Renal involvement in hypocomplementaemic urticarial vasculitis syndrome: a report of three paediatric cases

Anti-C1q antibodies: a biomarker for diagnosis and management of lupus nephritis. A narrative review

Nephritis is a frequent and severe complication of Systemic Lupus Erythematous (SLE). The clinical course of lupus nephritis (LN) is usually characterized by alternating phases of remission and exacerbation. Flares of LN can lead to deterioration of kidney function, necessitating timely diagnosis and therapy. The presence of autoantibodies against C1q (anti-C1qAb) in the sera of SLE patients has been reported in various studies. Some research suggests that the presence and changes in the titer of anti-C1qAb may be associated with the development of LN, as well as with LN activity and renal flares. However, the exact role of anti-C1qAb in LN remains a subject of debate. Despite variability in the results of published studies, anti-C1qAb hold promise as noninvasive markers for assessing LN activity in SLE patients. Measuring anti-C1qAb levels could aid in diagnosing and managing LN during periods of both inactive disease and renal flares. Nevertheless, larger controlled trials with standardized laboratory assays are necessary to further establish the utility of anti-C1qAb in predicting the reactivation and remission of LN and guiding treatment strategies.

Biopsy-proven kidney involvement in hypocomplementemic urticarial vasculitis

BACKGROUND

Hypocomplementemic urticarial vasculitis (HUV) is a rare systemic vasculitis. We aimed to describe the kidney involvement of HUV in a multicenter national cohort with an extended follow-up.

METHODS

All patients with HUV (international Schwartz criteria) with a biopsy-proven kidney involvement, identified through a survey of the French Vasculitis Study Group (FVSG), were included. A systematic literature review on kidney involvement of HUV was performed.

RESULTS

Twelve patients were included, among whom 8 had positive anti-C1q antibodies. All presented with proteinuria, from mild to nephrotic, and 8 displayed acute kidney injury (AKI), requiring temporary haemodialysis in 2. Kidney biopsy showed membrano-proliferative glomerulonephritis (MPGN) in 8 patients, pauci-immune crescentic GN or necrotizing vasculitis in 3 patients (with a mild to severe interstitial inflammation), and an isolated interstitial nephritis in 1 patient. C1q deposits were observed in the glomeruli (n = 6), tubules (n = 4) or renal arterioles (n = 3) of 8 patients. All patients received corticosteroids, and 9 were also treated with immunosuppressants or apheresis. After a mean follow-up of 8.9 years, 6 patients had a preserved renal function, but 2 patients had developed stage 3-4 chronic kidney disease (CKD) and 4 patients had reached end-stage kidney disease (ESKD), among whom 1 had received a kidney transplant.

CONCLUSION

Renal involvement of HUV can be responsible for severe AKI, CKD and ESRD. It is not always associated with circulating anti-C1q antibodies. Kidney biopsy shows mostly MPGN or crescentic GN, with frequent C1q deposits in the glomeruli, tubules or arterioles.

Circulating C1q levels in health and disease, more than just a biomarker

C1q is the recognition molecule of the classical pathway of the complement system. By binding to its targets, such as antigen-bound immunoglobulins or C-reactive protein, C1q contributes to the innate defense against infections. However, C1q also plays several other roles beyond its traditional role in complement activation. Circulating levels of C1q are determined in routine diagnostics as biomarker in several diseases. Decreased C1q levels are present in several autoimmune conditions. The decreased levels reflect the consumption of C1q by complement activation and serves as a biomarker for disease activity. In contrast, increased C1q levels are present in infectious and inflammatory diseases and may serve as a diagnostic biomarker. The increased levels of C1q are still incompletely understood but are suggested to modulate the adaptive immune response as C1q is known to impact on the maturation status of antigen-presenting cells and C1q impacts directly on T cells leading to decreased T-cell activity in high C1q conditions. In this review, we provide a comprehensive overview of the current literature on circulating levels of C1q in health and disease, and discuss how C1q can both protect against infections as well as maintain tolerance by regulating adaptive immunity.

Kidney Involvement in Hypocomplementemic Urticarial Vasculitis Syndrome-A Case-Based Review

Hypocomplementemic urticarial vasculitis syndrome (HUVS), or McDuffie syndrome, is a rare small vessel vasculitis associated with urticaria, hypocomplementemia and positivity of anti-C1q antibodies. In rare cases, HUVS can manifest as an immune-complex mediated glomerulonephritis with a membranoproliferative pattern of injury. Due to the rarity of this disorder, little is known about the clinical manifestation, pathogenesis, treatment response and outcome of such patients. We describe here three cases of HUVS with severe renal involvement. These patients had a rapidly progressive form of glomerulonephritis with severe nephrotic syndrome against a background of a membranoproliferative pattern of glomerular injury with extensive crescent formation. Therefore, these patients required aggressive induction and maintenance immunosuppressive therapy, with a clinical and renal response in two patients, while the third patient progressed to end-stage renal disease. Because of the rarity of this condition, there are few data regarding the clinical presentation, pathology and outcome of such patients. Accordingly, we provide an extensive literature review of cases reported from 1976 until 2020 and place them in the context of the current knowledge of HUVS pathogenesis. We identified 60 patients with HUVS and renal involvement that had adequate clinical data reported, out of which 52 patients underwent a percutaneous kidney biopsy. The most frequent renal manifestation was hematuria associated with proteinuria (70% of patients), while one third had abnormal kidney function on presentation (estimated glomerular filtration (GFR) below 60 mL/min/1.73 m²). The most frequent glomerular pattern of injury was membranoproliferative (35%), followed by mesangioproliferative (21%) and membranous (19%). Similar to other systemic vasculitis, renal involvement carries a poorer prognosis, but the outcome can be improved by aggressive immunosuppressive treatment.

[Nephropathy associated with hypocomplementemic urticarial vasculitis: A case report and literature review]

Hypocomplementemic urticarial vasculitis is a rare systemic vasculitis, affecting small vessels, characterised by chronicle urticaria, hypocomplementemia, and systemic manifestations. Renal involvement, whose prevalence varies between 9% and 60%, is mainly glomerular. We here report the case of a 59 years old woman presenting kidney failure, associated with chronicle urticaria and arthralgias. Laboratory investigation showed haematuria, proteinuria, hypocomplementemia and anti-SSa antibody positivity. A percutaneous kidney biopsy revealed focal and segmental glomerulonephritis associated with an acute interstitial nephritis. Hypocomplementemic urticarial vasculitis diagnosis was established after identifying anti-C1q antibodies. The lack of a dry syndrome, the negativity of a Schirmer test and the lack of sialadenitis on a salivary gland biopsy excluded an associated Gougerot-Sjögren Syndrome. The patient was treated with hydroxychloroquine and low-dose steroids, enabling a clinical and biological recovery. Of the 82 cases in the literature describing hypocomplementemic urticarial vasculitis associated nephropathies, 72 (88%) were a glomerular impairment, most frequently secondary to membranoproliferative glomerulonephritis. Only 6 (7%) tubulo-interstitial nephritis have been reported, 4 of them being associated with a glomerulonephritis. Patients were more likely to be women, aged in their third decade. The most frequent renal manifestations were haematuria (60%), and proteinuria (52%). Kidney failure was rarely observed (22%), with a fairly good renal prognosis. Hypocomplementemic urticarial vasculitis was associated with a systemic disease in 11 (13%) patients. In the absence of recommendations, the treatment strategy remains to be defined.

Stroke due to Vasculitis in Children and Adults

The vasculitides are diseases characterized by inflammation of blood vessels and inflammatory leukocytes in vessel walls. There is an increased propensity for ischemic stroke, resulting from compromise of vessel lumina with distal tissue ischemia; and hemorrhagic or nonhemorrhagic stroke, and aneurysmal formation and bleeding, due to loss of vessel integrity.

Treatment of urticarial vasculitis: A systematic review

Urticarial vasculitis (UV) is a difficult-to-treat condition characterized by long-lasting urticarial rashes and histopathologic findings of leukocytoclastic vasculitis. Treatment is dictated by the severity of skin and systemic involvement and the underlying systemic disease. This is a comprehensive systematic review of the efficacy of current UV treatment options. We searched for relevant studies in 7 databases, including MEDLINE, Scopus, and Web of Science. In total, 261 eligible studies and 789 unique patients with UV were included in the systematic review. Most patients with UV are adult women with chronic (≥6 weeks) and systemic disease. UV is mostly idiopathic but can be associated with drugs, malignancy, autoimmunity, and infections. It usually resolves with their withdrawal or cure. Corticosteroids are effective for the treatment of skin symptoms in more than 80% of patients with UV. However, their long-term administration can lead to potentially serious adverse effects. The addition of immunomodulatory or immunosuppressive agents often allows corticosteroid tapering and improves the efficacy of therapy. Biologicals, including omalizumab, as well as corticosteroids, cyclophosphamide, dapsone, mycophenolate mofetil, plasmapheresis, colchicine, hydroxychloroquine, intravenous immunoglobulin, nonsteroidal anti-inflammatory drugs, and cyclosporine, can be effective for both skin and systemic symptoms in patients with UV. H₁-antihistamines, montelukast, danazol, H₂-antihistamines, pentoxifylline, doxepin, and tranexamic acid are not effective in most patients with UV. As of yet, no drugs have been approved for UV, and management recommendations are based mostly on case reports and retrospective studies. Prospective studies investigating the effects of treatment on the signs and symptoms of UV are needed.

The clinical spectrum and therapeutic management of hypocomplementemic urticarial vasculitis: data from a French nationwide study of fifty-seven patients

OBJECTIVE

Hypocomplementemic urticarial vasculitis (HUV) is an uncommon vasculitis of unknown etiology that is rarely described in the literature. We undertook this study to analyze the clinical spectrum and the therapeutic management of patients with HUV.

METHODS

We conducted a French nationwide retrospective study that included 57 patients with chronic urticaria, histologic leukocytoclastic vasculitis, and hypocomplementemia. We assessed clinical and laboratory data and evaluated the patients' cutaneous and immunologic responses to therapy. We evaluated treatment efficacy by measuring the time to treatment failure.

RESULTS

Urticarial lesions were typically more pruritic than painful and were associated with angioedema in 51% of patients, purpura in 35%, and livedo reticularis in 14%. Extracutaneous manifestations included constitutional symptoms (in 56% of patients) as well as musculoskeletal involvement (in 82%), ocular involvement (in 56%), pulmonary involvement (in 19%), gastrointestinal involvement (in 18%), and kidney involvement (in 14%). Patients with HUV typically presented with low C1q levels and normal C1 inhibitor levels, in association with anti-C1q antibodies in 55% of patients. Hydroxychloroquine or colchicine seemed to be as effective as corticosteroids as first-line therapy. In patients with relapsing and/or refractory disease, rates of cutaneous and immunologic response to therapy seemed to be higher with conventional immunosuppressive agents, in particular, azathioprine, mycophenolate mofetil, or cyclophosphamide, while a rituximab-based regimen tended to have higher efficacy. Finally, a cutaneous response to therapy was strongly associated with an immunologic response to therapy.

CONCLUSION

HUV represents an uncommon systemic and relapsing vasculitis with various manifestations, mainly, musculoskeletal and ocular involvement associated with anti-C1q antibodies, which were found in approximately half of the patients. The best strategy for treating HUV has yet to be defined.