IgG antineutrophil cytoplasmic antibodies in IgA nephropathy: a clinical variant?

The Presence of ANCA in IgA Crescentic Nephropathy Does Not Lead to Worse Prognosis with Intensive Rescue Treatment

BACKGROUND

Immunoglobulin A nephropathy (IgAN) is the most common glomerulonephritis worldwide. The concomitant presence of both crescentic proliferation and anti-neutrophil cytoplasmic autoantibodies (ANCA) in this pathology represents a rare coincidence. However, it is not clear to what extent the presence of ANCA (IgA or IgG) in these patients could have any clinical significance. The aim of the current work is to describe the presence of ANCA (IgA or IgG) in patients with IgAN and crescentic proliferation and its possible clinical implications.

METHODS

We retrospectively recruited all patients in our center with a histological diagnosis of IgAN with crescentic proliferation between January 2013 and December 2020. The main demographic and clinicopathologic data, fundamental histological characteristics, as well as the treatments implemented and main kidney outcomes, were collected and analyzed at a 6 and 12-month follow-up.

RESULTS

Between January 2013 and December 2020, a total of 17 adults were diagnosed with concomitant crescentic proliferation through a kidney biopsy of IgAN. Five (29.4%) patients showed ANCA, three (60%) showed IgA-ANCA and two (40%) showed IgG-ANCA. All ANCA-positive patients had some degree of crescentic proliferation. At diagnosis, the mean age of patients was 48 years old (range: 27-75). Nine of them were women (52%) and the most common clinical presentation was hypertension (71%). At the time of biopsy, the mean serum creatinine and proteinuria were 2.2 mg/dL (DS 1.42) and 3.5 g/mgCr (DS 1.22), respectively, with no statistical differences between ANCA-positive and -negative patients. Histological analyses showed that 11 out of the 12 (91%) ANCA-negative IgAN patients displayed less than 25% cellular crescents, whereas 100% of ANCA-positive IgAN patients displayed more than 25% cellular crescents (p = 0.04). Notably, five (30%) patients displayed fibrinoid necrosis, with four of them (80%) being IgAN-ANCA-positive (p = 0.01). Only one ANCA-negative patient needed renal replacement therapy (RRT) upon admission (5%). The mean serum creatinine and proteinuria were 1.94 mg/dL (DS 1.71) and 1.45 g/gCr (DS 1.78), respectively, within 6 months of immunosuppressive therapy. At 12-month follow-up, the mean creatinine was 1.57 mg/dL (DS 1). Four (23.5%) patients needed RRT at the end of the follow-up and four (23.5%) patients died.

CONCLUSIONS

Probably due to the limited number of IgAN-ANCA-positive and IgAN-ANCA-negative patients, no significant differences were found between the clinical and laboratory characteristics. IgAN-ANCA-negative patients seemed to display less extracapillary proliferation than IgAN-ANCA-positive patients, who tended to show significantly higher fibrinoid necrosis. There were no differences regarding renal prognosis and patient survival after aggressive immunosuppressive therapy within 6 and 12 months when comparing the two samples.

Pathogenesis of Uveitic Glaucoma

Uveitic glaucoma consists one of the most serious complications of intraocular inflammation and, despite its rarity, is considered as one of the leading causes of preventable loss of vision worldwide. It has been associated with a wide spectrum of inflammatory diseases, but its pathogenesis is still not fully comprehended. It appears that the type of inflammation, the steroid-response and the anatomical alterations of the anterior chamber play a pivotal role. To our knowledge, the mechanisms may be both acute and chronic. The main targets of the treatment are to control the inflammation and reduce the intraocular pressure (IOP). The management of glaucoma associated with uveitis remains an extremely challenging condition for ophthalmologists. The successful treatment of uveitic glaucoma is inextricably correlated with prompt and immediate therapeutic decisions. Very often a solid collaboration between clinicians from different specialties may be required for treating the underlying disease.

Further understanding of its pathogenesis can indicate therapeutic targets and may lead to the development of new and more efficient therapeutic approaches. New glaucoma surgical modalities may ameliorate the prognosis after surgical intervention, but this calls for further evaluation. This study aims to highlight the complexity of uveitic glaucoma analyzing the main pathogenetic mechanisms and the correlations with the inflammatory response.

Clinical features of IgA nephropathy with serum ANCA positivity: a retrospective case-control study

Background

The coexistence of IgA nephropathy (IgAN) and antineutrophil cytoplasmic autoantibodies (ANCAs) is relatively rare. Only a few studies have reported the features of these patients.

Methods

We studied the clinical and histological features of 20 ANCA-positive IgAN patients. They were compared with ANCA-negative IgAN patients (n = 40) and ANCA-associated systemic vasculitis (AASV) patients (n = 40) with a randomly selected and matched proportion of crescentic glomeruli. Furthermore, 9 ANCA-positive crescentic IgAN patients out of the 20 cases were compared with two control groups with crescentic nephritis.

Results

ANCA-positive IgAN patients showed older age, lower haemoglobin and higher inflammatory indicator levels at baseline, and a higher percentage of general symptoms and pulmonary involvement, compared with ANCA-negative IgAN patients, and were comparable to AASV patients. Histologically, there was a significantly higher percentage of fibrinoid necrosis in glomeruli in ANCA-positive IgAN patients and in AASV patients compared with ANCA-negative IgAN patients (35, 25 and 0%, respectively, P = 0.003). After immunosuppressive therapy, ANCA-positive crescentic IgAN patients were more likely to withdraw from dialysis (75 versus 9.1%, P = 0.03) and not to reach end-stage renal disease within 6 months (11.1 versus 66.7%, P = 0.01) compared with ANCA-negative crescentic IgAN patients.

Conclusions

IgAN patients with ANCA positivity showed more severe clinical and histological features when compared with ANCA-negative IgAN patients and were comparable to AASV patients. However, renal prognosis was relatively better in ANCA-positive crescentic IgAN patients after aggressive immunosuppressive therapy in the short term, compared with ANCA-negative patients.

MPO-ANCA-positive IgA nephropathy successfully treated with tonsillectomy

A 20-year-old Japanese woman was admitted to a hospital because of gross hematuria. She was diagnosed with IgA nephropathy with a poor prognosis, based on the formation of many crescents in the glomerulus and monocyte infiltration in the interstitium in a renal biopsy specimen in February 2003. Myeloperoxidase (MPO)-antineutrophil cytoplasmic antibody (ANCA) was not identified at that time. After treatment with high-dose steroid pulse therapy and heparin/warfarin, her urinary protein improved, to 0.5 g/day. However, 1 year after the steroid pulse therapy, urinary protein was increased to 1.2 g/day, associated with repeated episodes of tonsillitis. A second renal biopsy was performed, and showed an improving tendency, compared to the findings of the previous one, although some crescent formation and adhesions of Bowman's capsule remained. Interestingly, MPO-ANCA was positive in the serological examination done at this time. One month and a half after the second renal biopsy, she had a tonsillectomy, followed by a regimen of 5 mg oral prednisolone daily, in order to prevent the progression of IgA nephropathy. After the tonsillectomy, her urinary protein level was markedly improved, at 0.14 g/day. Her creatinine clearance was ameliorated, at 102 ml/min, and in addition, MPO-ANCA had disappeared. This case suggests that an inflammation such as tonsillitis may be associated not only with the activity of IgA nephropathy but also with the production of MPO-ANCA.

Pathogénie des vascularites systémiques primitives (II): vascularites ANCA-négatives

The pathogenesis of different types of systemic vasculitis negative for antineutrophil cytoplasm antibodies (ANCA) and involving small or medium-sized vessels is not very well documented. During polyarteritis nodosa (PAN), which is related to hepatitis B virus (HBV) infection, as well as during cryoglobulinemic vasculitides, associated with hepatitis C virus (HCV), and probably during Henoch Schönlein purpura, histological lesions may result from the deposition of immune complexes formed from viral antigens and from antibodies responsible for the activation of the classic complement pathway and for recruitment of polymorphonuclear neutrophils. Two other mechanisms are discussed for other types of ANCA-negative systemic vasculitis: immune complex deposition and sheer stress at arterial bifurcation points. A bacterial superantigen is suspected in Kawasaki disease but remains unproved.

Simultaneous occurrence of diabetic glomerulosclerosis, IgA nephropathy, crescentic glomerulonephritis, and myeloperoxidase-antineutrophil cytoplasmic antibody seropositivity in a Chinese patient

We report the case of a 72-year-old woman with a long-standing history of diabetes mellitus who presented with heavy proteinuria and rapid deterioration in renal function. She had a high titer of myeloperoxidase-antineutrophil cytoplasmic antibody (MPO-ANCA). The renal biopsy specimen revealed features of diabetic glomerulosclerosis, crescentic glomerulonephritis, and IgA nephropathy. Treatment with steroid and cyclophosphamide resulted in significant improvement in renal function and normalization of MPO-ANCA level. This case highlights the importance of having a high index of suspicion for coexisting glomerulonephritis in diabetic patients presenting with proteinuria. The clinical course of patients with diabetic glomerulosclerosis, IgA nephropathy, crescentic glomerulonephritis, and MPO-ANCA seropositivity seems to resemble that of ANCA-associated, rapidly progressive glomerulonephritis and is potentially amenable to aggressive immunosuppressive therapy.

Schönlein-henoch purpura in children and adults: diagnosis, pathophysiology and management

Schönlein-Henoch syndrome is a form of systemic small-vessel vasculitis, characterised by vascular and/or mesangial immunoglobulin A1 deposits. The main clinical manifestations are vascular purpura, predominating on the lower limbs, and articular, gastrointestinal and renal symptoms. Pulmonary, cardiac, genital and neurological symptoms have also be observed. The syndrome usually affects children, whereas it is rare in adults. The frequency of renal involvement varies between individual studies (from 20 to 100%). Renal manifestations are usually mild and transient, although chronic nephropathies may occur. Overall, an estimated 2% of children with Schönlein-Henoch purpura progress to renal failure and up to 20% of children with nephritis treated in specialised centres require haemodialysis. The renal prognosis appears to be worse in adults. Aetiological investigations are required, as a triggering factor is found in approximately half the patients (e.g. viral, bacterial and parasitic infections, drugs, toxins, systemic diseases and cancer). Dapsone has beneficial effects on cutaneous, gastrointestinal and articular manifestations in adults, especially those with chronic forms. Corticosteroids may be useful for refractory abdominal pain. Methylprednisolone pulse therapy, immunosuppressive drugs (e.g. cyclophosphamide and azathioprine), plasma exchange and polyclonal immunoglobulin therapy are beneficial in very rare life-threatening forms of the disease and in rare instances where renal function is compromised.

Renal histopathology and clinical course in 94 patients with Wegener's granulomatosis

BACKGROUND

The main purpose of this study was to examine histopathological changes seen in renal biopsies from patients with Wegener's granulomatosis (WG) with varying degrees of renal involvement and to study possible correlations between the morphological variables and the severity of the disease.

METHODS

Ninety-four patients with WG and active renal disease were included in this retrospective study. All patients had a percutaneous renal biopsy taken on their first admission to the hospital and 14 patients had a second biopsy. The patients were followed for a median of 42.5 months (range 0.5-184).

RESULTS

Segmental necrotizing glomerulonephritis and extracapillary proliferation were present in 85.1 and 91.5% respectively. Of seven patients (7.4%) with normal serum creatinine and urinary protein excretion <0.5 g/day, all had crescents and six had segmental glomerular necrosis. Serum creatinine at biopsy correlated significantly with the percentage of glomeruli with crescents (rho=0.52, P=0.0004), with necrosis (rho=0.36, P=0.002) and with the percentage of normal glomeruli (rho=-0.55, P=0.0003). On a multivariate analysis, only the percentage of normal glomeruli was significantly associated with renal function and development of end-stage renal disease. In 14 second biopsies after a mean of 41.2 (+/-26) months, chronicity scores had increased significantly in 13 biopsies in spite of full immunosuppressive treatment.

CONCLUSION

Although renal biopsy is of value in defining renal involvement in WG, it is of limited help in the early stage of the disease in predicting renal outcome for the individual patient. A follow-up biopsy can be useful in revealing the degree of activity and chronicity and hence be of importance for the choice of further therapy.

What is the difference between IgA nephropathy and Henoch-Schönlein purpura nephritis?

Henoch-Schönlein purpura nephritis (HSPN) and IgA nephropathy (IgAN) are considered to be related diseases since both can be encountered consecutively in the same patient, they have been described in twins, and bear identical pathological and biological abnormalities. Apart from the presence of extrarenal clinical signs found only in HSPN, other differences are noticed between the two diseases. The peak age ranges between 15 and 30 years for a diagnosis of IgAN, whereas HSPN is mainly seen in childhood. Nephritic and/or nephrotic syndromes are more often seen at presentation in HSPN. In contrast to IgAN, HSPN has been described in association with hypersensitivity. Endocapillary and extracapillary inflammations as well as fibrin deposits in the glomerulus are more frequent in HSPN. No major biological differences have been found between the two illnesses, except for a larger size of circulating IgA-containing complexes (IgA-CC) and a greater incidence of increased plasma IgE levels in HSPN. As tissue infiltration by leukocytes is a major feature of HSPN vasculitis, a possible role of a more potent activation of the latter cells by IgA-CC and/or circulating chemokines in HSPN should be considered. Further studies are required to elucidate this possible mechanism as well as the role of hypersensitivity in HSPN.

Idiopathic IgA nephropathy with segmental necrotizing lesions of the capillary wall

BACKGROUND

Segmental glomerular necrosis has been described in the biopsy material in a minority of patients with idiopathic IgA nephropathy in the oldest studies on this disease, but this marker of active capillaritis has received little attention in the subsequent literature, and its significance and relevance for the clinical outcome is still unknown.

METHODS

Thirty-five out of 340 patients (10.3%) biopsied in our division at the San Carlo Hospital since 1974 showed active segmental necrotizing lesions. The morphological features and the natural history of this group of patients were compared with those of a control group of 229 patients who had comparable serum creatinine and extent of glomerular sclerosis, but who lacked active segmental necrosis.

RESULTS

Patients with the necrotic variant showed a significantly more marked extracapillary proliferation and interstitial accumulation of monocytes and T lymphocytes and, in the segmental areas of necrotizing and extracapillary lesions, infiltration of monocytes, deposition of fibrinogen, and expression of the adhesion molecule vascular cell adhesion molecule-1. No difference was found in the presenting clinical syndrome. The clinical course was frequently characterized by acute flare ups, and the progression to end-stage renal failure was more frequent, although actuarial renal survival was not significantly worse (P = 0.07). The aggressive treatment with steroids and cyclophosphamide, carried out in 20 of the 35 patients, has probably been beneficial, justifying the multicenter controlled trial that recently has been initiated.

CONCLUSIONS

Vasculitic lesions of the glomerular capillaries, with histologic and immunohistological features similar to those of Henoch-Schönlein purpura and antineutrophil cytoplasmic antibody-positive renal vasculitis, were found in 10% of patients with idiopathic IgAN. Clinical features at presentation did not differ from those of the other patients with IgAN, and despite of the more frequent occurrences of recurrent acute flare ups, rapid progression to end-stage renal failure was a rare phenomenon, even in untreated patients.

ANCA-associated crescentic glomerulonephritis with mesangial IgA deposits

Antineutrophil cytoplasmic autoantibodies (ANCA) are commonly associated with a necrotizing and crescentic glomerulonephritis (GN) that is pauci-immune, with few or no glomerular immune complex deposits detectable by immunofluorescence (IF) or electron microscopy (EM). Immunoglobulin A (IgA) nephropathy may also be manifest as a crescentic GN, but it is characterized by mesangial immune complex deposits containing IgA and is rarely associated with myeloperoxidase (MPO)- or proteinase 3 (PR3)-specific ANCA when an enzyme immunoassay is used to detect these antibodies. This report describes six patients with severe crescentic GN with mesangial IgA deposits by IF and mesangial electron-dense deposits by EM in patients with positive ANCA serological test results (four patients, anti-PR3; one patient, anti-MPO; one patient, anti-PR3 and anti-MPO). Patients presented with acute or progressive renal insufficiency, hematuria, proteinuria (nephrotic range in two patients), and hypertension. Three patients had evidence of systemic vasculitis: two patients at initial presentation and one patient later in the clinical course. Renal biopsy specimens showed crescents in greater than 50% of glomeruli in all cases, but only mild, focal and segmental mesangial and endocapillary hypercellularity, more typical of ANCA-associated crescentic GN than of crescentic IgA nephropathy without associated ANCA. Semiquantitative analysis of mesangial and endocapillary cellularity performed on renal biopsy slides from these six patients and from eight ANCA-negative patients with IgA nephropathy and crescents in greater than 50% of glomeruli showed significantly greater hypercellularity in the ANCA-negative cases. Three of five ANCA-positive patients for whom follow-up clinical data were available showed improved renal function after treatment with cyclophosphamide and corticosteroids and have not developed end-stage renal disease 17, 20, and 25 months postbiopsy. The remaining two patients were dialysis dependent at the time of biopsy and have remained so despite treatment with cyclophosphamide and corticosteroids. The findings suggest an overlap syndrome of ANCA-associated crescentic GN and IgA nephropathy that resembles the former both histologically and in its potential to respond to aggressive therapy if detected relatively early in its course.

Familial occurrence of systemic vasculitis and rapidly progressive glomerulonephritis

Two familial clusters of systemic vasculitis are described. In one family, microscopic polyangiitis and rapidly progressive glomerulonephritis occurred in HLA-identical siblings; in the second family, 3 second- and fourth-degree related members were affected by Wegener's granulomatosis. Published clusters of systemic vasculitides and Goodpasture's syndrome are reviewed, and, together with the observed families, the evidence for genetic susceptibility and a causative role of environmental factors for these diseases with special emphasis on the HLA system is discussed.