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

“Efecto de la restricción calórica en la activación de la microglía en ratones BALB/c”

La microglía es la célula inmunocompetente del sistema nervioso central, su función es preservar la homeostasis y funcionamiento adecuado del mismo; sin embargo, en un ambiente de inflamación crónica se le ha relacionado con daño al tejido nervioso. La restricción calórica (RC) es un método dietético empleado para retrasar la aparición de enfermedades crónico-degenerativas y la inflamación crónica, además de mejorar la efectividad de las funciones leucocitarias en la homeostasis del organismo. El objetivo de este estudio fue analizar el efecto que tiene la restricción calórica en las funciones de la microglía. Se obtuvieron células mononucleares purificadas de cerebro y médula espinal de ratones BALB/c clasificados como ad libitum (AL), con restricción calórica (RC; 30% de reducción en la ingestión de alimentos) o con dieta hiper-energética (HE; suplementado con sacarosa al 40% en el agua para beber), durante 4 semanas. Las células obtenidas fueron analizadas por citometría de flujo, empleando anticuerpos para los marcadores CD45, CD11b, MHC-I, MHC-II, CD80 y CD86. El consumo de alimento, agua y peso corporal fueron monitoreados a lo largo del estudio. Los resultados muestran que los ratones con RC ingirieron una mayor cantidad de líquido, menor cantidad de alimento y ganaron menos peso corporal que los ratones del grupo AL. No se observaron diferencias en estos parámetros entre los grupos HE y AL. La RC aumentó significativamente la expresión de MHC-I en las células de la microglía en comparación con los grupos AL y HE, junto con una tendencia para el grupo RC a expresar menor CD80 y mayor CD86. Nuestros resultados sugieren que la microglía en animales bajo RC presenta un fenotipo que puede favorecer la tolerancia inmunológica al incrementar la presentación de antígenos propios en ausencia de co-estimulación, lo que puede favorecer la homeostasis del tejido nervioso en condiciones normales

Description of CD8+ Regulatory T Lymphocytes and Their Specific Intervention in Graft-versus-Host and Infectious Diseases, Autoimmunity, and Cancer

Gershon and Kondo described CD8+ Treg lymphocytes as the first ones with regulating activity due to their tolerance ability to foreign antigens and their capacity to inhibit the proliferation of other lymphocytes. Regardless, CD8+ Treg lymphocytes have not been fully described—unlike CD4+ Treg lymphocytes—because of their low numbers in blood and the lack of specific and accurate population markers. Still, these lymphocytes have been studied for the past 30 years, even after finding difficulties during investigations. As a result, studies have identified markers that define their subpopulations. This review is focused on the expression of cell membrane markers as CD25, CD122, CD103, CTLA-4, CD39, CD73, LAG-3, and FasL as well as soluble molecules such as FoxP3, IFN-γ, IL-10, TGF-β, IL-34, and IL-35, in addition to the lack of expression of cell activation markers such as CD28, CD127 CD45RC, and CD49d. This work also underlines the importance of identifying some of these markers in infections with several pathogens, autoimmunity, cancer, and graft-versus-host disease as a strategy in their prevention, monitoring, and cure

Oral Immunization of Mice with Gamma-Irradiated <i>Brucella neotomae</i> Induces Protection against Intraperitoneal and Intranasal Challenge with Virulent <i>B. abortus</i> 2308

<div><p><i>Brucella</i> spp. are Gram-negative, facultative intracellular coccobacilli that cause one of the most frequently encountered zoonosis worldwide. Humans naturally acquire infection through consumption of contaminated dairy and meat products and through direct exposure to aborted animal tissues and fluids. No vaccine against brucellosis is available for use in humans. In this study, we tested the ability of orally inoculated gamma-irradiated <i>B. neotomae</i> and <i>B. abortus</i> RB51 in a prime-boost immunization approach to induce antigen-specific humoral and cell mediated immunity and protection against challenge with virulent <i>B. abortus</i> 2308. Heterologous prime-boost vaccination with <i>B. abortus</i> RB51 and <i>B. neotomae</i> and homologous prime-boost vaccination of mice with <i>B. neotomae</i> led to the production of serum and mucosal antibodies specific to the smooth LPS. The elicited serum antibodies included the isotypes of IgM, IgG1, IgG2a, IgG2b and IgG3. All oral vaccination regimens induced antigen-specific CD4⁺ and CD8⁺ T cells capable of secreting IFN-γ and TNF-α. Upon intra-peritoneal challenge, mice vaccinated with <i>B. neotomae</i> showed the highest level of resistance against virulent <i>B. abortus</i> 2308 colonization in spleen and liver. Experiments with different doses of <i>B. neotomae</i> showed that all tested doses of 10⁹, 10¹⁰ and 10¹¹ CFU-equivalent conferred significant protection against the intra-peritoneal challenge. However, a dose of 10¹¹ CFU-equivalent of <i>B. neotomae</i> was required for affording protection against intranasal challenge as shown by the reduced bacterial colonization in spleens and lungs. Taken together, these results demonstrate the feasibility of using gamma-irradiated <i>B. neotomae</i> as an effective and safe oral vaccine to induce protection against respiratory and systemic infections with virulent <i>Brucella</i>.</p></div

ELISA detection of IgG, IgM, IgA antibodies specific to <i>B. neotomae</i> LPS (A), and RB51 total antigens (B) in the intestinal secretions of mice vaccinated with gamma-irradiated RB51, <b><i>B. neotomae</i></b>, RB51/<i>B. neotomae</i> and <b><i>B. neotomae</i></b>/RB51, or inoculated with saline.

<p>Intestinal secretions were collected at 2 weeks after the last booster vaccination, were diluted 1 in 10 and assayed for the presence of LPS-specific (A) and RB51-specific (B) antibodies. Results are shown as mean ± standard deviation (<i>n</i> = 4) of absorbance at 450 nm of the color developed. *Significantly different from the corresponding saline group (<i>P</i><0.05). ^ff Significantly different from the corresponding vaccination groups (<i>P</i><0.05).</p

Protection against intra-nasal challenge with virulent <i>B. abortus</i> 2308 following oral homologous prime-boost immunization of mice with multiple vaccine doses of gamma-irradiated <i>B. neotomae</i>.

a<p>Units of protection were calculated by subtracting the mean log₁₀ CFU for a vaccinated group from the mean log₁₀ CFU of the corresponding saline control group.</p><p>*Significantly different from the corresponding saline group (<i>P</i><0.05).</p><p>**Not significantly different from the corresponding saline group (<i>P</i>>0.05).</p><p>Protection against intra-nasal challenge with virulent <i>B. abortus</i> 2308 following oral homologous prime-boost immunization of mice with multiple vaccine doses of gamma-irradiated <i>B. neotomae</i>.</p

Flow cytometric analysis showing the percentage of interferon-γ secreting (A), and tumor necrosis factor-α secreting (B) CD4⁺ and CD8⁺ T cells in the spleens of BALB/c mice immunized with gamma-irradiated RB51, <i>B. neotomae</i>, RB51/<i>B. neotomae</i> and <i>B. neotomae</i>/RB51, or inoculated with saline following in vitro stimulation with media (unstimulated), gamma-irradiated <i>B. neotomae</i> and gamma-irradiated RB51.

<p>*Significantly different from the corresponding unstimulated control (<i>P</i><0.05). ^ff Significantly different from the corresponding vaccination groups with irradiated RB51 stimulation (<i>P</i><0.05).</p

Immunization schedule.

<p>Immunization schedule.</p

Protection against intra-peritoneal challenge with virulent <i>B. abortus</i> 2308 following oral homologous prime-boost immunization of mice with multiple vaccine doses of gamma-irradiated <i>B. neotomae</i>.

a<p>Units of protection were calculated by subtracting the mean log₁₀ CFU for a vaccinated group from the mean log₁₀ CFU of the corresponding saline control group.</p><p>*Significantly different from the corresponding saline group (<i>P</i><0.05).</p><p>**Not significantly different from the corresponding saline group (<i>P</i>>0.05).</p><p>Protection against intra-peritoneal challenge with virulent <i>B. abortus</i> 2308 following oral homologous prime-boost immunization of mice with multiple vaccine doses of gamma-irradiated <i>B. neotomae</i>.</p