Histological heterogeneity of glomerular segmental lesions in focal segmental glomerulosclerosis

Focal segmental glomerulosclerosis (FSGS) involves considerable histological heterogeneity in terms of location and quality of the glomerular segmental lesions. The present study investigated the heterogeneity of segmental lesions in each variant of FSGS, determined by the Columbia classification, and its clinical relevance. All glomerular segmental lesions of 80 cases of primary FSGS were evaluated histologically based on location [tip (TIP), perihilar (PH), or not otherwise specified (NOS)], and quality (cellular or fibrous). Among the 1,299 glomeruli of the 80 biopsy specimens, 210 glomeruli (16.2%) had segmental lesions, comprising 57 (27%) cellular TIP, 4 (2%) fibrous TIP, 42 (20%) cellular NOS, 86 (41%) fibrous NOS, and 21 (10%) fibrous PH lesions. Each case was also classified into one of the five histological variants of the Columbia classification: collapsing (COL), TIP, cellular (CEL), PH, or NOS. Overlap of segmental lesions in different location categories was seen in the COL, TIP, and PH variants, and heterogeneity of quality was apparent in the COL and CEL variants. Histological findings of the CEL variant (endocapillary hypercellularity) were observed in nine of the 13 COL variants. Both location and quality correlated with disease duration, degree of proteinuria, and histological severity of global glomerular sclerosis and tubulo-interstitial lesions. These results demonstrated the histological heterogeneity of glomerular segmental lesions in all variants of the Columbia classification, except NOS. However, the fidelity of location and dominance of histological features were generally conserved in the TIP and PH variants. The COL and CEL variants warrant further investigation because of their overlapping histological findings and apparent histological heterogeneity in the glomerular segmental lesions

高糖条件下でのラット腹膜中皮細胞におけるMAPKの動態

腹膜硬化症は腹膜透析の重大な合併症であり,誘因の一つとして長期にわたる腹膜への高糖暴露が報告されているが,その発症機序に関しては不明な点が多い.腹膜中皮細胞は透析液による暴露を最も受ける細胞である.今回我々は,培養腹膜中皮細胞に高糖刺激を行い, mitogen-activated protein kinase (MAPK)の動態を評価した.ラット腹膜中皮細胞は 0.5% FCS含有DMEM培地で24時間培養した後, 4%グルコースと4%マニトール刺激を行った.細胞増殖能はWST-1法を用いて測定し,上清中のfibronectin (FN)およびMAPKの変化はWestern blottingで半定量化した. FN mRNAの変化はRT-PCRで判定した. 4%グルコースと4%マニトール刺激は,いずれも経時的にFN mRNAとFN蛋白を増加させた.また, 4%グルコースと4%マニトール刺激は,いずれもMAPKのうちextracellular signal-regulated kinase (ERK)とp38MAPKを活性化し, MAPK阻害剤で4%グルコースによるFN mRNA増加は抑制された.最後に, 4%グルコース刺激によるFNの増加は, transforming growth factor (TGF)-β中和抗体の添加で抑制されず,培養上清中へのTGF-βの分泌増加を伴わなかった.これらの結果より,高糖刺激によるFNの増加には, TGF-βを介さないMAPKの活性化が関与していると考えられた.同濃度のマニトール刺激でも,グルコースと同様に MAPKの活性化やFNの増加が見られたことから,高糖刺激は浸透圧刺激として作用したものと思われた.したがって,高糖刺激によりMAPKが活性化された結果として,腹膜中皮細胞によるFNの産生が亢進し,腹膜線維化を惹起していることが示唆された.Peritoneal fibrosis is a serious complication in long-term continuous ambulatory peritoneal dialysis (CAPD) patients, but the underlying mechanism is not well understood. Since high glucose activates the p38 mitogen-activated protein kinase (MAPK) pathway in various kinds of cells, and because mesothelial cells always exposed to high glucose dialysate, we investigated the involvement of MAPK in rat peritoneal mesothelial cells (PMCs) under high glucose conditions. Rat PMCs were grown in Dulbecco\u27s modified Eagle\u27s medium with 0.5% FBS in 24 hours and then exposed to 4% glucose or 4% mannitol. Cell viability was assessed by using WST-1 assay. Fibronectin (FN) accumulation in the supernatant was determined by Western blot. Reverse transcription-polymerase chain reaction (RT-PCR) and Western blot were performed to determine mRNA and protein expression, respectively. High glucose and mannitol caused time-dependently increase in FN accumulation and FN mRNA in rat PMCs. High glucose also activated the extracellulaer signal-regulated kinase (ERK) and p38 MAPK. These increase in FN accumulation were not inhibited with anti-transforming growth factor (TGF)-β neutralizing antibody. Moreover, high glucose does not promote TGF-β accumulation in the culture media. Therefore, MAPK pathway may play an important role in high glucose-induced FN accumulation via TGF-β-independent mechanism. It is considered that high glucose acts as osmotic stimulation in the regulation of FN production in these cells. Taken together, these findings suggest that the activation of MAPK signaling pathways in rat PMCs by high glucose may contribute to the pathogenesis of peritoneal fibrosis in CAPD therapy

IgA腎症患者における血清vascular endothelial growth factor濃度と疾患活動性

当教室で腎生検によりIgA腎症と組織診断が得られ,臨床データ解析が可能であった31症例を対象とした.対照として,22例の健常者から採血した.IgA腎症は,軽症群と進行群に分けて検討した.比較症例として,IgA沈着を認めない巣状糸球体硬化症(FGS)を無作為に選択した.すべての症例はインフォームドコンセントを得たのち検討した.IgA腎症における疾患活動性を判定するために,血清vascular endothelial growth factor (VEGF)濃度の測定が有用であるか検討するのが,本研究の目的である.血清VEGF濃度は,VEGF_とVEGF_を認識する2種類の抗体を用いたsandwich ELISAで測定した.疾患活動性として,一日尿蛋白量,血尿の程度,クレアチニン・クリアランス(Ccr)および糸球体における半月体形成率を用いた.進行群のIgA腎症における血清VEGF濃度(70.6±7.8pg/ml)は,健常者(22.6±3.8pg/ml),軽症群のIgA腎症(374±3.8pg/ml)およびFGS症例(34.1±4.9pg/ml)に比し,有意に高値を示した(p<0.01).また,IgA腎症においては,半月体形成率の多い群で,血清VEGF濃度は有意に高値を示した(p<0.01).血尿の程度との相関はなかったが,進行群のIgA腎症における血清VEGF濃度と尿蛋白量との間には,正の相関(r=0.54,p<0.05)が認められた.よって,IgA腎症の血清VEGF濃度は,疾患活動性を反映している可能性がある.To investigate if serum levels of vascular endothelial growth factor (VEGF) reflect disease activity of IgA nephropathy, the serum VEGF levels were measured in 31 patients with IgA nephropathy and 13 patients with focal glomerulosclerosis (FGS) without glomerular IgA deposition as controls using a sandwich ELISA method. The serum VEGF levels of patients with advanced stage IgA nephropathy (70.59 ± 7.84 pg/ml) were significantly higher than those in mild stage IgA nephropathy (37.36 ± 3.8 pg/ml), FGS (34.14 ± 4.87 pg/ml) and the healthy controls (22.6 ± 3.8 pg/ml). The results demonstrated that advanced stage IgA nephropathy patients with heavy proteinuria and the presence of glomerular crescents had high serum VEGF levels. This suggested that measurement of serum VEGF levels is potentially useful in evaluating the degree of renal injury in patients with IgA nephropathy

IgA腎症患者に対するアンジオテンシン受容体拮抗薬の治療効果

IgA腎症患者に対するアンジオテンシン受容体拮抗薬(ARB)の蛋白尿減少効果を,男性7例,女性10例の計17症例で検討した.このうち,15例はlosartanで,2例はcandesartanで加療した.加療後,30%以上の蛋白尿減少を認めた群をresponder(R)群,それ以外をnon-responder(NR)群としたところ,R群は9例,NR群は8例であった.両群間にステロイドやACE阻害薬の併用など,臨床上の有意差は認めなかった.また,病理組織学的にも両群間に有意差を認めなかった.一方,R群ではARBの治療前後において,平均血圧(MAP)を有意に低下させたが,NR群では降圧効果を認めなかった.また,ARBによる降圧効果と蛋白尿減少効果は相関することも明らかになった.以上より,ARBはlgA腎症患者に対し,血圧に依存して蛋白尿を減少させると考えられる.The aim of the present study was to examine the antiproteinuric effects of two angiotensin II receptor blockers (ARB), losartan and candesartan, in patients with IgA nephropathy. Seventeen patients (7 men and 10 women; mean age, 43.2 ± 12.9 years) were enrolled in this study. Fifteen patients was given 12.5～100 mg/day of losartan, and two patients ware given 2～8 mg/day of candesartan. Nine patients responded to the treatment (R group) and 8 patients did not (NR group). The clinical parameters, including the percentage of patients who also received steroid or angiotensin-converting enzyme inhibitor combination therapy, were not significantly different between the groups. The administration of an ARB significantly reduced the proteinuria from a basal value of 1.0 ± 0.4 g/day to 0.4 ± 0.4 g/day (p<0.05), with this effect appearing 3.0 ± 2.2 months after the start of treatment. An additional reduction in proteinuria was observed when the ARB dose was increased in the R group, but this effect was not observed in the NR group. Moreover, the ARB treatment significantly reduced the mean arterial pressure (MAP) from a basal value of 98.2 ± 12.8 mmHg to 90.5 ± 13.3 mmHg in the R group (p<0.05). However, the MAP remained unchanged throughout the study in the NR group (93.8 ± 16.8 vs. 99.6 ± 10.7 mmHg). After the ARB treatment, a weak but significant correlation was found when the MAPs were compared with the levels of proteinuria (r=0.271, p=0.024). Finally, no significant difference in the pathological factors of the two groups was observed. In conclusion, our study shows that, the addition of an ARB to the conventional therapy for IgA nephropathy has an additive anti-proteinuric effect that is related to a reduction in blood pressure

Neutral solution low in glucose degradation products is associated with less peritoneal fibrosis and vascular sclerosis in patients receiving peritoneal dialysis.

♦ Background: The effects of novel biocompatible peritoneal dialysis (PD) solutions on human peritoneal membrane pathology have yet to be determined. Quantitative evaluation of human peritoneal biopsy specimens may reveal the effects of the new solutions on peritoneal membrane pathology. ♦ Methods: Peritoneal specimens from 24 PD patients being treated with either acidic solution containing high-glucose degradation products [GDPs (n = 12)] or neutral solution with low GDPs (n = 12) were investigated at the end of PD. As controls, pre-PD peritoneal specimens, obtained from 13 patients at PD catheter insertion, were also investigated. The extent of peritoneal fibrosis, vascular sclerosis, and advanced glycation end-product (AGE) accumulation were evaluated by quantitative or semi-quantitative methods. The average densities of CD31-positive vessels and podoplanin-positive lymphatic vessels were also determined. ♦ Results: Peritoneal membrane fibrosis, vascular sclerosis, and AGE accumulation were significantly suppressed in the neutral group compared with the acidic group. The neutral group also showed lower peritoneal equilibration test scores and preserved ultrafiltration volume. The density of blood capillaries, but not of lymphatic capillaries, was significantly increased in the neutral group compared with the acidic and pre-PD groups. ♦ Conclusions: Neutral solutions with low GDPs are associated with less peritoneal membrane fibrosis and vascular sclerosis through suppression of AGE accumulation. However, contrary to expectation, blood capillary density was increased in the neutral group. The altered contents of the new PD solutions modified peritoneal membrane morphology and function in patients undergoing PD