Immune Complex-mediated Disease Research Articles

Clinicopathological features and outcomes of PLA2R-related membranous nephropathy with renal glycosuria.

Membranous nephropathy (MN) is an immune complex-mediated disease. Massive proteinuria can lead to Fanconi syndrome, clinically manifesting as renal glycosuria. The prevalence and prognosis of M-type phospholipase A2 receptor (PLA2R)-related MN with renal glycosuria remain unknown. Patients diagnosed with PLA2R-related MN with renal glycosuria were reviewed, and the control group comprised patients with MN without renal glycosuria who were randomly selected at a ratio of 1:3. 50 patients diagnosed with PLA2R-related MN with renal glycosuria from January 2015 to January 2020 were included, with a prevalence of 2.3%. Compared with patients without renal glycosuria, those with renal glycosuria exhibited greater proteinuria, lower estimated glomerular filtration rate (eGFR), and higher use of diuretics, anticoagulants, antibiotics, traditional Chinese medicine, and tacrolimus within 3 months prior to renal biopsy (all p<0.05). Histologically, patients with renal glycosuria exhibited more severe pathological stages, acute/chronic tubulointerstitial lesions, and tubulointerstitial inflammation (all p<0.05). Of the 10 patients treated with rituximab (RTX), proteinuria remission was maintained in 6 (60%) patients, and urine glucose remission was achieved in 5 of these 6 patients (83.3%). Multivariate Cox regression analysis showed that renal glycosuria and age &gt;50 years were independent risk factors for end-stage renal disease (ESRD) or a 30% reduction in the eGFR in patients with PLA2R-related MN. PLA2R-related MN patients with renal glycosuria presented with more severe clinicopathological manifestations and worse prognoses. Nephrotoxic drugs should be administered rationally, and RTX should be considered as a promising treatment option.

In the Pursuit of Precision: Novel Target Therapies Revolutionizing SLE Care

Systemic lupus erythematosus (SLE) is a chronic, autoimmune, immune complex-mediated disease affecting mainly females at a young age. The disease etiology is still unknown, and different genetic and epigenetic factors related to disease onset and manifestations are being explored. The standard treatment regimen for SLE includes the long-term use of corticosteroids and non-specific immunosuppressive agents, often limited by co-morbidities or related side effects. However, recent advances in disease pathogenesis clarifying the role of inflammatory cytokines, chemokines, immune cells, and co-stimulation molecules have made a more practical, targeted approach possible, leading to personalized treatment strategies. This review summarizes current knowledge about SLE-targeted therapies in clinical practice.

A retrospective study on the direct immunofluorescence findings in pigmented purpuric dermatosis.

Pigmented purpuric dermatosis (PPD) is characterized by grouped petechiae, purpuric macules, and pigmentation in the bilateral lower extremities. It runs a chronic and relapsing course. Pathophysiology is poorly understood, but it has been proposed to be an immune-complex disease or capillaritis. This study aimed to determine the incidence and patterns of positive direct immunofluorescence (DIF) findings in patients with clinically and histopathologically confirmed PPD. The association between DIF deposition type and clinical profile was also analyzed. Patients with a clinical and histopathologic PPD diagnosis who had undergone DIF studies at a tertiary medical center with attached dermatopathology and immunofluorescence diagnostic centers between January 2002 and December 2021 were included in this study. Data on age, sex, disease duration, comorbidities, and drug intake were collected from medical records. There were 65 patients who satisfied the inclusion criteria. Among them, 58 (89%) had at least one positive finding and 53 (82%) were vascular deposition of immunoglobulin (Ig), complement, or fibrinogen. The most common vascular deposition was fibrinogen (71%) followed by C3 (62%), IgM (18%), IgA (6%), and IgG (3%). Fibrinogen deposition was associated with hypertension (p < 0.03). There was no association between vascular DIF deposition of IgG, IgA, and C3, with age, sex, comorbidities, disease duration, and drug history. The most common DIF findings in PPD were vascular deposition of fibrinogen and C3, with or without Ig presence. DIF findings supported a vascular origin in PPD but not an immune complex-mediated disease. Hypertension was associated with fibrinogen deposition and may play a role in its pathophysiology.

Identification of key genes and imbalance of immune cell infiltration in immunoglobulin A associated vasculitis nephritis by integrated bioinformatic analysis.

IgAV, the most common systemic vasculitis in childhood, is an immunoglobulin A-associated immune complex-mediated disease and its underlying molecular mechanisms are not fully understood. This study attempted to identify differentially expressed genes (DEGs) and find dysregulated immune cell types in IgAV to find the underlying pathogenesis for IgAVN. GSE102114 datasets were obtained from the Gene Expression Omnibus (GEO) database to identify DEGs. Then, the protein-protein interaction (PPI) network of the DEGs was constructed using the STRING database. And key hub genes were identified by cytoHubba plug-in, performed functional enrichment analyses and followed by verification using PCR based on patient samples. Finally, the abundance of 24 immune cells were detected by Immune Cell Abundance Identifier (ImmuCellAI) to estimate the proportions and dysregulation of immune cell types within IgAVN. A total of 4200 DEGs were screened in IgAVN patients compared to Health Donor, including 2004 upregulated and 2196 downregulated genes. Of the top 10 hub genes from PPI network, STAT1, TLR4, PTEN, UBB, HSPA8, ATP5B, UBA52, and CDC42 were verified significantly upregulated in more patients. Enrichment analyses indicated that hub genes were primarily enriched in Toll-like receptor (TLR) signaling pathway, nucleotide oligomerization domain (NOD)-like receptor signaling pathway, and Th17 signaling pathways. Moreover, we found a diversity of immune cells in IgAVN, consisting mainly of T cells. Finally, this study suggests that the overdifferentiation of Th2 cells, Th17 cells and Tfh cells may be involved in the occurrence and development of IgAVN. We screened out the key genes, pathways and maladjusted immune cells and associated with the pathogenesis of IgAVN. The unique characteristics of IgAV-infiltrating immune cell subsets were confirmed, providing new insights for future molecular targeted therapy and a direction for immunological research on IgAVN.

Immunosupression in IgA Nephropathy

IgA Nephropathy (IgAN) is one of the most frequent types of glomerulonephritis encountered in adults from Western countries and Asia. IgAN is responsible for approximately 40% of end-stage renal disease (ESRD) mediated by glomerular impairment. The majority of adult IgAN patients present a slowly progressive pattern towards ESRD. Current types of treatment are based mainly on supportive care: i.e., life style risk factors, measures that lower blood pressure and reduce proteinuria, weight loss, smoking cessation or glycaemia control. Because IgAN is an immune complex-mediated disease, immunosuppression therapy gains more and more attention as a modality of treatment. Despite the beneficial effects, the value of immunosuppression remains controversial due to high rates of adverse reactions. The aim of this review is to highlight the benefits and limitations of promoting immunosuppression in IgAN with mild to moderate proteinuria despite supportive antiproteinuric therapy up titrated to maximum tolerated doses.

IgA Vasculitis with Nephritis in Adults: Histological and Clinical Assessment.

Patients with IgA vasculitis (IgAV), an immune complex-mediated disease, may exhibit kidney involvement—IgAV with nephritis (IgAVN). The kidney-biopsy histopathologic features of IgAVN are similar to those of IgA nephropathy, but little is known about histopathologic disease severity based on the interval between purpura onset and diagnostic kidney biopsy. We assessed kidney histopathology and clinical and laboratory data in a cohort of adult patients with IgAVN (n = 110). The cases were grouped based on the interval between the onset of purpura and kidney biopsy: Group 1 (G1, <1 month, n = 14), Group 2 (G2, 1–6 months, n = 58), and Group 3 (G3, >6 months, n = 38). Glomerular leukocytes were more common in G1 than in the other groups (p = 0.0008). The proportion of neutrophils among peripheral-blood leukocytes was the highest in the patients biopsied within a month after onset of purpura (G1: 71 ± 8%). In the patients with an interval >6 months, the neutrophil proportion was lower, 60%. Moreover, the glomerular mesangial proliferation score correlated with the serum total IgA concentration (p = 0.0056). In conclusion, IgAVN patients biopsied <1 month from purpura onset showed an elevated percentage of blood neutrophils and glomerular leukocytes, consistent with an acute-onset inflammatory reaction. In all IgAVN patients, the mesangial proliferation score correlated with the serum IgA level.

Antinucleosomal Antibodies and Its Correlation to SLE Manifestations

Subject: SLE is an autoimmune disease with skin, joint, renal, cardiovascular, and nervous manifestations. The disease is classified as an immune complex-mediated disease and is characterized by the production of various autoantibodies. Until now, more than 100 autoantibodies have been identified. Patients and methods: This study was performed on 200 SLE patients. All of them were females and their ages ranged from 20 to 49 years. All participants in this study were subjected to physical examination, thorough history taking including age, sex, age of onset, duration of SLE disease, family history, and SLEDAI. Laboratory investigations included: CBC, ESR, liver function tests, renal function tests, ANA, Anti-dsDNA, CRP, Complements C3, C4, and Anti-NCS. Results: There was a highly significant inverse correlation between anti-NCS antibodies and Hb level, a significant direct correlation between anti-NCS antibodies and 24hr proteinuria, a significant inverse correlation between anti-NCS antibodies and complements (C3 and C4), a significant correlation between anti-NCS antibodies and anti dsDNA antibodies, a significant correlation between anti-NCS and disease activity, SLEDAI, and renal affection. Conclusion: Anti-NCS antibody can be a useful tool in the diagnosis of SLE especially in patients who are negative for anti-ds DNA antibodies.

Correlation of clinicopathological characteristics and direct immunofluorescence studies in oral lichenoid lesion in Thai patients.

To investigate the correlation between the clinicopathological characteristics, serum antinuclear antibody (ANA) and direct immunofluorescence (DIF) findings in oral lichen planus (OLP) and oral lichenoid lesion (OLL). Fifty three Thai patients with red and white lesions were divided into 3 groups: 17 cases of OLP, 19 cases of OLL and 17 cases of oral lichenoid drug reaction (OLDR), respectively. The medical records, photographs, histopathological evaluation and laboratory ANA and DIF results were analyzed. Atrophic pattern was the most commonly found pattern in the OLDR, OLP and OLL groups. In the OLP group, the DIF interpretation confirmed only 41.2% of cases as OLP, with 23.5% each as lichen planus (LP)/lupus erythematosus (LE) or negative findings. In the OLL group, the most common DIF interpretation (31.6% each) was LP/LE or non-specific finding. In the OLDR group, DIF interpretation was OLP or LP/LE (23.5% each), with 5.9% each of immune complex-mediated disease, compatible with OLP, and mixed connective tissue disease. Interestingly, 1 case in the OLDR group demonstrated mild to moderate dysplasia. There were no significant differences in ANA positivity or patterns between the 3 groups. An OLP-like lesion could be diagnosed as OLP, OLP/LE, chronic ulcerative-like lesion, immune-mediated disease or dysplasia.

Elevation of serum CD5L concentration is correlated with disease activity in patients with systemic lupus erythematosus

Systemic lupus erythematosus (SLE) is characterized by an autoantibody- and immune complex-mediated inflammatory disease. Since CD5-like (CD5L), also known as apoptosis inhibitor of macrophage (AIM), is as an apoptosis inhibitor that protects the survival of macrophages, T cells, and NKT against proapoptotic agents, which plays an important role in the pathogenesis of various inflammatory diseases, we investigated the possible aberrant production of CD5L and its clinical implications in SLE patients. We measured the serum concentration and ex vivo production of CD5L in 68 SLE patients and 60 sex- and age- matched control individuals using an enzyme-linked immunoabsorbent assay. Serum CD5L concentrations were significantly higher in SLE patients than in healthy control subjects. Increase in CD5L concentration correlated positively and significantly with SLE Disease Activity Index (SLEDAI) score in all SLE patients. Besides, CD5L titers were positively correlated with anti-double stranded DNA antibody (anti-dsDNA) titers, ESR and C-reactive protein (CRP) levels, and negatively correlated with complement 3 (C3) and C4 levels. Serum CD5L concentrations could be significantly decreased after effective treatment of SLE. In addition, the ex vivo release of CD5L upon mitogen activation of peripheral blood mononuclear cells was significantly higher in the SLE groups than in the healthy control group. The above results suggest that the up-regulated production of CD5L is important in the immunopathogenesis of SLE, and may serve as a potential disease marker for the monitoring of SLE disease severity and therapeutic efficacy.

Crosstalk between TLR4 and Notch1 signaling in the IgA nephropathy during inflammatory response.

IgA nephropathy (IgAN) is an immune complex-mediated disease involved in the kidney disease. Recent studies have revealed that Notch signaling-related genes are aberrantly expressed in various cell types and maybe associate with inflammation-induced carcinogenesis. The aim of our study was to investigate the function of Notch1 in the inflammatory response of IgAN. The expression of Notch1, Jagged1 and NICD1 in 52 IgAN renal tissues and 20 control renal tissues was first determined using quantitative real-time PCR and Western blot. ELISA was then used to estimate the inflammatory response of human podocytes to LPS. NF-κB activity was measured using dual-luciferase reporter assay. Activation of Notch1 and NF-κB signaling pathway was assessed using Western blot. The expression of Notch1, NICD1 and Jagged1 was significantly higher in IgAN renal tissues than control renal tissues (P<0.05). LPS treatment resulted in an obvious increase of MCP-1, IL-8 and phosphorylated NF-κB p65 in podocytes polymeric IgA (pIgA) IgAN group compared to control group (P<0.05 for all). Activated Notch1 and its target genes, Hes1 and Hey1 were also enhanced upon LPS stimulation. Silencing of Notch1 signaling with inhibitor DAPT, NF-κB activation and LPS-induced inflammatory response were obviously attenuated, whereas Notch1 activator Jagged1 could markedly restore NF-κB activity and LPS-induced inflammatory response (P<0.05 for all). Crosstalk between TLR4 and Notch1 signaling regulates the inflammatory response in the IgAN and maybe plays an important role in the progression of IgAN.

De novo immune complex deposition in kidney allografts: a series of 32 patients

Immune complex deposition in kidney allografts can include both recurrent and de novo processes. Recurrent glomerulonephritis is a well-recognized phenomenon and has been shown to be a common cause of allograft failure. De novo immune complex-mediated disease remains relatively poorly characterized, likely owing to the less frequent use of immunofluorescence and electron microscopy in the transplant setting. We performed a retrospective review of kidney allograft biopsies showing glomerular immune complex deposition. Cases with de novo deposits were identified and further organized into two groups depending on whether the immune complex deposition could be clinically and/or histologically classified. Thirty-two patients with de novo immune complex deposition were identified over a 7-year period. A broad range of immune complex-mediated injuries were observed, the majority (63%) of which could be readily classified either clinically or histologically. These included cases of membranous glomerulonephropathy, IgA nephropathy, infection-related glomerulonephritis and glomerulonephritis related to an underlying autoimmune process. A smaller subset of patients (37%) demonstrated immune complex deposition that was difficult to histologically or clinically classify. These patients typically showed mild mesangial immune complex deposition with co-dominant IgG and IgM staining by immunofluorescence microscopy. The presence of concurrent antibody-mediated rejection and donor-specific antibody positivity was significantly higher in the unclassifiable group. The significance of these deposits and their possible relationship to allograft rejection deserves further investigation.

Cardiogenic shock as the initial presentation of systemic lupus erythematosus

&lt;p class="abstract"&gt;&lt;span lang="EN-IN"&gt;Childhood onset systemic lupus erythematosus (SLE) is a rare entity and comprise less than 20% of all cases of lupus. Prepubertal onset is even rarer as most cases are reported in adolescent age group. SLE is an immune-complex mediated disease with multiorgan involvement. We report a case of a 12 year old female child with cardiogenic shock, myocarditis and pyrexia&lt;/span&gt;&lt;span lang="EN-IN"&gt;. &lt;/span&gt;&lt;/p&gt;

Immunoglobulin A nephropathy: a pathophysiology view.

IgA nephropathy is one of the leading causes of primary glomerulonephritis worldwide and an important etiology of renal disease in young adults. IgA nephropathy is considered an immune complex-mediated disease. This review article summarizes recent evidence on the pathophysiology of IgA nephropathy. Current studies indicate an ordered sequence of multi-hits as fundamental to disease occurrence. Altered glycan structures in the hinge region of the heavy chains of IgA1 molecules act as auto-antigens, potentially triggering the production of glycan-specific autoantibodies. Recognition of novel epitopes by IgA and IgG antibodies leads to the formation of immune complexes galactose deficient-IgA1/anti-glycan IgG or IgA. Immune complexes of IgA combined with FcαRI/CD89 have also been implicated in disease exacerbation. These nephritogenic immune complexes are formed in the circulation and deposited in renal mesangium. Deposited immune complexes ultimately induce glomerular injury, through the release of pro-inflammatory cytokines, secretion of chemokines and the resultant migration of macrophages into the kidney. The TfR1/CD71 receptor has a pivotal role in mesangial cells. New signaling intracellular mechanisms have also been described. The knowledge of the whole pathophysiology of this disease could provide the rational bases for developing novel approaches for diagnosis, for monitoring disease activity, and for disease-specific treatment.

Identification of a novel Aleutian mink disease virus B-cell epitope using a monoclonal antibody against VP2 protein

Aleutian mink disease virus (AMDV) is a parvovirus that causes an immune complex-mediated disease in minks. Capsid protein VP2 is a major structural viral protein and can be used to diagnose AMDV. In this study, a specific monoclonal antibody, 1M13, was produced against the AMDV VP2 protein (amino acids 291–502). A linear VP2-protein epitope was identified by subjecting a series of partially overlapping synthesized peptides to be enzyme-linked immunosorbent assay (ELISA) analysis. The results indicated that 386HLQQNFSTRYIYD398 was the minimal linear epitope that could be recognized by mAb 1M13. ELISA assays revealed that mink anti-AMDV sera could also recognize the minimal linear epitope. Sequence alignments demonstrated that the linear epitope is highly conserved among AMDV strains except 386H and is less conserved among Raccoon dog amdovirus, Gray fox amdovirus, Red fox amdovirus, Bat parvovirus and Mink enteritis parvovirus. Taken together, the generation of this VP2-specific mAb with a defined linear peptide epitope may have potential applications in the development of suitable diagnostic techniques for AMDV.

A novel mechanism for enhanced neutrophil recruitment, retention, and podocyte damage in immune complex-mediated glomerular disease.

Abstract Glomerulonephritis (GN) is characterized by immune complex deposition and ensuing inflammation within the glomerulus of the kidney. Frank J. Dixon, a pioneer in immunologic kidney disease research, reported in 1965 that injection of nephrotoxic antibodies in rats and rabbits resulted in proteinuria and glomerular accumulation of neutrophils, and that depletion of circulating neutrophils reduced this immune-mediated glomerular damage and proteinuria. In the decades since, studies have confirmed a role for glomerular neutrophil accumulation in human GN, but the mechanisms for neutrophil recruitment and neutrophil-directed injury have not been resolved. We previously reported genetic variants for a NF-κB inhibitor ABIN1 as risks for GN. Others also report that glomerular ABIN1 gene expression is altered in GN in mice and humans. Here we present that transgenic disruption of ABIN1 function results in exacerbated podocyte injury, glomerular expression of inflammatory mediators, and glomerular recruitment and retention of neutrophils in a mouse model of acute antibody-mediated GN. Moreover, a novel inhibitor of neutrophil granule release (SNAP23 peptide) also attenuates podocyte injury in this model. These in vivo findings are supported by in vitro experiments showing that secretome from homologous ABIN1 mutant podocytes activates neutrophil chemotaxis and granule release and neutrophil granule contents specifically disrupts cytoskeletal organization of ABIN1 mutant podocytes. These studies unfold a role for ABIN1 dysfunction in a novel neutrophil-mediated mechanism of podocyte injury in GN and presents inhibition of neutrophil granule release as a promising novel therapeutic direction for kidney inflammation.

Manifestations of Complement-Mediated and Immune Complex-Mediated Membranoproliferative Glomerulonephritis: A Comparative Consecutive Series

Membranoproliferative glomerulonephritis (MPGN) recently was reclassified to reflect the underlying cause as a complement-mediated and immune complex-mediated disease. This classification is based on renal biopsy immunofluorescence examination, making the former electron-microscopy classification obsolete. In this report, we describe related eye findings in patients with MPGN based on the new classification. Retrospective case series. All Mayo Clinic Rochester patients with pathology-confirmed complement- and immune complex-mediated MPGN who had available ophthalmology records from 1997 through 2014 were included in this study. The medical and pathologic records of patients with MPGN and eye examination results were reviewed from years 1997 through2014. The number of patients and the number of eyes with MPGN-related pathologic features were examined. Visual acuity also was considered. There were 23 patients with complement-mediated MPGN and available eye examination results. Of these, 9 patients (39%) and 17 eyes (37%) had retinal pathologic features that likely were related to the same underlying pathophysiologic process as their renal disease. Five patients (22%) and 6 eyes (13%) had significant vision loss. There were 23 patients with immune complex-mediated MPGN and available eye examination results. Only 2 (9%) of these patients (4 eyes) had retinal pathologic features that potentially could be related to the same underlying pathophysiologic process as their renal disease, and neither had vision loss. Retinal abnormalities are more prominent among patients with complement-mediated MPGN when compared with patients with immune complex-mediated MPGN. It is critical for ophthalmologists to recognize the updated MPGN classification system, and all patients with complement-mediated MPGN require screening eye examinations.

Change in intrarenal Ghrelin expression in immune complex-mediated glomerular disease in dogs.

Ghrelin is a peptide hormone that is mainly produced by the stomach. The kidney is a major source of local ghrelin, and maintaining body fluid balance is considered a critical role of renal ghrelin. However, there are no reports on renal ghrelin in small animal medicine. The present study investigated the intrarenal localization of and change in ghrelin expression in dogs with immune complex-mediated glomerulonephritis (ICGN). Ghrelin immunoreactivity (IR) was observed in the distal tubules of normal kidneys. Ghrelin IR was weak in ICGN kidneys, and the quantitative ghrelin IR score was significantly lower in ICGN kidneys than in normal kidneys. In cases of ICGN, plasma creatinine concentrations showed a positive correlation with the ghrelin IR score.

Purpura rhumatoïde de l’adulte

Henoch-Schönlein purpura is a systemic vasculitis of the small vessels characterized by perivascular leucocyte infiltrates. It is an immunoglobulin A-related immune complex-mediated disease involving the skin, the joints and the gastrointestinal system. Renal disease may sometimes be associated to these clinical manifestations. Prevalence of the nephritis is highly variable, depending on the series. More rarely, other organs such as the lungs, the heart or the nervous system may be involved. The clinical diagnosis is confirmed by histopathology of the skin (leukocytoclastic vasculitis) and kidney (endo-capillary proliferative glomerulonephritis), showing IgA deposits in these tissues. Short-term prognosis depends on the severity of digestive involvement, but long-term prognosis depends on the renal disease. Recent publications of pediatric and adult series show that the chronic renal failure may progress, sometimes more than ten years after the initial flare. Treatment is usually supportive. The benefit of more specific treatments (corticosteroids or immunosuppressive drugs) in severe visceral forms (usually abdominal or kidney) has not yet been established.

Elevated serum levels of visfatin in patients with henoch-schönlein purpura.

BackgroundHenoch-Schönlein purpura (HSP) is an immune complex-mediated disease predominantly characterized by the deposition of circulating immune complexes containing immunoglobulin A (IgA) on the walls of small vessels. Although the pathogenesis of HSP is not yet fully understood, some researchers proposed that B-cell activation might play a critical role in the development of this disease.ObjectiveTo investigate the serum levels of visfatin (pre-B-cell colony-enhancing factor), B-cell-activating factor (BAFF), and CXCL13, and to analyze their association with disease severity.MethodsThe serum levels of visfatin, BAFF, and CXCL13 were measured by using a double-antibody sandwich enzyme-linked immunosorbent assay (ELISA) in 43 patients with HSP and 45 controls. The serum levels of IgA anticardiolipin antibodies (ACA) were detected by using a double-antigen sandwich ELISA.ResultsLevels of visfatin but not BAFF and CXCL13 were significantly elevated in the sera of patients with HSP in the acute stage, and restored to normal levels in the convalescent stage. Furthermore, serum levels of visfatin were significantly higher in patients with HSP having renal involvement than in those without renal involvement. Serum levels of visfatin were correlated with the severity of HSP and serum concentration of ACA-IgA.ConclusionWe show for the first time that the serum levels of visfatin are abnormally elevated in patients with HSP. Visfatin may be associated with the pathogenesis of HSP.

Neonatal Fc Receptor Promotes Immune Complex–Mediated Glomerular Disease

The neonatal Fc receptor (FcRn) is a major regulator of IgG and albumin homeostasis systemically and in the kidneys. We investigated the role of FcRn in the development of immune complex-mediated glomerular disease in mice. C57Bl/6 mice immunized with the noncollagenous domain of the α3 chain of type IV collagen (α3NC1) developed albuminuria associated with granular capillary loop deposition of exogenous antigen, mouse IgG, C3 and C5b-9, and podocyte injury. High-resolution imaging showed abundant IgG deposition in the expanded glomerular basement membrane, especially in regions corresponding to subepithelial electron dense deposits. FcRn-null and -humanized mice immunized with α3NC1 developed no albuminuria and had lower levels of serum IgG anti-α3NC1 antibodies and reduced glomerular deposition of IgG, antigen, and complement. Our results show that FcRn promotes the formation of subepithelial immune complexes and subsequent glomerular pathology leading to proteinuria, potentially by maintaining higher serum levels of pathogenic IgG antibodies. Therefore, reducing pathogenic IgG levels by pharmacologic inhibition of FcRn may provide a novel approach for the treatment of immune complex-mediated glomerular diseases. As proof of concept, we showed that a peptide inhibiting the interaction between human FcRn and human IgG accelerated the degradation of human IgG anti-α3NC1 autoantibodies injected into FCRN-humanized mice as effectively as genetic ablation of FcRn, thus preventing the glomerular deposition of immune complexes containing human IgG.