d-Methionine reduces tobramycin-induced ototoxicity without antimicrobial interference in animal models.

BACKGROUND: Tobramycin is a critical cystic fibrosis treatment however it causes ototoxicity. This study tested d-methionine protection from tobramycin-induced ototoxicity and potential antimicrobial interference. METHODS: Auditory brainstem responses (ABRs) and outer hair cell (OHC) quantifications measured protection in guinea pigs treated with tobramycin and a range of d-methionine doses. In vitro antimicrobial interference studies tested inhibition and post antibiotic effect assays. In vivo antimicrobial interference studies tested normal and neutropenic Escherichia coli murine survival and intraperitoneal lavage bacterial counts. RESULTS: d-Methionine conferred significant ABR threshold shift reductions. OHC protection was less robust but significant at 20kHz in the 420mg/kg/day group. In vitro studies did not detect d-methionine-induced antimicrobial interference. In vivo studies did not detect d-methionine-induced interference in normal or neutropenic mice. CONCLUSIONS: d-Methionine protects from tobramycin-induced ototoxicity without antimicrobial interference. The study results suggest d-met as a potential otoprotectant from clinical tobramycin use in cystic fibrosis patients.

Secretory leukocyte protease inhibitor binds to Neisseria gonorrhoeae outer membrane opacity protein and is bactericidal.

PROBLEM: Secretory leukocyte protease inhibitor (SLPI) is an innate immune peptide present on the genitourinary tract mucosa that has antimicrobial activity. In this study, we investigated the interaction of SLPI with Neisseria gonorrhoeae. METHOD OF STUDY: ELISA and far-Western blots were used to analyze binding of SLPI to gonococci. The binding site for SLPI was identified by tryptic digests and mass spectrometry. Antimicrobial activity of SLPI for gonococci was determined using bactericidal assays. SLPI protein levels in cell supernatants were measured by ELISA, and SLPI mRNA levels were assessed by quantitative RT-PCR. RESULTS: SLPI bound directly to the gonococcal Opa protein and was bactericidal. Epithelial cells from the reproductive tract constitutively expressed SLPI at different levels. Gonococcal infection of cells did not affect SLPI expression. CONCLUSION: We conclude that SLPI is bactericidal for gonococci and is expressed by reproductive tract epithelial cells and thus is likely to play a role in the pathogenesis of gonococcal infection.

Comparative studies of glycosaminoglycan involvement in Chlamydia pneumoniae and C. trachomatis invasion of host cells.

The role of glycosaminoglycans (GAGs) in the invasion of host cells by Chlamydia pneumoniae strains TW-183 and A-03 was investigated and compared with the role of invasion by C. trachomatis serovars L2 and E. The quantities of epithelial and endothelial cell-surface GAGs, as well as chlamydial elementary body (EB)-surface GAGs, were investigated. When specific enzymes were used to cleave GAGs from host cells or EBs, decreased infection rates were observed with C. pneumoniae and C. trachomatis serovar L2 in epithelial cells, but not in endothelial cells. Larger decreases in infection occurred with enzyme-treated EBs in GAG-deficient Chinese hamster ovary (CHO) cells. EBs grown in GAG-deficient CHO cells resulted in lower amounts of EB surface GAGs and decreased infectivity of epithelial cells. The results indicate that C. pneumoniae and C. trachomatis L2 EB-surface GAGs and host cell-surface GAGs are involved in invasion of bronchial epithelial cells but not of human umbilical vein endothelial cells.

Use of mandelic acid condensation polymer (SAMMA), a new antimicrobial contraceptive agent, for vaginal prophylaxis.

OBJECTIVE: To assess the contraceptive properties, antimicrobial activity, and safety of mandelic acid condensation polymer (SAMMA). DESIGN: Experimental study of SAMMA's in vitro and in vivo properties. SETTING: Academic research laboratories. PATIENT(S): Healthy volunteers for semen donation in an academic research environment. INTERVENTION(S): Inhibition of sperm function indicators, conception, sexually transmitted infection-causing pathogens (including HIV), and lactobacilli was evaluated. Safety indicators were studied. MAIN OUTCOME MEASURE(S): Quantitation of SAMMA's effect on microbial infectivity or multiplication and on sperm function in vitro; evaluation of contraceptive efficacy in vivo; assessment of safety in vitro and in vivo. RESULT(S): Mandelic acid condensation polymer is not cytotoxic toward lactobacilli, microbial host cells, and spermatozoa. The compound inhibits hyaluronidase and acrosin, induces sperm acrosomal loss, and is contraceptive in the rabbit model. Mandelic acid condensation polymer prevents infectivity of HIV and herpesviruses 1 and 2 and, to a lesser extent, of Chlamydia trachomatis. It inhibits the multiplication of Neisseria gonorrhoeae. Mandelic acid condensation polymer is not mutagenic, has low acute oral toxicity, and is safe in the rabbit vaginal irritation assay. CONCLUSION(S): Mandelic acid condensation polymer inhibits sperm function, is contraceptive, has broad-spectrum antimicrobial activity, and is highly safe. Further development as a microbicide is warranted.

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.

Preclinical evaluation of sodium cellulose sulfate (Ushercell) as a contraceptive antimicrobial agent.

The spread of sexually transmitted infections (STIs) and limited methods for control of pregnancies presents high risks to the reproductive health of women. Methods controlled by women and directed toward disease prevention and contraception are needed. We report on preclinical studies of the biological properties of sodium cellulose sulfate (Ushercell) currently being developed for use as a topical contraceptive antimicrobial agent. Ushercell was evaluated with tests designed to identify its contraceptive and antimicrobial properties. Ushercell inhibits hyaluronidase (reversible; IC50 = 1.7 mg/mL), impairs sperm penetration of cervical mucus (approximately 70% inhibition at 1 mg/mL), and acts as a stimulus for acrosomal loss (IC50 = 52 ng/mL). It prevents conception in rabbits when added to spermatozoa (approximately 95% inhibition at 1 mg/mL) or when vaginally applied (complete contraception by 45 mg) before insemination. However, up to 50 mg/mL, Ushercell does not irreversibly immobilize spermatozoa, suggesting that Ushercell is not cytotoxic. Ushercell has a broad spectrum of antimicrobial activity in vitro. Inhibited microbes include human immunodeficiency viruses (different laboratory strains and clinical isolates; IC50 values range from 3 to 78 microg/mL), herpes viruses, HSV-1 (IC50 = 59 ng/mL) and HSV-2 (lC50 = 24 ng/mL), Neisseria gonorrhoeae (IC50 = 2 microg/mL), and Chlamydia trachomatis (IC50 = 78 microg/mL). In contrast, Ushercell does not inhibit growth of beneficial vaginal bacteria, Lactobacillus gasseri, at 5 mg/mL. These results suggest that the antimicrobial effects of Ushercell are selective, and not likely mediated by nonspecific cytotoxic mechanisms. These data provide the basis for further clinical development of Ushercell as a vaginal agent to prevent unplanned pregnancy and STIs.