The Uncertain Significance of Anti–Glomerular Basement Membrane Antibody Among HIV-Infected Persons With Kidney Disease

False-positive Serum Antiglomerular Basement Membrane Antibody due to Bovine Serum Albumin-containing Surgical Adhesive: A Case Report

Antiglomerular basement membrane (GBM) disease has a poor prognosis. The rapid detection of serum anti-GBM antibody using an enzyme immunoassay, which has a high sensitivity and specificity, leads to an early diagnosis and improved prognosis. We report a case of acute kidney injury with false-positive anti-GBM antibody. A man in his early fifties underwent aortic arch replacement using bovine serum albumin (BSA)-containing surgical adhesion. After intravenous administration of vancomycin for a fever, he developed acute kidney injury without an abnormal urinalysis, and his anti-GBM antibody titer (fluorescence enzyme immunoassay [FEIA]) was 70.4 IU/mL. A kidney biopsy showed acute tubular injury and minor glomerular abnormalities without immunoglobulin G deposits, suggesting no evidence of anti-GBM glomerulonephritis. Consistent with the false-positive anti-GBM antibody test results, anti-GBM antibody determined using a chemiluminescent enzyme immunoassay was negative. A serum sample showed crossbinding to the FEIA plate from which the GBM antigen was removed. This finding indicated a nonspecific reaction to BSA, which contains a coating solution for the FEIA plate. This reaction was likely caused by anti-BSA antibody produced using BSA-containing surgical adhesion. Our findings suggest emerging challenges in diagnosing anti-GBM disease. Nephrologists must remain vigilant regarding false-positive anti-GBM antibody test results, particularly in cases evaluated with immunoassays that contain BSA.

Autoimmunity and Infection in Glomerular Disease

The ongoing glomerular damage of infections is not limited to the most widely known form of post-streptococcal glomerulonephritis, which is today less common in the Western world; other forms of glomerulonephritis are associated with several bacterial, viral and parasitic pathogens. The mechanisms responsible range from the direct damage of glomerular cells to the formation and deposition of immunocomplexes to molecular mimicry to the secretion of superantigens. Similarly, in the course of glomerular disease, infections are more frequent than in the general population due to the loss of immunoglobulins in urine and the immunosuppressive agents used to treat the autoimmune disease that decrease the activity of the immune system. Recognizing this two-way link, understanding its pathogenetic mechanism, and identifying the most appropriate therapeutic choice are essential for the personalized management of patients. In this continuously developing field, this short review summarizes the current state of the art as support for physicians, who are increasingly involved in managing patients with glomerular disease and infections.

Renal autoimmunity: The role of bacterial and viral infections, an extensive review

Autoimmunity is a process by which the loss of self-tolerance results in an immune attack against the body own tissues and organs. For autoimmunity to occur, various elements serving as triggers were described by which infections are considered one of the leading factors. In turn, renal involvement in autoimmune diseases, whether by an organ-specific attack, or as part of a systemic disease process, is well known. As bacterial and viral infections are considered to be common triggers for autoimmunity in general, we aimed to study their association with renal autoimmunity in particular. We performed an extensive search of the recent and relevant medical literature regarding renal autoimmunity syndromes such as infection-associated glomerulonephritis and vasculitis, associated with bacterial and viral infections. By utilizing PubMed and Google Scholar search engines, over 200 articles and case reports were reviewed. Among other mechanisms, direct infection of the renal parenchyma, molecular mimicry, induction of B-cells or secretion of superantigens, bacterial and viral pathogens were found to correlate with the development of renal autoimmunity. Nevertheless, this was not true for all pathogens, as some mimic autoimmune diseases and others show a surprisingly protective effect. The exact immunopathogenesis is yet to be determined, however. For conclusion, bacterial and viral infections are linked to renal autoimmunity by both direct damage and as mediators of systemic diseases. Further research particularly on the immunopathogenetic mechanisms of renal autoimmunity associated with infections is required.

The prevalence and immunological features of anti-glomerular basement membrane antibody in patients with HIV

Background

Anti-glomerular basement membrane disease (GBM) is an autoimmune disease caused by the deposition of circulating anti-GBM antibodies. Non-collagen region of α3 chain of type IV collagen (α3(IV)NC1) is one of the main target antigens, in which E_A and E_B are the most classical antigen epitopes. It has been reported that anti-GBM antibodies can be detected in HIV patients; however, its immunological characteristics are still unclear.

Objectives

In this study, the positive rate of the anti-GBM antibodies in HIV and the immunological characteristics of the target antigens were clarified.

Methods

A total of 93 HIV patients diagnosed in Beijing Youan Hospital from November 2017 to January 2018 were included. Enzyme-linked immunosorbent assay was used to measure the serum IgG autoantibodies specifically against GBM in these patients, as well as their subtypes and antigen spectra.

Results

It was found that five out of the 93 patients with HIV had low to moderate levels of anti-GBM antibodies. However, these patients presented with no clinical manifestation of any kidney injury or pulmonary hemorrhages. Compared with HIV patients with negative antibodies, there were no significant differences in gender, age, CD4⁺T cell count and HIV viral load. All sera of five patients recognized non-collagenous domain1 (NC1) of alpha 3 chain of type IV collagen [(α3(IV)NC1] as classic anti-GBM patients, followed by α5(IV)NC1. The antibodies against α3(IV)NC1 were IgG3 predominant, while these antibodies did not react with either of the classic epitopes on α3 (E_A and E_B).

Conclusion

These data suggest a distinct immunological profile of anti-GBM antibodies in patients with HIV, and might explain the non-pathogenic features of HIV associated anti-GBM antibodies.

Crescentic glomerulonephritis with anti-GBM antibody but no glomerular deposition

Background

Anti-glomerular basement membrane (GBM) antibodies are highly specific for Goodpasture’s or anti-GBM disease, in which they are generally directed against the non-collagenous (NC1) domain of the alpha 3 chain of type IV collagen(α3(IV)), and less commonly, toward the α 4(IV) or α 5(IV) chains, which form a triple helical structure in GBM and alveolar basement membrane (ABM). Alterations in the hexameric structure of the NC1 (α3 (IV)), allows novel epitopes to be exposed and an immune response to develop, with subsequent linear antibody deposition along the GBM, leading to a crescentic glomerulonephritis. Positive anti-GBM antibodies are assumed to be pathogenic and capable of binding GBM in vivo, especially in the context of rapidly progressive glomerulonephritis.

We have investigated patients with circulating anti-GBM antibodies, reactive to α3 (IV) and human GBM by immunoassays and Western blotting respectively, with focal necrotising crescentic glomerulonephritis but no linear GBM antibody deposition on immunohistochemistry. Three out of four were also ANCA positive. Despite not binding native GBM, patients’ sera showed linear binding to primate glomeruli by indirect immunofluorescence, in the 2 cases tested. Following treatment, significant improvements in kidney function were found in 3/4 patients.

Case presentation

We present four patients with crescentic glomerulonephritis and circulating anti-GBM antibodies, but no glomerular binding.

Conclusions

These novel findings, demonstrate that in some patients anti-GBM antibodies may not bind their own GBM. This has important implications for clinical diagnosis, suggesting that histological confirmation of kidney injury by anti-GBM antibodies should be obtained, as non-binding GBM antibodies may be associated with significant renal recovery.

Electronic supplementary material

The online version of this article (10.1186/s12882-018-1027-x) contains supplementary material, which is available to authorized users.

HIV associated kidney diseases: Clarifying concordance between renal failure in HIV infection and histopathologic manifestations at kidney biopsy

Patients with HIV infection have a wide spectrum of renal diseases. Some are known to be the direct effect of the viral infection while others are renal diseases that also occur in uninfected populations. HIV associated nephropathy (HIVAN) is considered to be a subtype of primary focal and segmental glomerulosclerosis that is distinct in HIV infected patients. It is more frequent in the African-American population and associated with mutations of the apolipoprotein L1 (APOL1) gene. HIV associated immune complex kidney disease (HIVICD) encompasses a spectrum of HIV associated renal diseases characterized by the presence of immune complex deposition within glomeruli. Thrombotic microangiopathy (TMA) is a complication of HIV infection that presents with hemolytic anemia, thrombocytopenia, and renal failure. TMA in HIV patients is associated with very high mortality. Lastly, the multitude of antiretroviral drugs used for treatment of HIV infections can result in nephrotoxicity. Although a kidney biopsy may not be the first line study for renal disease, knowledge of the different histopathologic features of HIV-associated and unassociated diseases is of paramount importance in the treatment and subsequent outcome of renal function in HIV infected patients. In this review we will describe the histopathologic features and discuss the pathophysiology of the entities previously named.

HIV-associated immune complex kidney disease

The introduction in the late 20(th) century of combination antiretroviral therapy (cART) to treat patients infected with HIV has changed the natural history of the disease from an acute illness that rapidly culminates in death, to a chronic condition that can be managed with medications. Over the past decade the epidemiology of kidney disease in US patients infected with HIV has changed, perhaps because of the increased availability and use of cART. Patients with HIV infection exhibit unique immunologic characteristics, including immunodeficiency and dysregulation of immunoglobulin synthetic responses and T-cell function, which can result in glomerular immune complex deposition and subsequent kidney injury. This Review examines the differential diagnoses of HIV-associated immune complex kidney diseases (HIVICD), and discusses the clinical manifestations and mechanisms underlying their development. We address the issues associated with treatment, clinical outcomes, and research needs to enhance our ability to diagnose and optimally treat patients with HIVICD.

An Unusual Case of Anti-GBM Antibody Elevation in HIV-Associated Nephropathy

Introduction. The most commonly seen glomerular disease in HIV infected patients is HIV-associated nephropathy (HIVAN); however, a multitude of other nephropathies can occur in HIV infection with an almost equal cumulative frequency. We report an unusual case of a patient with clinical and histological evidence of HIVAN in which the diagnosis was initially confounded by the finding of an elevated serum anti-glomerular basement membrane (anti-GBM) antibody. Case Presentation. We present a case of a 27-year-old African American female with a history of schizophrenia, cocaine abuse, and HIV infection who upon admission to our hospital was found to have severe acute kidney injury requiring hemodialysis. Urine studies revealed nephrotic range proteinuria and a serological workup was positive for anti-GBM antibody elevation with a value of 91 units (normal: 0–20 units). A renal biopsy revealed HIVAN with no evidence of crescentic glomerulonephritis or anti-GBM disease. Conclusion. This case highlights the need for careful interpretation of anti-GBM antibody tests in HIV infected patients with kidney disease and, in particular, the need for biopsy confirmation of the diagnosis prior to starting therapy. More research is needed to study the prognostic correlation between the degree of anti-GBM antibody elevation in HIVAN and disease severity.

AKI in an HIV patient

The renal manifestations of patients infected with HIV are diverse. Patients may have podocytopathies ranging from a minimal-change-type lesions to FSGS or collapsing glomerulopathy. Furthermore, such patients produce a variety of autoantibodies without clinical signs of the disease. Antiretroviral drugs also cause renal injury, including crystals and tubular injury, acute interstitial nephritis, or mitochondrial toxicity. In these circumstances, it is essential to perform a renal biopsy for diagnosis and to guide treatment. Here we describe a patient with HIV who presented with AKI and hematuria without concomitant systemic manifestations. Renal biopsy elucidated the cause of acute deterioration of kidney function.

Glomerular disease in patients with infectious processes developing antineutrophil cytoplasmic antibodies

To identify differences in treatment and outcome of various types of glomerulonephritis developing in the course of infections triggering antineutrophil cytoplasmic antibody (ANCA) formation, we analyzed published reports of 50 patients. Immunosuppressives were added to antibiotics in 22 of 23 patients with pauci-immune glomerulonephritis. Improvement was noted in 85% of 20 patients with information on outcomes. Death rate was 13%. Corticosteroids were added to antibiotics in about 50% of 19 patients with postinfectious glomerulonephritis. Improvement rate was 74%, and death rate was 26%. Two patients with mixed histological features were analyzed under both pauci-immune and post-infectious glomerulonephritis categories. In 9 patients with other renal histology, treatment consisted of antibiotics alone (7 patients), antibiotics plus immunosuppressives (1 patient), or immunosuppressives alone (1 patient). Improvement rate was 67%, permanent renal failure rate was 22%, and death rate was 11%. One patient with antiglomerular basement disease glomerulonephritis required maintenance hemodialysis. Glomerulonephritis developing in patients who became ANCA-positive during the course of an infection is associated with significant mortality. The histological type of the glomerulonephritis guides the choice of treatment. Pauci-immune glomerulonephritis is usually treated with addition of immunosuppressives to antibiotics.

Performance evaluation of a novel chemiluminescence assay for detection of anti-GBM antibodies: an international multicenter study

BACKGROUND

Autoantibodies to the non-collagen region (NC1) of the alpha-3 subunit of collagen IV represent a serological hallmark in the diagnosis of Goodpasture's syndrome (GPS). The objective of our study was to carefully analyze the performance characteristics of a novel anti-glomerular basement membrane (GBM) chemiluminescence immunoassay (CIA).

METHODS

Sera from patients with GPS (n = 90) were collected from four clinical centers. Samples from different disease groups (n = 397) and healthy individuals (n = 400) were used as controls. All samples were tested for anti-GBM antibodies by a rapid, random access CIA (QUANTA Flash™ GBM). Most of the samples were also tested using other methods including different commercial anti-GBM IgG assays and research assays for anti-GBM IgA and IgM.

RESULTS

The sensitivity and specificity of the novel CIA was 95.6% [95% confidence interval (CI) 89.0-98.8%] and 99.6% (95% CI 98.9-99.9%), respectively. Receiver operating characteristic analysis showed good discrimination between GPS patients and controls. The area under the curve was 0.98 (CI 0.96-1.0). The three anti-GBM antibody-positive samples from the control group were from two healthy individuals and one human immunodeficiency virus (HIV)-infected patient. All three individuals had low levels of anti-GBM antibodies [20, 24 and 25 chemiluminescent unit (CU), cutoff 20 CU]. When the results of the new CIA were compared to other methods, good agreement was observed: 95.8% (kappa = 0.92) versus EliA™ GBM, 97.4% (kappa = 0.95) versus both BINDAZYME™ Anti-GBM and QUANTA Lite® GBM. Anti-GBM IgA was detectable in low concentrations in patients with GPS and was associated with anti-GBM IgG but was less useful in discriminating GPS patients and controls. No discrimination was found for anti-GBM IgM.

CONCLUSION

The novel QUANTA Flash™ GBM CIA demonstrated good sensitivity and specificity and had good agreement with other methods. Our data confirm that ∼5% of patients with GPS do not have detectable levels of anti-GBM antibodies.

Immune complex renal disease and human immunodeficiency virus infection

Immune complex glomerulonephritis is a common diagnosis in renal biopsy series of human immunodeficiency virus (HIV)-infected patients. There are a variety of glomerulonephritides associated with HIV infection, including IgA nephropathy, membranoproliferative glomerulonephritis, membranous nephropathy, lupus-like glomerulonephritis, immunotactoid glomerulopathy, and fibrillary glomerulonephritis. In addition, HIV-related proteins may be implicated in circulating immune complexes directly related to a response to the infection. In some cases, the relationship of the HIV infection to the glomerulonephritis is unclear. HIV infection is associated with the development of polyclonal hypergammaglobulinemia, which can promote the development of circulating immune complexes. It is not clear if HIV-associated glomerulonephritis is caused by the passive trapping of these circulating immune complexes or the in situ deposition of antibodies binding to HIV viral antigens. Some renal lesions that are seen in the setting of HIV infection more likely may be related to the presence of a co-infection such as hepatitis C virus infection. The optimal therapy for immune complex glomerulonephritis in the setting of HIV infection is unknown. Because of the underlying immunosuppressed state of many HIV-infected patients, caution with traditional cytotoxic therapies is advised. The role of antiretroviral therapy in modifying the course of these renal lesions is unclear.

Virus-induced cellular immune mechanisms of injury to the kidney

Cellular immune systems play an important role in determining renal outcomes in virus-induced kidney diseases. Highlighted briefly are five different locations along the development of adaptive immune responses to viral infection that may promote injury to the renal parenchyma and the loss of renal function. This may occur because adaptive immune cells directly target infected renal parenchymal cells or because the kidney becomes a bystander organ of adaptive immune cell-mediated injury. Examples from recent studies are provided to illustrate how this may lead to clinically relevant renal disease.

HIV-1 infection and the kidney: an evolving challenge in HIV medicine

With the advent of highly active antiretroviral therapy (HAART), the incidence of opportunistic infections has declined substantially, and cardiovascular, liver, and renal diseases have emerged as major causes of morbidity and mortality in individuals with human immunodeficiency virus (HIV). Acute renal failure is common in HIV-infected patients and is associated with acute infection and medication-related nephrotoxicity. HIV-associated nephropathy is the most common cause of chronic kidney disease in HIV-positive African American populations and may respond to HAART. Other important HIV-associated renal diseases include HIV immune complex kidney diseases and thrombotic microangiopathy. The increasing importance of non-HIV-associated diseases, such as diabetes mellitus, hypertension, and vascular disease, to the burden of chronic kidney disease has been recognized, focusing attention on prevention and control of these diseases in HIV-positive individuals. HIV-positive individuals who experience progression to end-stage renal disease and who have undetectable HIV-1 viral loads while receiving HAART should be evaluated for renal transplant. Emerging evidence suggests that HIV-positive individuals may have graft and patient survival comparable to HIV-negative individuals. Several studies suggest that HIV-1 can potentially infect renal cells, and HIV transgenic mice have clarified the roles of a number of HIV proteins in the pathogenesis of HIV-associated renal disease. Host factors may modify disease expression at the level of cytokine networks and the renal microvasculature and contribute to the pathogenic effects of HIV-1 infection on the kidney.