Bacterial infection-related glomerulonephritis in adults

Drowning in Fluid: Post-infectious Glomerulonephritis Presenting as Acute Heart Failure

Staphylococcal infection is as common as streptococcal infection as a cause of infection-related glomerulonephritis (IRGN). It is seen more frequently in the pediatric population and is relatively rare in adults. Glomerular disease manifests as either nephritic or nephrotic syndrome. A high index of suspicion is necessary for diagnosing this condition as it can be mistaken for other common conditions in the elderly. IRGN may present as volume overload and may masquerade as cardiorenal syndrome type 1 in patients with preexisting heart failure, emphasizing the importance of distinguishing between the two because the treatment and prognosis may be different. We present an older adult male who was evaluated for suspected acute decompensation of heart failure in the setting of recent left knee septic arthritis and was found to have IRGN. This diagnosis may be delayed or missed due to it mimicking similar conditions and it requires a high index of suspicion.

Outcomes of patients with infective endocarditis-associated acute kidney injury: a retrospective cohort study

Background

The outcomes of patients with infective endocarditis (IE)-associated acute kidney injury (AKI) are poorly understood.

Methods

This retrospective cohort study was conducted in a tertiary hospital in China to analyze the short- and long-term outcomes among patients with IE-associated AKI. The risk factors for 90-day mortality, long-term outcomes and kidney non-recovery were analyzed via multivariable logistic regression, the Cox regression, and the Fine-Gray competing risk model, respectively.

Results

Among 294 patients with IE-associated AKI, 14.3% died within 90 days, and the risk factors for 90-day mortality were similar to those identified in the general IE population. Among the 230 AKI survivors in whom 90-day kidney recovery could be assessed, 17.4% did not recover kidney function at 90 days. Kidney non-recovery at 90 days was associated with an increased risk of the long-term composite outcome of mortality, end-stage renal disease or sustained doubling of serum creatinine [hazard ratio (HR) 3.00, 95% confidence interval (CI) 1.19-7.59]. Five variables were related to kidney non-recovery: low baseline estimated glomerular filtration rate (eGFR) (HR 2.52, 95% CI 1.73-3.65), stage of AKI (HR 3.03, 95% CI 2.07-4.42 for stage 3), shock (HR 5.56, 95% CI 3.02-10.22), glomerulonephritis-related AKI (HR 3.04, 95% CI 1.93-4.77) and drug-related AKI (HR 2.77, 95% CI 1.86-4.13).

Conclusion

Patients with IE-associated AKI had a high 90-day mortality, and a substantial proportion of survivors did not recover kidney function at 90 days. Kidney non-recovery at 90 days was associated with adverse long-term outcomes. Low baseline eGFR, severe AKI, shock, drug-related AKI and glomerulonephritis-related AKI were risk factors for kidney non-recovery.

Cold Plasma Activity Against Biofilm Formation of Prosthetic Joint Infection Pathogens

Periprosthetic joint infections occur in 1-2% of all patients undergoing prosthetic joint surgeries. Although strong efforts have been made to reduce infection rates, conventional therapies like one- or two-stage revisions have failed to lower the infection rates. Cold atmospheric plasma (CAP) has shown promising results in reducing bacterial loads on surfaces. In this study, we aimed to investigate the ability of CAP to reduce the bacterial load on metal surfaces with varying distances and different plasma compositions below a temperature suitable for in vivo applications. Methods: Biofilm was formed with Staphylococcus aureus ATCC 29213 and Staphylococcus epidermidis ATCC 12228 cultures on TMZF discs. Plasma treatments using air plasma and argon plasma were conducted on discs containing the established biofilm while the temperature was measured. During the experiments, the duration and the distance of plasma application varied. Afterwards, colony-forming units were counted. Results: The results of this study showed that air and argon plasma could be considered for applications during surgeries at a 1 cm distance. While air plasma showed the highest efficiency in CFU reduction, the temperature generation due to the presence of oxygen poses a limitation concerning the duration of application. The use of argon as a plasma generator does not show the temperature limitation in correlation to exposure time. The use of air plasma with a distance of 1 cm to the application site and an exposure time of 5 s showed the most effective bacterial reduction while not exceeding tissue-damaging temperatures.

Gene variant C3 glomerulonephritis with chronic urinary tract infection: A case report and literature review

RATIONALE

C3 glomerulonephritis (C3GN) is 1 type of C3 nephropathy which is a rare glomerular disease associated with abnormal regulation of the alternative complement pathway. This review reports a rare case of C3GN with repeated urinary tract infection and summarizes the clinical features, differential diagnosis, treatment, and outcome of patients with C3GN.

PATIENT CONCERNS

A 44-year-old woman was admitted to our hospital because of proteinuria increased for more than 8 years.

DIAGNOSES

The patient was finally diagnosed with C3GN by renal biopsy and gene testing.

INTERVENTIONS

The patient was worried about the side effects of drugs and strongly refused to use glucocorticoids and immunosuppressants, so she was given angiotensin II receptor blocker monotherapy for glomerulonephritis and quinolones for urinary tract infection.

OUTCOMES

Serum creatinine, proteinuria, and serum complement c3 levels remained stable. Our case is still under continuous follow-up.

LESSONS

Clinical diagnosis of C3GN is difficult to make as there are many differential diagnoses, especially post infection nephritis. This case emphasizes the importance of renal biopsy in the diagnosis of C3GN, but the relationship between gram-negative bacilli and C3GN is still unclear. In addition, gene mutation is also involved in the pathogenesis of C3GN, and the treatment of C3GN still needs to be explored.

Case Series of Infection-Related Glomerulonephritis in Quebec Indigenous Peoples

Rationale

Infection-related glomerulonephritis (IRGN) is an immune-mediated glomerulonephritis caused by extra-renal infectious diseases. There has been an important shift in epidemiology in recent years, with a significant proportion of adults affected. The incidence of IRGN is higher amongst Indigenous populations and especially in those with multiple comorbidities. Beginning in 2019, we observed several IRGN cases amongst adult Indigenous peoples referred to the McGill University Health Center (MUHC). The aim of this article is to describe the demographic, clinical, and outcome data of these individuals and highlight the heterogeneity of IRGN in this population through 2 illustrative cases.

Presenting concerns of the patient

In total, 8 cases of IRGN were identified between 2019 and 2022. All patients presented with features of acute glomerulonephritis.

Diagnoses

All patients had documented evidence of an infection that preceded their diagnosis of IRGN. IRGN was not the initial clinical diagnosis in all cases.

Interventions

Half the patients received immunosuppression while the others received supportive care only.

Outcomes

Four patients required initiation of hemodialysis at time of presentation and at 2 years of follow-up, 3 of the 4 remained hemodialysis-dependent.

Teaching points

Our case series emphasizes the heterogenous clinical, laboratory, and pathological presentations that make the diagnosis of IRGN quite challenging. A high index of suspicion should be present when a patient presents with acute kidney injury, features of a glomerulonephritis, and an infection, especially those with multiple comorbidities and a preceding history of chronic kidney disease.

Parvovirus B19-related membranoproliferative glomerulonephritis presenting with positive glomerular staining for nephritis-associated plasmin receptor: a case report and review of the literature

Several cases of glomerulonephritis occurring after infection with human parvovirus B19 (PVB19) have been reported. However, the pathogenesis and clinicopathological features of PVB19-related glomerulonephritis remain elusive. We describe the case of a 34 year-old woman who showed nephrotic syndrome and microscopic hematuria 10 days after PVB19 infection. Blood pressure and renal function were within normal ranges. Laboratory tests showed positive results for anti-PVB19 immunoglobulin (Ig)M antibody and complement 3 (C3) hypocomplementemia. Antibody to streptolysin O (ASO) was slightly elevated, but bacterial cultures yielded no colonies. Light microscopy of renal biopsy was compatible with membranoproliferative glomerulonephritis (MPGN). Immunofluorescence microscopy showed intense staining for C3 and faint staining for IgG on the glomerular capillary wall and paramesangial area. Electron micrography showed subendothelial electron-dense deposits (EDDs), but hump-shaped subepithelial EDDs were not evident. PBV19-DNA was absent from renal tissue. Moreover, glomeruli showed positive staining for nephritis-associated plasmin receptor (NAPlr) and plasmin activity with similar distribution. Around 6 months after PVB19 infection, levels of anti-PVB19 IgM antibody spontaneously tuned negative with an apparent reduction of proteinuria and improvement of hypocomplementemia, although ASO level remained unchanged. This appears to represent the first description of positive glomerular staining for NAPlr in MPGN after PVB19 infection. Based on a review of 27 cases, including our own case, the MPGN lesions could be attributable to PVB19 infection. Clinicopathological features of this case were incompatible with post-streptococcal acute glomerulonephritis. We presume that a PBV19-derived glomerular pathogen that cross-reacts with anti-NAPlr antibody might be involved in the development of PVB19-related MPGN.

Association between house dust endotoxin and kidney injury: findings from the national health and nutrition examination survey (NHANES) 2005-2006

BACKGROUND

House dust endotoxin is thought to be associated with systemic inflammatory responses and respiratory diseases. Previous studies have indicated that lung injury and systemic inflammation could lead to kidney damage. However, the potential link between house dust endotoxin and the increased risk of kidney injury remains unexplored.

OBJECTIVES

This cross-sectional study and retrospective study aim to investigate the relationship between house dust endotoxin levels and renal markers, specifically the urinary albumin-to-creatinine ratio (UACR) and estimated glomerular filtration rate (eGFR), utilizing data from the NHANES 2005-2006 survey cycle.

RESULTS

Proteinuria was assessed using the UACR, with values categorized into negative (UACR ≤ 30 mg/g) and positive (UACR > 30 mg/g) groups. Significant differences in house dust endotoxin levels were observed between these groups (p value = 0.003). Weighted logistic regression analysis indicated that higher levels of house dust endotoxin were associated with an increased rate of positive UACR (OR [95% CI]: 1.57 [1.20, 2.05]; p value = 0.003). This association remained significant after adjusting for covariates such as age, gender, race, poverty income ratio (PIR), Type 2 Diabetes Mellitus (T2DM), and hypertension (OR [95% CI]: 1.46 [1.08, 1.97]; p-Value = 0.021). However, no significant correlation was found between house dust endotoxin levels and eGFR (Estimate [95% CI]: 1.19 [-1.28, 3.66]; p value = 0.32).

CONCLUSIONS

Our findings suggest a significant association between house dust endotoxin levels and proteinuria, based on data from the NHANES 2005-2006 survey cycle. This association indicates that elevated levels of house dust endotoxin may be linked to kidney damage. Further research is necessary to elucidate the specific relationship between exposure to house dust endotoxin and the risk of developing kidney disease.

Chemical constituents and biological activities of endophytic fungi from Fagopyrum dibotrys

Background

Fagopyrum dibotrys is an important wild food and feed germplasm resource. It has high nutritional and medicinal value and is rich in natural products, including flavonoids, phenolic acids, coumarins, and alkaloids. Endophytic fungi in F. dibotrys have emerged as valuable sources of natural products. However, studies on the biological activity and chemical composition of these endophytic fungi remain limited.

Methods

In this paper, a new method to obtain natural active ingredients by fermentation of endophytic fungi from medicinal plants was proposed. Then the antioxidant and pathogenic activities of the endophytic fungi extracts were determined in vitro. In addition, secondary metabolites produced by endophytic fungi with medicinal activity were analyzed by high performance liquid chromatography-tandem mass spectrometry (LC-MS).

Results

Among the 95 endophytic fungal strains in F. dibotrys, four strains with high phenol yields were selected by reaction: Alternaria alstroemeriae (J2), Fusarium oxysporum (J15), Colletotrichum karsti (J74), and Colletotrichum boninense (J61). Compared with those of various extracts, the ethyl acetate fractions of A. alstroemeriae (J2), F. oxysporum (J15), and C. boninense (J61) exhibited superior antioxidant and antibacterial properties. The results indicated that the fungal extract was an excellent natural antioxidant and might be a potential antibacterial agent. The DPPH free radical clearance of A. alstroemeriae was 94.96 ± 0.004%. These findings indicated that A. alstroemeriae had strong antioxidant activity. In addition, the extract of A. alstroemeriae had good antibacterial activity against Escherichia coli and Staphylococcus aureus, with MICs of 0.5 and 0.05 mg/mL, respectively. The chemical constituents of the ethyl acetate extract from A. alstroemeriae were further analyzed by liquid chromatography-mass spectrometry (LC-MS). We noted that A. alstroemeriae can create a variety of medicinal substances that have high value in medicine, such as caffeic acid (884.75 ng/mL), 3-phenyllactic acid (240.72 ng/mL) and norlichexanthone (74.36 ng/mL).

Discussion

In summary, many valuable active substances and medicinal substances can be obtained through the study of endophytic fungi of F. dibotrys.

Rapidly Progressive Glomerulonephritis

Rapidly progressive glomerulonephritis (RPGN) is a syndrome characterized by a swift decline in kidney function, often over a few months, accompanied by features of nephritic syndrome. It can result in decreased urine output and commonly involves the presence of extensive crescents in kidney biopsies. RPGN is classified into 3 main types based on immune deposit distribution and visualization through immunofluorescence and electron microscopy: antiglomerular basement membrane disease, immune complex glomerulonephritis, and pauci-immune glomerulonephritis. Early diagnosis and prompt treatment are critical to prevent progression to ESRD. Standard treatment options for RPGN include glucocorticoids, cyclophosphamide, or rituximab, with plasma exchange especially important for antiglomerular basement membrane disease and select cases of ANCA-associated vasculitis. Clinical trials for glomerular diseases have primarily excluded patients with RPGN or dialysis dependence. Establishment of clinical registries is required for the optimization of therapeutic protocols for the treatment of RPGN.

Circular RNAs as novel biomarkers in glomerular diseases

Circular RNAs (circRNAs) regulate gene expression and biological procedures by controlling target genes or downstream pathways by sponging their related miRNA (s). Three types of circRNAs have been identified; exonic circRNAs (ecircRNAs), intronic RNAs (ciRNAs), and exon-intron circRNAs (ElciRNAs). It is clarified that altered levels of circRNAs have dynamic pathological and physiological functions in kidney diseases. Evidence suggests that circRNAs can be considered novel diagnostic biomarkers and therapeutic targets for renal diseases. Glomerulonephritis (GN) is a general term used to refer to a wide range of glomerular diseases. GN is an important cause of chronic kidney diseases. Here, we review the biogenesis of circRNAs, and their molecular and physiological functions in the kidney. Moreover, the dysregulated expression of circRNAs and their biological functions are discussed in primary and secondary glomerulonephritis. Moreover, diagnostic and therapeutic values of circRNAs in distinguishing or treating different types of GN are highlighted.

ANCA-Negative Pauci-Immune Glomerulonephritis Associated with Bartonella Endocarditis

Kidney complications can occur due to infective endocarditis, one of which is glomerulonephritis. Most often, an immune complex or complement-mediated glomerulonephritis is seen on kidney biopsy. In a minor subset of cases, pauci-immune glomerulonephritis may be present. Most often, such patients will demonstrate the presence of antineutrophil cytoplasmic antibodies (ANCA) on serologic testing. A growing number of cases of ANCA-associated glomerulonephritis due to Bartonella endocarditis have been reported. This type of endocarditis can present diagnostic difficulties given that these patients are often culture negative. Herein, we report a challenging case of ANCA-negative pauci-immune glomerulonephritis showing florid crescents on biopsy that was associated with Bartonella endocarditis.

The role of complement in kidney disease: conclusions from a Kidney Disease: Improving Global Outcomes (KDIGO) Controversies Conference

Uncontrolled complement activation can cause or contribute to glomerular injury in multiple kidney diseases. Although complement activation plays a causal role in atypical hemolytic uremic syndrome and C3 glomerulopathy, over the past decade, a rapidly accumulating body of evidence has shown a role for complement activation in multiple other kidney diseases, including diabetic nephropathy and several glomerulonephritides. The number of available complement inhibitor therapies has also increased during the same period. In 2022, Kidney Diseases: Improving Global Outcomes (KDIGO) convened a Controversies Conference, "The Role of Complement in Kidney Disease," to address the expanding role of complement dysregulation in the pathophysiology, diagnosis, and management of various glomerular diseases, diabetic nephropathy, and other forms of hemolytic uremic syndrome. Conference participants reviewed the evidence for complement playing a primary causal or secondary role in progression for several disease states and considered how evidence of complement involvement might inform management. Participating patients with various complement-mediated diseases and caregivers described concerns related to life planning, implications surrounding genetic testing, and the need for inclusive implementation of effective novel therapies into clinical practice. The value of biomarkers in monitoring disease course and the role of the glomerular microenvironment in complement response were examined, and key gaps in knowledge and research priorities were identified.

Diagnostic Challenges and Emerging Pathogeneses of Selected Glomerulopathies

Recent progress in glomerular immune complex and complement-mediated diseases have refined diagnostic categories and informed mechanistic understanding of disease development in pediatric patients. Herein, we discuss selected advances in 3 categories. First, membranous nephropathy antigens are increasingly utilized to characterize disease in pediatric patients and include phospholipase A2 receptor (PLA2R), Semaphorin 3B (Sema3B), neural epidermal growth factor-like 1 (NELL1), and protocadherin FAT1, as well as the lupus membranous-associated antigens exostosin 1/2 (EXT1/2), neural cell adhesion molecule 1 (NCAM1), and transforming growth factor beta receptor 3 (TGFBR3). Second, we examine advances in techniques for paraffin and light chain immunofluorescence (IF), including the former's function as a salvage technique and their necessity for diagnosis in adolescent cases of membranous-like glomerulopathy with masked IgG kappa deposits (MGMID) and proliferative glomerulonephritis with monotypic Ig deposits (PGNMID), respectively. Finally, progress in understanding the roles of complement in pediatric glomerular disease is reviewed, with specific attention to overlapping clinical, histologic, and genetic or functional alternative complement pathway (AP) abnormalities among C3 glomerulopathy (C3G), infection-related and post-infectious GN, "atypical" post-infectious GN, immune complex mediated membranoproliferative glomerulonephritis (IC-MPGN), and atypical hemolytic uremic syndrome (aHUS).

Treatments for pathogen infection rescued 2 patients with renal artery rupture after kidney transplantation: A case report

RATIONALE

Renal artery rupture due to allograft infection, especially by fungi, is a serious clinical complication that can occur after kidney transplantation, and may lead to graft loss and death.

PATIENT CONCERNS

Two kidney recipients from China who developed renal artery rupture at our hospital on 5 days (47-year-old female) and 45 days (39-year-old male) after surgery.

DIAGNOSES

The male had immunoglobulin A nephropathy as a primary disease, and experienced a postoperative attack of vascular rejection and mixed infection by Mucor and bacteria. The female had chronic glomerulonephritis as a primary disease, and experienced renal artery rupture near the anastomosis site with infection by fungi and other pathogens.

INTERVENTIONS

The male received resection of the implanted kidney and antibiotic therapy with intravenous vancomycin (0.5 g, 2 days) and amphotericin B (530 mg in 33 days). The female received replacing the segment of renal arterial and internal iliac artery by saphenous vein, as well as antibiotic therapy with amphotericin B (320 mg in 8 days).

OUTCOMES

The male was recovered and received a second transplantation, while the female was discharged on postoperative day 19.

LESSONS

In both patients, prompt surgery and aggressive treatment with an antifungal drug (amphotericin B) and antidrugs led to successful rescue.

Short-Term Outcomes of Infection-Related Glomerulonephritis in Diabetes Mellitus

Background and objective Infection-related glomerulonephritis (IRGN) in adults, particularly the diabetic population, has a grave prognosis with many patients progressing to dialysis-dependent renal failure. Indian data on this entity are very scarce. This study attempts to correlate the clinicopathological factors related to diabetic IRGN and its short-term outcomes. Subjects and methods A retrospective analysis of all diabetic patients with biopsy-proven IRGN between January 2017 and August 2021 was conducted. Factors affecting outcomes such as clinical characteristics, urine examination, complete blood count, serum biochemistry, renal biopsy, and follow-up data were obtained and analyzed to determine the risk of progression to chronic kidney disease (CKD)/end-stage renal disease (ESRD). Univariate/multivariate analysis and receiver operating characteristic (ROC) curve were performed to identify independent risk factors affecting outcomes. Results A total of 40 diabetic patients with IRGN was included in the study, with a mean age of 53.08 ± 10 years, comprising predominantly males (60%). Infective foci were occult in majority (37.5%). Isolated low C3 levels were documented in the majority, while three patients (7.5%) had normal complement levels. Complete renal recovery was noted in 15 patients (37.5%), while 12 patients (30%) progressed to ESRD. Anuria or uremia at presentation, glomerulosclerosis >28.6%, interstitial fibrosis with tubular atrophy (IFTA) >17.5%, and diabetic nephropathy correlated to poor renal recovery. No correlation was observed between endocapillary proliferation, the pattern of deposits, the prevalence of crescents, and complement levels with the outcome. Conclusion IRGN is a common immune-mediated clinical entity among diabetics and often requires renal replacement therapy. Anuria or uremia at presentation, diabetic nephropathy, elevated glomerulosclerosis, and IFTA were associated with poor renal recovery. Complement levels and crescents had no impact on the outcome.

The Pulsing Paradox: Successful Steroid Therapy in Infection-Related Glomerulonephritis

The patterns of infection-related glomerulonephritis (IRGN) are rapidly changing in terms of age at presentation and sources of infection. The existing literature on the use of steroids in IRGN is inconsistent. A diabetic male in his sixties presented with features of anasarca, bilateral flank pain, and acute pulmonary edema. He had a non-healing ulcer over his right leg, with pus culture showing growth of methicillin-resistant Staphylococcus aureus (MRSA). Computed tomography (CT) of the kidneys, ureter, and bladder (KUB) showed features of bilateral pyelonephritis. The patient went on to develop acute renal failure and eventually required hemodialysis. A renal biopsy was performed, and features of IRGN with crescents were noted. Considering the presence of crescents in renal biopsy, a trial of steroids was given under antibiotic cover, which resulted in a near-complete resolution of renal failure.

[Nephropathology of infectious disease]

Infections can affect the kidney via different pathways. Urinary tract infections can directly involve the renal tissue by spreading along pre-existing canalicular structures. Such an ascending infection can manifest as a highly active and purulent or even abscessing interstitial nephritis or as a chronic-fibrosing process in recurrent pyelonephritis. Viral infections can also use the canalicular route as in polyomavirus nephropathy or spread via the blood stream in a hematogenous manner as in the case of cytomegalovirus or hantavirus infections. Likewise, bacterial infections can reach the kidney via the blood in the case of systemic infection. Another large group of nephropathies taking place as a sequel of infections includes infection-related glomerulonephritides (IRGN), which are mediated by a series of immunological mechanisms. These IRGN can be subdivided according to their temporal association with the infectious process, occurring either after the infection has healed (postinfectious) or accompanying the ongoing infectious process (parainfectious). The latter, in particular, is of increasing importance in the daily practice of nephropathologists, especially in older patients. A number of other glomerulonephritis forms, i.e., membranous or membranoproliferative forms, can occur as a consequence of infection. In addition, infections can trigger nephropathies, such as thrombotic microangiopathy. The present article gives an overview of morphologic changes in renal parenchyma that take place as a consequence of infectious processes, with particular focus on IRGN.

Pediatric IgA-Dominant Infection-Related Glomerulonephritis

The concept of infection-related glomerulonephritis (IRGN) has been introduced as adults diagnosed with glomerulonephritis often have coexisting active infections. Furthermore, IgA-dominant IRGN is associated with staphylococcal infections in adults with comorbidities, which often progress to end-stage renal disease. Little is known about IgA-dominant IRGN in children, and no consensus for a management strategy of this condition has been reached. We describe the case of a 9-year-old boy with IgA-dominant IRGN that was diagnosed using specific staining for nephritis-associated plasmin receptor (NAPlr)/plasmin activity and galactose-deficient IgA1 (Gd-IgA1), a marker of IgA nephropathy. The patient was successfully treated using a combination of prednisolone, mizoribine (an immunosuppressive drug), and lisinopril (an angiotensin-converting enzyme inhibitor) and three courses of methylprednisolone pulse therapy. The patient was admitted to our hospital with generalized edema, gross hematuria, proteinuria, hypertension, and renal dysfunction. Hypocomplementemia contributed to a diagnosis of IRGN, although the causative organism was unknown. A renal biopsy performed when the patient presented with nephrotic syndrome showed IgA deposition, positive staining for NAPlr, and negative staining for Gd-IgA1, in addition to findings consistent with IRGN, leading to a pathologic diagnosis of IgA-dominant IRGN. The histological staining for NAPlr/plasmin activity and Gd-IgA1, together with clinical symptoms, could be helpful for diagnosing IgA-dominant IRGN. Our findings indicate that otherwise healthy children can also develop IgA-dominant IRGN. Therefore, early diagnosis and aggressive treatment should be considered when IgA-dominant IRGN is suspected to avoid the possibility of incomplete recovery of renal function.

The State-of-the-Art Antibacterial Activities of Glycyrrhizin: A Comprehensive Review

Licorice (Glycyrrhiza glabra) is a plant of the genus Glycyrrhiza in the family Fabaceae/Leguminosae and is a renowned natural herb with a long history of medicinal use dating back to ancient times. Glycyrrhizin (GLY), the main active component of licorice, serves as a widely utilized therapeutic agent in clinical practice. GLY exhibits diverse medicinal properties, including anti-inflammatory, antibacterial, antiviral, antitumor, immunomodulatory, intestinal environment maintenance, and liver protection effects. However, current research primarily emphasizes GLY's antiviral activity, while providing limited insight into its antibacterial properties. GLY demonstrates a broad spectrum of antibacterial activity via inhibiting the growth of bacteria by targeting bacterial enzymes, impacting cell membrane formation, and altering membrane permeability. Moreover, GLY can also bolster host immunity by activating pertinent immune pathways, thereby enhancing pathogen clearance. This paper reviews GLY's inhibitory mechanisms against various pathogenic bacteria-induced pathological changes, its role as a high-mobility group box 1 inhibitor in immune regulation, and its efficacy in combating diseases caused by pathogenic bacteria. Furthermore, combining GLY with other antibiotics reduces the minimum inhibitory concentration, potentially aiding in the clinical development of combination therapies against drug-resistant bacteria. Sources of information were searched using PubMed, Web of Science, Science Direct, and GreenMedical for the keywords "licorice", "Glycyrrhizin", "antibacterial", "anti-inflammatory", "HMGB1", and combinations thereof, mainly from articles published from 1979 to 2024, with no language restrictions. Screening was carried out by one author and supplemented by others. Papers with experimental flaws in their experimental design and papers that did not meet expectations (antifungal papers, etc.) were excluded.

Native and prosthetic valve infective endocarditis complicated by rapidly progressive glomerulonephritis and its diagnostic challenges and therapeutic implications

Key Clinical Message

Concomitant native and prosthetic valve infective endocarditis (IE) is very rare, and both can rarely be complicated by rapidly progressive glomerulonephritis (RPGN). This diagnosis has therapeutic implications, as not all RPGN need immunosuppression therapy.

Abstract

Native and prosthetic valve infective endocarditis (IE) may be rarely complicated by rapidly progressive glomerulonephritis (RPGN). The diagnosis of IE as a cause of RPGN may be missed, and patients may be subjected to inappropriate immune suppressive therapy. Moreover, IE involving multi-valves has rarely been described, and there are only few case reports of simultaneous native and prosthetic valve endocarditis. Here, we present a case of 34-year-old female patient who has RPGN and whose initial workup missed IE. However, further workup revealed a diagnosis of native and prosthetic valve IE and our patient, who would have been subjected to inappropriate immune suppressive therapy, was treated with intravenous antibiotics alone and discharged with improvement.

Infection-Related Glomerulonephritis Due to Subacute Bacterial Endocarditis in the Aortic Valve: A Case Report

Infection-related glomerulonephritis (IRGN) is a rare but severe complication of bacterial infections, including subacute bacterial endocarditis (SBE). We present a case of a 15-year-old male with bilateral lower limb swelling, facial puffiness, frothy urine, and dyspnea. Laboratory investigations revealed abnormal kidney function tests and imaging studies confirmed infective endocarditis. Blood cultures isolated Burkholderia cepacia and methicillin-resistant coagulase-negative Staphylococcus. Kidney biopsy confirmed immune complex-mediated glomerulonephritis. The patient received multidisciplinary care, including respiratory support, hemodialysis, antibiotics, and blood transfusion. This case highlights the importance of recognizing and promptly managing IRGN secondary to SBE to prevent irreversible renal damage and systemic complications.

Apoptosis in post-streptococcal glomerulonephritis and mechanisms for failed of inflammation resolution

Post-streptococcal glomerulonephritis is a condition resulting from infection by group A beta-hemolytic streptococcus. The main mechanism involves the formation of immune complexes formed in the circulation or in situ on the glomerular basement membrane, which activates complement and causes various inflammatory processes. Cellular mechanisms have been reported in the induction of kidney damage represented by the infiltration of innate cells (neutrophils and monocyte/macrophages) and adaptive cells (CD4 + lymphocytes and CD8 + lymphocytes) of the immune system. These cells induce kidney damage through various mechanisms. It has been reported that nephritogenic antigens are capable of inducing inflammatory processes early, even before the formation of immune complexes. Usually, this disease progresses towards clinical and renal normalization; however, in a smaller number of patients, it evolves into chronicity and persistent kidney damage. Hypotheses have been proposed regarding the mechanisms underlying this progression to chronicity including failure to induce apoptosis and failure to phagocytose apoptotic cells, allowing these cells to undergo membrane permeabilization and release pro-inflammatory molecules into the environment, thereby perpetuating renal inflammation. Other mechanisms involved include persistent infection, genetic background of the host's complement system, tubulointerstitial changes, and pre-existing kidney damage due to old age and comorbidities.

Chronological Changes in the Histology of Infection-Related Glomerulonephritis in Renal Allograft: A Case Report

We report the histological changes over time for a patient with infection-related glomerulonephritis (IRGN) that developed in a transplanted kidney. A 47-year-old man had undergone renal transplantation 3 years ago for end-stage kidney disease (ESKD). After several episodes of acute rejection, the patient was in a stable CKD condition. The abrupt development of severe microscopic hematuria and renal dysfunction was observed approximately 2 weeks after the onset of a phlegmon in his right leg. An allograft biopsy showed prominent glomerular endocapillary proliferation on light microscopy, granular C3 deposition on immunofluorescent microscopy, and subepithelial electron-dense deposits on electron microscopy, suggesting IRGN accompanied by moderate interstitial fibrosis and tubular atrophy (IFTA). Positive glomerular staining for nephritis-associated plasmin receptor (NAPlr) and plasmin activity, which are biomarkers of bacterial IRGN, supported the diagnosis. Although the infection was completely cured with antibiotic therapy, renal dysfunction persisted. A re-biopsy of the allograft 2 months later revealed resolution of the glomerular endocapillary proliferation and negative staining for NAPlr/plasmin activity, with worsening IFTA. We showed, for the first time, the chronological changes in infiltrating cells and histological markers of IRGN in transplanted kidneys. Glomerular changes, including NAPlr/plasmin activity staining, almost disappeared after the cessation of infection, while interstitial changes continuously progressed, contributing to ESKD progression.

Infection-Associated Glomerulonephritis

The nephritic syndrome has been associated with a wide variety of infections, spanning many organisms and myriad clinical presentations. Infection-associated glomerulonephritis is challenging to diagnose given the many confounding factors linking kidney injury to infection; however, urine microscopy can assist in identifying abnormal cellular elements suggestive of glomerulonephritis. Kidney biopsy remains the gold standard for diagnosing the underlying pathologic lesion. Treatment of infection-associated glomerulonephritis centers around aggressive and complete treatment of the underlying infectious driver. It is often hard to know exactly when immunosuppression may be required in addition to treating the infection.

Membranoproliferative Glomerulonephritis Pattern of Injury

Membranoproliferative glomerulonephritis (MPGN) is no longer a disease but a pattern of injury in various diseases. Characterized by electron-dense deposits, mesangial proliferation, and duplication of the glomerular basement membrane, MPGN was previously classified by findings seen by electron microscopy. However, recognizing complement dysfunction in relation to cases with the MPGN pattern of injury substantially changed our view of its pathogenesis. A new classification, including immune complex-mediated and complement-mediated MPGN, has become preferable and has been adopted by international guidelines. Despite these advancements, accurate diagnosis of MPGN remains a clinical challenge, given the pathological and clinical similarities between immune complex-mediated and complement-mediated MPGN. Additional testing, such as molecular and genetic testing, is often necessary. Here, we will summarize our current understanding of the MPGN pattern of injury from a pathology perspective as an introductory article in the following chapters.

Anti-factor H antibody-positive C3 glomerulonephritis secondary to poststreptococcal acute glomerulonephritis with diabetic nephropathy

Poststreptococcal acute kidney glomerulonephritis (PSAGN) has been seen in adults in recent years, especially in patients with type 2 diabetes mellitus, and the renal prognosis has not always been good. There have been cases of PSAGN in which complete remission was not achieved and hematuria and proteinuria persisted, leading to end-stage renal disease. Previous reports showed that the patients subjected to PSAGN have an underlying defect in regulating the alternative pathway of complement, and they identified that antibodies to the C3 convertase, C3 nephritic factors (C3NeF), are involved. C3NeF stabilizes C3 convertase, sustains C3 activation, and causes C3 glomerulonephritis (C3GN). On the other hand, factor H is a glycoprotein that suppresses the overactivation of the alternative pathway by decaying the C3 convertase. Anti-factor H (aFH) antibodies interfere with factor H and cause the same activation of the alternative pathway as C3NeF. However, a limited number of reports describe the clinical course of C3GN with aFH antibodies. We encountered a 49-year-old Japanese man with type 2 diabetes mellitus. He was referred to our hospital because of his elevated serum creatinine, proteinuria, hematuria, and developed edema on both legs. He was diagnosed as PSAGN at the first kidney biopsy, and his renal function improved and edema and hematuria disappeared, but proteinuria persisted after 5 months. He was diagnosed as C3GN at the second kidney biopsy. In our case, no C3NeF was detected. However, a high titer of aFH antibodies was detected in stored serum from the initial presentation, providing a unified diagnosis of aFH antibody-positive C3GN secondary to PSAGN. He progressed to end-stage renal disease (ESRD) and hemodialysis was started. The persistence of high levels of aFH autoantibodies may have caused C3GN secondary to PSAGN due to activating the alternative complement pathway, which eventually worsened the nephropathy and led to ESRD.

Glomerulonephritis and Septic Pulmonary Embolism: A Rare but Life-Threatening Complication of Permanent Pacemaker Implantation

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.

Nephrotic "full-house" glomerulonephritis successfully treated with antibiotics alone in secondary syphilis: a case report

A Japanese female in her twenties developed general edema with heavy proteinuria, and was referred to our hospital. She exhibited the common clinical manifestation of idiopathic nephrotic syndrome with massive proteinuria (20.37 g/day), hypoalbuminemia (1.8 g/dL), and hypercholesterolemia (300 mg/dL). Routine admission tests were positive results for both the rapid plasma reagin latex agglutination test for syphilis (RPR) and the Treponema pallidum particle agglutination assay (TPHA). As such, we made her a diagnosis of nephrotic syndrome due to secondary syphilis. Renal biopsy revealed "full-house" nephropathy. Following the commencement of penicillin treatment, she developed skin rash, indicating the Jarisch-Herxheimer reaction (JHR). Her nephrotic syndrome responded rapidly and she achieved complete remission with antibiotic therapy alone after 4 weeks. In light of the increasing incidence of syphilis in Japan, clinicians should consider syphilis as a reversible cause of nephrotic syndrome.

Mechanisms that potentially contribute to the development of post-streptococcal glomerulonephritis

Post-streptococcal glomerulonephritis (PSGN) is primarily associated with preceding group A streptococcal skin or throat infections, now mainly observed in economically disadvantaged communities. This condition significantly predisposes individuals to later-life chronic kidney disease and concurrent renal complications, with the elderly experiencing increased severity and less favourable outcomes. Streptococcal pyrogenic exotoxin B and nephritis-associated plasmin receptor are identified nephritogenic antigens (nephritogens). Pathogenesis of PSGN is multifactorial. It can involve the formation of antigen-antibody immune complexes, causing inflammatory damage to renal glomeruli. Deposition of circulating immune complexes or in situ formation of immune complexes in glomeruli, or both, results in glomerulonephritis. Additionally, molecular mimicry is hypothesized as a mechanism, wherein cross-reactivity between anti-streptococcal antibodies and glomerular intrinsic matrix proteins leads to glomerulonephritis. Besides, as observed in clinical studies, streptococcal inhibitor of complement, a streptococcal-secreted protein, can also be associated with PSGN. However, the interplay between these streptococcal antigens in the pathogenesis of PSGN necessitates further investigation. Despite the clinical significance of PSGN, the lack of credible animal models poses challenges in understanding the association between streptococcal antigens and the disease process. This review outlines the postulated mechanisms implicated in the development of PSGN with possible therapeutic approaches.

Infective Endocarditis Caused by Streptococcus sanguinis Resulting in Stroke, Ruptured Infected Pseudoaneurysm of Superior Mesenteric Artery, and Rapidly Progressive Glomerulonephritis

A 71-year-old-man was admitted to our hospital with a cerebral embolism and diagnosed with infective endocarditis (IE) caused by Streptococcus sanguinis. Mitral valve replacement was performed. About one month later, he experienced sudden abdominal pain and shock due to a ruptured infected mesenteric artery pseudoaneurysm. Forty-four days after abdominal surgery, he presented with rapidly progressive glomerulonephritis with anti-glomerular basement membrane antibodies. He was treated with plasma exchange and prednisolone, and his renal function gradually improved. Since postoperative complications often occur within a few years after surgery for IE, careful follow-up is important, even after antimicrobial therapy and valve surgery.

Clinicopathological differences between Bartonella and other bacterial endocarditis-related glomerulonephritis - our experience and a pooled analysis

Background

Although Staphylococcus aureus is the leading cause of acute infective endocarditis (IE) in adults, Bartonella spp. has concomitantly emerged as the leading cause of "blood culture-negative IE" (BCNE). Pre-disposing factors, clinical presentation and kidney biopsy findings in Bartonella IE-associated glomerulonephritis (GN) show subtle differences and some unique features relative to other bacterial infection-related GNs. We highlight these features along with key diagnostic clues and management approach in Bartonella IE-associated GN.

Methods

We conducted a pooled analysis of 89 cases of Bartonella IE-associated GN (54 published case reports and case series; 18 published conference abstracts identified using an English literature search of several commonly used literature search modalities); and four unpublished cases from our institution.

Results

Bartonella henselae and Bartonella quintana are the most commonly implicated species causing IE in humans. Subacute presentation, affecting damaged native and/or prosthetic heart valves, high titer anti-neutrophil cytoplasmic antibodies (ANCA), mainly proteinase-3 (PR-3) specificity, fastidious nature and lack of positive blood cultures of these Gram-negative bacilli, a higher frequency of focal glomerular crescents compared to other bacterial infection-related GNs are some of the salient features of Bartonella IE-associated GN. C3-dominant, but frequent C1q and IgM immunofluorescence staining is seen on biopsy. A "full-house" immunofluorescence staining pattern is also described but can be seen in IE -associated GN due to other bacteria as well. Non-specific generalized symptoms, cytopenia, heart failure and other organ damage due to embolic phenomena are the highlights on clinical presentation needing a multi-disciplinary approach for management. Awareness of the updated modified Duke criteria for IE, a high index of suspicion for underlying infection despite negative microbiologic cultures, history of exposure to animals, particularly infected cats, and use of send-out serologic tests for Bartonella spp. early in the course of management can help in early diagnosis and initiation of appropriate treatment.

Conclusion

Diagnosis of IE-associated GN can be challenging particularly with BCNE. The number of Bartonella IE-associated GN cases in a single institution tends to be less than IE due to gram positive cocci, however Bartonella is currently the leading cause of BCNE. We provide a much-needed discussion on this topic.

Non-Diabetic Renal Diseases in Diabetic Patients with Emphasis on Infection-Related Glomerulonephritis

Background:

Non -diabetic renal diseases (NDRDs) in diabetics are treatable and therefore have better prognosis. Infection-related glomerulonephritis (IRGN) is being frequently reported as NDRD.

Objective:

We attempt to study the clinicopathologic spectrum of diabetic patients with biopsy proven IRGN.

Materials and Methods:

This was a retrospective analysis of renal biopsies performed in diabetic patients from January 2014 to June 2021. Demographic data, clinical features, and other laboratory findings were collected. The renal biopsies were classified into diabetic nephropathy (DN) and NDRD. The patients with diagnosis of IRGN were studied in detail.

Results:

Of the 1972 renal biopsies done in diabetic patients, 537 were NDRD and 1233 were DN. The commonest NDRD was tubulo-interstitial nephritis (n = 173) followed by IRGN (n = 74). The IRGN cases were in the age range of 5-78 years (median-53.5) with M: F = 3.4:1. The median duration of diabetes was six years, with median HbA1c = 7.5. Proteinuria ranged from 0.041 to 13 g/day (median = 1.95) with median serum creatinine of 3.7 mg%. History of preceding infection was present in nine cases. These patients presented with rapidly progressive renal failure (RPRF, 17), nephritic syndrome (27), nephrotic syndrome (27), and asymptomatic proteinuria (3). Median C3-level was 47 mg/dl. The biopsies showed classic endocapillary hypercellularity with neutrophils in mesangium, 45 cases had associated DN. Immunofluorescence performed in 54 cases showed coarse granular deposits of C3C.

Conclusions:

IRGN should be kept in mind in diabetic patients presenting with RPRF or nephrotic proteinuria. The biopsy and immunofluorescence helps in accurate diagnosis.

The five types of glomerulonephritis classified by pathogenesis, activity and chronicity (GN-AC)

Glomerulonephritis (GN) is a diverse group of immune-mediated disorders. Currently, GN is classified largely by histological patterns that are difficult to understand and teach, and most importantly, do not indicate treatment choices. Indeed, altered systemic immunity is the primary pathogenic process and the key therapeutic target in GN. Here, we apply a conceptual framework of immune-mediated disorders to GN guided by immunopathogenesis and hence immunophenotyping: (i) infection-related GN require pathogen identification and control; (ii) autoimmunity-related GN, defined by presence of autoantibodies and (iii) alloimmunity-related GN in transplant recipients both require the suppression of adaptive immunity in lymphoid organs and bone marrow; (iv) autoinflammation-related GN, e.g. inborn errors of immunity diagnosed by genetic testing, requires suppression of single cytokine or complement pathways; and (v) Monoclonal gammopathy-related GN requires B or plasma cell clone-directed therapy. A new GN classification should include disease category, immunological activity to tailor the use of the increasing number of immunomodulatory drugs, and chronicity to trigger standard chronic kidney disease care including the evolving spectrum of cardio-renoprotective drugs. Certain biomarkers allow diagnosis and the assessment of immunological activity and disease chronicity without kidney biopsy. The use of these five GN categories and a therapy-focused GN classification is likely to overcome some of the existing hurdles in GN research, management and teaching by reflecting disease pathogenesis and guiding the therapeutic approach.

IgA-dominant infection-related glomerulonephritis with NAPlr-positive tubulointerstitial nephritis

Infection-related glomerulonephritis (IRGN) is one of the most common causes of acute kidney injury (AKI). Positive glomerular staining of the nephritis-associated plasmin receptor (NAPlr) has been reported as a useful biomarker of IRGN. Although the infection can provoke acute tubulointerstitial nephritis (AIN), there are few reports of positive staining for NAPlr with AIN. We report a case of methicillin-sensitive Staphylococcus aureus (MSSA) infection-related nephritis complicated with AIN, which showed positive staining for tubulointerstitial NAPlr. The patient developed AKI and nephrotic syndrome during an intraperitoneal MSSA infection. A diagnosis of IRGN complicated by infection-related acute tubulointerstitial nephritis (IRAIN) was made based on glomerular endocapillary proliferation with tubulointerstitial infiltrating cells and tubular atrophy. Tubulointerstitial infiltrating cells were positive for NAPlr staining and plasmin activity. Treatment of the infection by antibiotics and drainage did not improve the AKI, but steroid administration improved that. NAPlr evaluation is a helpful tool for identifying causes of AIN during infection.

Bacterial infection-related glomerulonephritis in patients with diabetes

AIM

Diabetic patients are prone to infections, thus making them a unique cohort at risk of developing bacterial infection-related glomerulonephritis (IRGN).

METHODS

In total, 1693 adult diabetic patients underwent kidney biopsy between 2005 and 2021 at our tertiary care hospital in South India. Of these, 121 consecutive cases which met criteria of bacterial IRGN were included in this study.

RESULTS

The mean age of the cohort was 53.1 ± 10.1 years and 83/121 (68.5%) were males. Majority (98.3%) had type 2 diabetes for a median duration of 6 (IQR, 2-12) years. The most common sites of infection were skin (47/121, 38.8%) and urinary tract (15/121, 12.4%). Fifty percent (58/121) of patients had underlying advanced diabetic kidney disease (DKD). Isolated C3 deposits (without immunoglobulin) occurred in 66/121 (54.5%) patients predominantly in advanced DKD patients. IgA-dominant glomerulonephritis occurred in only 9/121 (7.4%) patients. Short-course oral steroid was given to 86/121 (71.1%) patients. Steroid related dysglycemia and immunosuppression related infections occurred in 9/61 (14.8%) and 16/61 (26.2%) patients respectively. Of the 90 patients with follow up details >3 months, 46 (51.1%) progressed to kidney failure over a median period of 0.5 (IQR, 0-7.2) months. Patients diagnosed in the latter half of our study period (2013-2021) were older, less commonly presented with fever, had more pronounced hypocomplementemia and severe renal histology predominantly with a 'starry sky' immunofluorescence pattern.

CONCLUSION

Superimposed bacterial IRGN on underlying DKD is associated with poor renal outcomes. Use of short course steroid was associated with significant toxicity.

Clinicopathologic Characteristics of PANDAS in a Young Adult: A Case Report

Pediatric autoimmune neuropsychiatric disorder associated with streptococcal infections (PANDAS) is an acute onset or exacerbation of neuropsychiatric symptoms following a group A streptococcus infection. It is believed to be a result of autoimmune response to streptococcal infection, but there is insufficient evidence to fully support this theory. Although this disease is primarily thought to be a disease of childhood, it is reported to occur also in adults. PANDAS is a well-defined clinical entity, but the neuropathology of this condition has not been established yet. We describe the clinical course of a 26-year-old female diagnosed with PANDAS. She committed suicide and her brain was biobanked for further studies. We examined the banked tissue and performed special stains, immunohistochemical, and immunofluorescence analyses to characterize the neuropathology of this condition. Histology of the temporal lobes, hippocampus, and basal ganglia shows mild gliosis and Alzheimer's type II astrocytes. Acute hypoxic ischemic changes were noted in hippocampus CA1 and CA2 areas. Immunostaining shows increased parenchymal/perivascular GFAP staining and many vessels with mild increases in CD3-, CD4-, and CD25-stained lymphocytes in the basal ganglia. The findings suggest that CD4- and CD25-positive T cells might have an important role in understanding the neuroinflammation and pathogenesis of this condition. The case represents the first neuropathological evaluation report for PANDAS.

Food allergy masquerading as persistent proteinuria in post-infectious glomerulonephritis: a case report

BACKGROUND

Post-infectious glomerulonephritis (PIGN) is one of the most common causes of pediatric acute glomerulonephritis. Immune system dysregulation manifesting as food allergy may predispose PIGN patients to nephrotic-range proteinuria.

CASE PRESENTATION

The patient was a 3-year-old male that presented with edema, gross hematuria and reduced urine output following a mild fever, rhinorrhea and lethargy. Due to the persistence of proteinuria and hematuria, he underwent a kidney biopsy. The patient was diagnosed with atypical PIGN and was placed on oral prednisolone. During treatment, a relationship between the consumption of dairy products and the degree of proteinuria was noted. The clinical manifestations and urinalysis indices improved upon steroid discontinuation and initiation of a hypoallergic diet.

CONCLUSION

The association between the degree of proteinuria and consumption of dairy products in this PIGN patient led to the identification of food allergy as an underlying factor for nephrotic-range proteinuria.

Mechanisms of bacterial inhibition and tolerance around cold atmospheric plasma

The grim situation of bacterial infection has undoubtedly become a major threat to human health. In the context of frequent use of antibiotics, a new bactericidal method is urgently needed to fight against drug-resistant bacteria caused by non-standard use of antibiotics. Cold atmospheric plasma (CAP) is composed of a variety of bactericidal species, which has excellent bactericidal effect on microbes. However, the mechanism of interaction between CAP and bacteria is not completely clear. In this paper, we summarize the mechanisms of bacterial killing by CAP in a systematic manner, discuss the responses of bacteria to CAP treatment that are considered to be related to tolerance and their underlying mechanisms, review the recent advances in bactericidal applications of CAP finally. This review indicates that CAP inhibition and tolerance of survival bacteria are a set of closely related mechanisms and suggests that there might be other mechanisms of tolerance to survival bacteria that had not been discovered yet. In conclusion, this review shows that CAP has complex and diverse bactericidal mechanisms, and has excellent bactericidal effect on bacteria at appropriate doses. KEY POINTS: • The bactericidal mechanism of CAP is complex and diverse. • There are few resistant bacteria but tolerant bacteria during CAP treatment. • There is excellent germicidal effect when CAP in combination with other disinfectants.

The Development of a Comprehensive Clinicopathologic Registry for Glomerular Diseases Using Natural Language Processing

Background

Glomerulonephritis (GN) represents a common cause of chronic kidney disease, and treatment to slow or prevent progression of GN is associated with significant morbidity. Large patient registries have improved the understanding of risk stratification, treatment selection, and definitions of treatment response in GN, but can be resource-intensive, with incomplete patient capture.

Objective

To describe the creation of a comprehensive clinicopathologic registry for all patients undergoing kidney biopsy in Manitoba, using natural language processing software for data extraction from pathology reports, as well as to describe cohort characteristics and outcomes.

Design

Retrospective population-based cohort study.

Setting

Tertiary care center in the province of Manitoba.

Patients

All patients undergoing a kidney biopsy in the province of Manitoba from 2002 to 2019.

Measurements

Descriptive statistics are presented for the most common glomerular diseases, along with outcomes of kidney failure and mortality for the individual diseases.

Methods

Data from native kidney biopsy reports from January 2002 to December 2019 were extracted into a structured database using a natural language processing algorithm employing regular expressions. The pathology database was then linked with population-level clinical, laboratory, and medication data, creating a comprehensive clinicopathologic registry. Kaplan-Meier curves and Cox models were constructed to assess the relationship between type of GN and outcomes of kidney failure and mortality.

Results

Of 2421 available biopsies, 2103 individuals were linked to administrative data, of which 1292 had a common glomerular disease. The incidence of yearly biopsies increased almost 3-fold over the study period. Among common glomerular diseases, immunoglobulin A (IgA) nephropathy was the most common (28.6%), whereas infection-related GN had the highest proportions of kidney failure (70.3%) and all-cause mortality (42.3%). Predictors of kidney failure included urine albumin-to-creatinine ratio at the time of biopsy (adjusted hazard ratio [HR] = 1.43, 95% confidence interval [CI] = 1.24-1.65), whereas predictors of mortality included age at the time of biopsy (adjusted HR = 1.05, 95% CI = 1.04-1.06) and infection-related GN (adjusted HR = 1.85, 95% CI = 1.14-2.99, compared with the reference category of IgA nephropathy).

Limitations

Retrospective, single-center study with a relatively small number of biopsies.

Conclusions

Creation of a comprehensive glomerular diseases registry is feasible and can be facilitated through the use of novel data extraction methods. This registry will facilitate further epidemiological research in GN.

Targeted Transcriptional Analysis of IgA Vasculitis, IgA Nephropathy, and IgA-Dominant Infection-Related Glomerulonephritis Reveals Both Distinct and Overlapping Immune Signatures

Key Points

Skin IL-9, calprotectin, and KIR gene expression may be predictive of subsequent kidney involvement in patients with IgAV. Histologically similar patients with IgAN, IgAV, and IgA-IRGN can be distinguished by their immune transcriptomes. Kidney biopsies from patients with IgA-IRGN are enriched for transcripts involved in granulocyte chemotaxis.

Background

IgA vasculitis (IgAV), IgA nephropathy (IgAN), and IgA-dominant infection-related glomerulonephritis (IgA-IRGN) have shared histopathologic features, but differences in clinical management and prognosis. The most serious IgAV organ involvement is in the kidneys (IgAV nephritis). In this study, we hypothesized that targeted immune transcript profiling could aid in (1 ) predicting the development of IgAV nephritis in patients with cutaneous IgAV and (2 ) differentiating IgAN, IgAV, and IgA-IRGN.

Methods

RNA was extracted from 24 formalin-fixed paraffin-embedded tissue specimens (16 kidney, 8 skin) from 21 patients with IgAV nephritis (n=7), IgAN (n=5), and IgA-IRGN (n=4), and IgAV skin biopsies from patients with (n=3) and without (n=5) IgAV nephritis. Differential gene expression and gene set enrichment analysis were performed on a total of 594 transcripts (Nanostring immunology panel) profiled using the nCounter system.

Results

Skin biopsies in patients with IgAV who develop kidney involvement exhibit reduced S100A8/S100A9 , IL9 , and killer cell immunoglobulin-like receptor expression. The kidney tissue immune transcriptomes of IgAN, IgAV, and IgA-IRGN are largely overlapping. IgA-IRGN kidney biopsies are, however, uniquely enriched for transcripts involved in granulocyte chemotaxis.

Conclusion

This study identifies immune transcript signatures that may predict IgAV nephritis in skin biopsies and distinguish IgA-IRGN from IgAN and IgAV in kidney biopsies.

Infection-Related Cryoglobulinemic Glomerulonephritis with Serum Anti-Factor B Antibodies Identified and Staining for NAPlr/Plasmin Activity Due to Infective Endocarditis

In this rare case of infection-related cryoglobulinemic glomerulonephritis with infective endocarditis, a 78-year-old male presented with an acute onset of fever and rapidly progressive glomerulonephritis. His blood culture results were positive for Cutibacterium modestum, and transesophageal echocardiography showed vegetation. He was diagnosed with endocarditis. His serum immunoglobulin M, IgM-cryoglobulin, and proteinase-3-anti-neutrophil cytoplasmic antibody levels were elevated, and his serum complement 3 (C3) and C4 levels were decreased. Renal biopsy results showed endocapillary proliferation, mesangial cell proliferation, and no necrotizing lesions on light microscopy, with strong positive staining for IgM, C3, and C1q in the capillary wall. Electron microscopy showed deposits in the mesangial area in the form of fibrous structures without any humps. Histological examination confirmed a diagnosis of cryoglobulinemic glomerulonephritis. Further examination showed the presence of serum anti-factor B antibodies and positive staining for nephritis-associated plasmin receptor and plasmin activity in the glomeruli, suggesting infective endocarditis-induced cryoglobulinemic glomerulonephritis.

Clinico-Pathogenic Similarities and Differences between Infection-Related Glomerulonephritis and C3 Glomerulopathy

Recently, the comprehensive concept of "infection-related glomerulonephritis (IRGN)" has replaced that of postinfectious glomerulonephritis (PIGN) because of the diverse infection patterns, epidemiology, clinical features, and pathogenesis. In addition to evidence of infection, hypocomplementemia particularly depresses serum complement 3 (C3), with endocapillary proliferative and exudative GN developing into membranoproliferative glomerulonephritis (MPGN); also, C3-dominant or co-dominant glomerular immunofluorescence staining is central for diagnosing IRGN. Moreover, nephritis-associated plasmin receptor (NAPlr), originally isolated from the cytoplasmic fraction of group A Streptococci, is vital as an essential inducer of C3-dominant glomerular injury and is a key diagnostic biomarker for IRGN. Meanwhile, "C3 glomerulopathy (C3G)", also showing a histological pattern of MPGN due to acquired or genetic dysregulation of the complement alternative pathway (AP), mimics C3-dominant IRGN. Initially, C3G was characterized by intensive "isolated C3" deposition on glomeruli. However, updated definitions allow for glomerular deposition of other complement factors or immunoglobulins if C3 positivity is dominant and at least two orders of magnitude greater than any other immunoreactant, which makes it challenging to quickly distinguish pathomorphological findings between IRGN and C3G. As for NAPlr, it was demonstrated to induce complement AP activation directly in vitro, and it aggravates glomerular injury in the development of IRGN. A recent report identified anti-factor B autoantibodies as a contributing factor for complement AP activation in pediatric patients with PIGN. Moreover, C3G with glomerular NAPlr deposition without evidence of infection was reported. Taken together, the clinico-pathogenic features of IRGN overlap considerably with those of C3G. In this review, similarities and differences between the two diseases are highlighted.

Proteomic Analysis of Complement Proteins in Glomerular Diseases

Introduction

Complement plays an important role in the pathogenesis of glomerulonephritis (GN). Even though the underlying etiology of GN might be different, complement activation with subsequent glomerular deposition of complement proteins result in glomerular injury and progression of the lesions. Routine immunofluorescence microscopy (IF) includes staining for only complement factors C3c and C1q. Therefore, with regard to evaluation of the complement pathways, routine kidney biopsy provides only limited information.

Methods

In this study, using laser microdissection of glomeruli followed by mass spectrometry, complement proteins and pathways involved in GN were analyzed.

Results

We found that C3 followed by C9 are the most abundant complement proteins in GN, indicating activation of classical or lectin or alternative, and terminal pathways, either exclusively or in a combination of pathways. Furthermore, depending on the type of GN, C4A and/or C4B were also present. Therefore, membranous nephropathy (MN), fibrillary GN, and infection-related GN showed C4A dominant pathways, whereas lupus nephritis (LN), proliferative GN with monoclonal Ig deposits, monoclonal Ig deposition disease (MIDD), and immunotactoid glomerulopathy showed C4B dominant pathways. Significant deposition of complement regulatory proteins, factor H-related protein-1 (FHR-1) and factor H-related protein-5 (FHR-5), were also detected in most GN.

Conclusions

This study shows accumulation of specific complement proteins in GN. The complement pathways, complement proteins, and the amount of complement protein deposition are variable in different types of GN. Selective targeting of complement pathways may be a novel option in the treatment of GN.

The Diagnostic Conundrum of Glomerular Crescents With IgA Deposits

INTRODUCTION

Glomerulonephritis (GN) with crescents and IgA deposits in kidney biopsy poses a frequent diagnostic and therapeutic dilemma because of multiple possibilities.

METHODS

Native kidney biopsies showing glomerular IgA deposition and crescents (excluding lupus nephritis) were identified from our biopsy archives between 2010 and 2021. Detailed clinicopathologic features were assessed. One-year clinical follow-up on a subset of cases was obtained.

RESULTS

A total of 285 cases were identified, and these clustered into IgA nephropathy (IgAN, n = 108), Staphylococcus or other infection-associated GN/infection-related GN (SAGN/IRGN, n = 43), and antineutrophil cytoplasmic antibody-associated GN (ANCA-GN, n = 26) based on a constellation of clinicopathologic features, but 101 cases (group X) could not be definitively differentiated. The reasons have been elucidated, most important being atypical combination of clinicopathologic features and lack of definitive evidence of active infection. Follow-up (on 72/101 cases) revealed that clinicians' working diagnosis was IgAN in 43%, SAGN/IRGN in 22%, ANCA-GN in 28%, and others in 7% of the cases, but treatment approach varied from supportive or antibiotics to immunosuppression in each subgroup. Comparing these cases as "received immunosuppression" versus "non-immunosuppression," only 2 features differed, namely C3-dominant staining, and possibility of recent infection (both higher in the no-immunosuppression group) (P < 0.05). Renal loss was higher in the non-immunosuppression subgroup, but not statistically significant (P = 0.11).

CONCLUSION

Diagnostic overlap may remain unresolved in a substantial number of kidney biopsies with glomerular crescents and IgA deposits. A case-by-case approach, appropriate antibiotics if infection is ongoing, and consideration for cautious immunosuppressive treatment for progressive renal dysfunction may be needed for best chance of renal recovery.

Streptococcal Infection-related Glomerulonephritis in an Elderly Diabetic Patient Complicated by Hemophagocytic Syndrome and Cytomegalovirus Nephritis

There has been a significant shift in epidemiology and renal outcomes of infection-related glomerulonephritis (IRGN) in recent years. The renal prognosis of IRGN is often poor in adults, especially in the elderly and diabetics. We herein report an elderly diabetic patient with IRGN due to streptococcal infection complicated by hemophagocytic syndrome and cytomegalovirus nephritis, which is uncommon among non-transplant patients. Infection control and steroids did not recover the patient's renal function. For elderly IRGN patients with diabetes, a further investigation of the most effective treatment for related renal outcomes is needed.

Proliferative glomerulonephritis with monoclonal immunoglobulin G3 lambda deposits accompanied by glomerular positive staining for nephritis-associated plasmin receptor and related plasmin activity: A report of two cases

Proliferative glomerulonephritis with monoclonal immunoglobulin (Ig) G deposits (PGNMID) is a relatively uncommon entity of monoclonal gammopathy of renal significance, and its detailed pathogenesis is not well understood. We, herein, report two cases of patients with PGNMID; their renal biopsy showed glomerular histological features of membranoproliferative glomerulonephritis pattern with endocapillary proliferation accompanied by non-organized granular electron-dense deposits that consisted of monoclonal IgG3-lambda. Neither symptomatic episodes of preceding infection nor infection foci were found in both patients; however, glomerular positive staining for nephritis-associated plasmin receptor (NAPlr) and related plasmin activity were observed. Although NAPlr was originally considered as a candidate nephritogenic protein for post-streptococcal acute glomerulonephritis, its positive staining and related plasmin activity have been observed in glomeruli of various cases with bacterial infection-related glomerulonephritis and is considered to be a general histological biomarker of infection-related glomerulonephritis. The present cases suggest that evaluation of immunoreactivity for NAPlr and related plasmin activity in glomeruli provides an important clue regarding the infection-related pathogenesis of PGNMID.

Renal biopsy in systemic infections: expect the unexpected

Infection-related glomerulonephritis is well recognized in patients with ongoing infections. It can be missed, however, if the infection is unusual or undetected. We present three cases where the renal biopsy findings prompted the identification or treatment of systemic infections.Case 1: A 84-year-old male presented with acute kidney injury (AKI) and IgA vasculitis on skin biopsy. A renal biopsy showed active glomerulonephritis with abundant neutrophils and predominantly mesangial immune complex deposits containing IgA. The findings prompted an infectious workup which was positive for COVID-19, suggesting exacerbation of IgA nephropathy by recent COVID-19 infection. Case 2: A 31-year-old female status post kidney transplant for granulomatosis with polyangiitis (GPA) had recent pregnancy with preterm delivery, disseminated herpes simplex virus (HSV) infection with HSV hepatitis, E. coli on urine culture, and AKI. A renal biopsy showed proliferative glomerulonephritis with subendothelial and mesangial immune complex deposits containing IgG and C3. The findings were most consistent with infection-related immune complex glomerulonephritis, most likely HSV-related. Case 3: A 78-year-old female presented with AKI, proteinuria, hematuria, and positive p-ANCA. Clinically, ANCA vasculitis was suspected, and renal biopsy did show focal, segmental, necrotizing glomerulonephritis. However, immunofluorescence and electron microscopy showed IgM-rich deposits in the mesangium. The unusual presentation prompted an infectious workup including a Bartonella antibody panel which showed very high titers, suggesting Bartonella endocarditis.Infection-related glomerulonephritis has a wide variety of presentations histologically and clinically. The three cases we present here emphasize the importance of recognizing these entities to help guide treatment and improve patient care.

Nephritis-Associated Plasmin Receptor (NAPlr): An Essential Inducer of C3-Dominant Glomerular Injury and a Potential Key Diagnostic Biomarker of Infection-Related Glomerulonephritis (IRGN)

Nephritis-associated plasmin receptor (NAPlr) was originally isolated from the cytoplasmic fraction of group A Streptococci, and was found to be the same molecule as streptococcal glyceraldehyde-3-phosphate dehydrogenase (GAPDH) and plasmin receptor (Plr) on the basis of nucleotide and amino acid sequence homology. Its main functions include GAPDH activity, plasmin-binding capacity, and direct activation of the complement alternative pathway (A-P). Plasmin trapped by deposited NAPlr triggers the degradation of extracellular matrix proteins, such as glomerular basement membranes and mesangial matrix, and the accumulation of macrophages and neutrophils, leading to the induction of plasmin-related endocapillary glomerular inflammation. Deposited NAPlr at glomerular endocapillary site directly activates the complement A-P, and the endocapillary release of complement-related anaphylatoxins, C3a and C5a, amplify the in situ endocapillary glomerular inflammation. Subsequently, circulating and in situ-formed immune complexes participate in the glomerular injury resulting in NAPlr-mediated glomerulonephritis. The disease framework of infection-related glomerulonephritis (IRGN) has been further expanded. GAPDH of various bacteria other than Streptococci have been found to react with anti-NAPlr antibodies and to possess plasmin-binding activities, allowing glomerular NAPlr and plasmin activity to be utilized as key biomarkers of IRGN.

Efficacy of Corticosteroids in Infection-Related Glomerulonephritis–A Randomized Controlled Trial

Introduction

Infection-related glomerulonephritis (IRGN) is associated with glomerular immune complex deposition along with complement activation. Steroids may attenuate glomerular injury and thereby improve renal outcomes.

Methods

We randomly assigned patients who had biopsy-proven IRGN and serum creatinine greater than 1.5 mg/dl to receive corticosteroids plus supportive care (intervention arm), or supportive care alone (control arm). Patients were followed up for 6 months. The primary outcome was complete renal recovery at 6 months. Safety of steroid therapy was also assessed.

Results

A total of 52 patients underwent randomization. At 6 months, 17 of 26 patients (65.4%) in the intervention arm and 14 of 26 patients (53.8%) in the control arm had complete renal recovery (odds ratio 1.6; 95% confidence interval, 0.5–4.9; P = 0.397). There was no statistically significant difference in any of the secondary outcomes. Adverse events occurred in 12 patients (46.2%) in the intervention arm and 2 patients (7.7%) in the control arm (P = 0.002).

Conclusion

In this single-center trial, corticosteroids did not result in a statistically significant increase in rates of complete renal recovery at 6 months. There was a significantly increased risk of adverse events associated with the use of corticosteroids.