Mesangial IgA deposits in two patients with AIDS-related complex

Clinicopathologic features of IgA-dominant infection-associated glomerulonephritis: a pooled analysis of 78 cases

BACKGROUNDS

IgA-dominant infection-associated glomerulonephritis (IgA-dominant IAGN) is a unique form of glomerulonephritis. There are numerous case reports in the literature. However, the risk factors, treatment approach, and outcomes of the disease are not clearly characterized.

METHODS

We completed a pooled analysis based on published literature. Clinical features, laboratory findings, and histopathological changes were analyzed. A logistic regression model was employed to identify the determinants of disease outcome, for example, end-stage renal disease (ESRD) or death.

RESULTS

Seventy-eight patients with IgA-dominant IAGN from 28 reports were analyzed. All of these patients showed granular IgA deposits predominantly along the glomerular peripheral capillary walls using immunofluorescence and majority showed subepithelial 'hump-shaped' electron-dense deposits using electron microscopy. The majority of patients had hematuria (76/78), proteinuria (75/78), acute kidney injury (AKI) (66/78) and hypocomplementemia (43/75) without a previous history of renal disease. All of the patients had clinical infections at the time of presentation. Skin infections (19/78) and visceral abscesses (15/78) were frequently encountered, and staphylococcus was the most common pathogen. After treatment with antibiotics and/or supportive therapy, the renal function of 42 patients (54.5%) improved, 9 patients (11.7%) had persistent renal dysfunction, 15 patients (19.5%) progressed to ESRD, and 11 patients (14.3%) died. A multivariate regression analysis revealed that age (odds ratio [OR], 30.71; 95% confidence interval [CI], 2.53-373.07; p = 0.007) and diabetes mellitus (DM) (OR, 16.65; 95% CI, 1.18-235.84; p = 0.038) were independent risk factors for ESRD or death.

CONCLUSIONS

IgA-dominant IAGN has unique clinicopathological manifestations and treatment responses. Age and DM are independent risk factors associated with an unfavorable prognosis for IgA-dominant IAGN.

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.

Absence of age-related increase in systolic blood pressure in ambulatory patients with HIV infection

BACKGROUND

Systolic blood pressure is well known to increase significantly with age and is strongly correlated with stroke and coronary artery disease. We and other investigators have reported a low prevalence of hypertension in subgroups of patients with HIV infection. In the present study, we examined an ambulatory population of patients with HIV infection to determine whether in the outpatient setting they may lack an age-related increase in systolic blood pressure.

METHODS

In an ambulatory outpatient practice, medical records of 178 consecutive patients with HIV infection and those of 200 control subjects were examined. Systolic and diastolic blood pressure and other clinical and laboratory variables were recorded. Scatter plots were generated to compare age with systolic blood pressure. Spearman rank correlation analysis was carried out to determine the relationship between systolic blood pressure and age and other variables.

RESULTS

Patients ranged in age from 13 to 69 years. There was only a very slight increase (which did not achieve statistical significance) in systolic blood pressure with aging in the patients with HIV infection, in contrast to the control population, in which an age-related increase in systolic blood pressure was seen that was comparable to published Framingham data. Mean systolic blood pressure for the group as a whole was 118.2 +/- 1.1 mm Hg. Mean serum albumin was 4.2 +/- 0.04 g/dL and was only slightly diminished in older patients. Mean serum cholesterol was 176.8 +/- 3.4 mg/dL and this bore no relationship to aging. More advanced stages of HIV infection also did not correlate with the lack of age-associated systolic hypertension.

CONCLUSION

The present population of ambulatory patients infected with HIV seem to lack an age-related increase in systolic blood pressure; this may be caused by such variables as autonomic dysfunction or factors that may attenuate the development of atherosclerosis.

Renal TGF-beta in HIV-associated kidney diseases

Human immunodeficiency virus (HIV)-1 infection may be complicated by progressive renal glomerular disease, including focal segmental glomerulosclerosis (FSGS) and proliferative glomerulonephritis. We examined renal tissue from 71 patients, including biopsies and autopsies from patients in the presence and absence of HIV-1 infection. We assessed the extent of TGF-beta, interstitial fibrosis, and interstitial CD45-positive cellular infiltrate using immunohistochemistry. Extracellular TGF-beta 1/beta 3 was largely confined to the renal interstitium, with the highest scores in HIV-seropositive renal disease and crescentic nephritis. Among all biopsies, the TGF-beta 1/beta 3 score correlated with the fibrosis score (r = 0.79, P < 0.0001) and with the CD45 score (r = 0.60, P < 0.0001). Biopsies from HIV-infected patients, taken together, showed marginally more TGF-beta 1/beta 3 compared to biopsies from HIV-uninfected patients (P = 0.05); similarly, HIV-associated FSGS showed marginally more TGF-beta 1/beta 3 compared to FSGS biopsies obtained from HIV-uninfected patients (P = 0.05). Intracellular TGF-beta 1 and TGF-beta 3 were both expressed by renal tubular epithelial cells and in extraglomerular crescents, whereas TGF-beta 3 was also present within interstitial mononuclear cells and eosinophils, and, exclusively in HIV-infected patients, within glomerular cells. In conclusion, TGF-beta expression was increased in several progressive glomerular diseases, and was particularly but not uniquely elevated in HIV-associated renal diseases.

HIV-associated immune-mediated renal disease

Although focal glomerulosclerosis is the most common renal disease, other proliferative glomerulonephritides are encountered in HIV-infected patients. We studied four HIV-infected patients with renal insufficiency, proteinuria, and proliferative glomerulonephritis, consistent with immune-mediated disease, to investigate the role of the virus and immune complexes in the pathogenesis of the nephropathy. Circulating immune complexes (CICs) and HIV-reactive antibodies were measured and characterized in each patient. Renal biopsy tissue was acid eluted, and the eluate analyzed. DNA extracted from biopsies was subjected to the polymerase chain reaction (PCR) to detect HIV genome. CICs were detected in each patient: an IgA-p24 HIV antigen complex and an IgG antibody-gp 120 HIV antigen complex in two patients; two patients had an IgG-p24 HIV antigen complex. Identical complexes were eluted from renal tissue in the first three patients; p24 HIV antigen, and complement from the fourth. The eluted antibodies reacted with the HIV antigens from the isolated CICs. Direct immunofluorescence for viral antigen in the eluted glomerular tissue revealed HIV antigens; PCR confirmed the presence of gag genome in all four biopsies. We conclude both circulating and in-situ HIV antigen-specific immune complexes may be associated with glomerulonephritis in HIV infected patients. Viral incorporation into renal tissue may be important in the pathogenesis of HIV-associated renal disease.

Shared idiotypes in mesangial deposits in IgA nephropathy are not disease-specific

The antigenic specificity of the mesangial IgA in IgA nephropathy (IgAN) remains unknown. Because shared antigenic specificities may be reflected in the usage of shared idiotypes, we prepared five monoclonal anti-idiotypic antibodies (MoAbs) specific for the mesangial IgA eluted from the kidney of an IgAN patient. All five MoAbs reacted with the same idiotype, which proved to be of a public nature. Although the idiotype could be identified in the mesangial deposits of the majority of IgAN patients studied, it was not specific for the disease because it was also found in the glomerular deposits of other types of glomerulonephritis. The idiotype was also expressed in polyethylene glycol precipitates of sera and in pokeweed mitogen-induced plasma cells from both IgAN patients and healthy controls. The conclusion that no disease-specific idiotypes are present in the renal eluate was further supported by the failure to produce polyclonal anti-idiotypic antibodies by immunizing a rabbit with the eluted mesangial IgA. Our results support the concept that mesangial IgA deposits in IgAN are of a polyclonal nature.

Viral DNA in microdissected renal biopsy tissue from HIV infected patients with nephrotic syndrome

Focal glomerulosclerosis (FGS) has been considered as HIV-associated nephropathy, a specific renal complication of infection. To determine whether renal disease in HIV infected patients has one highly prevalent pathologic expression, and whether renal parenchymal viral genomic incorporation affects pathologic outcome, we reviewed renal biopsies performed at our center. Twenty-eight HIV infected patients with nephrotic range proteinuria underwent renal biopsy for diagnosis of renal disease: 85.7% led homosexual or bisexual lifestyles; 10.7% admitted to intravenous drug use; and 85.7% were Black. Only 53.6% had FGS; 28.6% had glomerulonephritis. Two patients had diabetic renal disease; 93.3% of patients with FGS and 87.5% of patients with glomerulonephritis were Black. Paraffin slides of twenty-two of the patients' renal biopsies were evaluated by polymerase chain reaction (PCR) for the presence of HIV DNA, using primers and probes to the gag gene, detected by liquid hybridization and polyacrylamide gel electrophoresis. Twenty-one of the twenty-two evaluated tissue specimens showed the presence of HIV DNA. Microdissection studies of glomeruli, tubules, interstitial cells and infiltrating inflammatory cells showed the presence of HIV genome in all but interstitial cells. HIV infected patients without renal disease also had positive PCR evaluations of microdissected tissue, while non-infected patients were all negative. We conclude that although focal glomerulosclerosis is the most common renal pathologic lesion in patients with HIV infection and nephrotic range proteinuria, glomerulonephritis is a relatively frequent finding. HIV genome is present in renal tissue in HIV infected subjects with nephrotic range proteinuria, but is also found in HIV infected subjects without nephropathy.(ABSTRACT TRUNCATED AT 250 WORDS)

Human immunodeficiency virus nephropathy

Varying components of the syndrome of human immunodeficiency virus nephropathy (HIVN) have been described, the most pertinent including proteinuria/nephrotic syndrome, progressive azotemia, normal blood pressure, enlarged and hyperechoic kidneys, rapid progression to end-stage renal disease (ESRD), and no response to treatment regimens. The diagnosis of HIVN requires identification of excessive proteinuria or albuminuria, determined by a total protein excretion on a timed urine collection or a high protein/creatinine ratio in a random specimen. Various pathological lesions have been found in HIVN. The lesion of focal and segmental sclerosis (FS/FSS) is most characteristic in adults and usually is associated with a rapid demise. FS/FSS also has been described in approximately one-half of the pediatric patients reported in the literature (31/64). Despite progression to ESRD, the clinical course in children with HIVN is less fulminant than in adults. Other reported histological findings include primarily mesangial hyperplasia as well as minimal change, focal necrotizing glomerulonephritis or lupus nephritis, and hemolytic uremic syndrome. In addition to glomerular pathology, interstitial findings of dilated tubules filled with a unique proteinaceous material, atrophied tubular epithelium, and interstitial cell infiltration are very common. On electron microscopy, most investigators have found tubuloreticular inclusion bodies in endothelial cells of glomerular capillaries. Treatment of patients who develop ESRD remains highly controversial. Most adult patients treated with hemodialysis have succumbed rapidly; peritoneal dialysis has been better tolerated. Transplantation in patients with HIV infection must be considered to be tentative, with reports of acceleration towards full blown acquired immunodeficiency syndrome in some and uneventful 5-year survival in others.(ABSTRACT TRUNCATED AT 250 WORDS)

IgA-anti-Fab autoantibodies and disease progression in AIDS

There is increasing evidence that autoimmune phenomena contribute to the pathogenesis of the acquired immunodeficiency syndrome (AIDS). We investigated the relationship between IgA autoantibodies directed against the Fab part of the IgG molecule and disease progression in 87 HIV-infected hemophilia patients. AIDS patients demonstrated a significantly higher serum IgA-anti-Fab activity than HIV-positive (HIV+) patients with AIDS-related complex (ARC) (P < 0.02), HIV+ patients without AIDS/ARC (P < 0.0001), HIV negative (HIV-) patients (P = 0.0001), or healthy controls (P < 0.0001). Moreover, an inverse association was observed between serum IgA-anti-Fab activity and CD4+ cell counts (r = -0.396, P < 10(-6)). This close association was confirmed in longitudinal studies of symptomatic patients. IgA-anti-Fab antibodies are suggested to play an important role in the immunopathogenesis of AIDS, and their determination may be helpful in the monitoring of HIV-infected patients.

Secretory immunoglobulins in serum from human immunodeficiency virus (HIV)-infected patients

Infection by the human immunodeficiency virus is associated with polyclonal B cell activation and increased levels of serum IgA. In order to characterize the molecular species of serum IgA, we have measured total IgA, IgA1, and IgA2 in sera from 60 HIV-1-infected patients and 40 healthy controls. In addition, secretory IgA (S-IgA), secretory IgM (S-IgM), free immunoreactive secretory component (SC), and the distribution of monomeric and polymeric IgA were determined. The data confirm the elevation of total serum IgA levels in HIV-1-infected patients, and both IgA1 and IgA2 concentrations are elevated. Furthermore, the data show a substantial increase in serum levels of both monomeric and polymeric IgA. Serum S-IgA levels were significantly increased in CDC group II patients versus controls and more frequently elevated in CDC group IV patients. The highest S-IgA levels were found among patients with the lowest blood CD4+ cell counts. Serum S-IgA levels were not correlated with serum levels of either total IgA or polymeric IgA. Serum S-IgM levels were also increased in HIV-1-infected patients and positively correlated with serum S-IgA levels. Conversely, serum levels of free SC were not altered. An increase in serum S-IgA was not related to human hepatitis B virus infection and/or to hepatic dysfunction or to diarrhea or overt intestinal infection. The data indicate that secretory Ig (S-IgM and S-IgA), which are likely to be produced at mucosal sites, increase in the serum of HIV-1-infected patients.

Binding of serum immunoglobulins to collagens in IgA nephropathy and HIV infection

The mechanism of the binding of IgA to the mesangium in IgA nephropathy (IgAN) is unknown. Interactions between IgA and components of the mesangial matrix may contribute. We measured by enzyme-linked immunosorbent assay the binding of serum IgA, IgG, and IgM from patients with IgAN, human immunodeficiency virus type I (HIV) infection, and healthy controls to purified native collagen types I to VI, and to an extract of normal kidney tissue. HIV infection is an appropriate disease control because of the lack of mesangial IgA deposits, despite high serum levels of IgA and IgA1-containing immune complexes. Increased levels of IgA-binding to collagen types I and V and the kidney extract were found only in IgAN. Both IgAN and HIV-infected patients had increased IgA-binding to collagen types II, III, and VI. Preabsorption of the sera with gelatin substantially reduced the IgA-binding to collagen types I to IV, but not to types V and VI. This finding suggests that the binding to collagen type V is not fibronectin-mediated, but may reflect autoantibody formation. Thus, fibronectin-mediated IgA-collagen interactions are not specific for IgAN, and their pathogenetic role is questionable. The role of IgA anti-collagen type V antibodies requires further study.

IgA nephritis in a child with human immunodeficiency virus: a unique form of human immunodeficiency virus-associated nephropathy?

A 9-year-old boy is presented who was antibody positive for human immunodeficiency virus (HIV) and who had recurrent episodes of gross hematuria. Renal biopsy revealed findings typical of IgA nephropathy but also showed electron-microscopic abnormalities seen with HIV-associated nephropathy. In addition, IgA antibodies to multiple HIV proteins were detected in serum by Western blot analysis, and circulating immune complexes of the IgA class were present. Although HIV-associated nephropathy and IgA nephropathy are thought to be distinct conditions, five adults with a similar combination of findings have been reported, and our patient adds to the evidence for a link between these two entities in some patients. We propose that the histological parallels between the conditions may merely represent the limited renal responses available to multiple types of injuries, and we support the attempts underway to probe renal tissue for the HIV genome.

IgA nephropathy in a child with human immunodeficiency virus type 1 infection

Infection with the human immunodeficiency virus type 1 (HIV-1) can cause a spectrum of renal disease, termed acquired immunodeficiency syndrome (AIDS) nephropathy. The most common clinical manifestations of kidney involvement in HIV-1-infected patients are proteinuria and/or nephrotic syndrome, and the histopathological pattern usually reveals focal segmental glomerulosclerosis. We describe an 8-year-old child with AIDS who presented with recurrent gross hematuria. A kidney biopsy demonstrated IgA nephropathy. This unique case indicates that the range of kidney disease in HIV-infected children may be broader than originally thought, and that these patients warrant a complete evaluation of any renal abnormality.