Sex Differences in the Response to Viral Infections: TLR8 and TLR9 Ligand Stimulation Induce Higher IL10 Production in Males

BACKGROUND: Susceptibility to viral infections as well as their severity are higher in men than in women. Heightened antiviral responses typical of women are effective for rapid virus clearance, but if excessively high or prolonged, can result in chronic/inflammatory pathologies. We investigated whether this variability could be in part attributable to differences in the response to the Toll-Like Receptors (TLR) more involved in the virus recognition. METHODS: Cytokine production by peripheral blood mononuclear cells (PBMCs) from male and female healthy donors after stimulation with Toll-like receptors (TLR) 3, 7, 8, 9 ligands or with viruses (influenza and Herpes-simplex-1) was evaluated. RESULTS: Compared to females, PBMCs from males produced not only lower amounts of IFN-α in response to TLR7 ligands but also higher amounts of the immunosuppressive cytokine IL10 after stimulation with TLR8 and TLR9 ligands or viruses. IL10 production after TLR9 ligands or HSV-1 stimulation was significantly related with plasma levels of sex hormones in both groups, whereas no correlation was found in cytokines produced following TLR7 and TLR8 stimulation. CONCLUSIONS: Given the role of an early production of IL10 by cells of innate immunity in modulating innate and adaptive immune response to viruses, we suggest that sex-related difference in its production following viral nucleic acid stimulation of TLRs may be involved in the sex-related variability in response to viral infections

Modulation of the immune and inflammatory responses by Plasmodium falciparum schizont extracts: role of myeloid dendritic cells in effector and regulatory functions of CD4+ lymphocytes.

The optimal immune response to malaria infection comprises rapid induction of inflammatory responses promptly counteracted by regulatory mechanisms to prevent immunopathology. To evaluate the role of dendritic cells (DC) in the balance of parasite-induced inflammatory/anti-inflammatory mechanisms, we studied the activity of monocyte-derived dendritic cells (MDDC), previously exposed to soluble extracts of Plasmodium falciparum-infected red blood cells (PfSE), in the differentiation of CD4 cells isolated from donors never exposed to malaria infection. We show that MDDC exposed to PfSE are extremely efficient to induce a contemporary differentiation of TH1 effector cells and T regulatory (Treg) cells in CD4 T cells even when exposed to low concentrations of parasitic extracts. Treg cells induced by MDDC infected with PfSE (MDDC-PfSE) produce transforming growth factor beta (TGF-β) and interleukin 10 (IL-10) and are endowed with strong suppressive properties. They also show phenotypical and functional peculiarities, such as the contemporary expression of markers of Treg and TH1 differentiation and higher sensitivity to TLR4 ligands both inducing an increasing production of suppressive cytokines. On the whole, our data indicate that MDDC exposed to PfSE orchestrate a well-balanced immune response with timely differentiation of TH1 and Treg cells in CD4 cells from nonimmune donors and suggest that, during the infection, the role of MDCC could be particularly relevant in low-parasitemia conditions

IL10 production by PBMCs following TLR9 stimulation or infection with HSV-1 and sex hormones-correlation.

<p>Panel A: IL10 production by PBMCs from males (n = 20) and females (n = 40) following stimulation with ODN 2006 as TLR9 ligand. Panel B: Spearman rank correlation analysis between IL10 production and DHS levels in the male group. Panel C: Spearman rank correlation analysis between IL10 production and E2 levels in the female group. Panel D: IL10 production by PBMCs from males (n = 20, mean age, years 47±14, range 22–62, females in post menopausal age (n = 20, mean age 59±7, range 48–71) and females in reproductive age (n = 20, mean age 33±9 range 25–54), following stimulation with CpG-ODN 2006 as TLR9 ligand. Panel E: IL10 production by PBMCs from males, females in post-menopausal age (n = 20, mean age 59±7, range 48–71), and females in reproductive age (n = 20, mean age 33±9, range 25–54) following infection with HSV-1. Data of IL10 production are calculated as mean IL10 production in stimulated cultures – mean IL10 production of unstimulated cultures. Data are presented as box-and-whisker plots, with boxes extend from the 25^th percentile to the 75^th percentile, with a horizontal line at the median while whiskers extend to the lowest and highest data point. Black stars indicate mean values. Statistical analysis was performed by two-tailed non-parametric Mann-Whitney test. Significance levels were fixed at p<0.05. Analysis of linear trends was performed using Spearman rank correlation. The level of statistical significance was set at p<0.05. IL10 concentrations in unstimulated or mock-infected cultures ranged between 2 and 68 pg/ml (mean 28.3±1.6). No significant differences between the groups were detected.</p

IFN-α production by PBMCs following TLR stimulation or infection with influenza virus or HSV-1.

<p>Panel A: PBMCs from males (n = 20) or from females (n = 40) were stimulated with Imiquimod as TLR7 ligand, ssRNA40 as TLR8 ligand or infected with influenza virus (PR8). Panel B: PBMC from males or females were stimulated with Poly(I:C) as TLR3 ligand, ODN 2006 as TLR9 ligand or infected with HSV-1. IFN-α was measured in culture supernatants by immunoplex array. Data for each donor are calculated as mean IFN-α production in stimulated cultures – mean IFN-α production of unstimulated cultures. Data are presented as box-and-whisker plots, with boxes extend from the 25^th percentile to the 75^th percentile, with a horizontal line at the median while whiskers extend to the lowest and highest data point. Black stars indicate mean values. Statistical analysis was performed by two-tailed non parametric Mann-Whitney test. Significance levels were fixed at p<0.05. IFN-α concentrations in unstimulated or mock-infected cultures ranged between 2 and 30 pg/ml (mean 9.2±1.4). No significant differences between the groups were detected.</p

IL10 production by PBMCs following TLR8, TLR7, TLR3 stimulation or infection with influenza virus.

<p>PBMCs from males (n = 20) or from females (n = 40) were stimulated with ssRNA40 as TLR8 ligand, Imiquimod as TLR7 ligand, Poly(I:C) as TLR3 ligand (Panel A) or infected with PR8 influenza virus (Panel B). IL10 was measured in culture supernatants by immunoplex array. Data for each donor are calculated as mean IL10 production from stimulated cultures – mean IL10 production of unstimulated cultures. Data are presented as box-and-whisker plots, with boxes extend from the 25^th percentile to the 75^th percentile, with a horizontal line at the median while whiskers extend to the lowest and highest data point. Black stars indicate mean values. IL10 concentrations in unstimulated or Mock-infected cultures ranged between 2 and 68 pg/ml (mean 28.3±1.6). Statistical analysis was performed by two-tailed non parametric Mann-Whitney test. Significance levels were fixed at p<0.05.</p