Infection-related glomerulonephritis (IRGN) is an immunologically mediated glomerular injury triggered by an extrarenal infection. Infective endocarditis-associated glomerular nephritis is an entity caused by infection of the cardiac valves. IRGN is most common in children, and post-streptococcal glomerulonephritis (PSGN) is commonest in the age group of 2-14 years. In contrast to childhood PSGN and epidemic PSGN, which usually resolve completely with antibiotics, IRGN in adults has a guarded prognosis. Cardiovascular implantable electronic device-associated infective endocarditis (CIED-IE) is a phenomenon for which the incidence is on the rise (0.1-5.1%). The most frequent CIED-IE pathogens were staphylococci or other Gram-positive bacteria. CIED-IE poses difficult management problems for the clinician. We present the case of a 50-year-old patient with a pacemaker who was found to have infective endocarditis and septic embolism.

OBJECTIVE: With the in-depth study of complement dysregulation, glomerulonephritis with dominant C3 has received increasing attention, with a variety of pathologic types and large differences in symptoms and prognosis between pathologic types. This study analyzes the clinical, pathological, and prognostic characteristics of different pathological types of glomerulonephritis with dominant C3, aiming to avoid misdiagnosis and missed diagnoses.
METHODS: The clinical, pathological, and follow-up data of 52 patients diagnosed as glomerulonephritis with dominant C3 by renal biopsy from June 2013 to October 2022 were retrospectively analyzed. According to the clinical feature and results of pathology, 15 patients with post-infectious glomerulonephritis (PIGN) and 37 patients with of non-infectious glomerulonephritis (N-PIGN) were classified. N-PIGN subgroup analysis was performed, and 16 patients were assigned into a C3-alone-deposition group and 21 in a C3-dominant-deposition group, or 27 in a C3 glomerulopathy (C3G) group and 10 in a non-C3 nephropathy (N-C3G) group.
RESULTS: The PIGN group had lower creatinine values (84.60 μmol/L vs179.62 μmol/L, P=0.001), lower complement C3 values (0.36 g/L vs0.74 g/L, P<0.001) at biopsy, and less severe pathological chronic lesions compared with the N-PIGN group. In the N-PIGN subgroup analysis, the C3-dominant-deposition group had higher creatinine values (235.30 μmol/L vs106.70 μmol/L, P=0.004) and higher 24-hour urine protein values (4 025.62 mg vs1 981.11 mg, P=0.037) than the C3-alone-deposition group. The prognosis of kidney in the PIGN group (P=0.049), the C3-alone-deposition group (P=0.017), and the C3G group (P=0.018) was better than that in the N-PIGN group, the C3-dominant-deposition group, and the N-C3G group, respectively.
CONCLUSIONS: Glomerulonephritis with dominant C3 covers a variety of pathological types, and PIGN needs to be excluded before diagnosing C3G because of considerable overlap with atypical PIGN and C3G; in addition, the deposition of C1q complement under fluorescence microscope may indicate poor renal prognosis, and relevant diagnosis, treatment, and follow-up should be strengthened.
目的: 随着对补体失调研究的深入，以C3沉积为主的肾小球肾炎日益受到关注，其病理类型多样，且病理类型间症状及预后差异具有异质性。为避免误诊及漏诊，本研究分析不同病理类型C3沉积为主的肾小球肾炎的临床、病理及预后特点。方法: 回顾性分析52例2013年6月至2022年10月行肾活检诊断为以C3沉积为主肾小球肾炎患者的临床、病理及随访资料。根据临床表现以及病理检查结果分为感染后肾小球肾炎(post-infectious glomerulonephritis，PIGN)组(n=15)和非感染后肾小球肾炎(non-post-infectious glomerulonephritis，N-PIGN)组(n=37)。进一步行N-PIGN亚组分析，分为C3独立沉积组(n=16)与C3复合沉积组(n=21)，或C3肾病(C3 glomerulopathy，C3G)组(n=27)与非C3肾病(N-C3G)组(n=10)。结果: PIGN组相较于N-PIGN组，活检时血清肌酐值更低(84.60 μmol/L vs 179.62 μmol/L，P=0.001)，补体C3值更低(0.36 g/L vs0.74 g/L，P<0.001)，病理慢性化病变程度更轻。在N-PIGN亚组分析中，C3复合沉积组较C3独立沉积组血清肌酐值更高(235.30 μmol/L vs106.70 μmol/L，P=0.004)，24 h尿蛋白值更高(4 025.62 mg vs1 981.11 mg，P=0.037)。PIGN组的预后好于N-PIGN组(P=0.049)，C3独立沉积组的预后好于C3复合沉积组(P=0.017)，C3G组的预后好于N-C3G (P=0.018)。结论: C3沉积为主的肾小球肾炎涵盖多种病理类型，诊断C3G前需先排除PIGN，但对于非典型PIGN患者仍需要警惕C3G叠加或者相互转化；此外，荧光显微镜下经典补体C1q的沉积可能提示肾预后不良，应加强相关诊治与随访。.

Syphilis is a curable sexually transmitted infection caused by the spirochete Treponema pallidum. Its clinical manifestations are variable as it has a remarkable aptitude to imitate a spectrum of clinical pictures. This phenomenon has bestowed upon it the epithet \"the great imitator\" within the medical literature. The escalating global prevalence of syphilis cases underscores the importance of shedding light on its rare manifestations. Syphilitic nephropathy is an uncommon manifestation of secondary syphilis. Here, we report two cases of syphilis-related nephropathy, the first presented as a nephrotic syndrome, and the second as a nephritic syndrome. Both cases had a favorable outcome after treatment of syphilis with benzathine penicillin G.

Post-infectious glomerulonephritis (PIGN) is an immune complex mediated glomerular injury occurring because of an infection, most commonly with group A beta-hemolytic streptococcus in children. C3 glomerulopathy (C3G) is a distinct clinicopathological entity occurring secondary to dysregulation of alternate complement pathway encompassing both C3 glomerulonephritis (C3GN) and dense deposit disease (DDD). While most patients with PIGN attain complete remission with normalized complement levels by 6-8 weeks after presentation, patients with C3G continue to have hypocomplementemia with high rates of progressive kidney disease. Here, we report a patient diagnosed with dense deposit disease after his initial presentation with PIGN three years prior. While current literature continues to explore the overlapping and distinguishing features of PIGN and C3G, including how underlying defects in the alternate complement pathway may commonly contribute to both diseases, this case further exemplifies the importance of recognizing the clinico-pathogenic features of PIGN and C3G in pediatric patients with glomerulonephritis.

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Glomerulonephritis (GN) is a complex disease with intricate underlying pathogenic mechanisms. The possible role of underlying complement dysregulation is not fully elucidated in some GN subsets, especially in the setting of autoimmunity or infection. In the current study, diagnosed cases of lupus nephritis (LN) and post-infectious GN (PIGN) were recruited for molecular genetic analysis and targeted next-generation DNA sequencing was performed for two main complement regulating genes: in the fluid phase; CFH, and on tissue surfaces; MCP. Three heterozygous pathogenic variants in CFH (Q172*, W701*, and W1096*) and one likely pathogenic heterozygous variant in MCP (C223R) have been identified in four of the studied LN cases. Additionally, among the several detected variants of uncertain significance, one novel variant (CFH:F614S) was identified in 74% of the studied LN cases and in 65% of the studied PIGN cases. This variant was detected for the first time in the Egyptian population. These findings suggest that subtle mutations may be present in complement regulating genes in patients with immune-complex mediated category of GN that may add to the disease pathogenesis. These findings also call for further studies to delineate the impact of these gene variants on the protein function, the disease course, and outcome.

The clinical trajectory for patients with primary membranous nephropathy ranges widely from spontaneous remission to a rapid decline in kidney function. Etiologies for rapid progression with membranous nephropathy include concurrent bilateral renal vein thrombosis, malignant hypertension, and crescentic membranous nephropathy. Given the wide heterogeneity in prognosis, timing of immunosuppressive therapy is often challenging and centers around an individual patient\'s perceived risk for rapidly progressive disease.
Herein, we describe the clinical course of a young patient who initially developed a typical presentation of membranous nephropathy with consistent kidney biopsy findings. Given clinical stability, a six month observation period was undertaken prior to initiating immunosuppression. Within this observation window, the patient developed community acquired pneumonia followed several weeks later by a sudden, rapid decline in kidney function requiring dialysis. Repeat kidney biopsy revealed post-infectious glomerulonephritis superimposed upon a background of membranous nephropathy. Immunosuppressive therapy resulted in a favorable long-term outcome with normalization of kidney function and remission of nephrotic syndrome. To our knowledge, this is the first report of the simultaneous occurrence of these two glomerular disease processes.
This case illustrates the value of repeat kidney biopsy during an atypical course of membranous nephropathy. Superimposed glomerular disease processes should be considered during a course of rapidly progressive membranous nephropathy.

The timely diagnosis and treatment of post-infectious glomerulonephritis (PIGN) is currently limited by the erased and low-symptom nature of the disease, which leads to the search for informative biological markers of the disease, which can be used as immunological indicators of blood and urine. The study was carried out in order to establish the characteristic changes in the immunological parameters of blood and urine in patients with PIGN. The study included 60 patients with PIGN from among the patients, hospitalized in the nephrology department of the Republican Clinical Hospital of Health Care Ministry of the Chuvash Republic in 2015-2018. In addition to the generally accepted research methods, the patients underwent: 1) the determination of indicators of innate and acquired immune response in the blood (CD3+ -, CD3+ CD4+-, CD3+CD8+-, CD4+CD25+-, CD95+-, CD20+-, CD14+CD282+-, CD14+CD284+- cells; levels of IgG, IgA, IgM, circulating immune complexes, C3, C4) and urine (levels of IgG, IgA, IgM, C3, C4); 2) the determination of the levels of cytokines - IL-1β, Ra-IL-1β, IL-2, IL-4, IL-8, IL-10, IL-17A in blood serum and urine. The data obtained were compared with those of the group of healthy individuals. The changes in blood immunological parameters, identified in the group of patients with PIGN, indicate the activation of innate immunity (the increase in the number of CD14+TLR2+- cells) and the humoral component of adaptive immunity (the increase in the number of B-lymphocytes, hyperimmunoglobulinemia - the increase in IgM and IgA levels) against the background of the decrease in the number of T (CD3+) - lymphocytes and regulatory (CD4+CD25high) - cells, hypocomplementemia (decreased levels of C3, C4). The increase in the content of C3, IgG and IgA was found in the urine. The cytokine profile of blood in patients with PIGN was characterized by the increase in the levels of pro- and anti-inflammatory cytokines IL-1β, Ra-IL-1β, IL-2, IL-8, IL-10, IL-17A, with the exception of IL-4, which remained on the levels of healthy individuals. The cytokine profile of urine in patients was characterized by the increase in the levels of pro-inflammatory cytokines IL-1β, IL-2, IL-8, IL-17A and anti-inflammatory cytokine - IL-10, with no changes in the content of Ra-IL-1β and IL-4. The revealed features of the immunological profile of blood and urine in patients with PIGN reflect the immunopathogenetic mechanisms of this disease.

Acute post-infections glomerulonephritis (APIGN) is a frequent cause of glomerulonephritis and represents the most common cause of acute glomerulonephritis in children. It can evolve to severe acute renal failure and chronic kidney disease or even end-stage kidney disease. The precise pathophysiological mechanisms of APIGN are still incompletely understood. The implication of the alternative complement pathway and the potential benefits of C5 blockade have been recently highlighted, in particular in the presence of a C3 Nephritic Factor (C3Nef), anti-Factor B or H autoantibodies. We report two children with severe APIGN, successfully treated with eculizumab. The first patient presented a severe form of APIGN with advanced renal failure and anuria, associated with a decreased level of C3 and an increased level of soluble C5b-9, in the presence of a C3NeF autoantibody. The second case had a severe oliguric APIGN associated with low C3 level. Kidney biopsy confirmed the diagnosis of APIGN in both cases. Eculizumab allowed full renal function recovery and the avoidance of dialysis in both cases. In conclusion, the alternative and terminal complement pathways activation might be common in PIGN, and in severe cases, eculizumab might help.