Slow human immunodeficiency virus (HIV) infectivity correlated with low HIV coreceptor levels

Purified Versus Plasma Alpha-1 Antitrypsin Effects on Cellular Activities

By adding purified exogenous alpha-1 antitrypsin (AAT) to peripheral blood mononuclear cells in 20% autologous serum and measuring AAT-induced cellular adherence, it was determined that purified AAT differs from plasma AAT. The known association of AAT with lipoproteins and the negative feedback between AAT and low-density lipoprotein (LDL) suggest that purification may separate AAT from a plasma component such as LDL that participates in their normal plasma functions.

Serpin A1 and CD91 as host instruments against HIV-1 infection: are extracellular antiviral peptides acting as intracellular messengers?

Serpin A1 (alpha1-antitrypsin, alpha1-proteinase inhibitor) has been shown to be a non-cytolytic antiviral factor present in blood and effective against HIV infection. The best known physiological role of serpin A1 is to inhibit neutrophil elastase, a proteinase which is secreted by neutrophils at sites of infection and inflammation. Decreased HIV-infectivity is associated with decreased density of membrane-associated elastase. The enzyme may facilitate binding of the HIV membrane protein gp120 to host cells, and it specifically cleaves SDF-1, the physiological ligand of the HIV-1 co-receptor CXCR4. It has been suggested that one of the actions of serpin A1 as antiviral agent is to reduce HIV infectivity, and this property could be due to elastase inhibition. However, the most dramatic effect of serpin A1 is inhibition of HIV production. In vitro experiments indicate that the C-terminal peptide of serpin A1, produced during the formation of the complex of serpin with serine proteinases, may be responsible for the inhibition of HIV-1 expression in infected cells. This peptide, an integral part of the serpin-enzyme complex, is internalized by several scavenger receptors. Peptides corresponding to the C-terminal section of serpin A1 inhibit HIV-1 long-terminal-repeat-driven transcription and interact with nuclear proteins, such as alpha1-fetoprotein transcription factor. LDL-receptor-related protein 1 (LRP1/CD91), the best known receptor for serpin-enzyme complexes, is up-regulated in monocytes of HIV-1-infected true non-progressors. CD91 could be one of the major players in host resistance against HIV-1. It has the capacity of internalizing antiviral peptides such as serpin C-terminal fragments and alpha-defensins, and is at the same time the receptor for heat-shock proteins in antigen-presenting cells, in which chaperoned viral peptides could lead to the induction of cytotoxic T-cell responses.

HIV-1 preferentially binds receptors copatched with cell-surface elastase

Human leukocyte elastase (HLE) interacts with HIV-1 glycoprotein (gp)41, suggesting a nonenzymatic receptor function for HLE in the context of HIV-1. HLE is found localized to the cell surface, but not granules in HIV permissive clones, and to granules, but not the cell surface of HIV nonpermissive clones. Inducing cell-surface HLE expression on HLE null, HIV nonpermissive clones permits HIV infectivity. HIV binding and infectivity diminish in proportion to HLE RNA subtraction. HIV binding and infectivity show dose dependence for the natural HLE ligand alpha1 proteinase inhibitor (alpha1antitrypsin, alpha1PI). Chemokines prevent, whereas alpha1PI promotes, copatching of HLE with the canonical HIV receptors. Recent demonstration that decreased viral RNA is significantly correlated with decreased circulating alpha1PI in HIV seropositive individuals is consistent with a model in which HLE and alpha1PI can serve as HIV coreceptor and cofactor, respectively, and potentially participate in the pathophysiology of HIV disease progression.

Self antigen prognostic for human immunodeficiency virus disease progression

We have recently found that an extracellular protein, alpha(1) proteinase inhibitor (alpha(1)PI; alpha(1) antitrypsin), is required for in vitro human immunodeficiency virus (HIV) infectivity outcome. We show here in a study of HIV-seropositive patients that decreased viral load is significantly correlated with decreased circulating alpha(1)PI. In the asymptomatic category of HIV disease, 100% of patients manifest deficient levels of active alpha(1)PI, a condition known to lead to degenerative lung diseases and a dramatically reduced life span. Further, HIV-associated alpha(1)PI deficiency is correlated with circulating anti-alpha(1)PI immunoglobulin G. These results suggest that preventing HIV-associated alpha(1)PI deficiency may provide a strategic target for preventing HIV-associated pathophysiology.