Miscellaneous HIV-associated Renal Diseases
A. Brad Farris, III, MD
TERMINOLOGY
Abbreviations
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HIV-associated renal diseases (HIV-ARD)
Definitions
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Renal diseases other than collapsing glomerulopathy (HIVAN) that occur particularly in patients infected with HIV, due to direct effect on kidney, altered immune system, or drug toxicity
HIV-ASSOCIATED LUPUS-LIKE GLOMERULONEPHRITIS
Terminology
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Chronic immune complex disease in HIV-infected patients that has LM, IF, and EM features of lupus nephritis, but patients have no other evidence of lupus nephritis
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Described by Haas et al and Nochy et al
Pathogenesis
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Probably related to immune dysregulation
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Loss of CD4(+) T regulatory cells causes autoimmune disease
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Role of infectious agent not excluded
Incidence
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Possibly 2nd most common form of glomerular lesions (after HIVAN) in HIV patients undergoing biopsy
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Many (13/14 in the Haas Baltimore study) were African-American
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Nochy’s study in Europe showed equal proportions of whites and blacks having lupus-like GN
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In series of > 100 biopsies for glomerular disease in HIV(+) patients, 3% had lupus-like GN
Presentation
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Hematuria and proteinuria/nephrotic syndrome
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Share other features such as anemia, leukopenia, multiorgan involvement, and serositis
Laboratory Tests
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± ANA and anti-double-stranded (ds) DNA and ↓ complements
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Assessment somewhat complicated because some HIV patients have low-titer ANAs
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Screening of > 150 patients with AIDS found 19 to be ANA(+) but only 2 at high titer and none anti-dsDNA Ab(+)
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Treatment
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Corticosteroids, ACE inhibitors, highly active antiretroviral therapy (HAART) have all been used
Prognosis
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Outcome can be poor, because many patients present with advanced disease
Microscopic Pathology
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Focal/diffuse proliferative GN or membranous nephropathy
Immunofluorescence
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“Full house” pattern of IgG, IgA, IgM, C3, and C1q
Electron Microscopy
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Essentially all have tubuloreticular inclusions
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Most common pattern appears to be combination of mesangial, subendothelial, subepithelial, and intramembranous deposits
Differential Diagnosis
IgA NEPHROPATHY
Terminology
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IgA(+) glomerular disease arising in HIV(+) patients that has clinical and pathologic aspects similar to idiopathic IgA nephropathy
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Reports have also included Henoch-Schönlein purpura with nephritis
Pathogenesis
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Deposits eluted from glomeruli have shown specificity for HIV envelope (e.g., gp41, gp120, gp160) or core proteins (e.g., p24) (Kimmel et al)
Incidence
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Series (many of which are from Europe) indicate higher incidence of IgA nephropathy in white patients with HIV infection
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Data conflicts regarding prevalence of IgA deposits in patients dying from AIDS
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Some series indicate high prevalence of IgA deposits in AIDS patients, but this does not necessarily correlate with increased IgA nephropathy rate
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Presentation
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Hematuria and low-grade proteinuria are common
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May present with Henoch-Schönlein purpura (HSP)-type picture (rash [leukocytoclastic angiitis of the skin], etc.)
Laboratory Tests
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Associated with IgA-containing cryoglobulins
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↑ IgA levels, IgA-containing circulating immune complexes, and IgA-rheumatoid factor
Treatment
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ACE inhibitors may be useful
Prognosis
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Thought to be same as IgA nephropathy in non-HIV-infected patients
Microscopic Pathology
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Does not differ drastically from conventional IgA nephropathy seen in absence of HIV
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Mesangial proliferation ± collapsing glomerulosclerosis (coexisting HIVAN)
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Immunofluorescence
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Shows mesangial IgA deposits like conventional IgA nephropathy seen in absence of HIV
Electron Microscopy
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In contrast with idiopathic IgA nephropathy, there are also numerous tubuloreticular structures that provide a clue to presence of HIV
THROMBOTIC MICROANGIOPATHY (TMA)
Terminology
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TMA associated with HIV infection
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Both syndromes resembling thrombotic thrombocytopenic purpura (TTP) and hemolytic uremic syndrome (HUS) can occur in HIV-infected patients
Pathogenesis
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Etiology not known
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HIV injury to endothelium or infection of megakaryocytes may be involved
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Escherichia coli 0157:H7 appears not to be involved
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Appears that ADAMTS13 level is not ↓ in HIV-associated TMA as it is in TTP
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Etiology role has been attributed to CMV infection, cryptosporidiosis, AIDS-related neoplasia, drugs, and antiphospholipid antibodies
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Incidence
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Human data are lacking
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Multicenter autopsy study showed 15 of 214 patients (7%) with deaths attributable to AIDS had evidence of TMA
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French study (Peraldi et al) attributed rapid decline in renal function to HUS-type syndrome in 32 of 92 patients
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6/27 (22.2%) pigtailed macaques (Macaca nemestrina) acutely infected with HIV-2 developed histological and EM features of renal TMA such as glomerular capillary platelet thrombi and mesangiolysis
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Presentation
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Acute renal failure ± proteinuria and hematuria
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Microangiopathic hemolytic anemia and thrombocytopenia
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Presentations may be classified as either HUS or TTP (neurologic symptoms and fever)
Laboratory Tests
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± thrombocytopenia ± schistocytosis
Treatment
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Treatment of underlying HIV may be best approach
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Plasmapheresis and fresh frozen plasma have been used
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Rituximab and corticosteroids have been used
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Hemodialysis may be needed at presentation
Prognosis
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High mortality: More severe in HIV-infected patients than in non-HIV-infected patients
Microscopic Pathology
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Pathologic findings are similar to those of TMA in non-HIV-infected patients
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Mucoid arterial intimal hyperplasia and intraluminal thrombi may be observed
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Fragmented intramural RBCs in vessels
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May coexist with HIVAN
Immunofluorescence

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