Glycerol monolaurate prevents mucosal SIV transmission

Although there has been great progress in treating human immunodeficiency virus 1 (HIV-1) infection1, preventing transmission has thus far proven an elusive goal. Indeed, recent trials of a candidate vaccine and microbicide have been disappointing, both for want of efficacy and concerns about increased rates of transmission2–4. Nonetheless, studies of vaginal transmission in the simian immunodeficiency virus (SIV)–rhesus macaque (Macacca mulatta) model point to opportunities at the earliest stages of infection in which a vaccine or microbicide might be protective, by limiting the expansion of infected founder populations at the portal of entry5,6. Here we show in this SIV–macaque model, that an outside-in endocervical mucosal signalling system, involving MIP-3α (also known as CCL20), plasmacytoid dendritic cells and CCR5+ cell-attracting chemokines produced by these cells, in combination with the innate immune and inflammatory responses to infection in both cervix and vagina, recruits CD4+ T cells to fuel this obligate expansion. We then show that glycerol monolaurate—a widely used antimicrobial compound7with inhibitory activity against the production of MIP-3α and other proinflammatory cytokines8—can inhibit mucosal signalling and the innate and inflammatory response to HIV-1 and SIV in vitro, and in vivo it can protect rhesus macaques from acute infection despite repeated intra-vaginal exposure to high doses of SIV. This new approach, plausibly linked to interfering with innate host responses that recruit the target cells necessary to establish systemic infection, opens a promising new avenue for the development of effective interventions to blockHIV-1 mucosal transmission

Glycerol monolaurate prevents mucosal SIV transmission

Although there has been great progress in treating human immunodeficiency virus 1 (HIV-1) infection1, preventing transmission has thus far proven an elusive goal. Indeed, recent trials of a candidate vaccine and microbicide have been disappointing, both for want of efficacy and concerns about increased rates of transmission2–4. Nonetheless, studies of vaginal transmission in the simian immunodeficiency virus (SIV)–rhesus macaque (Macacca mulatta) model point to opportunities at the earliest stages of infection in which a vaccine or microbicide might be protective, by limiting the expansion of infected founder populations at the portal of entry5,6. Here we show in this SIV–macaque model, that an outside-in endocervical mucosal signalling system, involving MIP-3α (also known as CCL20), plasmacytoid dendritic cells and CCR5+ cell-attracting chemokines produced by these cells, in combination with the innate immune and inflammatory responses to infection in both cervix and vagina, recruits CD4+ T cells to fuel this obligate expansion. We then show that glycerol monolaurate—a widely used antimicrobial compound7with inhibitory activity against the production of MIP-3α and other proinflammatory cytokines8—can inhibit mucosal signalling and the innate and inflammatory response to HIV-1 and SIV in vitro, and in vivo it can protect rhesus macaques from acute infection despite repeated intra-vaginal exposure to high doses of SIV. This new approach, plausibly linked to interfering with innate host responses that recruit the target cells necessary to establish systemic infection, opens a promising new avenue for the development of effective interventions to blockHIV-1 mucosal transmission

Morphine Attenuates Apically-Directed Cytokine Secretion from Intestinal Epithelial Cells in Response to Enteric Pathogens

Epithelial cells represent the first line of host immune defense at mucosal surfaces. Although opioids appear to increase host susceptibility to infection, no studies have examined opioid effects on epithelial immune functions. We tested the hypothesis that morphine alters vectorial cytokine secretion from intestinal epithelial cell (IPEC-J2) monolayers in response to enteropathogens. Both entero-adherent Escherichia coli O157:H7 and entero-invasive Salmonella enterica serovar Typhimurium increased apically-directed IL-6 secretion and bi-directional IL-8 secretion from epithelial monolayers, but only IL-6 secretion evoked by E. coli was reduced by morphine acting through a naloxone-sensitive mechanism. Moreover, the respective type 4 and 5 Toll-like receptor agonists, lipopolysaccharide and flagellin, increased IL-8 secretion from monolayers, which was also attenuated by morphine pretreatment. These results suggest that morphine decreases cytokine secretion and potentially phagocyte migration and activation directed towards the mucosal surface; actions that could increase host susceptibility to some enteric infections

<i>E. faecalis</i> MN1 inhibits the IL-8 response of HVECs to the staphylococcal superantigen TSST-1.

<p><i>E. faecalis</i> MN1 (1×10⁷ CFU) was incubated with HVECs in the absence and presence of TSST-1 (100 µg/ml) for 6 h. Cell culture supernates were collected and IL-8 was measured by ELISA. *Significantly higher than all other conditions and #significantly lower than medium only control by one-way ANOVA [<i>F</i>(3,29) = 251.2, <i>p</i><0.0001] and Tukey's post-hoc test. N = 3–6 replicates.</p

<i>E. faecalis</i> MN1 low molecular weight fraction inhibits TSST-1-induced T cell proliferation.

<p><i>E. faecalis</i> MN1 supernate was treated with ethanol (80% final concentration), insoluble material was removed by centrifugation, soluble material (referred to as the low molecular weight fraction) was concentrated 480 times relative to the original culture fluid, and dilutions incubated with human PBMCs and TSST-1 (1 µg/well) in a superantigenicity assay to assess the ability of secreted factors to inhibit TSST-1-induced T cell proliferation. The PBMC control shows the average CPMs for PBMCs alone and TSST-1 shows the average CPMs for TSST-1 alone. Treatments 48× to 0.0048× were significantly different from TSST-1 alone by individual Student's <i>t</i> tests (*p<0.001). Three independent wells for each treatment were assayed for cell viability, and viability in all cases was >95%.</p

<i>E. faecalis</i> MN1 supernate inhibits TSST-1-induced T cell proliferation.

<p><i>E. faecalis</i> MN1 supernate was incubated with human PBMCs and TSST-1 (1 µg/well) in a superantigenicity assay to assess the ability of secreted factors to inhibit TSST-1-induced T cell proliferation. The two highest doses of supernate (20 and 2 µl per well) significantly inhibited T cell proliferation due to TSST-1 by individual Student's <i>t</i> tests (*p<0.001). The 0 µl control shows the average CPMs for PBMCs with and without TSST-1.</p

<i>E. faecalis</i> MN1 makes low levels of hydrogen peroxide.

<p><i>E. faecalis</i> MN1 and <i>L. crispatus</i> ATCC 33197 were grown overnight in KSFM tissue culture medium. Hydrogen peroxide production was measured using a H₂O₂ colorimetric detection assay kit.</p

<i>E. faecalis</i> MN1 inhibits the IL-8 response of HVECs to vaginal pathogens.

<p>HVECs were incubated with <i>C. albicans</i> (2×10⁵ CFU/well), <i>G. vaginalis</i> (2×10⁶ CFU/well), or <i>N. gonorrhoeae</i> (2×10⁶ CFU/well) in the absence or presence of <i>E. faecalis</i> MN1 (8×10⁶ CFU/well) for 6 h and IL-8 production was measured by ELISA. *In each case, <i>E. faecalis</i> MN1 significantly inhibited the IL-8 response of the cells to the pathogen by individual Student's <i>t</i> tests (p<0.01). N = 3 replicates.</p