In vitro cytomodulatory and immunomodulatory effects of bovine colostrum whey protein hydrolysates

Bovine colostrum possesses biological compounds involved in the development of the newborn. Among them, the proteins have drawn attention as a source of bioactive peptides. This study shows the in vitro cytotoxic and immunostimulatory potential of two colostrum whey protein (CWP) hydrolysates obtained by in vitro digestion with pepsin and pancreatin. MTT cell viability, apoptosis induction, polymorphonuclear proliferation and phagocytic activity assays were performed. Treatment with the hydrolysates induced a significant decrease in the viability of MDA-MB-231 cell lines due to apoptosis and also a significant increase in the proliferation of blood mononuclear cells. It could also be observed that for the RM-1 and PC-3 prostate cancer cell lines and for the two times of exposure (24 and 48 h), the hydrolysate H1 is significantly more cytotoxic than CWP. These results showed the potential of bovine CWP and its hydrolysates for the treatment of chronic diseases such as cancer

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

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

The Antiproliferative Effect of Cyclodipeptides from Pseudomonas aeruginosa PAO1 on HeLa Cells Involves Inhibition of Phosphorylation of Akt and S6k Kinases

Pseudomonas aeruginosa PAO1, a potential pathogen of plants and animals, produces the cyclodipeptides cyclo(l-Pro-l-Tyr), cyclo(l-Pro-l-Phe), and cyclo(l-Pro-l-Val) (PAO1-CDPs), whose effects have been implicated in inhibition of human tumor cell line proliferation. Our purpose was to investigate in depth in the mechanisms of HeLa cell proliferation inhibition by the PAO1-CDPs. The results indicate that PAO1-CDPs, both purified individually and in mixtures, inhibited HeLa cell proliferation by arresting the cell cycle at the G0–G1 transition. The crude PAO1-CDPs mixture promoted cell death in HeLa cells in a dose-dependent manner, showing efficacy similar to that of isolated PAO1-CDPs (LD50 of 60–250 µM) and inducing apoptosis with EC50 between 0.6 and 3.0 µM. Moreover, PAO1-CDPs showed a higher proapoptotic activity (~103–105 fold) than their synthetic analogs did. Subsequently, the PAO1-CDPs affected mitochondrial membrane potential and induced apoptosis by caspase-9-dependent pathway. The mechanism of inhibition of cells proliferation in HeLa cells involves inhibition of phosphorylation of both Akt-S473 and S6k-T389 protein kinases, showing a cyclic behavior of their expression and phosphorylation in a time and concentration-dependent fashion. Taken together our findings indicate that PI3K–Akt–mTOR–S6k signaling pathway blockage is involved in the antiproliferative effect of the PAO1-CDPs

A Toll/IL-1R/resistance domain-containing thioredoxin regulates phagocytosis in <it>Entamoeba histolytica</it>

<p>Abstract</p> <p>Background</p> <p><it>Entamoeba histolytica</it> is a protozoan parasite that infects humans and causes amebiasis affecting developing countries. Phagocytosis of epithelial cells, erythrocytes, leucocytes, and commensal microbiota bacteria is a major pathogenic mechanism used by this parasite. A Toll/IL-1R/Resistance (TIR) domain-containing protein is required in phagocytosis in the social ameba <it>Dictyostelium discoideum</it>, an ameba closely related to <it>Entamoeba histolytica</it> in phylogeny. In insects and vertebrates, TIR domain-containing proteins regulate phagocytic and cell activation. Therefore, we investigated whether <it>E. histolytica</it> expresses TIR domain-containing molecules that may be involved in the phagocytosis of erythrocytes and bacteria.</p> <p>Methods</p> <p>Using <it>in silico</it> analysis we explored in <it>Entamoeba histolytica</it> databases for TIR domain containing sequences. After silencing TIR domain containing sequences in trophozoites by siRNA we evaluated phagocytosis of erythrocytes and bacteria.</p> <p>Results</p> <p>We identified an <it>E. histolytica</it> thioredoxin containing a TIR-like domain. The secondary and tertiary structure of this sequence exhibited structural similarity to TIR domain family. Thioredoxin transcripts silenced in <it>E. histolytica</it> trophozoites decreased erythrocytes and <it>E. coli</it> phagocytosis.</p> <p>Conclusion</p> <p>TIR domain-containing thioredoxin of <it>E. histolytica</it> could be an important element in erythrocytes and bacteria phagocytosis.</p