Biomedical subjects

Gary A Jarvis

Publications and source records attributed to Gary A Jarvis.

13 recordsLinked to original sources

PubMed2006

Affinity-purified human immunoglobulin G that binds a lacto-N-neotetraose-dependent lipooligosaccharide structure is bactericidal for serogroup B Neisseria meningitidis.

Despite technological advances, no vaccine to prevent serogroup B meningococcal disease is available. The failure to develop a vaccine has shifted the focus to an alternative outer membrane structure, lipooligosaccharide (LOS), because disseminated disease induces bactericidal immunoglobulin G (IgG) that binds LOS. The purpose of this study was to identify the LOS structure(s) that induces human bactericidal IgG by purification and characterization of these antibodies. Human LOS IgG antibodies were affinity purified by passage of intravenous immunoglobulin through purified, type-specific LOS having a known structure coupled to epoxy-activated Sepharose 6B. Pathogenic group B strains representing the major LOS serotypes were used to examine the binding and bactericidal activities of four LOS-specific IgG preparations. All four LOS-specific IgG preparations bound to strains expressing homologous, as well as heterologous, LOS serotypes as determined by flow cytometry and an enzyme-linked immunosorbent assay. With human complement, IgG that was purified with L7 LOS was bactericidal for strains expressing L3,7 and L2,4 LOS, serotypes expressed by the majority of disease-associated group B and C meningococci. In conclusion, we purified human LOS-specific IgG that binds meningococci across LOS glycose-specific serotypes. An antigen that is dependent on the glycose lacto-N-neotetraose induces IgG in humans that is bactericidal for L2, L3, L4, and L7 strains. A vaccine containing this antigen would have the potential to protect against the vast majority of group B meningococcal strains.

Antibodies, Bacterial↗

PubMed2006

Gonococcal lipooligosaccharide suppresses HIV infection in human primary macrophages through induction of innate immunity.

Gonorrhea often occurs as a coinfection with human immunodeficiency virus (HIV). Lipooligosaccharide (LOS) is a component of the gonococcal outer membrane that induces innate immunity through engagement of Toll-like receptor 4 (TLR4). We investigated the effects that LOS from 5 different strains of Neisseria gonorrhoeae have on HIV infection and on HIV provirus in primary human macrophages. LOS-treated human primary macrophages developed resistance to new HIV infection as well as to HIV provirus. Gonococcal LOS from the 5 strains and lipopolysaccharide (LPS) from Escherichia coli showed no significant difference in their anti-HIV activities. Suppression of HIV provirus resulted from the induction of interferon (IFN)-beta and subsequent activation of signal transducer and activator of transcription 1. Neutralization of IFN-beta , but not IFN-alpha , via antibody significantly reduced the anti-HIV activity induced by LOS and LPS. We conclude that LOS expressed by various strains of N. gonorrhoeae induce specific innate immune responses through TLR4 signaling, resulting in anti-HIV activity in human primary macrophages in vitro.

Gonorrhea↗

PubMed2006

Biliary bacterial factors determine the path of gallstone formation.

BACKGROUND: Bacteria cause pigment gallstones and can act as a nidus for cholesterol gallstone formation. Bacterial factors that facilitate gallstone formation include beta-glucuronidase (bG), phospholipase (PhL), and slime. The current study sought to determine whether bacterial factors influence the path of gallstone formation. METHODS: A total of 382 gallstones were cultured and/or examined using scanning electron microscopy (SEM). Bacteria were tested for bG and slime production. Gallstone composition was determined using infrared spectrography. Ca-palmitate presence documented bacterial PhL production. Groups were identified based upon bacterial factors present: slime and bGPhL (slime/bGPhL), bGPhL only, and slime only. Influence of bacterial stone-forming factors on gallstone composition and morphology was analyzed. RESULTS: Bacteria were present in 75% of pigment, 76% of mixed, and 20% of cholesterol stones. Gallstones with bGPhL producing bacteria contained more pigment (71% vs. 26%, P < .0001). The slime/bGPhL group was associated (79%) with pigment stones, bGPhL was associated (56%) with mixed stones, while slime (or none) only was associated (67%) with cholesterol stones (P < .031, all comparisons). CONCLUSIONS: Bacterial properties determined the path of gallstone formation. Bacteria that produced all stone-forming factors promoted pigment stone formation, while those that produced only bGPhL promoted mixed stone formation. Bacteria that only produced slime lacked the ability to generate pigment solids, and consequently were more common in the centers of cholesterol stones. This shows how bacterial characteristics may govern the process of gallstone formation.

Adolescent↗

PubMed2005

Human T lymphotropic virus type II infection and humoral responses to pneumococcal polysaccharide and tetanus toxoid vaccines.

Infection with human T lymphotropic virus type II (HTLV-II) has been linked to an increased incidence of bacterial pneumonia. To determine whether HTLV-II infection is associated with impaired humoral immune responses, we immunized a cohort of HTLV-II-infected subjects and matched uninfected control subjects with 23-valent pneumococcal polysaccharide and tetanus toxoid vaccines. The pneumococcal polysaccharide vaccine elicited comparable and significant increases in concentrations of IgG against all 5 serotypes tested at 1 and 6 months after immunization in both groups. The avidity and opsonophagocytic functions of the anticapsular IgG were similar. The concentrations of tetanus toxoid-specific IgG also increased comparably and significantly over time in both groups. Thus, HTLV-II-infected persons develop robust humoral responses to potentially protective polysaccharide and protein vaccines.

Adult↗

PubMed2005

Binding of the Streptococcus gordonii surface glycoproteins GspB and Hsa to specific carbohydrate structures on platelet membrane glycoprotein Ibalpha.

GspB and Hsa are homologous serine-rich surface glycoproteins of Streptococcus gordonii strains M99 and Challis, respectively, that mediate the binding of these organisms to platelet membrane glycoprotein (GP) Ibalpha. Both GspB and Hsa consist of an N-terminal putative signal peptide, a short serine-rich region, a region (BR) that is rich in basic amino acids, a longer serine-rich region and a C-terminal cell wall anchoring domain. To further assess the mechanisms for GspB and Hsa binding, we investigated the binding of the BRs of GspB and Hsa (expressed as glutathione S-tranferase fusion proteins) to sialylated glycoproteins in vitro. Both fusion proteins showed significant levels of binding to sialylated moieties on fetuin and GPIbalpha. In contrast, the corresponding region of a GspB homologue of Streptococcus agalactiae, which is acidic rather than basic, showed no binding to either fetuin or GPIbalpha. As measured by surface plasmon resonance kinetic analysis, GspB- and Hsa-derived fusion proteins had high affinity for GPIbalpha, but with somewhat different dissociation constants. Dot blot analysis using a panel of synthesized oligosaccharides revealed that the BR of Hsa can bind both alpha(2-3) sialyllactosamine [NeuAcalpha(2-3)Galbeta(1-4)GlcNAc] and sialyl-T antigen [NeuAcalpha(2-3)Galbeta(1-3)GalNAc], whereas the BR of GspB only bound sialyl-T antigen. Moreover, far Western blotting using platelet membrane proteins revealed that GPIbalpha is the principal receptor for GspB and Hsa on human platelets. The combined results indicate that the BRs of GspB and Hsa are the binding domains of these adhesins. However, the subsets of carbohydrate structures on GPIbalpha recognized by the binding domains appear to be different between the two proteins.

Adhesins, Bacterial↗

PubMed2005

Candidate sulfonated and sulfated topical microbicides: comparison of anti-human immunodeficiency virus activities and mechanisms of action.

Poly(styrene 4-sulfonate), cellulose sulfate, polymethylenehydroquinone, and PRO 2000 are sulfated or sulfonated polymers (SPs) under development as topical microbicides. They are presumed to work through similar mechanisms of action, although to date there has been no extensive comparison of their anti-human immunodeficiency virus activities. To determine whether any of these candidate microbicides offers a potential advantage, their in vitro activities, mechanisms of action, stabilities in biological secretions, and toxicities were compared. All four compounds were found to be active against X4, R5, and dualtropic primary isolates and against X4 and R5 laboratory-adapted strains in CD4+ T cells, macrophages, and single-coreceptor cell lines. Our single-cycle experiments using pseudotyped virus suggest that all four SPs function at the binding and entry stages of the viral life cycle but differ in degree of postentry effect. Surface plasmon resonance analyses demonstrate that SPs bind to X4 and R5 monomeric glycoprotein 120 with similar high binding affinities. When mixed with cervicovaginal lavage fluid, SPs maintain inhibitory activity at concentrations achievable in formulations.

Administration, Topical↗

PubMed2004

Mannose-binding lectin binds to two major outer membrane proteins, opacity protein and porin, of Neisseria meningitidis.

Human mannose-binding lectin (MBL) provides a first line of defense against microorganisms by complement activation and/or opsonization in the absence of specific Ab. This serum collectin has been shown to activate complement when bound to repeating sugar moieties on several microorganisms, including encapsulated serogroup B and C meningococci, which leads to increased bacterial killing. In the present study, we sought to identify the meningococcal cell surface components to which MBL bound and to characterize such binding. Outer membrane complex containing both lipooligosaccharide (LOS) and proteins and LOS from Neisseria meningitidis were examined for MBL binding by dot blot and ELISA. MBL bound outer membrane complex but not LOS. The binding to bacteria by whole-cell ELISA did not require calcium and was not inhibited by N-acetyl-glucosamine or mannose. With the use of SDS-PAGE, immunoblot analysis, and mAbs specific for meningococcal opacity (Opa) proteins and porin proteins, we determined that MBL bound to Opa and porin protein B (porB). The N-terminal amino acid sequences of the two MBL binding proteins confirmed Opa and PorB. Purified PorB inhibited the binding of MBL to meningococci. Escherichia coli with surface-expressed gonococcal Opa bound significantly more MBL than did the control strain. The binding of human factor H to purified PorB was markedly inhibited by MBL in a dose-dependent manner. Meningococci incubated with human serum bound MBL as detected by ELISA. We conclude that MBL binds to meningococci by a novel target recognition of two nonglycosylated outer membrane proteins, Opa and PorB.

Bacterial Outer Membrane Proteins↗

PubMed2004

Candidate topical microbicides bind herpes simplex virus glycoprotein B and prevent viral entry and cell-to-cell spread.

Topical microbicides designed to prevent acquisition of sexually transmitted infections are urgently needed. Nonoxynol-9, the only commercially available spermicide, damages epithelium and may enhance human immunodeficiency virus transmission. The observation that herpes simplex virus (HSV) and human immunodeficiency virus bind heparan sulfate provided the rationale for the development of sulfated or sulfonated polymers as topical agents. Although several of the polymers have advanced to clinical trials, the spectrum and mechanism of anti-HSV activity and the effects on soluble mediators of inflammation have not been evaluated. The present studies address these gaps. The results indicate that PRO 2000, polystyrene sulfonate, cellulose sulfate, and polymethylenehydroquinone sulfonate inhibit HSV infection 10,000-fold and are active against clinical isolates, including an acyclovir-resistant variant. The compounds formed stable complexes with glycoprotein B and inhibit viral binding, entry, and cell-to-cell spread. The effects may be long lasting due to the high affinity and stability of the sulfated compound-virus complex, as evidenced by surface plasmon resonance studies. The candidate microbicides retained their antiviral activities in the presence of cervical secretions and over a broad pH range. There was little reduction in cell viability following repeated exposure of human endocervical cells to these compounds, although a reduction in secretory leukocyte protease inhibitor levels was observed. These studies support further development and rigorous evaluation of these candidate microbicides.

Anti-Infective Agents, Local↗

PubMed2003

Cholangitis: bacterial virulence factors that facilitate cholangiovenous reflux and tumor necrosis factor-alpha production.

In previous studies we noted that biliary bacteria produce slime and possess P1-fimbriae. The presence of gram-negative bacteria killed by complement correlated with serious biliary infections and induced more tumor necrosis factor-alpha (TNF-alpha) production in sera, suggesting a role for cytokine production and complement activation in biliary sepsis. This study examined bacterial virulence factors that facilitate cholangiovenous reflux (CVR) and TNF-alpha production in a rat model. Twenty-one biliary bacteria and two stool isolates were tested for slime production, sensitivity to complement killing, and hemolysin production. 10(7) Bacterial colony-forming units/ml (or saline control) were injected retrograde into the common bile ducts of Sprague-Dawley rats at a pressure of 30 cm H(2)O. Blood was obtained at 5 and 60 minutes after infusion for bacterial culture and TNF-alpha assay, respectively. The magnitude of slime production correlated inversely with the magnitude of bacterial CVR. Average bacterial colony-forming units were 1.4 x 10(5), 6.8 x 10(4), or 2.1 x 10(3) for bacteria with slime production 0 to 10, 11 to 99, or more than 100, respectively (P < 0.0001, analysis of variance). CVR was greater for serum-resistant bacteria (1.2 x 10(5) vs. 5.5 x 10(4) [P = 0.007, resistant vs. sensitive]), but TNF-alpha production was greater in serum-sensitive bacteria. TNF-alpha production as a function of bacterial reflux followed a logarithmic curve (R(2) = 0.75) for serum-sensitive bacteria but was linear (R(2) = 0.60) for serum-resistant bacteria. These data show how specific virulence factors explain why some bacterial species colonize without causing illness, whereas others colonize and cause sepsis. Although slime production was necessary for colonization, too much slime inhibited CVR. Although complement killing cleared bacteria from the circulation, it was also associated with increased TNF-alpha production, which can lead to septic manifestations. The most virulent bacterial species (from patients with sepsis) were killed by complement, but they still had significant CVR and were associated with increased TNF-alpha production.

Analysis of Variance↗

PubMed2003

Activation of toll-like receptor 2 (TLR2) and TLR4/MD2 by Neisseria is independent of capsule and lipooligosaccharide (LOS) sialylation but varies widely among LOS from different strains.

Lipooligosaccharide (LOS) structure and capsular polysaccharide of Neisseria meningitidis each greatly influence the virulence of the organism and the quality of host innate immune responses. In this study, we found that production of the proinflammatory cytokine tumor necrosis factor (TNF) by a human monocyte-derived cell line (THP-1) exposed to strains of N. meningitidis lacking capsule and/or with truncated LOS was similar to that elicited by the isogenic wild-type strain. These mutants also exhibited no difference in induction of the interleukin-8 (IL-8) promoter in a transfected HeLa cell system of Toll-like receptor 2 (TLR2) and TLR4/MD2 signaling. However, purified LOS from diverse strains of Neisseria (both N. meningitidis and N. gonorrhoeae) caused widely variant levels of IL-8 promoter induction in cells expressing MD2 that correlated with the production of TNF from THP-1 cells. These data suggest that although modification of the oligosaccharide chain of LOS and/or absence of capsule do not affect cell signaling mediated by TLR4/MD2, fine-structural differences in the LOS do influence signaling through TLR4/MD2 and, through this pathway, influence some of the proinflammatory responses elicited by Neisseria.

Bacterial Capsules↗

PubMed2003

Truncated galectin-3 inhibits tumor growth and metastasis in orthotopic nude mouse model of human breast cancer.

PURPOSE: The goal of this research was to evaluate a potential therapeutic agent for breast cancer based on galectin-3 that has been implicated in tumorigenicity and metastasis of breast cancer. The hypothesis was that therapy with NH(2)-terminally truncated form of galectin-3 (galectin-3C) will be efficacious for reduction in tumor growth and for inhibition of metastases. EXPERIMENTAL DESIGN: Recombinant human galectin-3 was produced in Escherichia coli from which galectin-3C was derived by collagenase enzyme digestion. Toxicity, pharmacokinetic, and organ biodistribution studies were performed in nude mice. For efficacy studies, nude mice bearing orthotopically implanted tumors derived from breast cancer cell line MDA-MB-435 were treated with galectin-3C or a vehicle control i.m. twice daily for 90 days. RESULTS: The maximum tolerated dose of galectin-3C in nude mice was determined to be >125 mg/kg without overt adverse effects. The elimination half-life when administered i.m. was found to be 3.0 h in the serum and 4.3 h in the cellular fraction of the blood. Organ biodistribution studies revealed that galectin-3C localized in the liver, kidneys, and spleen but not in the heart or lungs. We found that the mean tumor volumes and weights were statistically significantly less in mice treated with galectin-3C compared with control mice, and that fewer numbers of mice exhibited lymph node metastases in the treated group compared with the control group. CONCLUSIONS: Galectin-3C is not overtly toxic, and is efficacious in reducing metastases and tumor volumes and weights in primary tumors in an orthotopic nude mouse model of human breast cancer.

Animals↗

PubMed2002

Galectin-3 binds lactosaminylated lipooligosaccharides from Neisseria gonorrhoeae and is selectively expressed by mucosal epithelial cells that are infected.

Galectins are a family of beta-galactoside binding proteins that have been proposed as host receptors for bacteria because beta-galactoside carbohydrates are common in bacterial membrane glycolipid lipooligosaccharides (LOS) and lipopolysaccharides. We investigated the interaction of galectin-3 with gonococcal LOS that make lactosyl (Lc2 or Lac), paraglobosyl (nLc4; LNnT; lacto-N-neotetraose), gangliosyl (IV3GalNAcnLc4), and neolactohexaosyl (nLc6, lactonorhexaosyl) oligosaccharides. All but gangliosyl LOS terminate in beta-galactoside. Galectin-3 had the highest affinity for the nLc6 LOS, which is made by a strain that is highly infectious for the male urethra, but also bound nLc4 LOS and to a Lac LOS. The lacto-N-neotetraose tetrasaccharide was a more potent inhibitor of galectin-3 binding to LOS than either lactose or N-acetyllactosamine. The relative affinity of galectin-3 for gonococci mirrored its affinity for purified LOS. Western blot analysis revealed expression of galectin-3 by human endometrial adenocarcinoma and prostatic epithelial cells that can be invaded by gonococci. Immunohistochemistry of human fallopian tube epithelium showed localized expression of galectin-3 by non-ciliated cells, the specific cell gonococci invade in this tissue. We conclude that because of its location and affinity for gonococcal LOS galectin-3 could play a role in gonococcal infection.

Carbohydrate Sequence↗

PubMed2002

Gram-negative bacteria killed by complement are associated with more severe biliary infections and produce more tumor necrosis factor-alpha in sera.

BACKGROUND: We previously showed that gallstones contain bacteria and that illness severity correlates with bacterial presence. This study examined virulence differences of gram-negative biliary bacteria. METHODS: Gallstones and bile were cultured, and sera obtained, from 210 patients. Infection severity was staged as: none-no clinical infection; moderate-fever, leukocytosis; or severe-bacteremia, cholangitis, hypotension, abscess, or organ failure. Gram-negative biliary bacteria were tested against patient (and control) serum for complement-mediated bacterial killing and induction of tumor necrosis factor-alpha (TNFalpha) production (using cultured monocytes) with and without sera. These results were correlated with infection severity. RESULTS: A total of 98 (47%) patients had biliary bacteria. Infection severity distribution was none, 29%; moderate, 35%; and severe, 36%. Gram-negative organisms killed by complement were associated with more severe infections as follows: 13%, none; 60%, moderate; and 88%, severe infections (P =.024 and P <.0001, respectively vs none, chi-square test). TNFalpha production in sera increased 182 pg/mL with complement resistant bacteria, but increased 546 pg/mL with bacteria killed by complement (P <.0001, killed vs not killed, Student's t test). E coli and Klebsiella were the most virulent bacterial species. They were cultured from blood, usually killed by complement, and had the largest increase in TNFalpha production in sera. CONCLUSIONS: Gram-negative biliary bacteria killed by complement (as opposed to complement-resistant) were associated with more serious biliary infections including bacteremia and induced more TNFalpha production in sera. This suggests a potential role for complement activation and cytokine production in biliary sepsis.

Adolescent↗