Association between HIV distal symmetric polyneuropathy and Mycobacterium avium complex infection

Antigenic Complementarity Resulting in Idiotype–Antiidiotype Immune Complexes: Possible Contributor to AIDS Pathogenesis and Autoimmunity

One hundred and sixty seven combinations of viral + viral antibodies or viral + bacterial antibodies were tested for their ability to precipitate each other. Some antibodies produced against HIV epitopes recognize and precipitate some antibodies produced against cytomegalovirus (CMV), hepatitis B virus (HBV) core antigen, and Mycobacteria tuberculosis (MTb) and Staphylococcus epitopes but not those against HBV surface antigen, herpes simplex types 1 and 2 (HSV1 and HSV2) or Epstein-Barr virus (EBV), Streptococcus, or Escherichia coli. In addition, CMV antibodies precipitate those of HBV core and surface antigens as well as MTb, but not HSV, HSV2, EBV, Streptococcus or E. coli. HBV core (but not surface) antibodies precipitated Mycobacterium avium antibodies (MAv) but not MTb, Streptococcus, Staphylococcus or E. coli antibodies. Binding constants vary between kds of 10(-9) and 10(-7) M. Interactive antibodies act like idiotype-antiidiotype pairs suggesting that the inducing antigens are molecularly complementary. The resulting antibody interactions may explain the formation of circulating immune complexes that are commonly found in AIDS and in other diseases characterized by multiple, concurrent infections. This observation suggests that AIDS pathogenesis may involve autoimmune mechanisms in which the immune system attacks itself to form antibody-antibody circulating immune complexes that contribute to the hypergammaglobulinemia characteristic of AIDS. Complementary cofactor infections in AIDS may therefore contribute to the immunosuppression of the syndrome and difficulties treating these corresponding infections.

Prevalence of and risk factors for HIV-associated neuropathy in Melbourne, Australia 1993-2006

OBJECTIVES

The aim of the study was to describe the prevalence of and risk factors for HIV-associated sensory neuropathy (HIV-SN) in 2006 [the era of stavudine, didanosine and zalcitabine (dNRTI)-sparing highly active antiretroviral therapy (HAART)] and to compare our findings with data obtained in the same clinic in 1993 (pre-HAART) and 2001 (frequent use of dNRTI-containing HAART).

METHODS

This was a cross-sectional comparative study using convenience sampling. HIV-positive adults attending a tertiary referral clinic over a 2-week period were screened for HIV-SN using the AIDS Clinical Trials Group screening tool. HIV-SN was defined as present if the patient had both neuropathic symptoms and abnormal signs. Demographic, clinical, laboratory and treatment data were considered as possible risk factors for HIV-SN, and results were compared with data obtained in the same clinic in 1993 and 2001.

RESULTS

One hundred patients were screened. The prevalence of HIV-SN was 42%, which was unchanged since 2001 (44%) despite a significant reduction in the use of dNRTIs. HIV-SN remained much more common than in 1993 (42% vs 13%; P<0.0001). The only independent associations with HIV-SN in 2006 were increasing patient age and a history of exposure to either stavudine or indinavir. This compares with 1993 when neuropathy was increased in those with Mycobacterium avium complex infection, and 2001 when patient age and use of stavudine and didanosine were the independent associations with HIV-SN in this clinic.

CONCLUSIONS

HIV-SN remained common among ambulatory patients in 2006 (42% prevalence) despite a significant reduction in the use of dNRTIs. In addition to patient age and stavudine exposure, indinavir use may be a risk factor for HIV-SN.

HIV-1, chemokines and neurogenesis

HIV-1 infection of the brain results in a large number of behavioural defecits accompanied by diverse neuropathological signs. However,it is not clear how the virus produces these effects or exactly how the neuropathology and behavioural defecits are related. In this article we discuss the possibility that HIV-1 infection may negatively impact the process of neurogenesis in the adult brain and that this may contribute to HIV-1 related effects on the nervous system. We have previously demonstrated that the development of the dentate gyrus during embryogenesis requires signaling by the chemokine SDF-1 via its receptor CXCR4. We demonstrated that neural progenitor cells that give rise to dentate granule neurons express CXCR4 and other chemokine receptors and migrate into the nascent dentate gyrus along SDF-1 gradients. Animals deficient in CXCR4 receptors exhibit a malformed dentate gyrus in which the migration of neural progenitors is stalled. In the adult, neurogenesis continues in the dentate gyrus. Adult neural progenitor cells existing in the subgranlar zone, that produce granule neurons, express CXCR4 and other chemokine receptors, and granule neurons express SDF-1 suggesting that SDF-1/CXCR4 signaling is also important in adult neurogenesis. Because the cellular receptors for HIV-1 include chemokine receptors such as CXCR4 and CCR5 it is possible that the virus may interfere with SDF-1/CXCR4 signaling in the brain including disruption of the formation of new granule neurons in the adult brain.

Chemokines: integrators of pain and inflammation

Chronic (neuropathic) pain is one of the most widespread and intractable of human complaints, as well as being one of the most difficult syndromes to treat successfully with drugs or surgery. The development of new therapeutic approaches to the treatment of painful neuropathies requires a better understanding of the mechanisms that underlie the development of these chronic pain syndromes. It is clear that inflammatory responses often accompany the development of neuropathic pain, and here we discuss the idea that chemokines might be key to integrating the development of pain and inflammation and could furnish new leads in the search for effective analgesic agents for the treatment of painful neuropathies.

Antigenic complementarity among AIDS-associated infectious agents and molecular mimicry of lymphocyte proteins as inducers of lymphocytotoxic antibodies and circulating immune complexes

BACKGROUND

People at risk for acquired immunodeficiency syndrome (AIDS) have high rates of cofactor infections in addition to HIV, including cytomegalovirus, hepatitis viruses, Mycobacteria, Mycoplasmas, and Staphylococcus aureus. Most people with AIDS also develop lymphocytotoxic antibodies (LCTA) and circulating immune complexes (CIC). While HIV proteins mimic HLA antigens, many cofactor agents mimic CD4 antigens. It has therefore been proposed that cofactor infections may interact with HIV by producing complementary antigens that induce LCTA and CIC, and that the resulting immunological dysfunction is part of AIDS pathogenesis.

OBJECTIVES

To test (1) whether HIV and its cofactor infections elicit complementary (idiotype-anti-idiotype) antibodies, and (2) if any of these antibodies mimic anti-lymphocyte antibodies.

STUDY DESIGN

Two immunological methods are employed to test for antibody complementarity: (1) double antibody diffusion, a modification of Ouchterlony immunodiffusion, in which antibodies are tested for their ability to precipitate each other; (2) double-antibody ELISA, in which an antibody against one infectious agent is adsorbed to an ELISA plate and an antibody against a second agent is used to detect the first.

RESULTS

Data on over a thousand double antibody diffusion (DAD) and about 70 DA-ELISA experiments are reported. These show that only specific pairs of antibodies are complementary: HIV-CMV; HIV-HBV; HIV-tuberculosis; HIV-mycoplasmas; HIV-S. aureus; and CMV-mycoplasmas. In addition, HIV antibodies precipitate CD4 antibodies; CMV antibodies precipitate HLA-DR antibodies; while mycobacteria and mycoplasma antibodies precipitate macrophage antibodies.

CONCLUSIONS

Antibodies elicited by HIV infection can interact with antibodies elicited by cofactor infections to form CIC, and some of these antibodies mimic lymphocyte antibodies so that they may function as LCTA. Since LCTA and CIC are associated with increased lymphocyte death in AIDS, the immune response against cofactors in HIV may play a significant role in AIDS pathogenesis. The fact that both HIV and cofactors elicit antibodies with LCTA characteristics may pose problems for vaccine development.

The frequency of peripheral neuropathy in a group of HIV positive patients in Brazil

Peripheral neuropathy is a common neurological complication occurring in asymptomatic and symptomatic stages of HIV infection. The most common syndromes are distal symmetric polyneuropathy, inflammatory demielinating polyneuropathy, poliradiculopathy, mononeuropathy, mononeuropathy multiplex and autonomic neuropathy. PURPOSE: To evaluate the frequency of peripheral neuropathy in a group of HIV seropositive outpatients in São Paulo, Brazil. METHOD: Over a period of 17 months, 49 HIV+ patients where evaluated clinically. Laboratory analysis and electroneuromyography were requested to all patients. RESULTS: >Thirty four (69.4%) of the 49 patients had the diagnosis of peripheral neuropathy established on clinical grounds. The most common sign was impairment (97.1%) of sensibility. Thirteen (33.3%) of the 39 that were subjected to electroneuromyography had features of peripheral neuropathy, being a sensitive-motor axonal neuropathy the most common. No abnormalities were found in the laboratory analysis performed in 42 patients, except in four who had VDRL positive. CONCLUSION: A peripheral neuropathy was frequently found upon clinical examination in our group of HIV positive individuals.

The peripheral nerve complications of human immunodeficiency virus (HIV) infection

Peripheral nerve complications occurring in patients with human immunodeficiency virus (HIV) infection are frequent and challenging. This review discusses these various complications according to the degree of advancement of HIV disease. Particular emphasis is placed upon emerging causes of neuropathy found in the context of HIV disease, such as infection with hepatitis C and human T-lymphotropic virus type I, as well as neuropathies related to antiretroviral medications.