The Unfolded Protein Response Mediator PERK Governs Myeloid Cell-Driven Immunosuppression in Tumors through Inhibition of STING Signaling.

The primary mechanisms supporting immunoregulatory polarization of myeloid cells upon infiltration into tumors remain largely unexplored. Elucidation of these signals could enable better strategies to restore protective anti-tumor immunity. Here, we investigated the role of the intrinsic activation of the PKR-like endoplasmic reticulum (ER) kinase (PERK) in the immunoinhibitory actions of tumor-associated myeloid-derived suppressor cells (tumor-MDSCs). PERK signaling increased in tumor-MDSCs, and its deletion transformed MDSCs into myeloid cells that activated CD8+ T cell-mediated immunity against cancer. Tumor-MDSCs lacking PERK exhibited disrupted NRF2-driven antioxidant capacity and impaired mitochondrial respiratory homeostasis. Moreover, reduced NRF2 signaling in PERK-deficient MDSCs elicited cytosolic mitochondrial DNA elevation and, consequently, STING-dependent expression of anti-tumor type I interferon. Reactivation of NRF2 signaling, conditional deletion of STING, or blockade of type I interferon receptor I restored the immunoinhibitory potential of PERK-ablated MDSCs. Our findings demonstrate the pivotal role of PERK in tumor-MDSC functionality and unveil strategies to reprogram immunosuppressive myelopoiesis in tumors to boost cancer immunotherapy.

Polyphenol-rich extract induces apoptosis with immunogenic markers in melanoma cells through the ER stress-associated kinase PERK.

Polyphenols elicit antitumor activities, in part, through the induction of anti- or pro-oxidant effects in cancer cells which promote priming of protective anti-tumor immunity. We recently characterized a polyphenol-rich extract from Caesalpinia spinosa (P2Et) that stimulates in vivo antitumor responses against breast and melanoma tumor models via the promotion of immunogenic cancer cell death (ICD). However, the primary mediators whereby P2Et promotes ICD remained unknown. Here, we sought to elucidate the role that severe endoplasmic reticulum (ER) stress plays in mediating P2Et-induced apoptosis and ICD in murine melanoma cells. Our findings demonstrate a substantial selective induction of specific ER-stress mediators in B16-F10 melanoma cells treated with P2Et. While knockout of the ER stress-associated PKR-like ER kinase (PERK) prevented induction of apoptosis and expression of ICD markers in P2Et-treated cells, deletion of X-box binding protein 1 (Xbp1) did not. P2Et-driven activation of PERK in melanoma cells was found to promote ER-calcium release, disrupt mitochondrial membrane potential, and trigger upregulation of ICD drivers, surface calreticulin expression, and extracellular release of ATP and HMGB1. Notably, calcium release inhibition, but not targeting of PERK-driven integrated stress responses, prevented P2Et-induced apoptosis. Collectively, these results underline the central role of PERK-directed calcium release in mediating the antitumor and immunogenic actions of P2Et in melanoma cells.

Publisher Correction: ER stress-induced mediator C/EBP homologous protein thwarts effector T cell activity in tumors through T-bet repression.

An amendment to this paper has been published and can be accessed via a link at the top of the paper.

AMPK Alpha-1 Intrinsically Regulates the Function and Differentiation of Tumor Myeloid-Derived Suppressor Cells.

Myeloid-derived suppressor cells (MDSC) represent a primary mechanism of immune evasion in tumors and have emerged as a major obstacle for cancer immunotherapy. The immunoinhibitory activity of MDSC is tightly regulated by the tumor microenvironment and occurs through mechanistic mediators that remain unclear. Here, we elucidated the intrinsic interaction between the expression of AMP-activated protein kinase alpha (AMPKα) and the immunoregulatory activity of MDSC in tumors. AMPKα signaling was increased in tumor-MDSC from tumor-bearing mice and patients with ovarian cancer. Transcription of the Ampkα1-coding gene, Prkaa1, in tumor-MDSC was induced by cancer cell-derived granulocyte-monocyte colony-stimulating factor (GM-CSF) and occurred in a Stat5-dependent manner. Conditional deletion of Prkaa1 in myeloid cells, or therapeutic inhibition of Ampkα in tumor-bearing mice, delayed tumor growth, inhibited the immunosuppressive potential of MDSC, triggered antitumor CD8+ T-cell immunity, and boosted the efficacy of T-cell immunotherapy. Complementarily, therapeutic stimulation of AMPKα signaling intrinsically promoted MDSC immunoregulatory activity. In addition, Prkaa1 deletion antagonized the differentiation of monocytic-MDSC (M-MDSC) to macrophages and re-routed M-MDSC, but not granulocytic-MDSC (PMN-MDSC), into cells that elicited direct antitumor cytotoxic effects through nitric oxide synthase 2-mediated actions. Thus, our results demonstrate the primary role of AMPKα1 in the immunosuppressive effects induced by tumor-MDSC and support the therapeutic use of AMPK inhibitors to overcome MDSC-induced T-cell dysfunction in cancer. SIGNIFICANCE: AMPKα1 regulates the immunosuppressive activity and differentiation of tumor-MDSC, suggesting AMPK inhibition as a potential therapeutic strategy to restore protective myelopoiesis in cancer.

Corrigendum: Adenosine A2A Receptor Stimulation Inhibits TCR-Induced Notch1 Activation in CD8+T-Cells.

[This corrects the article DOI: 10.3389/fimmu.2019.00162.].

ER stress-induced mediator C/EBP homologous protein thwarts effector T cell activity in tumors through T-bet repression.

Understanding the intrinsic mediators that render CD8+ T cells dysfunctional in the tumor microenvironment is a requirement to develop more effective cancer immunotherapies. Here, we report that C/EBP homologous protein (Chop), a downstream sensor of severe endoplasmic reticulum (ER) stress, is a major negative regulator of the effector function of tumor-reactive CD8+ T cells. Chop expression is increased in tumor-infiltrating CD8+ T cells, which correlates with poor clinical outcome in ovarian cancer patients. Deletion of Chop in T cells improves spontaneous antitumor CD8+ T cell immunity and boosts the efficacy of T cell-based immunotherapy. Mechanistically, Chop in CD8+ T cells is elevated primarily through the ER stress-associated kinase Perk and a subsequent induction of Atf4; and directly represses the expression of T-bet, a master regulator of effector T cell function. These findings demonstrate the primary role of Chop in tumor-induced CD8+ T cell dysfunction and the therapeutic potential of blocking Chop or ER stress to unleash T cell-mediated antitumor immunity.

Adenosine A2A Receptor Stimulation Inhibits TCR-Induced Notch1 Activation in CD8+T-Cells.

Notch receptors signaling is required for optimal T-cell activation and function. T-cell receptor (TCR) engagement can activate Notch receptors in T-cells in a ligand-independent fashion. In this study, we examined the role of adenosine A2A receptor (A2AR) signaling pathway in regulating the activity of Notch1 induced by TCR stimulation in CD8+T-cells. A selective A2AR agonist decreased Notch1 protein expression and Notch1 cleavage, and reduced transcripts of Notch1-target genes Hes1 and Myc in activated CD8+T-cells. Inhibition of TCR-induced Notch1 expression by an A2AR agonist was accompanied by increased cAMP concentration and mimicked by forskolin. This effect was associated with reduced IFN-γ and granzyme B production. The effect of an A2AR agonist was abrogated by a selective A2AR antagonist and absent in CD8+T-cells harvested from A2AR-/- mice. Stimulation of A2AR reduced Notch1 receptor levels by inhibiting upstream TCR signals, including ZAP70 phosphorylation, in turn impairing the generation of the active Notch1 intracellular domain (N1ICD). Direct activation of PKC with PMA and ionomycin bypassed A2AR-induced Notch1 inhibition. Overexpression of N1ICD in CD8+T-cells prevented the suppressive effects of an A2AR agonist on proliferation and cytokine release during activation. Our results identify the A2AR signaling pathway as an important regulator of TCR-induced Notch1 receptor activation in CD8+T-cells, and Notch as an important target of the immune suppressive effects of A2AR. We propose a mechanism whereby A2AR impairs CD8 T-cells function through inhibition of Notch1 receptor activation.

Anti-Jagged Immunotherapy Inhibits MDSCs and Overcomes Tumor-Induced Tolerance.

Myeloid-derived suppressor cells (MDSC) are a major obstacle to promising forms of cancer immunotherapy, but tools to broadly limit their immunoregulatory effects remain lacking. In this study, we assessed the therapeutic effect of the humanized anti-Jagged1/2-blocking antibody CTX014 on MDSC-mediated T-cell suppression in tumor-bearing mice. CTX014 decreased tumor growth, affected the accumulation and tolerogenic activity of MDSCs in tumors, and inhibited the expression of immunosuppressive factors arginase I and iNOS. Consequently, anti-Jagged therapy overcame tumor-induced T-cell tolerance, increased the infiltration of reactive CD8+ T cells into tumors, and enhanced the efficacy of T-cell-based immunotherapy. Depletion of MDSC-like cells restored tumor growth in mice treated with anti-Jagged, whereas coinjection of MDSC-like cells from anti-Jagged-treated mice with cancer cells delayed tumor growth. Jagged1/2 was induced in MDSCs by tumor-derived factors via NFkB-p65 signaling, and conditional deletion of NFkB-p65 blocked MDSC function. Collectively, our results offer a preclinical proof of concept for the use of anti-Jagged1/2 to reprogram MDSC-mediated T-cell suppression in tumors, with implications to broadly improve the efficacy of cancer therapy. Cancer Res; 77(20); 5628-38. ©2017 AACR.

T cells conditioned with MDSC show an increased anti-tumor activity after adoptive T cell based immunotherapy.

The success of adoptive T cell-based immunotherapy (ACT) in cancer is limited in part by the accumulation of myeloid-derived suppressor cells (MDSC), which block several T cell functions, including T cell proliferation and the expression of various cytotoxic mediators. Paradoxically, the inhibition of CD8+ T cell differentiation into cytotoxic populations increased their efficacy after ACT into tumor-bearing hosts. Therefore, we aimed to test the impact of conditioning CD8+ T cells with MDSC on their differentiation potential and ACT efficacy. Our results indicate that MDSC impaired the progression of CD8+ T cells into effector populations, without altering their activation status, production of IL-2, or signaling through the T cell receptor. In addition, culture of CD8+ T cells with MDSC resulted in an increased ACT anti-tumor efficacy, which correlated with a higher frequency of the transferred T cells and elevated IFNγ production. Interestingly, activated CD62L+ CD8+ T cells were responsible for the enhanced anti-tumor activity showed by MDSC-exposed T cells. Additional results showed a decreased protein synthesis rate and lower activity of the mammalian/mechanistic target of rapamycin (mTOR) in T cells conditioned with MDSC. Silencing of the negative mTOR regulator tuberous sclerosis complex-2 in T cells co-cultured with MDSC restored mTOR activity, but resulted in T cell apoptosis. These results indicate that conditioning of T cells with MDSC induces stress survival pathways mediated by a blunted mTOR signaling, which regulated T cell differentiation and ACT efficacy. Continuation of this research will enable the development of better strategies to increase ACT responses in cancer.

l-Arginine depletion blunts antitumor T-cell responses by inducing myeloid-derived suppressor cells.

Enzymatic depletion of the nonessential amino acid l-Arginine (l-Arg) in patients with cancer by the administration of a pegylated form of the catabolic enzyme arginase I (peg-Arg I) has shown some promise as a therapeutic approach. However, l-Arg deprivation also suppresses T-cell responses in tumors. In this study, we sought to reconcile these observations by conducting a detailed analysis of the effects of peg-Arg I on normal T cells. Strikingly, we found that peg-Arg I blocked proliferation and cell-cycle progression in normal activated T cells without triggering apoptosis or blunting T-cell activation. These effects were associated with an inhibition of aerobic glycolysis in activated T cells, but not with significant alterations in mitochondrial oxidative respiration, which thereby regulated survival of T cells exposed to peg-Arg I. Further mechanistic investigations showed that the addition of citrulline, a metabolic precursor for l-Arg, rescued the antiproliferative effects of peg-Arg I on T cells in vitro. Moreover, serum levels of citrulline increased after in vivo administration of peg-Arg I. In support of the hypothesis that peg-Arg I acted indirectly to block T-cell responses in vivo, peg-Arg I inhibited T-cell proliferation in mice by inducing accumulation of myeloid-derived suppressor cells (MDSC). MDSC induction by peg-Arg I occurred through the general control nonrepressed-2 eIF2α kinase. Moreover, we found that peg-Arg I enhanced the growth of tumors in mice in a manner that correlated with higher MDSC numbers. Taken together, our results highlight the risks of the l-Arg-depleting therapy for cancer treatment and suggest a need for cotargeting MDSC in such therapeutic settings.

The stress-response sensor chop regulates the function and accumulation of myeloid-derived suppressor cells in tumors.

Adaptation of malignant cells to the hostile milieu present in tumors is an important determinant of their survival and growth. However, the interaction between tumor-linked stress and antitumor immunity remains poorly characterized. Here, we show the critical role of the cellular stress sensor C/EBP-homologous protein (Chop) in the accumulation and immune inhibitory activity of tumor-infiltrating myeloid-derived suppressor cells (MDSCs). MDSCs lacking Chop had decreased immune-regulatory functions and showed the ability to prime T cell function and induce antitumor responses. Chop expression in MDSCs was induced by tumor-linked reactive oxygen and nitrogen species and regulated by the activating-transcription factor-4. Chop-deficient MDSCs displayed reduced signaling through CCAAT/enhancer-binding protein-ß, leading to a decreased production of interleukin-6 (IL-6) and low expression of phospho-STAT3. IL-6 overexpression restored immune-suppressive activity of Chop-deficient MDSCs. These findings suggest the role of Chop in tumor-induced tolerance and the therapeutic potential of targeting Chop in MDSCs for cancer immunotherapy.

Rescue of notch-1 signaling in antigen-specific CD8+ T cells overcomes tumor-induced T-cell suppression and enhances immunotherapy in cancer.

An impaired antitumor immunity is found in patients with cancer and represents a major obstacle in the successful development of different forms of immunotherapy. Signaling through Notch receptors regulates the differentiation and function of many cell types, including immune cells. However, the effect of Notch in CD8(+) T-cell responses in tumors remains unclear. Thus, we aimed to determine the role of Notch signaling in CD8(+) T cells in the induction of tumor-induced suppression. Our results using conditional knockout mice show that Notch-1 and Notch-2 were critical for the proliferation and IFNγ production of activated CD8(+) T cells and were significantly decreased in tumor-infiltrating T cells. Conditional transgenic expression of Notch-1 intracellular domain (N1IC) in antigen-specific CD8(+) T cells did not affect activation or proliferation of CD8(+) T cells, but induced a central memory phenotype and increased cytotoxicity effects and granzyme B levels. Consequently, a higher antitumor response and resistance to tumor-induced tolerance were found after adoptive transfer of N1IC-transgenic CD8(+) T cells into tumor-bearing mice. Additional results showed that myeloid-derived suppressor cells (MDSC) blocked the expression of Notch-1 and Notch-2 in T cells through nitric oxide-dependent mechanisms. Interestingly, N1IC overexpression rendered CD8(+) T cells resistant to the tolerogenic effect induced by MDSC in vivo. Together, the results suggest the key role of Notch in the suppression of CD8(+) T-cell responses in tumors and the therapeutic potential of N1IC in antigen-specific CD8(+) T cells to reverse T-cell suppression and increase the efficacy of T cell-based immunotherapies in cancer.

Transcriptional profiling of gastric epithelial cells infected with wild type or arginase-deficient Helicobacter pylori.

BACKGROUND: Helicobacter pylori causes acute and chronic gastric inflammation induced by proinflammatory cytokines and chemokines secreted by cells of the gastric mucosa, including gastric epithelial cells. Previous studies have demonstrated that the bacterial arginase, RocF, is involved in inhibiting T cell proliferation and CD3ζ expression, suggesting that arginase could be involved in a more general dampening of the immune response, perhaps by down-regulation of certain pro-inflammatory mediators. RESULTS: Global transcriptome analysis was performed on AGS gastric epithelial cells infected for 16 hours with a wild type Helicobacter pylori strain 26695, an arginase mutant (rocF-) or a rocF+ complemented strain. H. pylori infection triggered altered host gene expression in genes involved in cell movement, death/growth/proliferation, and cellular function and maintenance. While the wild type strain stimulates host inflammatory pathways, the rocF- mutant induced significantly more expression of IL-8. The results of the microarray were verified using real-time PCR, and the differential levels of protein expression were confirmed by ELISA and Bioplex analysis. MIP-1B was also significantly secreted by AGS cells after H. pylori rocF- mutant infection, as determined by Bioplex. Even though not explored in this manuscript, the impact that the results presented here may have on the development of gastritis, warrant further research to understand the underlying mechanisms of the relationship between H. pylori RocF and IL-8 induction. CONCLUSIONS: We conclude that H. pylori arginase modulates multiple host signaling and metabolic pathways of infected gastric epithelial cells. Arginase may play a critical role in anti-inflammatory host responses that could contribute to the ability of H. pylori to establish chronic infections.

Association of haplotypes of inflammation-related genes with gastric preneoplastic lesions in African Americans and Caucasians.

Identification of biomarkers is needed for development of screening programs to prevent gastric cancer. Because racial differences exist in cancer rates, we aimed to evaluate the association between polymorphisms in inflammation-related genes and gastric preneoplastic lesions in African Americans and Caucasians from Louisiana, USA. Gastric biopsies from 569 adults (361 African Americans and 208 Caucasians) undergoing diagnostic endoscopy were used for histological diagnosis and genomic DNA extraction. Polymorphisms within eight genes (IL1B, IL8, IL6, TNF, PTGS2, ARG1, IL10 and TGFB1) were investigated by TaqMan. The cagA status of Helicobacter pylori infection was assessed by PCR. Haplotype logistic regression models were used to identify variables associated with intestinal metaplasia or dysplasia. African Americans carrying the haplotype IL1B-511T/-31C/+3954T, which includes the three risk-associated alleles at the IL1B locus, were more likely to being diagnosed with intestinal metaplasia or dysplasia than those carrying the most common haplotype T-C-C (adjusted OR: 2.51, 95% CI: 1.1-5.5). None of the polymorphisms were associated with intestinal metaplasia and dysplasia in Caucasians. Age and cagA-positive status were independent factors associated with these lesions. Haplotypes at the IL1B locus may participate in mediating the susceptibility to gastric carcinogenesis and might be useful as markers of advanced premalignant lesions in African Americans. Interestingly, carriage of IL1B+3954T allele seems to be the key factor, even though the role played by other polymorphisms cannot be excluded.

Cytokine genetic polymorphisms and prostate cancer aggressiveness.

Prostate cancer (PCa) is one of the most common cancers in the world. Inflammation has been described as a risk factor for PCa and depends on the production of cytokines in response to tissue damage or the presence of stimuli that induces cellular stress. Interindividual variation in cytokine production is partially controlled by single-nucleotide polymorphisms (SNPs) that have been associated with differential production of cytokines. We have recently showed that SNP-SNP interactions of cytokine genes are associated with PCa risk. However, little is known about the association of cytokine SNPs and PCa aggressiveness. In this study, we evaluated the association of 15 SNPs in five cytokine genes and aggressiveness of PCa in African- and Caucasian-American individuals. Caucasian Americans with the genotypes IL10-1082GG or IL1B+3954TT had 2.31-fold [95% confidence interval (CI) = 1.13-4.72] and 3.11 (95% CI = 1.20-8.06)-fold risk, respectively, of developing aggressive PCa, as compared with individuals without those genotypes. We did not find any associations in the African-American group. Using Multivariate Adaptive Regression Splines modeling for exploratory SNP-SNP interactions, our results showed that more aggressive PCa in Caucasians Americans is associated with the CT genotype at IL8-47 [odds ratios (OR) = 3.50; 95% CI = 1.13-10.88] or combined genotypes of IL1B-511CC and IL10-1082GG (OR = 3.38; 95% CI = 1.70-6.71). Unfortunately, the same analysis could not be performed in the African-Americans due to limited number of individuals. With limited sample size, the results from this study suggest that SNPs in cytokine genes may be associated with PCa aggressiveness. More extensive studies are warranted to validate our findings.

Interactions of cytokine gene polymorphisms in prostate cancer risk.

Prostate cancer (CaP) is the second leading cause of cancer death in American men. Chronic inflammation has been one of several factors associated with the development of CaP. Single-nucleotide polymorphisms (SNPs) in cytokine genes have been associated with increased inflammation, increased cytokine production and possibly increased CaP risk. However, the effects of cytokine SNPs on CaP susceptibility have not been consistent. Using the genomic DNA collected in a CaP case-control study (557 cases and 547 controls), we pilot tested the interactions of nine functionally characterized SNPs of three cytokine genes in CaP risk using the multivariate adaptive regression splines (MARS)-logit models. African-Americans with the IL10-819TT genotype had a lower CaP risk [odds ratio (OR) = 0.27, 95% confidence interval (CI) = 0.07-1.01], but subjects with the genotype combination of IL1B-511CT/TT and IL10-592CC had a higher CaP risk (OR = 2.56, 95% CI = 1.09-6.02). In Caucasians, higher CaP risk was associated with the IL10-1082AG/GG genotype (OR = 3.62, 95% CI = 1.42-9.28), the genotype combination of IL10-1082AA plus IL1B-31TT/TC (OR = 2.92, 95% CI = 1.13-7.55) and the genotype combination of TNF-238GG plus IL10-592AA (OR = 2.14, 95% CI = 1.05-4.38). Our results highlight the importance of cytokine SNPs and their interactions in CaP risk.

Ethnic differences in cytokine gene polymorphisms: potential implications for cancer development.

Differences in incidence and outcome of cancer among ethnic groups may be explained by biological and/or socio-economic factors. Genetic variations that affect chronic inflammation, a potentially important risk factor for carcinogenesis, may differ across ethnic groups. Such differences may help explain cancer disparities among these groups. Single nucleotide polymorphisms (SNPs) within cytokine genes can affect cytokine levels and the degree of inflammation. Associations between cancer and some cytokine SNPs have been suggested. However, these have not been consistently replicated among populations, suggesting that SNP function may differ according to ethnicity, or that SNPs alone do not completely account for regulation of inflammation. We examined seven polymorphisms in African-American (n = 294) and Caucasian (n = 299) newborns in Louisiana: IL1B-511C > T, IL1B-31T > C, IL1B + 3954C > T, IL1RN*2, IL10-1082G > A, IL10-592C > A, and TNF-308G > A. African-American newborns had significantly higher frequencies of IL1B-511T, IL1B-31C, IL10-1082A and IL10-592A alleles and complete linkage equilibrium between IL1B + 3954 and IL1B-31. In contrast, IL1B + 3954T, IL1RN*2, and TNF-308A were more frequent in Caucasian newborns and exhibited strong linkage disequilibrium between IL1B + 3954 and IL1B-31. All allelic frequencies were significantly different between groups. We hypothesize that these dissimilarities may contribute to differences in the inflammatory response and cancer incidence and mortality between African-Americans and Caucasians in Louisiana.

Gastric cancer risk in a Mexican population: role of Helicobacter pylori CagA positive infection and polymorphisms in interleukin-1 and -10 genes.

Several polymorphisms of the IL1B and IL10 gene promoters have been reported to be associated with gastric cancer risk in Caucasians. However, studies in other populations have shown differing results. We aimed to test for associations between polymorphisms in IL1B (-31 and +3954), IL10-592 and IL1RN variable number of tandem repeats (VNTR) and risk of gastric cancer in a Mexican population. DNA was extracted from sera of 183 gastric adenocarcinoma patients and 377 controls. The IL1B-31, IL1B+3954 and IL10-592 biallelic polymorphisms were discriminated using 5' Nuclease (TaqMan) assays and Pyrosequencing. The IL1RN penta-allelic VNTR polymorphism was genotyped using PCR followed by GeneScan analysis. A significant interaction was found between IL1B-31 and CagA status for the risk of intestinal-type gastric cancer (p = 0.023). Among CagA positive subjects, those with IL1B-31CC genotype had an increased risk of intestinal-type gastric cancer (OR 3.19, 95%CI = 1.05-9.68), compared to carriers of IL1B-31TT genotype. In contrast, among CagA negative subjects, no significant association of IL1B-31CC genotype with gastric cancer was observed. The IL10-592CC genotype was associated with more than doubling of the risk of the intestinal-type gastric cancer (OR, 2.20, 95%CI = 1.04-4.65). A nonsignificantly increased risk for intestinal-type gastric cancer was found in IL1RN*2 carriers (OR 1.49, 95%CI = 0.89-2.50). None of these polymorphisms was significantly related to the risk of diffuse-type gastric cancer. No significant association was found between risk of gastric cancer and the IL1B+3954 polymorphism. Individuals carrying 2 or more of the risk-associated alleles (IL1B-31C, IL1RN *2 and IL10-592C) were at increased risk for intestinal-type gastric cancer, compared to those with 0 or 1 risk-associated allele. The risk from multiple risk-associated alleles was especially high in subjects infected with CagA positive H. pylori. Our results support the identification of the IL1B-31 promoter polymorphism as a useful marker for risk of intestinal type gastric cancer in persons with CagA positive H. pylori infections.

Helicobacter pylori arginase inhibits T cell proliferation and reduces the expression of the TCR zeta-chain (CD3zeta).

Helicobacter pylori infects approximately half the human population. The outcomes of the infection range from gastritis to gastric cancer and appear to be associated with the immunity to H. pylori. Patients developing nonatrophic gastritis present a Th1 response without developing protective immunity, suggesting that this bacterium may have mechanisms to evade the immune response of the host. Several H. pylori proteins can impair macrophage and T cell function in vitro through mechanisms that are poorly understood. We tested the effect of H. pylori extracts and live H. pylori on Jurkat cells and freshly isolated human normal T lymphocytes to identify possible mechanisms by which the bacteria might impair T cell function. Jurkat cells or activated T lymphocytes cultured with an H. pylori sonicate had a reduced proliferation that was not caused by T cell apoptosis or impairment in the early T cell signaling events. Instead, both the H. pylori sonicate and live H. pylori induced a decreased expression of the CD3zeta-chain of the TCR. Coculture of live H. pylori with T cells demonstrated that the wild-type strain, but not the arginase mutant rocF(-), depleted L-arginine and caused a decrease in CD3zeta expression. Furthermore, arginase inhibitors reversed these events. These results suggest that H. pylori arginase is not only important for urea production, but may also impair T cell function during infection.

Evaluación del efecto de la remoción de la zona pelúcida de los oocitos sobre el desarrollo de embriones murinos obtenidos por fertilización in vitro / Evaluation of the effect of zona pellucida removal over the development of murine embryos obtained using in vitro fertilization

Con el objetivo de evaluar el efecto de la remoción de la zona pelúcida de oocitos sobre el desarrollo embrionario murino in vitro, y el potencial uso de este procedimiento en programas de reproducción asistida humana, se superovularon 84 ratonas. A los oocitos obtenidos se les removió la zona pelúcida mediante el uso de una solución de pH 2, posteriormente inseminados con diferentes concentraciones de espermatozoides; los embriones obtenidos cultivados in vitro hasta estadios preimplantatorios fueron transferidos a hembras pseudogestantes . Luego del tratamiento con la solución ácida se recuperaron 56 por ciento de los oocitos con una viabilidad del 83.6 por ciento, los oocitos fueron fertilizados normalmente en proporciones dependientes de la concentración de espermatozoides utilizada variando desde 25 hasta 66.6 por ciento, estos se desarrollaron hasta estadios preimplantatorios enun 45 por ciento, siendo esta proporción inferior comparada con los controles.. No se obtuvieron gestaciones de los embriones transferidos. Se demuestra que la remoción de la zona pelúcida es una técnica sencilla y viable, cuya única condición es la rápidez en su realización; es necesario usar bajasconcentraciones de espermatozoides para incrementar la proporción de fertilizaciones normales. Se confirman resultados de otros autores sobre la factibilidad de obtener embriones mediante la remoción de la zona pelúcida, aún en el humano. Queda por establecer el mínimo de espermatozoides necesarios para obtener la mayor proporción de fertilizaciones normales y explicar las razones del bajo desarrollode los embriones obtenidos.