CD4+ cytolytic effectors are inefficient in the clearance of Listeria monocytogenes

Cytotoxic T lymphocytes (CTL) recognize and lyse target cells through the interaction of the T-cell receptor complex with the class I or class II major histocompatibility complex (MHC). The production of class I-restricted CTL has been shown to be critical to the elimination of specific pathogens including . However, the function of class II-restricted CTL in the clearance of intracellular pathogens is poorly understood. H-2β-microglobulin-deficient mice (βM−/−) are not able to produce CD8 CTL in response to infection with . We used this model to evaluate the efficacy of class II-restricted CTL, in the absence of a class I-restricted response, during a primary infection with . We demonstrate that, despite their effectiveness in adoptive transfer of protection, -specific CD4 class II-restricted cytotoxic lymphocytes are ineffective in decreasing titres of in the spleen after an established infection. In βM−/− mice, persistence of in the spleen was found preferentially in class II-negative cells. Surprisingly, class I-restricted CTL from C57BL/6 mice were capable of decreasing bacterial titres during an established infection even in the absence of detectable class I on the surface of cells from βM−/− mice. These data strongly suggest that, in the absence of a class I-restricted response, pathogens that elicit a class II-restricted cytotoxic response may escape prompt eradication by the immune system

Machine-learning prediction of tumor antigen immunogenicity in the selection of therapeutic epitopes

Current tumor neoantigen calling algorithms primarily rely on epitope/major histocompatibility complex (MHC) binding affinity predictions to rank and select for potential epitope targets. These algorithms do not predict for epitope immunogenicity using approaches modeled from tumor-specific antigen data. Here, we describe peptide-intrinsic biochemical features associated with neoantigen and minor histocompatibility mismatch antigen immunogenicity and present a gradient boosting algorithm for predicting tumor antigen immunogenicity. This algorithm was validated in two murine tumor models and demonstrated the capacity to select for therapeutically active antigens. Immune correlates of neoantigen immunogenicity were studied in a pan-cancer data set from The Cancer Genome Atlas and demonstrated an association between expression of immunogenic neoantigens and immunity in colon and lung adenocarcinomas. Lastly, we present evidence for expression of an out-of-frame neoantigen that was capable of driving antitumor cytotoxic T-cell responses. With the growing clinical importance of tumor vaccine therapies, our approach may allow for better selection of therapeutically relevant tumor-specific antigens, including nonclas-sic out-of-frame antigens capable of driving antitumor immunity

A colitogenic memory CD4+ T cell population mediates gastrointestinal graft-versus-host disease

Damage to the gastrointestinal tract is a major cause of morbidity and mortality in graft-versus-host disease (GVHD) and is attributable to T cell–mediated inflammation. In this work, we identified a unique CD4+ T cell population that constitutively expresses the β2 integrin CD11c and displays a biased central memory phenotype and memory T cell transcriptional profile, innate-like properties, and increased expression of the gut-homing molecules α4β7 and CCR9. Using several complementary murine GVHD models, we determined that adoptive transfer and early accumulation of β2 integrin–expressing CD4+ T cells in the gastrointestinal tract initiated Th1-mediated proinflammatory cytokine production, augmented pathological damage in the colon, and increased mortality. The pathogenic effect of this CD4+ T cell population critically depended on coexpression of the IL-23 receptor, which was required for maximal inflammatory effects. Non–Foxp3-expressing CD4+ T cells produced IL-10, which regulated colonic inflammation and attenuated lethality in the absence of functional CD4+Foxp3+ T cells. Thus, the coordinate expression of CD11c and the IL-23 receptor defines an IL-10–regulated, colitogenic memory CD4+ T cell subset that is poised to initiate inflammation when there is loss of tolerance and breakdown of mucosal barriers

Type 2 innate lymphoid cells treat and prevent acute gastrointestinal graft-versus-host disease

Acute graft-versus-host disease (aGVHD) is the most common complication for patients undergoing allogeneic stem cell transplantation. Despite extremely aggressive therapy targeting donor T cells, patients with grade III or greater aGVHD of the lower GI tract, who do not respond to therapy with corticosteroids, have a dismal prognosis. Thus, efforts to improve understanding of the function of local immune and non-immune cells in regulating the inflammatory process in the GI tract during aGVHD are needed. Here, we demonstrate, using murine models of allogeneic BMT, that type 2 innate lymphoid cells (ILC2s) in the lower GI tract are sensitive to conditioning therapy and show very limited ability to repopulate from donor bone marrow. Infusion of donor ILC2s was effective in reducing the lethality of aGVHD and in treating lower GI tract disease. ILC2 infusion was associated with reduced donor proinflammatory Th1 and Th17 cells, accumulation of donor myeloid-derived suppressor cells (MDSCs) mediated by ILC2 production of IL-13, improved GI tract barrier function, and a preserved graft-versus-leukemia (GVL) response. Collectively, these findings suggest that infusion of donor ILC2s to restore gastrointestinal tract homeostasis may improve treatment of severe lower GI tract aGVHD

Effectiveness of an Algorithm-Based Approach to the Utilization of Plerixafor in Patients Undergoing Chemotherapy-Based Stem Cell Mobilization

AbstractAutologous stem cell transplantation remains a mainstay of therapy for diseases such as multiple myeloma and relapsed lymphoma. The use of plerixafor has been shown to augment the ability to collect adequate stem cells, but the optimal use of this agent when used with chemotherapy is not yet clear. We utilized an algorithm-based approach with the addition of plerixafor to 54 patients undergoing chemomobilization with reduced-dose etoposide who had a less than optimal preapheresis CD34+ cell count. We used a CD34+ precount of 20 cells/μL as a threshold to initiate stem cell apheresis. Ninety-four percent of patients were successfully collected and proceeded to transplantation. Fourteen of 51 (28%) patients who successfully collected required plerixafor to augment stem cell yield. Of the patients who successfully collected, 94% (89% of the entire population) were able to collect in 2 or fewer days. Compared with previous data from our institution, the rate of patients collecting > 4 × 106 CD34+ cells/kg in a single collection was increased from 39% to 69%. The safety profile of this approach was acceptable. The use of this algorithm-based method to determine when and whether to add plerixafor to chemomobilization was shown to be a successful and cost-effective approach to stem cell collection

Long-term remission in multiply relapsed enteropathy-associated T-cell lymphoma following CD30 CAR T-cell therapy

Enteropathy-associated T-cell lymphoma (EATL) is a rare lymphoma arising in the setting of celiac disease. Multiagent anthracycline-based chemotherapy alone is associated with poor long-term outcomes with a median overall survival of only 7 months. In patients who achieve a response to firstline therapy and are eligible for autologous stem cell transplantation (SCT), 5-year median overall survival can be improved to 50% to 60%. Because ~50% of patients with EATL express the CD30 antigen, targeted therapy with brentuximab vedotin has been explored with promising outcomes. We have recently completed a phase 1/2 study showing safety and efficacy of chimeric antigen receptor (CAR)–modified T cells targeting the CD30 molecule (CD30 CAR T cells) in CD301 Hodgkin lymphoma. Here we describe a patient with multiply relapsed EATL after previous allogeneic SCT (allo-SCT) who achieved a durable remission with CD30 CAR T cells

Antigen-capturing nanoparticles improve the abscopal effect and cancer immunotherapy

Immunotherapy holds tremendous promise for improving cancer treatment1. Administering radiotherapy with immunotherapy has been shown to improve immune responses and can elicit an “abscopal effect”2. Unfortunately, response rates for this strategy remain low3. Herein, we report an improved cancer immunotherapy approach that utilizes antigen-capturing nanoparticles (AC-NPs). We engineered several AC-NPs formulations and demonstrated that the set of protein antigens captured by each AC-NP formulation is dependent upon NP surface properties. We showed that AC-NPs deliver tumor specific proteins to antigen-presenting cells and significantly improve the efficacy of αPD-1 treatment using the B16F10 melanoma model, generating up to 20% cure rate as compared to 0% without AC-NPs. Mechanistic studies revealed that AC-NPs induced an expansion of CD8+ cytotoxic T cells and increased both CD4+/Treg and CD8+/Treg ratios. Our work presents a novel strategy for improving cancer immunotherapy with nanotechnology

B Cells and T Follicular Helper Cells Mediate Response to Checkpoint Inhibitors in High Mutation Burden Mouse Models of Breast Cancer

This study identifies mechanisms mediating responses to immune checkpoint inhibitors using mouse models of triple-negative breast cancer. By creating new mammary tumor models, we find that tumor mutation burden and specific immune cells are associated with response. Further, we developed a rich resource of single-cell RNA-seq and bulk mRNA-seq data of immunotherapy-treated and non-treated tumors from sensitive and resistant murine models. Using this, we uncover that immune checkpoint therapy induces T follicular helper cell activation of B cells to facilitate the anti-tumor response in these models. We also show that B cell activation of T cells and the generation of antibody are key to immunotherapy response and propose a new biomarker for immune checkpoint therapy. In total, this work presents resources of new preclinical models of breast cancer with large mRNA-seq and single-cell RNA-seq datasets annotated for sensitivity to therapy and uncovers new components of response to immune checkpoint inhibitors

L-Selectin Is Dispensable for T Regulatory Cell Function Postallogeneic Bone Marrow Transplantation: CD62L−/− Tregs Inhibit Acute GvHD

In murine models, the adoptive transfer of CD4+/CD25+ regulatory T cells (Tregs) inhibited graft-versus-host disease (GvHD). Previous work has indicated a critical role for the adhesion molecule L-selectin (CD62L) in the function of Tregs in preventing GvHD. Here we examined the capacity of naive wild-type (WT), CD62L−/− and ex vivo expanded CD62LLo Tregs to inhibit acute GvHD. Surprisingly, we found that CD62L−/− Tregs were potent suppressors of GvHD, whereas CD62LLo Tregs were unable to inhibit disease despite being functionally competent to suppress allo T cell responses in vitro. Concomitant with improved outcomes, WT and CD62L−/− Tregs significantly reduced liver pathology and systemic pro-inflammatory cytokine production, although CD62L−/− Tregs were less effective in reducing lung pathology. While accumulation of CD62L−/− Tregs in GvHD target organs was equivalent to WT Tregs, CD62L−/− Tregs did not migrate as well as WT Tregs to peripheral lymph nodes (PLNs) over the first 2 weeks posttransplantation. This work demonstrated that CD62L was dispensable for Treg-mediated protection from GvHD