Collaboration between tumor-specific CD4+ T cells and B cells in anti-cancer immunity

MHCII restriction demonstrates B cells have very limited capacity to activate tumour-specific CD4+ T cells in vivo

There has been growing interest in the role of B cells in antitumour immunity and potential use in adoptive cellular therapies. To date, the success of such therapies is limited. The intrinsic capacity of B cells to specifically activate tumour-specific CD4+ T cells in vivo via TCR-dependent interactions remains poorly defined. We have developed an in vivo tumour model that utilizes MHCII I-E restriction which limits antigen presentation to tumour-specific CD4 T cells to either tumour-specific B cells or host myeloid antigen presenting cells (APCs) in lymphopenic RAG-/-mice. We have previously shown that these naive tumour-specific CD4+ T cells can successfully eradicate established tumours in this model when activated by host APCs. When naïve tumour-specific B cells are the only source of I-E+ APC, very limited proliferation of naïve CD4+ T cells is observed, whereas host I-E+ APCs are potent T cell activators. B cells pre-activated with an anti-CD40 agonistic antibody in vivo support increased T cell proliferation, although far less than host APCs. CD4+ T cells that have already differentiated to an effector/central memory phenotype proliferate more readily in response to naïve B cells, although still 100-fold less than in response to host APCs. This study demonstrates that even in a significantly lymphopenic environment, myeloid APCs are the dominant primary activators of tumour-specific T cells, in contrast to the very limited capacity of tumour-specific B cells. This suggests that future anti-tumour therapies that incorporate activated B cells should also include mechanisms that activate host APCs.

A risk scoring system based on tumor microenvironment cells to predict prognosis and immune activity in triple-negative breast cancer

The tumor microenvironment (TME) interacting with the malignant cells plays a vital role in cancer development. Herein, we aim to establish and verify a scoring system based on the characteristics of TME cells for prognosis prediction and personalized treatment guidance in patients with triple-negative breast cancer (TNBC). 158 TNBC samples from The Cancer Genome Atlas (TCGA) were included as the training cohort, and Molecular Taxonomy of Breast Cancer International Consortium (METABRIC) (N = 297), as well as GSE58812 (N = 107), were included as the validation cohort. The enrichment scores of 64 immune and stromal cells were estimated by the xCell algorithm. In the training cohort, cells with prognostic significance were found out using univariate Cox regression analysis and further applied to the random survival forest (RSF) model. Based on the scores of M2 macrophages, CD8+ T cells, and CD4+ memory T cells, a risk scoring system was constructed, which divided TNBC patients into 4 phenotypes (M2low, M2highCD8+ThighCD4+Thigh, M2highCD8+ThighCD4+Tlow, and M2highCD8+Tlow). Furthermore, types 1 and 2 patients were merged into the low-risk group, while types 3 and 4 patients were in the high-risk group. The low-risk group had superior survival outcomes than the high-risk one, which was further confirmed in the validation cohort. Moreover, in the low-risk group, immune-related pathways were significantly enriched, and a higher level of antitumoral immune cells and immune checkpoint molecules, including PD-L1, PD-1, and CTLA-4, could be observed. Additionally, consistent results were achieved in the SYSUCC cohort when the scoring system was applied. In summary, this novel scoring system might predict the survival and immune activity of patients and might serve as a potential index for immunotherapy.

Recurrence Risk of Liver Cancer Post-hepatectomy Using Machine Learning and Study of Correlation With Immune Infiltration

Postoperative recurrence of liver cancer is the main obstacle to improving the survival rate of patients with liver cancer. We established an mRNA-based model to predict the risk of recurrence after hepatectomy for liver cancer and explored the relationship between immune infiltration and the risk of recurrence after hepatectomy for liver cancer. We performed a series of bioinformatics analyses on the gene expression profiles of patients with liver cancer, and selected 18 mRNAs as biomarkers for predicting the risk of recurrence of liver cancer using a machine learning method. At the same time, we evaluated the immune infiltration of the samples and conducted a joint analysis of the recurrence risk of liver cancer and found that B cell, B cell naive, T cell CD4⁺ memory resting, and T cell CD4⁺ were significantly correlated with the risk of postoperative recurrence of liver cancer. These results are helpful for early detection, intervention, and the individualized treatment of patients with liver cancer after surgical resection, and help to reveal the potential mechanism of liver cancer recurrence.

MHC Class I Deficiency in Solid Tumors and Therapeutic Strategies to Overcome It

It is now well accepted that the immune system can control cancer growth. However, tumors escape immune-mediated control through multiple mechanisms and the downregulation or loss of major histocompatibility class (MHC)-I molecules is a common immune escape mechanism in many cancers. MHC-I molecules present antigenic peptides to cytotoxic T cells, and MHC-I loss can render tumor cells invisible to the immune system. In this review, we examine the dysregulation of MHC-I expression in cancer, explore the nature of MHC-I-bound antigenic peptides recognized by immune cells, and discuss therapeutic strategies that can be used to overcome MHC-I deficiency in solid tumors, with a focus on the role of natural killer (NK) cells and CD4 T cells.

Heterogeneity in tertiary lymphoid structure B-cells correlates with patient survival in metastatic melanoma

BACKGROUND

Tertiary lymphoid structures (TLSs) are immune aggregates in peripheral tissues that may support adaptive immune responses. Their presence has been associated with clinical response to checkpoint blockade therapy (CBT), but it is unknown whether TLS have prognostic significance independent of CBT in melanoma. We hypothesized that TLS in melanoma metastases would be associated with increased intratumoral lymphocyte infiltration, but that the intra-TLS immunological milieu would be distinct from the intratumoral immunological milieu. We also hypothesized that the presence of TLS would be associated with improved survival, and that TLS maturation or intra-TLS lymphocyte activity would also correlate with survival.

METHODS

Cutaneous melanoma metastases (CMM) from 64 patients were evaluated by multiplex immunofluorescence for the presence and maturation status of TLS. Intra-TLS lymphocyte density, proliferation and B-cell Ig somatic hypermutation (AID+) were analyzed, as were markers of T-cell exhaustion and Th1/Tc1 differentiation. Associations between TLS maturation and intra-TLS immunologic activity were assessed, as well as associations with intratumoral immune cell infiltration. Independent associations with overall survival (OS) were assessed using log-rank tests and Cox proportional hazards models.

RESULTS

TLS were identified in 30 (47%) of 64 CMM (TLS+) and were associated with increased intratumoral lymphocyte infiltration. However, proliferation of intra-TLS lymphocytes did not correlate with intratumoral lymphocyte proliferation. Most were early TLS; however, subsets of primary or secondary follicle-like TLS were also present. TLS+ lesions were associated with lower risk of tumor recurrence after metastasectomy and with improved OS in multivariate analyses (HR 0.51, p=0.04). OS was longer for TLS with low fractions of CD21+ B-cells (HR 0.29, p=0.02) and shorter for those with low AID+ fraction of B-cells (HR 2.74, p=0.03).

CONCLUSIONS

The presence of TLS in CMMs is associated with improved OS in patients treated with surgery before CBT, but TLS vary widely in maturation state, in proportions of proliferating T and B cells, and in markers of B cell function, including AID and CD21. Importantly, these features have additional prognostic significance, which suggest that some TLS may have regulatory function, while others functioning to support antigen-driven immune responses, depending on the cellular composition and activation status.

Hijacked Immune Cells in the Tumor Microenvironment: Molecular Mechanisms of Immunosuppression and Cues to Improve T Cell-Based Immunotherapy of Solid Tumors

The understanding of the tumor microenvironment (TME) has been expanding in recent years in the context of interactions among different cell types, through direct cell–cell communication as well as through soluble factors. It has become evident that the development of a successful antitumor response depends on several TME factors. In this context, the number, type, and subsets of immune cells, as well as the functionality, memory, and exhaustion state of leukocytes are key factors of the TME. Both the presence and functionality of immune cells, in particular T cells, are regulated by cellular and soluble factors of the TME. In this regard, one fundamental reason for failure of antitumor responses is hijacked immune cells, which contribute to the immunosuppressive TME in multiple ways. Specifically, reactive oxygen species (ROS), metabolites, and anti-inflammatory cytokines have central roles in generating an immunosuppressive TME. In this review, we focused on recent developments in the immune cell constituents of the TME, and the micromilieu control of antitumor responses. Furthermore, we highlighted the current challenges of T cell-based immunotherapies and potential future strategies to consider for strengthening their effectiveness.

TLR3 Activation of Intratumoral CD103+ Dendritic Cells Modifies the Tumor Infiltrate Conferring Anti-tumor Immunity

An important challenge in cancer immunotherapy is to expand the number of patients that benefit from immune checkpoint inhibitors (CI), a fact that has been related to the pre-existence of an efficient anti-tumor immune response. Different strategies are being proposed to promote tumor immunity and to be used in combined therapies with CI. Recently, we reported that intratumoral administration of naked poly A:U, a dsRNA mimetic empirically used in early clinical trials with some success, delays tumor growth and prolongs mice survival in several murine cancer models. Here, we show that CD103⁺ cDC1 and, to a much lesser extent CD11b⁺ cDC2, are the only populations expressing TLR3 at the tumor site, and consequently could be potential targets of poly A:U. Upon poly A:U administration these cells become activated and elicit profound changes in the composition of the tumor immune infiltrate, switching the immune suppressive tumor environment to anti-tumor immunity. The sole administration of naked poly A:U promotes striking changes within the lymphoid compartment, with all the anti-tumoral parameters being enhanced: a higher frequency of CD8⁺ Granzyme B⁺ T cells, (lower Treg/CD8⁺ ratio) and an important expansion of tumor-antigen specific CD8⁺ T cells. Also, PD1/PDL1 showed an increased expression indicating that neutralization of this axis could be exploited in combination with poly A:U. Our results shed new light to promote further assays in this dsRNA mimetic to the clinical field.

Prognostic significance of CD44 in human colon cancer and gastric cancer: Evidence from bioinformatic analyses

CD44 is a well-recognized stem cell biomarker expressed in colon and gastric cancer. In order to identify whether CD44 mRNA could be used as a prognostic marker in colon and gastric cancer, bioinformatic analyses were used in this study. cBioPortal analysis and COSMIC analysis were used to explore the CD44 mutation. CD44 mRNA levels were evaluated by using SAGE Genie tools and Oncomine analysis. Kaplan-Meier Plotter was performed to identify the prognostic roles of CD44 mRNA in these two cancers. In this study, first, we found that low alteration frequency of CD44 mRNA in colon and gastric cancer. Second, the high CD44 mRNA level was found in colon and gastric cancer, and it correlated with a benign survival rate in gastric cancer. Third, CD4 and CD74 may be used as markers to predict the prognosis of colon and gastric cancer. However, the deep mechanism(s) of these results remains unclear, further studies have to be performed in the future.