The Role of Lipopeptidophosphoglycan in the Immune Response to Entamoeba histolytica

The sensing of Pathogen Associated Molecular Patterns (PAMPs) by innate immune receptors, such as Toll-like receptors (TLRs), is the first step in the inflammatory response to pathogens. Entamoeba histolytica, the etiological agent of amebiasis, has a surface molecule with the characteristics of a PAMP. This molecule, which was termed lipopeptidophosphoglycan (LPPG), is recognized through TLR2 and TLR4 and leads to the release of cytokines from human monocytes, macrophages, and dendritic cells; LPPG-activated dendritic cells have increased expression of costimulatory molecules. LPPG activates NKT cells in a CD1d-dependent manner, and this interaction limits amebic liver abscess development. LPPG also induces antibody production, and anti-LPPG antibodies prevent disease development in animal models of amebiasis. Because LPPG is recognized by both the innate and the adaptive immune system (it is a “Pamptigen”), it may be a good candidate to develop a vaccine against E. histolytica infection and an effective adjuvant

Inflammatory Cytokine Profile Associated with Metabolic Syndrome in Adult Patients with Type 1 Diabetes

Objective. To compare the serum concentration of IL-6, IL-10, TNF, IL-8, resistin, and adiponectin in type 1 diabetic patients with and without metabolic syndrome and to determine the cut-off point of the estimated glucose disposal rate that accurately differentiated these groups. Design. We conducted a cross-sectional evaluation of all patients in our type 1 diabetes clinic from January 2012 to January 2013. Patients were considered to have metabolic syndrome when they fulfilled the joint statement criteria and were evaluated for clinical, biochemical, and immunological features. Methods. We determined serum IL-6, IL-8, IL-10, and TNF with flow cytometry and adiponectin and resistin concentrations with enzyme linked immunosorbent assay in patients with and without metabolic syndrome. We also compared estimated glucose disposal rate between groups. Results. We tested 140 patients. Forty-four percent fulfilled the metabolic syndrome criteria ( = 61), 54% had central obesity, 30% had hypertriglyceridemia, 29% had hypoalphalipoproteinemia, and 19% had hypertension. We observed that resistin concentrations were higher in patients with MS. Conclusion. We found a high prevalence of MS in Mexican patients with T1D. The increased level of resistin may be related to the increased fat mass and could be involved in the development of insulin resistance

Natural Killer T Cells Activated by a Lipopeptidophosphoglycan from Entamoeba histolytica Are Critically Important To Control Amebic Liver Abscess

The innate immune response is supposed to play an essential role in the control of amebic liver abscess (ALA), a severe form of invasive amoebiasis due to infection with the protozoan parasite Entamoeba histolytica. In a mouse model for the disease, we previously demonstrated that Jα18-/- mice, lacking invariant natural killer T (iNKT) cells, suffer from more severe abscess development. Here we show that the specific activation of iNKT cells using α-galactosylceramide (α-GalCer) induces a significant reduction in the sizes of ALA lesions, whereas CD1d−/− mice develop more severe abscesses. We identified a lipopeptidophosphoglycan from E. histolytica membranes (EhLPPG) as a possible natural NKT cell ligand and show that the purified phosphoinositol (PI) moiety of this molecule induces protective IFN-γ but not IL-4 production in NKT cells. The main component of EhLPPG responsible for NKT cell activation is a diacylated PI, (1-O-[(28∶0)-lyso-glycero-3-phosphatidyl-]2-O-(C16:0)-Ins). IFN-γ production by NKT cells requires the presence of CD1d and simultaneously TLR receptor signalling through MyD88 and secretion of IL-12. Similar to α-GalCer application, EhLPPG treatment significantly reduces the severity of ALA in ameba-infected mice. Our results suggest that EhLPPG is an amebic molecule that is important for the limitation of ALA development and may explain why the majority of E. histolytica-infected individuals do not develop amebic liver abscess

Salmonella Typhi Porins OmpC and OmpF Are Potent Adjuvants for T-Dependent and T-Independent Antigens

Several microbial components, such as bacterial DNA and flagellin, have been used as experimental vaccine adjuvants because of their inherent capacity to efficiently activate innate immune responses. Likewise, our previous work has shown that the major Salmonella Typhi (S. Typhi) outer membrane proteins OmpC and OmpF (porins) are highly immunogenic protective antigens that efficiently stimulate innate and adaptive immune responses in the absence of exogenous adjuvants. Moreover, S. Typhi porins induce the expression of costimulatory molecules on antigen-presenting cells through toll-like receptor canonical signaling pathways. However, the potential of major S. Typhi porins to be used as vaccine adjuvants remains unknown. Here, we evaluated the adjuvant properties of S. Typhi porins against a range of experimental and clinically relevant antigens. Co-immunization of S. Typhi porins with ovalbumin (OVA), an otherwise poorly immunogenic antigen, enhanced anti-OVA IgG titers, antibody class switching, and affinity maturation. This adjuvant effect was dependent on CD4+ T-cell cooperation and was associated with an increase in IFN-γ, IL-17A, and IL-2 production by OVA-specific CD4+ T cells. Furthermore, co-immunization of S. Typhi porins with an inactivated H1N1 2009 pandemic influenza virus experimental vaccine elicited higher hemagglutinating anti-influenza IgG titers, antibody class switching, and affinity maturation. Unexpectedly, co-administration of S. Typhi porins with purified, unconjugated Vi capsular polysaccharide vaccine (Vi CPS)—a T-independent antigen—induced higher IgG antibody titers and class switching. Together, our results suggest that S. Typhi porins OmpC and OmpF are versatile vaccine adjuvants, which could be used to enhance T-cell immune responses toward a Th1/Th17 profile, while improving antibody responses to otherwise poorly immunogenic T-dependent and T-independent antigens

Two Salmonella OmpC K(b)-Restricted Epitopes for CD8(+)-T-Cell Recognition

We report the identification of two peptides from Salmonella OmpC porin that can bind to major histocompatibility complex class I K(b) molecules and are targets of cytotoxic T lymphocytes from Salmonella-infected mice. These peptides are conserved in gram-negative bacterial porins and are the first Salmonella porin-specific epitopes described for possible CD8(+)-T-cell elimination of infected cells

Modulation of immune response by bacterial lipopolysaccharides

Lipopolysaccharide (LPS) is a molecule that is profusely found on the outer membrane of Gram-negative bacteria and is also a potent stimulator of the immune response. As the main molecule on the bacterial surface, is also the most biologically active. The immune response of the host is activated by the recognition of LPS through Toll-like receptor 4 (TLR4) and this receptor-ligand interaction is closely linked to LPS structure. Microorganisms have evolved systems to control the expression and structure of LPS, producing structural variants that are used for modulating the host immune responses during infection. Examples of this include Helicobacter pylori, Francisella tularensis, Chlamydia trachomatis and Salmonella spp. High concentrations of LPS can cause fever, increased heart rate and lead to septic shock and death. However, at relatively low concentrations some LPS are highly active immunomodulators, which can induce non-specific resistance to invading microorganisms. The elucidation of the molecular and cellular mechanisms involved in the recognition of LPS and its structural variants has been fundamental to understand inflammation and is currently a pivotal field of research to understand the innate immune response, inflammation, the complex host-pathogen relationship and has important implications for the rational development of new immunomodulators and adjuvants

Inflammatory Cytokine Profile Associated with Metabolic Syndrome in Adult Patients with Type 1 Diabetes

Objective. To compare the serum concentration of IL-6, IL-10, TNF, IL-8, resistin, and adiponectin in type 1 diabetic patients with and without metabolic syndrome and to determine the cut-off point of the estimated glucose disposal rate that accurately differentiated these groups. Design. We conducted a cross-sectional evaluation of all patients in our type 1 diabetes clinic from January 2012 to January 2013. Patients were considered to have metabolic syndrome when they fulfilled the joint statement criteria and were evaluated for clinical, biochemical, and immunological features. Methods. We determined serum IL-6, IL-8, IL-10, and TNF with flow cytometry and adiponectin and resistin concentrations with enzyme linked immunosorbent assay in patients with and without metabolic syndrome. We also compared estimated glucose disposal rate between groups. Results. We tested 140 patients. Forty-four percent fulfilled the metabolic syndrome criteria (n=61), 54% had central obesity, 30% had hypertriglyceridemia, 29% had hypoalphalipoproteinemia, and 19% had hypertension. We observed that resistin concentrations were higher in patients with MS. Conclusion. We found a high prevalence of MS in Mexican patients with T1D. The increased level of resistin may be related to the increased fat mass and could be involved in the development of insulin resistance