Immune or autoimmune?

Differential pattern in circulating nitrogen derivatives, lactoferrin, and anti-lactoferrin antibodies in HIV type 1 and HIV type 2 infections

HIV-1 infection is associated with a dramatic reduction in antioxidative molecules both at the cellular level and in the circulation. This is particularly so for lactoferrin, an iron-binding protein involved in natural defenses (antimicrobial and antiviral activities, etc.) and found in whole secretions, including milk and mucus. In addition to its ability to chelate iron ions, lactoferrin inhibits hydroxy radical formation and interacts with nitric oxide (NO). Levels of plasma lactoferrin decreased in HIV-1-infected patients in correlation with progression of the disease, and highly specific anti-lactoferrin autoantibodies increased. This profile was specific to HIV-1 infection; it was not found in HIV-2-infected patients. In parallel with the drop in lactoferrin, a marked increase in circulating nitrogen derivatives was observed in HIV-1-infected patients, whereas low levels were found in normal donors and in HIV-2-infected patients. These data suggested hyperstimulation of the NO pathway throughout HIV-1 but not HIV-2 infection. This overproduction of NO could play an important role in the development of AIDS symptoms and signs.

Multiple organ dysfunction syndrome: exploring the paradigm of complex nonlinear systems

OBJECTIVES

The objectives of this article are to introduce and explore a novel paradigm based on complex nonlinear systems, and to evaluate its application to critical care research regarding the systemic host response and multiple organ dysfunction syndrome (MODS).

DATA SOURCES

Published original work, review articles, scientific abstracts and books, as well as our personal files.

STUDY SELECTION

Studies were selected for their relevance to the applications of nonlinear complex systems, to critical care medicine, and to the concepts presented.

DATA EXTRACTION

We extracted all applicable data.

DATA SYNTHESIS

Following a brief review of MODS, an introduction to complex nonlinear systems is presented, including clear concepts, definitions, and properties. By examining the multiple, nonlinear, interrelated, and variable interactions between the metabolic, neural, endocrine, immune, and inflammatory systems; data regarding interconnected antibody networks; and the redundant, nonlinear, interdependent nature of the inflammatory response, we present the hypothesis that the systemic host response to trauma, shock, or sepsis must be evaluated as a complex nonlinear system. This model provides a new explanation for the failure of trials using various antimediator therapies in the treatment of patients with sepsis and MODS. Understanding the host response as a complex nonlinear system offers innovative means of studying critical care patients, specifically by suggesting a greater focus on systemic properties. We hypothesize that analysis of variability and connectivity of individual variables offer a novel means of evaluating and differentiating the systemic properties of a complex nonlinear system. Current applications of evaluating variability and connectivity are discussed, and insights regarding future research are offered.

CONCLUSION

The paradigm offered by the study of complex nonlinear systems suggests new insights to pursue research to evaluate, monitor, and treat patients with MODS.

Neutralization of HIV type 1 infectivity by serum antibodies from a subset of autoimmune patients with mixed connective tissue disease

Mixed connective tissue disease (MCTD) is a rheumatic disorder with clinical similarities to HIV-1 infection, and with characteristic autoimmune anti-RNP antibodies specific for the U1 snRNP splicing complex. Anti-RNP antibodies cross-react with the HIV-1 surface, owing to multiple homologies between the gp120/41 envelope complex and the 70K protein of U1 snRNP. A key epitope of 70K, its RNA-binding site, is homologous to a dominant B and T cell epitope in the third variable loop (V3) of gp120. In this study, we tested the ability of anti-RNP sera to inhibit HIV-1 infectivity in vitro. Of nine sera tested, five were 70-99% effective in neutralizing one or more HIV-1 strains. One serum was > 99% effective in neutralizing HIV-1MN, and 86 and 77% effective against the primary isolates HIV-1(CO) and HIV-1(JR-FL), respectively, an efficacy equal to that of a pool of broadly neutralizing antibodies from HIV-1-infected subjects (HIVIG). The mean neutralizing titer of anti-RNP sera against HIV-1(JR-FL) was 3.9-fold higher than that of HIVIG. Neutralizing potency was associated with high reactivity to gp120 by ELISA, and with the presence of serum rheumatoid factor, known to enhance antibody neutralization of other viruses. The current findings provide further evidence that individuals unexposed to HIV-1 may develop immunologic resistance by alternative mechanisms, possibly including molecular mimicry, or exposure to as yet unidentified retroviruses. Thus MCTD, which involves both B and T cell reactivity to self-epitopes homologous to HIV-1, may elucidate new strategies for generating protective immunity to this virus.