Vaginal bacterial flora activates rat peritoneal mast cells

Phenylacetic acid, an anti-vaginitis metabolite produced by the vaginal symbiotic bacterium Chryseobacterium gleum

The human microbiome contains genetic information that regulates metabolic processes in response to host health and disease. While acidic vaginal pH is maintained in normal conditions, the pH level increases in infectious vaginitis. We propose that this change in the vaginal environment triggers the biosynthesis of anti-vaginitis metabolites. Gene expression levels of Chryseobacterium gleum, a vaginal symbiotic bacterium, were found to be affected by pH changes. The distinctive difference in the metabolic profiles between two C. gleum cultures incubated under acidic and neutral pH conditions was suggested to be an anti-vaginitis molecule, which was identified as phenylacetic acid (PAA) by spectroscopic data analysis. The antimicrobial activity of PAA was evaluated in vitro, showing greater toxicity toward Gardnerella vaginalis and Candida albicans, two major vaginal pathogens, relative to commensal Lactobacillus spp. The activation of myeloperoxidase, prostaglandin E2, and nuclear factor-κB, and the expression of cyclooxygenase-2 were reduced by an intravaginal administration of PAA in the vaginitis mouse model. In addition, PAA displayed the downregulation of mast cell activation. Therefore, PAA was suggested to be a messenger molecule that mediates interactions between the human microbiome and vaginal health.

Diverse exocytic pathways for mast cell mediators

Mast cells play pivotal roles in innate and adaptive immunities but are also culprits in allergy, autoimmunity, and cardiovascular diseases. Mast cells respond to environmental changes by initiating regulated exocytosis/secretion of various biologically active compounds called mediators (e.g. proteases, amines, and cytokines). Many of these mediators are stored in granules/lysosomes and rely on intricate degranulation processes for release. Mast cell stabilizers (e.g. sodium cromoglicate), which prevent such degranulation processes, have therefore been clinically employed to treat asthma and allergic rhinitis. However, it has become increasingly clear that different mast cell diseases often involve multiple mediators that rely on overlapping but distinct mechanisms for release. This review illustrates existing evidence that highlights the diverse exocytic pathways in mast cells. We also discuss strategies to delineate these pathways so as to identify unique molecular components which could serve as new drug targets for more effective and specific treatments against mast cell-related diseases.

Mast Cells in Lung Homeostasis: Beyond Type I Hypersensitivity

Lungs are indispensable organs for the respiratory process, and maintaining their homeostasis is essential for human health and survival. However, during the lifetime of an individual, the lungs suffer countless insults that put at risk their delicate organization and function. Many cells of the immune system participate to maintain this equilibrium and to keep functional lungs. Among these cells, mast cells have recently attracted attention because of their ability to rapidly secrete many chemical and biological mediators that modulate different processes like inflammation, angiogenesis, cell proliferation, etc. In this review, we focus on recent advances in the understanding of the role that mast cells play in lung protection during infections, and of the relation of mast cell responses to type I hypersensitivity-associated pathologies. Furthermore, we discuss the potential role of mast cells during wound healing in the lung and its association with lung cancer, and how mast cells could be exploited as therapeutic targets in some diseases

The mast cell in innate and adaptive immunity

Mast cells (MCs) were once considered only as effector cells in pathogenic IgE- and IgG-mediated responses such as allergy. However, developments over the last 15 years have suggested that MCs have evolved in vertebrates as beneficial effector cells that are involved in the very first inflammatory responses generated during infection. This pro-inflammatory environment has been demonstrated to be important for initiating innate responses in many different models of infection and more recently, in the development of adaptive immunity as well. Interestingly this latter finding has led to the discovery that small MC-activating compounds can behave as adjuvants in vaccine formulations. Thus, our continued understanding of the MC in the context of infectious disease is likely to not only expand our scope of the MC in the normal processes of immunity, but provide new therapeutic targets to combat disease.

Lipoteichoic acids selectively stimulate rat mast cells to cysteinyl leukotriene generation and affect mast cell migration after tumor necrosis factor (TNF)-priming

It is well established that mast cells play a critical role in the host defense against bacteria. Upon stimulation with bacteria and their antigens, mast cells release various mediators and cytokines that promote the development of inflammation at the site of infection. In the present study, we examined the ability of lipoteichoic acids (LTAs), some of the major components of cell walls of most gram-positive bacteria, to stimulate mast cell degranulation and histamine release as well as to generate of cysteinyl leukotrienes (LTs). We also studied the influence of LTAs on mast cell migration. Experiments were done on rat peritoneal mast cells and LTA from Staphyloccocus aureus and LTA from Bacillus subtilis were used. We have stated that neither S. aureus LTA nor B. subtilis LTA used at a wide range of concentrations (from 10(-4) to 10(5)ng/mL) induced mast cell degranulation and histamine release. However, stimulation of mast cells with both LTAs resulted in generation and release of significant levels of LTs. We have also documented that none of the LTAs stimulated rat mast cell migration, even in the presence of laminin. IL-6 priming did not influence mast cell migration towards LTAs, whereas, pretreatment of mast cells with TNF caused time-dependent mast cell migration in response to LTAs stimulation. Pretreatment of mast cells with anti-TNFR1 antibodies completely inhibited LTA-induced migratory response of TNF-primed mast cells. Our results showed that LTAs might be among important bacterial antigens involved in mast cell activation during bacterial infections.

Differential vaginal expression of interleukin-1 system cytokines in the presence of Mycoplasma hominis and Ureaplasma urealyticum in pregnant women

OBJECTIVE: The genital mycoplasmas, Ureaplasma urealyticum and Mycoplasma hominis, are commonly identified in the vagina of healthy pregnant women. However, these microorganisms are the most common isolates from the amniotic fluids of women in preterm labor. The mechanisms responsible for vaginal colonization and ascent to the uterus remain undetermined. We evaluated the association between U. urealyticum and M. hominis vaginal colonization and the presence of pro-inflammatory and anti-inflammatory interleukin-1 system components in asymptomatic pregnant women of different ethnicities. METHODS: Vaginal specimens, obtained from 224 first trimester pregnant women, were assayed for interleukin-1beta (IL-1beta) and IL-1 receptor antagonist (IL-1ra) concentrations by ELISA. U. urealyticum and M. hominis vaginal colonization were identified by polymerase chain reaction (PCR). RESULTS: Vaginal colonization with M. hominis was identified in 37 (16.5%) women, and was more prevalent in black (18.9%) and Hispanic (20.9%) than in white (4.2%) women (p = 0.01). U. urealyticum was present in 84 (37.5%) women and there was no ethnic disparity in its detection. M. hominis colonization was associated with elevated median vaginal IL-1beta concentrations in both black women (p = 0.02) and Hispanic women (p = 0.04), and was unrelated to vaginal IL-1ra concentrations. In marked contrast, U. urealyticum colonization was associated with elevations in vaginal IL-1ra levels, but not with IL-1beta concentrations, in black women (p = 0.02) and Hispanic women (p < 0.0001) and marginally in white women (p = 0.06). CONCLUSION: M. hominis colonization in healthy pregnant women is associated with localized pro-inflammatory immune activation, while U. urealyticum colonization is associated with immune suppression.

Influence of cigarette smoking on vitamin E, vitamin A, beta-carotene and lycopene concentrations in human pre-ovulatory follicular fluid

Increasing evidence suggests that fat soluble vitamins and micronutrients have the potential for local modulation of follicular development. Cigarette smoking has been associated with accelerated follicular depletion and derangement of reproductive functions. The present study was initiated to investigate the impact of cigarette smoking on follicular and plasma concentrations of vitamin A, vitamin E, lycopene and beta-carotene. Samples were collected from 17 smokers and 43 non-smoking women undergoing assisted reproduction techniques. Assays were carried out by a reverse-phase high-pressure liquid chromatography (HPLC) method. Smokers had significantly (P < 0.05) lower levels of follicular fluid beta-carotene in comparison to non-smokers (0.02 +/- 0.02 vs. 0.09 +/- 0.02, respectively). No other significant influences on follicular and plasma concentrations were noted. Smokers showed a significantly (P < 0.05) lower fertilization rate in comparison to non-smokers, (55.9 % vs. 71.5 % , respectively). It is postulated that follicular depletion of the antioxidant beta-carotene occurs in response to oxidative stress imposed by cigarette smoke.