池住 洋平

症例は5歳女児で、発熱、悪心、胸痛を主訴とした。砂遊びによる両手指の慢性湿疹に対して外用加療中であり、近医受診後も発熱が持続し、入院時には胸骨直上に辺縁不明瞭な発赤、腫脹を認め、CT検査で胸骨体の両側に低吸収帯を認めた。感染症の疑いで抗菌薬治療を開始し、血液培養でメチシリン耐性黄色ブドウ球菌(MRSA)が同定されたため、バンコマイシン(VCM)を併用した。その結果、解熱と胸痛の軽快が得られ、MRSAによる原発性胸骨骨髄炎と診断した。その後はCRP陰性化を確認してリネゾリド内服に変更し、VCMと併せて計6週間の抗MRSA薬による治療を行ったところ、炎症の再燃や血小板減少は認めなかった。本症例では手指の慢性湿疹が感染経路と考えられ、慢性湿疹を背景に持つ患児では薬剤耐性菌による全身性の感染症に留意する必要があると考えられた。

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.

Thrombotic microangiopathy (TMA) is a disease that causes organ damage due to microvascular hemolytic anemia, thrombocytopenia, and microvascular platelet thrombosis. Streptococcus pneumoniae-associated TMA (spTMA) is a rare complication of invasive pneumococcal infection. In addition, atypical hemolytic uremic syndrome (aHUS) is TMA associated with congenital or acquired dysregulation of complement activation. We report the case of a nine-month-old boy with refractory nephrotic syndrome complicated by spTMA in the setting of heterozygous complement factor-I (CFI) gene mutation and CFHR3-CFHR1 deletion. He repeatedly developed thrombocytopenia, anemia with schistocytes, hypocomplementemia, and abnormal coagulation triggered by infection, which manifested clinically with convulsions and an intraperitoneal hematoma. Eculizumab (a monoclonal humanized anti-C5 antibody) provided transient symptomatic benefit including improvement in thrombocytopenia; however, he developed unexplained cardiac arrest and was declared brain dead a few days later. In this report, we highlight the diagnostic challenges of this case and the causal relationship between spTMA and complement abnormalities and consider the contribution of heterozygous mutation of CFI and CFHR3-CFHR1 deletion.

Abstract Alport syndrome is a hereditary disorder characterized by renal impairment, hearing loss, and ocular symptoms and is caused by COL4A3, COL4A4, and COL4A5 mutations. Here, we report the case of 3-year-old boy with isolated hematuria detected in routine preventative urinary screening conducted in 3-year-old children. He carried a novel variant, NM_033380.3:c. 1032 + 1 G > A, which caused a splicing abnormality in COL4A5. He was diagnosed with X-linked Alport syndrome.

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>