Tumor-infiltrating OX40+ lymphocytes is an independent positive prognostic factor for patients with pancreatic ductal adenocarcinoma.

PURPOSE: OX40 signaling pathway occupies a vital place in anti-tumor immunity; however, the role of tumor-infiltrating OX40+ lymphocytes in pancreatic ductal adenocarcinoma (PDAC) remains to be identified. METHODS: A total of 325 sequential PDAC patients who received curative tumor resection between January 2014 and December 2016 were enrolled. Tissues of these patients were immunohistochemically assessed for tumor infiltration of CD4+ T cells, CD8+ cytotoxic T cells (CTLs), and OX40+ lymphocytes. The frequency of OX40+ tumor-infiltrating lymphocytes (TILs) was then analyzed to various clinicopathological features, densities of tumor infiltration of CD4+ T cells and CTLs, and survival analysis was conducted using Kaplan-Meier (KM) curves. The risk scores of associated markers were calculated by the Cox proportional-hazards model. RESULTS: Our results showed that higher OX40+ lymphocytes infiltration was significantly correlated with superior median overall survival (OS) (25.8 vs 13.4 months, P < 0.001). Additionally, using univariate and multivariate Cox proportional hazards analyses, this study revealed that together with tumor differentiation, tumor size, serum CA199 levels, serum CA125 levels, and the infiltration of intratumoral CD8+ T cells. The abundance of OX40+ lymphocytes within the tumor was continued to be an independent predictor for OS (P = 0.023, HR = 0.713, 95% CI: 0.532-0.954). CONCLUSIONS: This study demonstrated that intratumoral infiltration by a high number of OX40+ lymphocytes is a novel biomarker for favorable prognosis in resected PDAC patients, which implies that OX40-agonist-based immunotherapy might be a potential target in PDAC patients.

Blocking drug-induced autophagy with chloroquine in HCT-116 colon cancer cells enhances DC maturation and T cell responses induced by tumor cell lysate.

Autophagy is an important mechanism for tumor escape, allowing tumor cells to recover from the damage induced by chemotherapy, radiation therapy, and immunotherapy and contributing to the development of resistance. The pharmacological inhibition of autophagy contributes to increase the efficacy of antineoplastic agents. Exposing tumor cells to low concentrations of select autophagy-inducing antineoplastic agents increases their immunogenicity and enhances their ability to stimulate dendritic cell (DC) maturation. We tested whether the application of an autophagy-inhibiting agent, chloroquine (CQ), in combination with low concentrations of 5-fluorouracil (5-FU) increases the ability of tumor cells to induce DC maturation. DCs sensitized with the lysate of HCT-116 cells previously exposed to such a combination enhanced the DC maturation/activation ability. These matured DCs also increased the allogeneic responsiveness of both CD4+ and CD8+ T cells, which showed a greater proliferative response than those from DCs sensitized with control lysates. The T cells expanded in such cocultures were CD69+ and PD-1- and produced higher levels of IFN-γ and lower levels of IL-10, consistent with the preferential activation of Th1 cells. Cocultures of autologous DCs and lymphocytes improved the generation of cytotoxic T lymphocytes, as assessed by the expression of CD107a, perforin, and granzyme B. The drug combination increased the expression of genes related to the CEACAM family (BECN1, ATGs, MAPLC3B, ULK1, SQSTM1) and tumor suppressors (PCBP1). Furthermore, the decreased expression of genes related to metastasis and tumor progression (BNIP3, BNIP3L, FOSL2, HES1, LAMB3, LOXL2, NDRG1, P4HA1, PIK3R2) was noted. The combination of 5-FU and CQ increases the ability of tumor cells to drive DC maturation and enhances the ability of DCs to stimulate T cell responses.

Limited Foxp3+ Regulatory T Cells Response During Acute Trypanosoma cruzi Infection Is Required to Allow the Emergence of Robust Parasite-Specific CD8+ T Cell Immunity.

While it is now acknowledged that CD4+ T cells expressing CD25 and Foxp3 (Treg cells) regulate immune responses and, consequently, influence the pathogenesis of infectious diseases, the regulatory response mediated by Treg cells upon infection by Trypanosoma cruzi was still poorly characterized. In order to understand the role of Treg cells during infection by this protozoan parasite, we determined in time and space the magnitude of the regulatory response and the phenotypic, functional and transcriptional features of the Treg cell population in infected mice. Contrary to the accumulation of Treg cells reported in most chronic infections in mice and humans, experimental T. cruzi infection was characterized by sustained numbers but decreased relative frequency of Treg cells. The reduction in Treg cell frequency resulted from a massive accumulation of effector immune cells, and inversely correlated with the magnitude of the effector immune response as well as with emergence of acute immunopathology. In order to understand the causes underlying the marked reduction in Treg cell frequency, we evaluated the dynamics of the Treg cell population and found a low proliferation rate and limited accrual of peripheral Treg cells during infection. We also observed that Treg cells became activated and acquired a phenotypic and transcriptional profile consistent with suppression of type 1 inflammatory responses. To assess the biological relevance of the relative reduction in Treg cells frequency observed during T. cruzi infection, we transferred in vitro differentiated Treg cells at early moments, when the deregulation of the ratio between regulatory and conventional T cells becomes significant. Intravenous injection of Treg cells dampened parasite-specific CD8+ T cell immunity and affected parasite control in blood and tissues. Altogether, our results show that limited Treg cell response during the acute phase of T. cruzi infection enables the emergence of protective anti-parasite CD8+ T cell immunity and critically influences host resistance.

In vivo electroporation enhances vaccine-mediated therapeutic control of human papilloma virus-associated tumors by the activation of multifunctional and effector memory CD8+ T cells.

In vivo electroporation (EP) has reignited the clinical interest on DNA vaccines as immunotherapeutic approaches to control different types of cancer. EP has been associated with increased immune response potency, but its capacity in influencing immunomodulation remains unclear. Here we evaluated the impact of in vivo EP on the induction of cellular immune responses and therapeutic effects of a DNA vaccine targeting human papillomavirus-induced tumors. Our results demonstrate that association of EP with the conventional intramuscular administration route promoted a more efficient activation of multifunctional and effector memory CD8+ T cells with enhanced cytotoxic activity. Furthermore, EP increased tumor infiltration of CD8+ T cells and avoided tumor recurrences. Finally, our results demonstrated that EP promotes local migration of antigen presenting cells that enhances with vaccine co-delivery. Altogether the present evidences shed further light on the in vivo electroporation action and its impact on the immunogenicity of DNA vaccines.

Cytotoxic cell involvement in human cutaneous leishmaniasis: assessments in active disease, under therapy and after clinical cure.

Cutaneous leishmaniasis (CL) is an important public health issue worldwide. The control of Leishmania infection depends on cellular immune mechanisms, and the inflammatory response may contribute to pathogenesis. A beneficial role of CD8(+) T lymphocytes has been proposed; nevertheless, other studies suggest a cytotoxic role of CD8(+) T lymphocytes involved in tissue damage, showing controversial role of these cells. The goal of the current study was to understand the immunopathology of CL and determine the profile of cytotoxic cells--such as CD4(+) T, natural killer and natural killer T cells--that might be involved in triggering immunological mechanisms, and may lead to cure or disease progression. The frequencies of cytotoxic cell populations in peripheral blood, obtained from patients with active disease, during treatment and after clinical healing, were assessed by flow cytometry. Cytotoxicity could not be related to a deleterious role in Leishmania braziliensis infection, as patients with active CL showed similar percentages of degranulation to healthy individuals (HI). Cured patients exhibited a lower percentage of degranulating cells, which may be due to a downregulation of the immune response. The understanding of the immunopathological mechanisms involved in CL and the commitment of cytotoxic cells enables improvements in therapeutic strategies.

Cytotoxic T cell adjuvant effects of three Salmonella enterica flagellins

Bacterial flagellins are important virulence-associated factors and strong inducers of inflammatory responses in mammalian hosts. Flagellins have also been investigated as potential vaccine adjuvants, either for induction of humoral or cellular immune responses, to different target antigens. In this study we investigated the adjuvant properties of three Salmonella enterica flagellins types (FliCd, FliCi and FljB) to an ovalbumin-derived CD8+ T cell-restricted epitope (OVA257264). Although mice immunized with the three tested flagellins elicited antigen-specific activated CD8+ T cells, only animals immunized with FliCi and FliCd flagellins admixed with ovalbumin mounted specific in vivo cytotoxic responses to peptide-pulsed target cells. The present results indicate that Salmonella flagellins are endowed with type-specific adjuvant effects toward murine CD8+ T cells, a feature that may impact their use as adjuvants for prophylatic or therapeutic vaccines.

As flagelinas bacterianas são importantes fatores associados à virulência e potentes indutores de resposta inflamatória em mamíferos. Estas moléculas são também investigadas como potencial adjuvante para uso em vacinas na indução de resposta imune humoral e celular para diferentes antígenos alvo. No presente estudo investigamos as propriedades adjuvantes de três tipos de flagelinas de Salmonella enterica (FliCd, FliCi e FljB) para um epítopo derivado da ovalbumina específico para células T CD8+. As três flagelinas testadas induziram respostas de células T CD8+ específicas em camundongos imunizados, porém, somente animais imunizados com as flagelinas FliCi e FliCd co-administradas com ovalbumina montaram resposta citotóxica específica in vivo para células-alvo pulsadas com peptídeo OVA. Os resultados apresentados indicam que flagelinas de Salmonella são dotadas de efeitos adjuvantes tipo-específico frente a células T CD8+ in vivo, uma característica que pode gerar impactos no uso dessas proteínas como adjuvantes em vacinas profiláticas ou terapêuticas.

Cytotoxic T cell adjuvant effects of three Salmonella enterica flagellins.

Bacterial flagellins are important virulence-associated factors and strong inducers of inflammatory responses in mammalian hosts. Flagellins have also been investigated as potential vaccine adjuvants, either for induction of humoral or cellular immune responses, to different target antigens. In this study we investigated the adjuvant properties of three Salmonella enterica flagellins types (FliCd, FliCi and FljB) to an ovalbumin-derived CD8(+) T cell-restricted epitope (OVA257-264). Although mice immunized with the three tested flagellins elicited antigen-specific activated CD8(+) T cells, only animals immunized with FliCi and FliCd flagellins admixed with ovalbumin mounted specific in vivo cytotoxic responses to peptide-pulsed target cells. The present results indicate that Salmonella flagellins are endowed with type-specific adjuvant effects toward murine CD8(+) T cells, a feature that may impact their use as adjuvants for prophylatic or therapeutic vaccines.

Cytotoxic T cell adjuvant effects of three Salmonella enterica flagellins

Bacterial flagellins are important virulence-associated factors and strong inducers of inflammatory responses in mammalian hosts. Flagellins have also been investigated as potential vaccine adjuvants, either for induction of humoral or cellular immune responses, to different target antigens. In this study we investigated the adjuvant properties of three Salmonella enterica flagellins types (FliCd, FliCi and FljB) to an ovalbumin-derived CD8+ T cell-restricted epitope (OVA257264). Although mice immunized with the three tested flagellins elicited antigen-specific activated CD8+ T cells, only animals immunized with FliCi and FliCd flagellins admixed with ovalbumin mounted specific in vivo cytotoxic responses to peptide-pulsed target cells. The present results indicate that Salmonella flagellins are endowed with type-specific adjuvant effects toward murine CD8+ T cells, a feature that may impact their use as adjuvants for prophylatic or therapeutic vaccines.

As flagelinas bacterianas são importantes fatores associados à virulência e potentes indutores de resposta inflamatória em mamíferos. Estas moléculas são também investigadas como potencial adjuvante para uso em vacinas na indução de resposta imune humoral e celular para diferentes antígenos alvo. No presente estudo investigamos as propriedades adjuvantes de três tipos de flagelinas de Salmonella enterica (FliCd, FliCi e FljB) para um epítopo derivado da ovalbumina específico para células T CD8+. As três flagelinas testadas induziram respostas de células T CD8+ específicas em camundongos imunizados, porém, somente animais imunizados com as flagelinas FliCi e FliCd co-administradas com ovalbumina montaram resposta citotóxica específica in vivo para células-alvo pulsadas com peptídeo OVA. Os resultados apresentados indicam que flagelinas de Salmonella são dotadas de efeitos adjuvantes tipo-específico frente a células T CD8+ in vivo, uma característica que pode gerar impactos no uso dessas proteínas como adjuvantes em vacinas profiláticas ou terapêuticas.