Intestinal microbial metabolites are conjectured to affect mucosal integrity through an incompletely characterized mechanism. Here we showed that microbial-specific indoles regulated intestinal ...barrier function through the xenobiotic sensor, pregnane X receptor (PXR). Indole 3-propionic acid (IPA), in the context of indole, is a ligand for PXR in vivo, and IPA downregulated enterocyte TNF-α while it upregulated junctional protein-coding mRNAs. PXR-deficient (Nr1i2−/−) mice showed a distinctly “leaky” gut physiology coupled with upregulation of the Toll-like receptor (TLR) signaling pathway. These defects in the epithelial barrier were corrected in Nr1i2−/−Tlr4−/− mice. Our results demonstrate that a direct chemical communication between the intestinal symbionts and PXR regulates mucosal integrity through a pathway that involves luminal sensing and signaling by TLR4.
•Pregnane X receptor (PXR) is a physiologic regulator of intestinal permeability•Microbial-derived indoles can regulate intestinal barrier function through PXR•PXR regulates intestinal barrier function through TLR4•Specific indole-producing bacteria can reduce intestinal inflammation
How commensal microbial metabolites affect mucosal integrity and barrier function is unclear. Mani and colleagues show that indole 3 propionic acid regulates intestinal barrier permeability through the PXR-TLR4 pathway.
Yersinia pseudotuberculosis is a foodborne pathogen that subverts immune function by translocation of Yersinia outer protein (Yop) effectors into host cells. As adaptive γδ T cells protect the ...intestinal mucosa from pathogen invasion, we assessed whether Y. pseudotuberculosis subverts these cells in mice and humans. Tracking Yop translocation revealed that the preferential delivery of Yop effectors directly into murine Vγ4 and human Vδ2+ T cells inhibited anti-microbial IFNγ production. Subversion was mediated by the adhesin YadA, injectisome component YopB, and translocated YopJ effector. A broad anti-pathogen gene signature and STAT4 phosphorylation levels were inhibited by translocated YopJ. Thus, Y. pseudotuberculosis attachment and translocation of YopJ directly into adaptive γδ T cells is a major mechanism of immune subversion in mice and humans. This study uncovered a conserved Y. pseudotuberculosis pathway that subverts adaptive γδ T cell function to promote pathogenicity.
Cytosolic HSP90 requires multiple cochaperones in folding client proteins. However, the function of gp96 (HSP90b1, grp94), an HSP90 paralogue in the endoplasmic reticulum (ER), is believed to be ...independent of cochaperones. Here, we demonstrate that gp96 chaperones multiple Toll-like receptors (TLRs), but not TLR3, in a manner that is dependent on another ER luminal protein, CNPY3. gp96 directly interacts with CNPY3, and the complex dissociates in the presence of adenosine triphosphate (ATP). Genetic disruption of gp96-CNPY3 interaction completely abolishes their TLR chaperone function. Moreover, we demonstrate that TLR9 forms a multimolecular complex with gp96 and CNPY3, and the binding of TLR9 to either molecule requires the presence of the other. We suggest that CNPY3 interacts with the ATP-sensitive conformation of gp96 to promote substrate loading. Our study has thus established CNPY3 as a TLR-specific cochaperone for gp96.
CD8 tissue-resident memory T (T
) cells primarily reside in nonlymphoid tissues without recirculating and provide front-line protective immunity against infections and cancers. CD8 T
cells can be ...generally divided into CD69
CD103
T
cells (referred to as CD103
T
cells) and CD69
CD103
T
cells (referred to as CD103
T
cells). TGF-β plays a critical role in the development and maintenance of CD103
CD8 T
cells. In this review, we summarize the current understanding of tissue-specific activation of TGF-β mediated by integrins and how it contributes to CD103
CD8 T
cell development and maintenance. Furthermore, we discuss the underlying mechanisms utilized by TGF-β to regulate the development and maintenance of CD103
CD8 T
cells. Overall, this review highlights the importance of TGF-β in regulating this unique subset of memory CD8 T cells that may shed light on improving vaccine design to target this population.
(
) infection induces robust CD8 T cell responses, which play a critical role in resolving
during primary infection and provide protective immunity to re-infections. Comprehensive studies have been ...conducted to delineate the CD8 T cell response after
infection. In this review, the generation of the CD8 T cell response to
infection will be discussed. The role of dendritic cell subsets in acquiring and presenting
antigens to CD8 T cells and the events that occur during T cell priming and activation will be addressed. CD8 T cell expansion, differentiation and contraction as well as the signals that regulate these processes during
infection will be explored. Finally, the formation of memory CD8 T cell subsets in the circulation and in the intestine will be analyzed. Recently, the study of CD8 T cell responses to
infection has begun to shift focus from the intravenous infection model to a natural oral infection model as the humanized mouse and murinized
have become readily available. Recent findings in the generation of CD8 T cell responses to oral infection using murinized
will be explored throughout the review. Finally, CD8 T cell-mediated protective immunity against
infection and the use of
as a vaccine vector for cancer immunotherapy will be highlighted. Overall, this review will provide detailed knowledge on the biology of CD8 T cell responses after
infection that may shed light on improving rational vaccine design.
It is generally accepted that aging has detrimental effects on conventional T cell responses to systemic infections. However, most pathogens naturally invade the body through mucosal barriers. ...Although mucosal sites are highly enriched in unconventional immune sentinels like γδ T cells, little is currently known about the impact of aging on unconventional mucosal T cell responses. We previously established that foodborne infection with a mouse-adapted internalin A mutant Listeria monocytogenes (Lm) generates an adaptive intestinal memory CD44
CD27
Vγ4 T cells capable of co-producing IL-17A and IFNγ. Therefore, we used this model to evaluate the impact of aging on adaptive Vγ4 T cell responses elicited by foodborne infection.
Foodborne Lm infection of female Balb/c and C57BL/6 mice led to an increased adaptive CD44
CD27
Vγ4 T cell response associated with aging. Moreover, Lm-elicited CD44
CD27
Vγ4 T cells maintained diverse functional subsets despite some alterations favoring IL-17A production as mice aged. In contrast to the documented susceptibility of aged mice to intravenous Lm infection, mice contained bacteria after foodborne Lm infection suggesting that elevated bacterial burden was not a major factor driving the increased adaptive CD44
CD27
Vγ4 T cell response associated with mouse age. However, CD44
CD27
Vγ4 T cells accumulated in naïve mice as they aged suggesting that an increased precursor frequency contributes to the robust Lm-elicited mucosal response observed. Body mass did not appear to have a strong positive association with CD44
CD27
Vγ4 T cells within age groups. Although an increased adaptive CD44
CD27
Vγ4 T cell response may contribute to foodborne Lm resistance of C57BL/6 mice aged 19 or more months, neither anti-TCRδ or anti-IL-17A treatment impacted Lm colonization after primary infection. These results suggest that γδTCR signaling and IL-17A are dispensable for protection after primary foodborne Lm infection consistent with the role of conventional T cells during the early innate immune response to Lm.
Lm-elicited adaptive Vγ4 T cells appear resistant to immunosenescence and memory Vγ4 T cells could be utilized to provide protective immune functions during enteric infection of aged hosts. As such, oral immunization might offer an efficient therapeutic approach to generate unconventional memory T cells in the elderly.
Despite many years of research, cancer vaccines have largely been ineffective in the treatment of established cancers. Many barriers to immune-mediated destruction of malignant cells exist, and these ...likely limit the efficacy of cancer vaccines. In this study, we sought to enhance the efficacy of a cytomegalovirus (CMV)-based vaccine targeting melanoma by combining vaccination with other forms of immunotherapy. Adoptive cell therapy in humans and in animal models has been shown to be effective for tumor regression. Thus, in this study, we assessed whether CMV-based vaccines in combination with adoptively transferred antitumor T cells could provide greater antitumor protection than either therapy alone. Our results show that adoptive cell therapy greatly enhanced the antitumor effects of CMV-based vaccines targeting the foreign model antigen, OVA, or the melanoma differentiation antigen, gp100. Combination adoptive cell therapy and vaccination induced the upregulation of the inhibitory ligands, PD-L1, and Qa-1
, on B16 tumor cells. This expression paralleled the infiltration of tumors by vaccine-stimulated T cells which also expressed high levels of the receptors PD-1 and NKG2A/C/E, suggesting a potential mechanism of tumor immune evasion. Surprisingly, therapeutic blockade of the PD-1/PD-L1 and NKG2A/Qa-1
axes did not delay tumor growth following vaccination, suggesting that the presence of inhibitory ligands within malignant tissue may not be an effective biomarker for successful combination therapy with CMV-based vaccines. Overall, our studies show that therapeutic CMV-based vaccines in combination with adoptive T cell transfer alone are effective for tumor rejection.
Although murine γδ T cells are largely considered innate immune cells, they have recently been reported to form long-lived memory populations. Much remains unknown about the biology and specificity ...of memory γδ T cells. Here, we interrogated intestinal memory Vγ4 Vδ1 T cells generated after foodborne Listeria monocytogenes (Lm) infection to uncover an unanticipated complexity in the specificity of these cells. Deep TCR sequencing revealed that a subset of non-canonical Vδ1 clones are selected by Lm infection, consistent with antigen-specific clonal expansion. Ex vivo stimulations and in vivo heterologous challenge infections with diverse pathogenic bacteria revealed that Lm-elicited memory Vγ4 Vδ1 T cells are broadly reactive. The Vγ4 Vδ1 T cell recall response to Lm, Salmonella enterica serovar Typhimurium (STm) and Citrobacter rodentium was largely mediated by the γδTCR as internalizing the γδTCR prevented T cell expansion. Both broadly-reactive canonical and pathogen-selected non-canonical Vδ1 clones contributed to memory responses to Lm and STm. Interestingly, some non-canonical γδ T cell clones selected by Lm infection also responded after STm infection, suggesting some level of cross-reactivity. These findings underscore the promiscuous nature of memory γδ T cells and suggest that pathogen-elicited memory γδ T cells are potential targets for broad-spectrum anti-infective vaccines.
BackgroundGastrointestinal (GI) cancers, including colorectal, small intestine, and pancreatic cancer, pose a significant global public health challenge. Although effective in the short term, ...conventional treatment modalities such as surgery, radiotherapy, and chemotherapy often fail to provide lasting solutions. In this context, cancer vaccines have recently emerged as a promising avenue for immunotherapy, offering the potential to eradicate tumors while establishing durable protection. Listeria monocytogenes (Lm)-based cancer vaccines have emerged as a viable strategy to elicit a potent anti-tumors immunity. Intravenous (i.v.) delivery of Lm-based cancer vaccines can elicit a potent CD8 T cell response against tumors. Nevertheless, despite some promising outcomes reported in clinical trials, further refinements are needed to enhance the efficacy of this approach. Since our prior investigations have revealed that infecting mice with foodborne Lm induces GI focused CD8 T cell responses that are both qualitatively and quantitatively superior when compared to those induced by i.v. infection,1 we determined whether oral Lm immunization could protect mice against a model of colorectal cancer.MethodsA modified Lm strain was used to orally immunize mice by consumption of vaccine-inoculated bread. Lm vaccines were attenuated by deletion of the ActA and InlB virulence genes and modified to facilitate murine intestinal epithelial invasion by mutating InlA.2 We orally immunized mice with attenuated Lm vaccines, then evaluated the CD8 T cell response in gut and lymphoid tissues during the effector phase, at memory homeostasis, and after recall. We utilized multi-color flow cytometry to assess the immunogenicity of oral Lm vaccines. Sham or immunized mice received orthotopic transplantation of 1x106 MC38-ova colorectal cancer cells and tumor burden was visualized by colonoscopy.ResultsOral immunization with InlAM ΔActA ΔInlB Lm-ova vaccines induced widely disseminated effector and memory CD8 T cell responses. Vaccine elicited CD8 T cells were fully functional as measured by IFNg and TNF production. Oral Lm vaccines also induced durable memory CD8 T cells that recalled to target antigens. Oral immunization with InlAM ΔActA ΔInlB Lm-ova vaccines was safe. Mice did not lose weight after immunization and Lm remained confined to the gastrointestinal tissues. Finally, oral Lm immunization provided prophylactically protection against colorectal cancer, with a tumor rejection rate of 92%.ConclusionsAttenuated Lm is highly immunogenic and safe when administered orally. Oral immunization with highly-attenuated Lm provides prophylactic protection. Therapeutic efficacy is currently being evaluated.AcknowledgementsThis study is supported by the funds provided by the Research Foundation for the State University of New York and Stony Brook University (BSS), Department of Defense grant W81XWH-18-1-0217 (BSS), The G. Harold & Leila Y. Mathers Foundation (BSS, SB), and The Mark Foundation for Cancer Research (SB).ReferencesQiu, Khairallah, Chu, Imperato, Lei, Romanov, Atakilit, Puddington, Sheridan. Retinoic acid signaling during priming licenses intestinal CD103+ CD8 TRM cell differentiation. J Exp Med. 2023;220(5):e20210923Sheridan, Pham, Lee, Cauley, Puddington, Lefrançois. Oral infection drives a distinct population of intestinal resident memory CD8(+) T cells with enhanced protective function. Immunity. 2014;40(5):747–57.
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