Clinicopathological analysis of ANCA-associated glomerulonephritis focusing on plasma cell infiltrate

Clinical outcomes and clinico-pathological correlations in children with MPO-ANCA-associated glomerulonephritis showing renal arteritis

The aim of this study was to evaluate the clinical features, pathological characteristics, and prognosis in myeloperoxidase (MPO)-antineutrophil cytoplasmic antibodies (ANCA)-associated glomerulonephritis (AAGN) with renal arteritis. The study involved 97 children from five pediatric clinical centers with MPO-AAGN who exhibited distinct clinical features. The patients were divided into AAGN-A+ and AAGN-A-, based on the presence or absence of arteritis, and the disparities in clinical, histopathological characteristics, and prognosis between the two groups was evaluated. In contrast to the AAGN-A- group, the children in the AAGN-A+ group exhibited more pronounced clinical symptoms and renal pathological injury. Arteritis positively moderately correlated with the serum creatinine, interleukin-6, urinary neutrophil gelatinase-associated lipocalin, negatively moderately correlated with serum complement C3. The renal survival rate in the AAGN-A+ group was significantly poorer than AAGN-A- group (χ2 = 4.278, p = 0.039). Arteritis showed a good predictive value for end-stage kidney disease (ESKD), and C3 deposition, ANCA renal risk score and arteritis were independent risk factors for the development of ESKD in children with MPO-AAGN. Arteritis is a significant pathological change observed in children with MPO-AAGN, and the formation of arteritis may be related to the inflammatory response and activation of the complement system.

Immunohistological analysis reveals IgG1-dominant immunophenotype of tubulointerstitial nephritis unassociated with IgG4-related diseases

PURPOSE

Tubulointerstitial nephritis (TIN) has various etiologies, including IgG4-related disease (IgG4-RD), autoimmune diseases, antineutrophil cytoplasmic antibody (ANCA)-associated vasculitis (AAV), and others. IgG4-positive plasma cell infiltration can occasionally be found in TIN unrelated to IgG4-RD. Therefore, there may be problems with usage of IgG4 immunostaining to differentiate between TIN with and TIN without IgG4-RD. This study aimed to compare the proportion of plasma cells that are positive for each IgG subclass and to clarify the predominant IgG subclass trends and clinical characteristics associated with IgG4-RD and non-IgG4-related interstitial nephritis.

METHODS

The study enrolled 44 cases of TIN: 6 of IgG4-RD, 8 of autoimmune disease, 9 of AAV, and 21 of unknown disease group. In addition to clinical characteristics, IgG subclass composition of interstitial plasma cells was evaluated among 4 groups by immunohistochemistry.

RESULTS

IgG1 was the predominant IgG subclass in TIN unrelated to IgG4-RD. In the IgG4-RD group, the IgG subclass rate was high in both IgG1 and IgG4. The rate of average IgG4-positive cells was significantly lower in the autoimmune disease group and unknown disease group compared with the IgG4-RD group.

CONCLUSION

The present study revealed IgG1-dominant immune profiles of TIN unrelated to IgG4-RD. Further investigation is required to elucidate the clinicopathological differences between IgG1-dominant and IgG4-dominant groups in IgG4-RD.

Antineutrophil Cytoplasmic Autoantibody-negative Pauci-immune Necrotizing Glomerulonephritis with Plasma Cell-rich Tubulointerstitial Nephritis Complicated with Pleuritis and Digital Ischemia

Antineutrophil cytoplasmic autoantibody (ANCA)-associated vasculitis (AAV) predominantly affects small vessels. Almost all AAV patients are positive for myeloperoxidase- or proteinase 3-ANCA, and ANCA plays a crucial role in the pathogenesis of AAV. We herein report an ANCA-negative AAV patient with pauci-immune necrotizing glomerulonephritis and plasma cell-rich tubulointerstitial nephritis who was complicated with pleuritis and digital ischemia. ANCA-negative AAV is a rare clinical entity that is difficult to diagnose, and pleuritis and digital ischemia are rare manifestations of AAV. An early diagnosis and appropriate treatment are important, as any delay in the diagnosis may worsen the prognosis.

Clinical significance of kidney immune complex deposition in children with acute interstitial nephritis disease

BACKGROUND

Acute interstitial nephritis (AIN) is a relatively rare cause of acute kidney injury (AKI) in children. Immune complex (IC) deposition was rare in renal pathology of AIN.

METHODS

Based on the status and position of IC deposition, a total of 78 children with AIN were divided into two groups: the non-IC group and IC group. IC group was further divided into two subgroups: intraglomerular (IG)-IC group and extraglomerular (EG)-IC group. To compare the clinical and histological features, renal outcomes between groups.

RESULTS

The IC deposition, IG-IC and EG-IC deposition were observed in 22 (28.21%), 12 (15.38%) and 10 (12.82%) children, respectively. The IC group demonstrated a higher frequency of AKI, higher level of Scr, urine N-acetyl-β-D-glucosidase (NAG) enzyme, retinol-binding protein (RBP), neutrophil gelatinase-associated lipocalin (NGAL), higher frequency of neutrophils, plasma cells and eosinophils infiltrate, higher scores of interstitial inflammation (i), total inflammation (ti) and interstitial edema, lower level of estimated glomerular filtration rate (eGFR) as compared to non-IC group (p < 0.05, p < 0.01). EG-IC deposition positively moderate correlated with levels of RBP, IG-IC deposition positively moderate correlated with plasma cell infiltrate, interstitial inflammation (i), total inflammation (ti) and interstitial edema. Interstitial inflammation, EG-IC deposition and interstitial edema were risk factors for AKD in AIN, and interstitial fibrosis/tubular atrophy (IF/TA) was a risk factor for CKD in children with AIN.

CONCLUSION

IG-IC and EG-IC deposition positively correlated with severe clinical manifestations, glomerular and tubular injuries, and EG-IC deposition was risk factor for the progression of AIN in children.

Crescentic glomerulonephritis in children: short-term follow-up predicts long-term outcome

Background

Crescentic glomerulonephritis (CrGN) is a relatively rare but severe condition in childhood with the clinical feature of rapidly progressive glomerulonephritis (RPGN). The aim of this study is to investigate the clinicopathological features and prognosis of CrGN in children.

Methods

We retrospectively analyzed the clinical and laboratory data, renal pathological results, treatment, and outcome of 147 CrGN in two Chinese pediatric nephrology centers.

Results

Among the 147 children, there were 22 cases of type I (15.0%), 69 cases of type II (46.9%), and 56 cases of type III (38.1%). The mean percentages of crescents in CrGN I, II, and III were 85.3%, 68.7%, and 73.6%, respectively. The children with type I CrGN presented with more severe clinical manifestations and pathological lesions. The 3-month cumulative renal survival rates of types I, II, and III CrGN were 66.3%, 93.6%, and 75.6%, respectively. The 1-year cumulative renal survival rates of types I, II, and III CrGN were 56.9%, 85.3%, and 73.1%, respectively, and the 5-year cumulative renal survival rates of types I, II, and III CrGN were 33.8%, 73.5%, and 47.1%, respectively. The Kappa Consistency Test between the 3-month and 1-year total renal survival (82.1% vs. 74.7%) of the children was 0.683 (P < 0.001), and between the 1-year and 5-year total renal-free survival (78.3% vs. 69.1%) of the children was 0.476 (P < 0.001). The Bowman's Capsule Rupture (BCR), crescent, interstitial inflammation, and interstitial fibrosis/tubular atrophy (IF/TA) score were predictors of end-stage kidney disease (ESKD) risk but BCR showed better predictive value for ESKD than interstitial inflammation score (P = 0.027) and IF/TA score (P = 0.047).

Conclusion

Patients with type I tended to have the worst renal survival rates. The three-month renal prognosis could partially reflect the 1-year renal prognosis, and the 1-year mortality rate could partially reflect the 5-year mortality rate of children with CrGN.

[Basic nephropathology for pathologists-part 1 : Kidney biopsy-inflammation and immune complexes]

The assessment of kidney biopsies is mainly confined to specialized centres. However, sometimes a kidney biopsy is submitted to a general pathologist, and in addition peritumorous renal parenchyma in tumour nephrectomies can have concomitant non-neoplastic renal disease. Here we present a survey of inflammatory and immunologic changes in all renal compartments, which may in part indicate the need of prompt therapeutic intervention such as in vasculitis, glomerulonephritis and interstitial nephritis. It is important to take into account that renal involvement of vasculitis is mainly centred in glomeruli and only to a much lesser extent in arteries, and that the frequently observed interstitial inflammation very often is an epiphenomenon of another primary kidney disease and not an independent disease process. Typical renal patterns of injury are emphasised.

ANCA-associated vasculitis and IgG4-related disease overlap syndrome: a case report and literature review

Anti-neutrophil cytoplasmic antibodies (ANCA)-associated vasculitides are infrequent autoimmune diseases characterized by inflammation of the walls of small vessels leading to tissue and endothelial damage. On the other hand, IgG4-related disease is a fibroinflammatory disease characterized histologically by lymphoplasmacytic infiltrates with IgG4+ plasma cells, storiform fibrosis, and obliterative phlebitis that may affect nearly every organ of the body. There are similarities in clinical, serological, radiological, and histopathological features between both diseases, and hence, they usually mimic each other complicating the differential diagnosis. Furthermore, reports of patients with the coexistence of both conditions (overlap syndrome) have been reported. We herein report a patient with an unequivocal diagnosis of ANCA-associated vasculitis, specifically granulomatosis with polyangiitis (posterior uveitis, polyneuropathy, pauci-immune glomerulonephritis with crescent formation and granulomas, and MPO-ANCA positivity) and IgG4-related disease (thoracic aortitis, tubulointerstitial nephritis with prominent IgG4+ plasma cell infiltration, fibrosis, and obliterative arteritis, high levels of serum IgG4, and eosinophilia) overlap syndrome.

Neutrophils associate with Bowman's capsule rupture specifically in PR3-ANCA glomerulonephritis

Background

Renal involvement is a common and severe complication of ANCA (antineutrophil cytoplasmic antibody) associated vasculitis (AAV) potentially resulting in a pauci-immune necrotizing and crescentic antineutrophil cytoplasmic antibody (ANCA) glomerulonephritis (GN) with acute kidney injury (AKI), end-stage renal disease (ESRD) or death. We recently described that Bowman’s capsule rupture links glomerular damage to tubulointerstitial inflammation in ANCA-associated glomerulonephritis. Herein we provide a comprehensive histological subtyping of immune cell infiltrates in association with Bowman’s capsule rupture in ANCA GN.

Methods

A total of 44 kidney biopsies with ANCA GN were retrospectively included in a single-center observational study. Within a renal biopsy specimen, each glomerulus was scored separately for the presence of extensive and focal Bowman’s capsule rupture in injured glomeruli. Infiltrates of neutrophils, eosinophils, plasma cells, and mononucleated cells (macrophages, lymphocytes) were quantified as a fraction of the area of total cortical inflammation.

Results

Extensive Bowman’s capsule rupture was associated with tubulointerstitial inflammation containing infiltrates of neutrophils, eosinophils and plasma cells. A similar association was observed for the presence of focal Bowman’s capsule rupture, correlating with tubulointerstitial inflammation containing neutrophils, eosinophils and plasma cells. Multiple logistic regression confirmed that extensive Bowman’s capsule rupture correlated with tubulointerstitial inflammation containing neutrophils, and focal Bowman’s capsule rupture correlated with neutrophil and plasma cell infiltration. Furthermore, this association was specifically observed in PR3-ANCA GN.

Conclusion

To our knowledge, this is the first report linking Bowman’s capsule rupture directly to tubulointerstitial inflammation by immune cell subtypes. This underscores a pathomechanistic link between tubulointerstitial and glomerular lesions in ANCA GN and needs further investigation.

Graphical abstract

Comparative Histological Subtyping of Immune Cell Infiltrates in MPO-ANCA and PR3-ANCA Glomerulonephritis

Background

Acute kidney injury (AKI) is a common and severe complication of anti-neutrophil cytoplasmic antibodies (ANCA)-associated vasculitis (AAV), potentially leading to chronic kidney disease (CKD), end-stage renal disease (ESRD), or death. Pathogenic ANCAs, in particular proteinase 3 (PR3) and myeloperoxidase (MPO), trigger a deleterious immune response with intrarenal immune cell infiltration resulting in a pauci-immune necrotizing and crescentic glomerulonephritis (GN). However, a systematic analysis of intrarenal immune cell subtypes concerning neutrophils, eosinophils, plasma cells, and mononuclear cell infiltrates (macrophages, lymphocytes) in ANCA GN remains elusive. Therefore, we aimed to compare distinct immune cell infiltrates in association with clinicopathological findings in ANCA GN.

Methods

A total of 53 kidney biopsies with ANCA GN at the University Medical Center Göttingen were retrospectively analyzed. Histological infiltrates of neutrophils, eosinophils, plasma cells, and mononucleated cells (macrophages, lymphocytes) were quantified as a fraction of the total area of inflammation.

Results

Neutrophilic infiltrates were associated with glomerular necrosis and severe kidney injury in ANCA GN. Among tubulointerstitial lesions, intrarenal neutrophils correlated with interstitial inflammation, tubulitis, and inflammation in areas of interstitial fibrosis/tubular atrophy (IFTA), representing active inflammatory lesions. Concerning eosinophils, infiltrates were associated with severe kidney injury, interstitial inflammation, and cellular casts independent of glomerular lesions, implicating a distinct role in inflammation and damage in ANCA GN. Plasma cell infiltrates correlated with tubulitis and interstitial fibrosis and were associated with renal replacement therapy during the short-term disease course. Finally, mononuclear cell infiltrates correlated with severe kidney injury and active histopathological lesions (glomerular crescents, interstitial inflammation, tubulitis, inflammation, and tubulitis in areas of IFTA) besides chronic lesions (interstitial fibrosis and tubular atrophy) in ANCA GN. Interestingly, intrarenal subtypes of immune cell infiltrates differed in MPO-ANCA versus PR3-ANCA GN and were associated with distinct glomerular and tubulointerstitial lesions, implicating different pathogenic mechanisms of kidney injury in ANCA subtypes.

Conclusion

Our observations imply distinct pathomechanisms contributing to inflammation and renal injury in MPO vs. PR3-associated ANCA GN and potentially contribute to new therapeutic targets in specific ANCA subtypes.

A case of vasculitis case with unusual renal pathological findings presenting with rapidly progressing renal failure

Plasma cell infiltration may be an early lesion during renal invasion by ANCA-associated vasculitis (AAV), and AAV should be considered in the differential diagnosis with acute renal failure and systemic symptoms.

Elevation of erythrocyte sedimentation rate and C-reactive protein levels reflects renal interstitial inflammation in drug-induced acute tubulointerstitial nephritis

BACKGROUND

A renal biopsy is needed to define active inflammatory infiltration and guide therapeutic management in drug-induced acute tubulointerstitial nephritis (D-ATIN). However, factors such as various contraindications, refusal of informed consent and limited technical support may stop the biopsy process. It is thus of great importance to explore approaches that could deduce probable pathologic changes.

METHODS

A total of 81 biopsy-proven D-ATIN patients were enrolled from a prospective cohort of ATIN patients at Peking University First Hospital. The systemic inflammation score (SIS) was developed based on the CRP and ESR levels at biopsy, and patients were divided into high-SIS, median-SIS, and low-SIS groups. The demographic data, clinicopathologic features, and renal outcomes were compared.

RESULTS

The SIS was positively correlated with inflammatory cell infiltration and was inversely correlated with interstitial fibrosis. The number of interstitial inflammatory cells increased significantly with increasing SISs. The proportions of neutrophils and plasma cells were the highest in the high-SIS group compared with the other two groups. Prednisone (30-40 mg/day) was prescribed in all patients. The high-SIS group tended to have more favorable renal restoration than the other two groups. By 12 months postbiopsy, a decreased eGFR (< 60 mL/min/1.73 m²) was observed in 66.7% of medium-SIS patients, 32.4% of high-SIS patients, and 30.4% of low-SIS patients.

CONCLUSION

The SIS was positively correlated with active tubulointerstitial inflammation and therefore could help to aid therapeutic decisions in D-ATIN.

Characteristics and prognosis of ANCA-positive retroperitoneal fibrosis: A systematic literature review

OBJECTIVE

Anti-neutrophil cytoplasmic autoantibody (ANCA)-positive retroperitoneal fibrosis (RPF) is extremely rare. This study aimed to clarify the clinical characteristics and prognosis of patients with ANCA-positive RPF.

METHODS

We conducted a systematic literature review of articles reporting on ANCA-positive RPF from the database inception dates until March 8, 2020.

RESULTS

We identified 19 patients with ANCA-positive RPF with a mean age of 62 years; a male dominance (68.4%) was noted. Most patients presented with systemic symptoms and/or lower back or abdominal pain. Proteinase 3 (PR3) -ANCA positivity was predominant compared with myeloperoxidase (MPO)-ANCA (63.2% vs. 36.8%, respectively), and all patients showed elevated serum C-reactive protein levels. Of note, 26.7% of patients had isolated RPF without any other ANCA-associated systemic organ involvement. Regarding typical manifestations of ANCA- associated vasculitis, ear, nose, and throat involvement occurred in 26.3%, lung involvement in 36.8%, and kidney involvement (rapidly progressive glomerulonephritis) in 31.6% of patients. Necrosis and granulomatous inflammation, vasculitis, and multinucleated giant cells were pathologically observed in tissue sections of RPF, whereas tertiary lymphoid organ formation was not identified. Glucocorticoids with or without other immunosuppressive treatments were effective in most patients, but 4 patients experienced disease relapse during the clinical course. All relapsed patients were positive for PR3-ANCA.

CONCLUSION

Clinical features of ANCA-positive RPF are associated with systemic inflammatory components such as fever and elevated serum C-reactive protein levels. ANCA-. positive RPF presents as an "isolated" involved organ in one-third of patients. Immunosuppressive treatments are effective, but the disease can recur, particularly in PR3-ANCA-positive patients.

Advances in the diagnosis and management of IgG4 related disease

IgG4 related disease was recognized as a unified disease entity only 15 years ago. Awareness of IgG4 related disease has increased worldwide since then, and specialists are now familiar with most of its clinical manifestations. Involvement of the pancreato-biliary tract, retroperitoneum/aorta, head and neck, and salivary glands are the most frequently observed disease phenotypes, differing in epidemiological features, serological findings, and prognostic outcomes. In view of this multifaceted presentation, IgG4 related disease represents a great mimicker of many neoplastic, inflammatory, and infectious conditions. Histopathology remains key to diagnosis because reliable biomarkers are lacking. Recently released classification criteria will be invaluable in improving early recognition of the disease. IgG4 related disease is highly treatable and responds promptly to glucocorticoids, but it can lead to end stage organ failure and even death if unrecognized. Prolonged courses of corticosteroids are often needed to maintain remission because the disease relapses in most patients. Rapid advancement in our understanding of the pathophysiology of IgG4 related disease is leading to the identification of novel therapeutic targets and possible personalized approaches to treatment.