Proteins of 30 and 36 kilodaltons, membrane constituents of the Staphylococcus aureus L form, induce production of tumor necrosis factor alpha and activate the human immunodeficiency virus type 1 long terminal repeat

Analysis of colostrum IgA against bacteria involved in neonatal infections

OBJECTIVE

To describe e compare the specificity of IgA antibodies against bacteria extract of Klebsiella pneumoniae , Staphylococcus aureus , Escherichia coli , and Salmonella enteritidis .

METHODS

Colostrum samples were aseptically collected in the first 12 hours after C-section delivery. The specificity of IgA against bacteria extracts was analyzed by the Western blot.

RESULTS

The findings showed proteins of high molecular weight frequently detectable in the samples. S. aureus was the most frequently found bacterium in the samples (p<0.05). Approximately 93.8, 56.3, 62.5 and 60.4% of samples presented IgA reactive to S. aureus , K. pneumoniae , S. enteritidis, and E. coli, respectively. Roughly 40% of samples showed no IgA reactive to K. pneumoniae, S. enteritidis and E. coli .

CONCLUSION

Clinical evidence of the importance of breastfeeding for the immune protection of neonates was consistent with the observed immunological findings, since most samples showed IgA reactive against the species tested. The application and development of immunotherapies during pregnancy, focused on frequently detected antigens, could be an important tool to enhance the presence of IgA in colostrum.

Induction of multiple matrix metalloproteinases in human dermal and synovial fibroblasts by Staphylococcus aureus: implications in the pathogenesis of septic arthritis and other soft tissue infections

Infections of body tissue by Staphylococcus aureus are quickly followed by degradation of connective tissue. Patients with rheumatoid arthritis are more prone to S. aureus-mediated septic arthritis. Various types of collagen form the major structural matrix of different connective tissues of the body. These different collagens are degraded by specific matrix metalloproteinases (MMPs) produced by fibroblasts, other connective tissue cells, and inflammatory cells that are induced by interleukin-1 (IL-1) and tumor necrosis factor (TNF). To determine the host's contribution in the joint destruction of S. aureus-mediated septic arthritis, we analyzed the MMP expression profile in human dermal and synovial fibroblasts upon exposure to culture supernatant and whole cell lysates of S. aureus. Human dermal and synovial fibroblasts treated with cell lysate and filtered culture supernatants had significantly enhanced expression of MMP-1, MMP-2, MMP-3, MMP-7, MMP-10, and MMP-11 compared with the untreated controls (p < 0.05). In the S. aureus culture supernatant, the MMP induction activity was identified to be within the molecular-weight range of 30 to >50 kDa. The MMP expression profile was similar in fibroblasts exposed to a combination of IL-1/TNF. mRNA levels of several genes of the mitogen-activated protein kinase (MAPK) signal transduction pathway were significantly elevated in fibroblasts treated with S. aureus cell lysate and culture supernatant. Also, tyrosine phosphorylation was significantly higher in fibroblasts treated with S. aureus components. Tyrosine phosphorylation and MAPK gene expression patterns were similar in fibroblasts treated with a combination of IL-1/TNF and S. aureus. Mutants lacking staphylococcal accessory regulator (Sar) and accessory gene regulator (Agr), which cause significantly less severe septic arthritis in murine models, were able to induce expression of several MMP mRNA comparable with that of their isogenic parent strain but induced notably higher levels of tissue inhibitors of metalloproteinases (TIMPs). To our knowledge, this is the first report of induction of multiple MMP/TIMP expression from human dermal and synovial fibroblasts upon S. aureus treatment. We propose that host-derived MMPs contribute to the progressive joint destruction observed in S. aureus-mediated septic arthritis.

Community-associated methicillin-resistant Staphylococcus aureus in the patient with HIV infection

The prevalence of community-associated methicillin-resistant Staphylococcus aureus (CA-MRSA) has increased alarmingly in both the general population and the HIV-infected community. We look at the background of MRSA including the mechanisms of resistance, genetics, and trends in the individual with HIV infection. Numerous studies have investigated the risk factors for CA-MRSA. Other studies have further characterized the incidence of and risk factors for MRSA infections in the HIV community. Although one might not readily associate advanced HIV infection with increased susceptibility to bacterial pathogens, a number of studies have explained the mechanisms of this B-cell-mediated susceptibility. Invasive MRSA infections have spread into communities, are increasingly prevalent, and pose a public health challenge for their containment, prevention, and treatment.

Evolutionary expressed sequence tag analysis of Drosophila female reproductive tracts identifies genes subjected to positive selection

Genes whose products are involved in reproduction include some of the fastest-evolving genes found within the genomes of several organisms. Drosophila has long been used to study the function and evolutionary dynamics of genes thought to be involved in sperm competition and sexual conflict, two processes that have been hypothesized to drive the adaptive evolution of reproductive molecules. Several seminal fluid proteins (Acps) made in the Drosophila male reproductive tract show evidence of rapid adaptive evolution. To identify candidate genes in the female reproductive tract that may be involved in female-male interactions and that may thus have been subjected to adaptive evolution, we used an evolutionary bioinformatics approach to analyze sequences from a cDNA library that we have generated from Drosophila female reproductive tracts. We further demonstrate that several of these genes have been subjected to positive selection. Their expression in female reproductive tracts, presence of signal sequences/transmembrane domains, and rapid adaptive evolution indicate that they are prime candidates to encode female reproductive molecules that interact with rapidly evolving male Acps.

Considerations relating to the epidemiology of human immunodeficiency virus infection: the impact of bacterial antigens and consequences for treatment

OBJECTIVE

A treatment for patients with human immunodeficiency virus/acquired immune deficiency syndrome (HIV/AIDS) is presented, which is based on an isopathic method that appears to be effective in eliminating bacterial antigens from the body. The concept is based on a new hypothesis concerning the outbreak and spread of AIDS in Africa and worldwide.

SUBJECTS AND DESIGN

Laboratory data are presented from five European and seven African patients with HIV.

RESULTS

Oral administration of ultra-low doses of a lysate of Staphylococcus aureus Cowan I (12c potency) resulted in a significant increase of CD4 T-cell subsets and CD4/CD8 ratios in patients with HIV infection as well as in advanced stages of HIV disease, concomitant with the improvement of clinical HIV-related symptoms.

CONCLUSIONS

Based on epidemiologic data, the beginning of the African AIDS epidemic is related-to time, place, and circumstances-to the initial large-scale introduction of antibiotics in areas of Central Africa that would later comprise the AIDS belt. It is concluded that certain antimicrobial agents can enhance the formation of persistent bacterial superantigens, which may indicate a link between asymptomatic HIV carriers and the development of AIDS. According to this view, superantigens and bacterial cell wall components remaining in the body after antibiotic treatment cause a permanent activation of the immune system and would thus favor T-cell infection and viral replication in HIV-infected individuals.

Up-regulation of HIV coreceptors CXCR4 and CCR5 on CD4+ T cells during human endotoxemia and after stimulation with (myco)bacterial antigens: the role of cytokines

Concurrent infections in patients with human immunodeficiency virus (HIV) infection stimulate HIV replication. Chemokine receptors CXCR4 and CCR5 can act as HIV coreceptors. The authors hypothesized that concurrent infection increases the HIV load through up-regulation of CXCR4 and CCR5. Using experimental endotoxemia as a model of infection, changes in HIV coreceptor expression were assessed in 8 subjects injected with lipopolysaccharide (LPS, 4 ng/kg). The expression of CXCR4 and CCR5 on CD4+ T cells was increased 2- to 4-fold, 4 to 6 hours after LPS injection. In whole blood in vitro, LPS induced a time- and dose-dependent increase in the expression of CXCR4 and CCR5 on CD4+ T cells. Similar changes were observed after stimulation with cell wall components ofMycobacterium tuberculosis (lipoarabinnomannan) orStaphylococcus aureus (lipoteichoic acid), or with staphylococcal enterotoxin B. LPS increased viral infectivity of CD4-enriched peripheral blood mononuclear cells (PBMCs) with a T-tropic HIV strain. In contrast, M-tropic virus infectivity was reduced, possibly because of elevated levels of the CCR5 ligand cytokines RANTES and MIP-1β. LPS-stimulated up-regulation of CXCR4 and CCR5 in vitro was inhibited by anti-TNF and anti-IFNγ. Incubation with recombinant TNF or IFNγ mimicked the LPS effect. Anti–interleukin 10 (anti–IL-10) reduced CCR5 expression, without influencing CXCR4. In accordance, rIL-10 induced up-regulation of CCR5, but not of CXCR4. Intercurrent infections during HIV infection may up-regulate CXCR4 and CCR5 on CD4+ T cells, at least in part via the action of cytokines. Such infections may favor selectivity of HIV for CD4+ T cells expressing CXCR4.

Up-regulation of HIV coreceptors CXCR4 and CCR5 on CD4+ T cells during human endotoxemia and after stimulation with (myco)bacterial antigens: the role of cytokines

Concurrent infections in patients with human immunodeficiency virus (HIV) infection stimulate HIV replication. Chemokine receptors CXCR4 and CCR5 can act as HIV coreceptors. The authors hypothesized that concurrent infection increases the HIV load through up-regulation of CXCR4 and CCR5. Using experimental endotoxemia as a model of infection, changes in HIV coreceptor expression were assessed in 8 subjects injected with lipopolysaccharide (LPS, 4 ng/kg). The expression of CXCR4 and CCR5 on CD4+ T cells was increased 2- to 4-fold, 4 to 6 hours after LPS injection. In whole blood in vitro, LPS induced a time- and dose-dependent increase in the expression of CXCR4 and CCR5 on CD4+ T cells. Similar changes were observed after stimulation with cell wall components ofMycobacterium tuberculosis (lipoarabinnomannan) orStaphylococcus aureus (lipoteichoic acid), or with staphylococcal enterotoxin B. LPS increased viral infectivity of CD4-enriched peripheral blood mononuclear cells (PBMCs) with a T-tropic HIV strain. In contrast, M-tropic virus infectivity was reduced, possibly because of elevated levels of the CCR5 ligand cytokines RANTES and MIP-1β. LPS-stimulated up-regulation of CXCR4 and CCR5 in vitro was inhibited by anti-TNF and anti-IFNγ. Incubation with recombinant TNF or IFNγ mimicked the LPS effect. Anti–interleukin 10 (anti–IL-10) reduced CCR5 expression, without influencing CXCR4. In accordance, rIL-10 induced up-regulation of CCR5, but not of CXCR4. Intercurrent infections during HIV infection may up-regulate CXCR4 and CCR5 on CD4+ T cells, at least in part via the action of cytokines. Such infections may favor selectivity of HIV for CD4+ T cells expressing CXCR4.

Molecular cloning of a 32-kilodalton lipoprotein component of a novel iron-regulated Staphylococcus epidermidis ABC transporter

Our previous studies identified two iron-regulated cytoplasmic membrane proteins of 32 and 36 kDa expressed by both Staphylococcus epidermidis and Staphylococcus aureus. In this study we show by Triton X-114 phase partitioning and tritiated palmitic acid labelling that these proteins are lipoproteins which are anchored into the cytoplasmic membrane by their lipid-modified N termini. In common with those of some other gram-positive bacteria, these highly immunogenic lipoproteins were released from the bacterial cell into the culture supernatants, with release being promoted by growth of the bacteria under iron-restricted conditions. Immunoelectron microscopy with a monospecific rabbit antiserum to the 32-kDa S. epidermidis lipoprotein showed that the majority of the antigen was distributed throughout the staphylococcal cell wall. Only minor quantities were detected in the cytoplasmic membrane, and exposure of the lipoprotein on the bacterial surface was minimal. A monoclonal antibody raised to the 32-kDa lipoprotein of S. aureus was used in immunoblotting studies to investigate the conservation of this antigen among a variety of staphylococci. The monoclonal antibody reacted with polypeptides of 32 kDa in S. epidermidis and S. aureus and of 40 kDa in Staphylococcus hominis. No reactivity was detected with Staphylococcus lugdunensis, Staphylococcus cohni, or Staphylococcus haemolyticus. The gene encoding the 32-kDa lipoprotein from S. epidermidis has been isolated from a Lambda Zap II genomic DNA library and found to be a component of an iron-regulated operon encoding a novel ABC-type transporter. The operon contains three genes, designated sitA, -B, and -C, encoding an ATPase, a cytoplasmic membrane protein, and the 32-kDa lipoprotein, respectively. SitC shows significant homology both with a number of bacterial adhesins, including FimA of Streptococcus parasanguis and ScaA of Streptococcus gordonii, and with lipoproteins of a recently described family of ABC transporters with proven or putative metal ion transport functions. Although the solute specificity of this novel transporter has not yet been determined, we speculate that it may be involved in either siderophore- or transferrin-mediated iron uptake in S. epidermidis.

Staphylococcus aureus nasal colonization in HIV-seropositive and HIV-seronegative drug users

Nasal colonization plays an important role in the pathogenesis of Staphylococcus aureus infections. To identify characteristics associated with colonization, we studied a cross-section of a well-described cohort of HIV-seropositive and -seronegative active and former drug users considered at risk for staphylococcal infections. Sixty percent of the 217 subjects were Hispanic, 36% were women, 25% actively used injection drugs, 23% actively used inhalational drugs, 23% received antibiotics, and 35% were HIV-seropositive. Forty-one percent of subjects had positive nasal cultures for S. aureus. The antibiotic susceptibility patterns were similar to the local hospital's outpatient isolates and no dominant strain was identified by arbitrarily primed polymerase chain reaction (AB-PCR). Variables significantly and independently associated with colonization included antibiotic use (odds ratio [OR] = 0.37; confidence interval [CI] = 0.18-0.77), active inhalational drug use within the HIV-seropositive population (OR = 2.36; CI = 1.10-5.10) and female gender (OR = 1.97; CI = 1.09-3.57). Characteristics not independently associated included injection drug use, HIV status, and CD4 count. The association with active inhalational drug use, a novel finding, may reflect alterations in the integrity of the nasal mucosa. The lack of association between HIV infection and S. aureus colonization, which is contrary to most previous studies, could be explained by our rigorous control for confounding variables or by a limited statistical power due to the sample sizes.