated with the degree of proteinuria and interstitial damage ( r = 0.59, P &lt; 0.0001 and r = 0.75, P &lt; 0.0001; respectively). Combined immunostaining revealed that interstitial Sn+ macrophages and CD3+ T-cells co-localized in areas of tubulointerstitial damage with increased type I collagen deposition. There was significant correlation between the number of interstitial Sn+ macrophages and CD3+ T-cells ( r = 0.74, P &lt; 0.0001). Most patients responded to a 2 year period of glucocorticoid therapy with a reduction in proteinuria and glomerular lesions and this correlated with the reduction in the number of glomerular Sn+ macrophages. Conclusion. This study has identified Sn+ cells as a macrophage subset whose accumulation in the kidney correlates with proteinuria and histologic damage. These results, together with recent findings from animal studies, suggest that Sn+ macrophages may play an important role in progressive renal disease.

Background. Glomerular accmulation of leukocytes, including lymphocytes, is a common feature in most types of glomerulonephritis. However, the role of lymphocytes in progressive glomerulonephritis has not been elucidated. We examined the role of lymphocytes in the development of progressive mesangial proliferative glomerulonephritis induced by two injections of monoclonal antibody 1-22-3 in rats. Methods. To elucidate the role of lymphocytes, circulating lymphocytes were depleted using specific monoclonal antibodies to rat lymphocytes prior to the induction of progressive glomerulonephritis. The effects of lymphocyte depletion on proteinuria and glomerular alterations were assessed 7 and 56 days after the induction of progressive glomerulonephritis. Results. Significant glomerular accmulation of CD4+ T cells, CD8+ T cells, and ED3+-activated macrophage were observed after the induction of glomerulonephritis. Depletion studies showed that continuous treatment with anti-CD5, anti-CD4, or anti-CD8 treatment reduced proteinuria and ameliorated the glomerular lesions on day 56. Depletion of CD4+ T cells also reduced glomerular accmulation of CD8+ T cells and ED3+-activated macrophages, and reduced glomerular expression of mRNA for interferon-gamma (INF-gamma) (63.0% in anti-CD5 and 62.3% reduction in anti-CD4). Transit lymphocyte depletion limited in early stage of progressive glomerulonephritis demonstrated that CD4+ T-cell depletion, but not anti-CD8 treatment prevented glomerular injuries 56 days after the induction of progressive glomerulonephritis. Conclusion. CD4+ T cells played a central role in the development of progressive glomerulonephritis, controlling recruitment and activation of CD8+ cytotoxic cells and/or macrophages.

Macrophage accumulation is a prominent feature in most forms of human glomerulonephritis and correlates with renal dysfunction. Macrophages can directly mediate acute renal injury in animal models, but the mechanisms of macrophage activation required for mediating renal injury are unknown. This study examined whether activation of the Jun amino terminal kinase (JNK) signaling pathway is necessary for macrophage-mediated renal injury. An adoptive transfer model was used in which rats were immunized with sheep IgG (day -5), made leukopenic by administration of cyclophosphamide (CyPh) (day -2), and then injected with sheep anti-glomerular basement membrane (GBM) serum (day 0). Animals were then given an intravenous injection of bone marrow-derived macrophages (BMM) (day 1) and killed 24 h later (day 2). The induction of proteinuria and glomerular cell proliferation (PCNA(+) cells) in CyPh-treated anti-GBM disease was dependent on transfer of BMM. Exposure of BMM to the specific JNK inhibitor, SP600125, for 3 h before adoptive transfer had no effect on glomerular accumulation of BMM in CyPh-treated anti-GBM disease. However, SP600125 treatment of BMM caused a 75% reduction in proteinuria and a 70% reduction in glomerular cell proliferation (P &lt; 0.01 versus vehicle or untreated BMM). In conclusion, this study has defined a critical role for the JNK signaling pathway in macrophage-mediated renal injury.

Macrophages have been implicated in causing renal injury in both human and experimental kidney disease. The aim of the current study was to determine whether modulating the state of macrophage activation directly affects the capacity of these cells to cause renal injury. This was investigated using an adoptive transfer model in which macrophage activation can be manipulated in vitro, using interferon-gamma (IFN-gamma) or dexamethasone (Dex), and then macrophage-mediated renal injury determined in vivo. In this model, rats were made leukopenic by administration of cyclophosphamide (CyPh). Two days later (day 0), animals were injected with sheep anti-GBM serum followed by a single injection of rat NR8383 macrophages on day I and then killed 3 or 24 In after cell transfer. NR8383 macrophages were incubated IFN-gamma and/or Dex before adoptive transfer into animals. Induction of proteinuria and glomerular cell proliferation (PCNA+ cells) in this model was dependent on transfer of NR8383 macrophages. Exposure of macrophages to IFN-gamma for 18 h (but not 3 h) before transfer caused a twofold increase in the degree of proteinuria and glomerular cell proliferation compared with unstimulated cells (Nil versus IFN-gamma; P &lt; 0.001). This was due to an increase in the number of transferred macrophages within the glomerulus and a significant increase in degree of renal injury per transferred glomerular macrophage. IFN-gamma increased iNOS and PDGF-B gene expression and upregulated adhesion molecule expression in NR8383 macrophages. In contrast, exposure of NR8383 cells to Dex for 18 h (but not 1 h) abrogated renal injury due to a failure of transferred macrophages to accumulate within the glomerulus. In addition, Dex abrogated renal injury caused by IFN-gamma-stimulated macrophages. In conclusion, activation of macrophages by IFN-gamma, independent of any effect on other leukocytes or renal cells, can substantially augment macrophage-mediated renal injury. This IFN-gamma augmentation of renal injury is sensitive to the action of glucocor-ticoids, which act directly on macrophages to prevent their recruitment to the inflamed glomerulus. This study provides the first evidence that it is possible to directly modulate macrophage-mediated renal injury.

Background. Glomerular macrophage accumulation is a feature of proliferative human and experimental glomerulonephritis. However, our understanding of the role of macrophages in the induction of renal injury is based upon indirect evidence from depletion studies, most of which lack specificity for this cell type. Therefore, an adoptive transfer approach was used to directly assess the potential of macrophages to induce renal injury. Methods. Accelerated anti-glomerular basement membrane (anti-GBM) disease was induced in rats by immunization with sheep IgG (day -5), followed by administration of sheep anti-rat GBM serum (day 0), with animals killed on day 2. To facilitate the adoptive transfer studies, immunized animals were made leukopenic by cyclophosphamide (CyPh) given on day -2. Bone marrow-derived (BM) or NR8383 macrophages were transferred by tail vein injection 24 hours after injection of anti-GBM serum, with animals killed 3 or 24 hours after transfer. Results. Pretreatment with CyPh prevented glomerular leukocyte accumulation and completely inhibited proteinuria, glomerular cell proliferation and hypercellularity in accelerated anti-GBM disease. Adoptive transfer led to significant glomerular accumulation of BM or NR8383 macrophages within 3 hours of injection, and this was still evident 24 hours later. Adoptive transfer of BM or NR8383 macrophages induced proteinuria (63 +/- 16 BM vs. 5 +/- 2 mg/24 h CyPh control; P &lt; 0.001), glomerular cell proliferation (5.1 +/- 1.2 BM vs. 0.5 +/- 0.1 PCNA+ cells/gcs CyPh; P &lt; 0.001) and glomerular hypercellularity (51.2 +/- 2.0 BM vs. 41.9 +/- 0.9 nuclei/gcs CyPh; P &lt; 0.001). The degree of renal injury correlated with the number of transferred glomerular macrophages. Two-color immunostaining demonstrated that most glomerular proliferative cell nuclear antigen+ (PCNA+) proliferating cells were OX-7+ mesangial cells. CyPh treatment did not prevent up-regulation of glomerular intercellular adhesion molecule-1 (ICAM-1) and vascular cell adhesion molecule (VCAM-1) expression or an increase in urinary monocyte chemoattractant protein-1 (MCP-1) excretion. Conclusion. This study provides the first direct evidence that macrophages can induce renal injury in terms of proteinuria and mesangial cell proliferation.

Background. We established the reversible and the prolonged models of mesangial proliferative glomerulonephritis (GN) with anti-Thy 1 antibody 1-22-3. However, the essential factors leading to the prolonged glomerular alterations have not been identified. Methods. The expressions of several chemokines and cytokines were compared in the reversible and the prolonged models. Expression of fractalkine and the number of the fractalkine receptor CX3 CR1-positive cells in the glomeruli in the prolonged model were significantly higher than those in the reversible model. Then, the localization of fractalkine and the characteristics of CX3 CR1(+) cells were analyzed in glomeruli. To elucidate the significance of the fractalkine expression, we analyzed the expression in the model treated with angiotensin II receptor antagonist, candesartan. Results. Immunostaining of fractalkine was detected on endothelial cells on the fifth day, and fractalkine staining also was detected in the mesangial area on day 14. Major parts of the CX3 CR1(+) cells in the glomeruli were macrophages, especially ED3(+) cells. Candesartan treatment ameliorated the glomerular morphological findings at six weeks after disease induction. Although the treatment did not ameliorate the morphological finding at two weeks, decreased expression of fractalkine and CX3 CR1(+) were already detected at two weeks in rats treated with candesartan. Conclusions. Fractalkine expression and the recruitment of CX3 CR1(+) cells in glomeruli might play an important role in the development of the prolonged disease. These expressions could be predictors of the prolonged disease of the mesangial proliferative glomerulonephritis.

Background. We have previously reported that CD4 T lymphocytes and their cytokines contribute to development of Thy 1.1 glomerulonephritis (GN). FK506 is reported to suppress the production of Th1 cytokines. The aims of this study were to elucidate the role of Th1 cytokines on mesangial alteration and to examine whether FK506 is available for therapy of mesangial proliferative GN. Methods. The effects of daily treatments of FK506 from day -5 and from day +1 of Thy 1.1 GN induction on glomerular alterations were analyzed. Results. FK506 treatment with 1.0 and 0.3 mg/kg body weight (BW) daily from day 1 to day 4 significantly reduced the glomerular expression of mRNA for interferon-gamma (IFN-gamma; 1.0 mg/kg BW FK506, 32.4% to the placebo group, P &lt; 0.01) and IL-2 (55.6%, P &lt; 0.01) on day 5. FK506 treatment from day -5 of GN induction reduced proteinuria and glomerular alteration in a dose-dependent manner. Although no side effects were detected in rats with 0.3 mg/kg BW of FK506 treatment from day +1, the treatment also ameliorated proteinuria (day 14, 3.7 +/- 0.89 vs. 19.8 +/- 12.3 mg/100 g BW/day P &lt; 0.05) and glomerular alterations [total cell number, 63.1 +/- 3.1 vs. 80.2 +/- 7.4, P &lt; 0.01; matrix expansion, 0.90 +/- 0.30 vs. 1.34 +/- 0.27, P &lt; 0.05; &alpha;-smooth muscle actin (&alpha;SMA) expression; 1.20 +/- 0.12 vs. 1.96 +/- 0.29, P &lt; 0.01] on day 14. Conclusion. Th1 cytokines may play an important role in the development of mesangial proliferative glomerulonephritis, and could be targets for therapy. FK506 might be available for clinical use.

Background. From the observations of morphology seen in early phases of the experimental models of the irreversible mesangial proliferative glomerulonephritis, we hypothesized that podocyte injury is one of the important factors in bringing upon irreversible glomerular alterations. To verify this hypothesis, we investigated whether podocyte injury induced by puromycin aminonucleoside (PAN) injection affects the mesangial alterations of anti-Thy 1.1 glomerulonephritis. Methods. Female Wistar rats were injected with 0.5 mg monoclonal antibody (mAb) 1-22-3 five days after the injection of 10 mg or 5 mg/100 g body weight (BW) of puromycin aminonucleoside (PAN), and sacrificed at 7 days or 8 weeks after the mAb 1-22-3 injection. Results. Consecutive injections of 10 mg/100 g BW of PAN and mAb 1-22-3 caused the irreversible mesangial alteration with persistent proteinuria (at week 8, proteinuria 100.3 ± 57.8 mg/24 h, matrix score 1.13 ± 0.52, collagen type I score 2.04 ± 0.53, mRNA for collagen type I 227 ± 79% to the group with a single injection of 1-22-3). Although single injection of 5 mg/100 g BW of PAN was not capable of inducing abnormal proteinuria, consecutive injections of 5 mg/100 g BW of PAN and mAb 1-22-3 also caused irreversible mesangial alteration and persistent proteinuria. Conclusions. Podocyte injury might be an important factor that exacerbates mesangial proliferation and mesangial matrix expansion. The irreversible mesangial alterations caused by consecutive injections of PAN and mAb 1-22-3 may be a novel model that could be used to analyze the mechanism of progressive mesangial alteration.

Background: Increased numbers of lymphocytes have been identified in biopsy specimens of human mesangial proliferative glomerulonephritis (GN). However, the causal relationship between infiltrating T lymphocytes and mesangial changes in mesangial proliferative GN has not been previously evaluated. In this study, we elucidated the role of lymphocytes in the development of mesangial proliferative GN. Method: Immunohistological and flow cytometric analyses as well as a reverse transcription-polymerase chain reaction (RTPCR) studies were performed in monoclonal antibody (mAb) 1-22-3- induced Thy 1.1 GN. To elucidate the role of these lymphocytes, depletion studies were carried out using anti-CD8 mAb (OX-8), which depletes both CD8+ T lymphocytes and natural killer (NK) cells and anti-CD5 mAb (OX-19), which depletes both CD4+ and CD8+ T lymphocytes. Results: Immunofluorescence (IF) studies revealed that NK cells and CD4+ T lymphocytes were recruited into glomeruli. Glomerular mRNA expression for interferon-γ interleukin-2 (IL-2), IL-10, and perforin increased after induction of GN. Increased expressions of several chemokines, which have the potential to attract lymphocytes, were also detected. Anti-CD8 mAb treatment completely prevented the recruitment of NK cells: however, it had no protective effect on proteinuria and mesangial injury. By contrast, anti-CD5 mAb treatment suppressed the recruitment of CD4+ T lymphocytes into glomeruli and reduced proteinuria (60.4 ± 25.7 vs. 120.0 ± 32.3 mg/day, P &lt 0.05) and mesangial changes evaluated by total number of cells in glomeruli (63.2 ± 6.0 vs. 81.4 ± 5.9, P &lt 0.01) and α- smooth muscle actin staining score (1.4 ± 0.2 vs. 2.2 ± 0.4, P &lt 0.01) on day 14 after induction of GN. mRNA expression for IL-2 was significantly reduced by OX-19 treatment. Conclusion: T lymphocytes participate in the development of mesangial proliferative GN.