Qingzhu Jia

Forced miR-146a expression causes autoimmune lymphoproliferative syndrome in mice via downregulation of Fas in germinal center B cells

By inhibiting target gene expression, microRNAs (miRNAs) play major roles in various physiological and pathological processes. miR-146a, a miRNA induced upon lipopolysaccharide (LPS) stimulation and virus infection, is also highly expressed in patients with immune disorders such as rheumatoid arthritis, Sjögrens syndrome, and psoriasis. Whether the high level of miR-146a contributes to any of these pathogenesis-related processes remains unknown. To elucidate the function of miR-146a in vivo, we generated a transgenic (TG) mouse line overexpressing miR-146a. Starting at an early age, these TG mice developed spontaneous immune disorders that mimicked human autoimmune lymphoproliferative syndrome (ALPS) with distinct manifestations, including enlarged spleens and lymph nodes, inflammatory infiltration in the livers and lungs, increased levels of double-negative T cells in peripheral blood, and increased serum immunoglobulin G levels. Moreover, with the adoptive transfer approach, we found that the B-cell population was the major etiological factor and that the expression of Fas, a direct target of miR-146a, was significantly dampened in TG germinal center B cells. These results indicate that miR-146a may be involved in the pathogenesis of ALPS by targeting Fas and may therefore serve as a novel therapeutic target.

Diversity index of mucosal resident T lymphocyte repertoire predicts clinical prognosis in gastric cancer

A characteristic immunopathology of human cancers is the induction of tumor antigen-specific T lymphocyte responses within solid tumor tissues. Current strategies for immune monitoring focus on the quantification of the density and differentiation status of tumor-infiltrating T lymphocytes; however, properties of the TCR repertoire ‒ including antigen specificity, clonality, as well as its prognostic significance ‒ remain elusive. In this study, we enrolled 28 gastric cancer patients and collected tumor tissues, adjacent normal mucosal tissues, and peripheral blood samples to study the landscape and compartmentalization of these patients’ TCR β repertoire by deep sequencing analyses. Our results illustrated antigen-driven expansion within the tumor compartment and the contracted size of shared clonotypes in mucosa and peripheral blood. Most importantly, the diversity of mucosal T lymphocytes could independently predict prognosis, which strongly underscores critical roles of resident mucosal T-cells in executing post-surgery immunosurveillance against tumor relapse.

Rab25 upregulation correlates with the proliferation, migration, and invasion of renal cell carcinoma.

Renal cell carcinoma (RCC) is a common urological cancer with a poor prognosis. A recent cohort study revealed that the median survival of RCC patients was only 1.5 years and that <10% of the patients in the study survived up to 5 years. In tumor development, Rab GTPase are known to play potential roles such as regulation of cell proliferation, migration, invasion, communication, and drug resistance in multiple tumors. However, the correlation between Rabs expression and the occurrence, development, and metastasis of RCC remains unclear. In this study, we analyzed the transcriptional levels of 52 Rab GTPases in RCC patients. Our results showed that high levels of Rab25 expression were significantly correlated with RCC invasion classification (P < 0.01), lymph-node metastasis (P < 0.001), and pathological stage (P < 0.01). Conversely, in 786-O and A-498 cells, knocking down Rab25 protein expression inhibited cell proliferation, migration, and invasion. Our results also demonstrated that Rab25 is a target gene of let-7d, and further suggested that Rab25 upregulation in RCC is due to diminished expression of let-7d. These findings indicate that Rab25 might be a novel candidate molecule involved in RCC development, thus identifying a potential biological therapeutic target for RCC.

Association of CD8(+) T lymphocyte repertoire spreading with the severity of DRESS syndrome

T-cell receptor (TCR)-mediated cross-recognition is a major mechanism in the pathogenesis of drug reaction with eosinophilia and systemic symptoms (DRESS) syndrome. However, the characteristics of the TCR repertoire and the clinical significance of repertoire reformation throughout the course of DRESS are unknown. Here, we isolated CD4+ and CD8+ T-cells from peripheral blood of 8 DRESS patients at 10-day intervals and, sequenced CDR3-regions of the TCRB chain by high-throughput sequencing to analyze the dynamic reformation in the T-cell repertoire hierarchy. Compared with healthy donors, T-cell expanded in peripheral repertoires from DRESS patient. The extent of fluctuation of dominant CD8+ T-cell clones, but not of CD4+ counterparts, correlated positively with the clinical severity and helped classify the enrolled subjects into “fluctuant” and “flat” repertoire groups. The anti-herpesvirus response, which was measured using anti-EBV/HHV antibodies, and the proportion of the homologous CD8+ EBV-specific clonotypes, in the “fluctuant” group was substantial higher than that in the “flat” group. Furthermore, autoimmune sequelae were observed in a cured “fluctuant” patient. Collectively, the clinical relevance of the fluctuant CD8+ T-cell repertoires supports the notion that herpes virus-mediated continuously de novo priming of newly pathogenic CD8+ T-cell clones is an alternate mechanism responsible for the pathogenicity of DRESS.

Glimpse of natural selection of long-lived T-cell clones in healthy life.

Significance A healthy life requires T cells to provide immunity against infections while maintaining immune tolerance to self and commensal antigens. The diversity of T-cell clones evolves in an individual’s life due to competition between preexisting clones and clones continuously generated from the thymus. It is not known whether antigen-experienced T-cell clones are randomly replaced by new clones or selectively retained for long-term keeping in healthy living conditions. Here, we tracked long-lived T-cell clones in mice without infections or immune challenges. Our study revealed that healthy living conditions select regulatory T-cell clones that may be necessary to maintain the immune-tolerant status of long-lived T-cell clones against self or commensal antigens shared across different mice. Homeostatic maintenance of T cells with broad clonal diversity is influenced by both continuing output of young T cells from the thymus and ongoing turnover of preexisting clones in the periphery. In the absence of infection, self and commensal antigens are thought to play important roles in selection and homeostatic maintenance of the T-cell pool. Most naïve T cells are short-lived due to lack of antigen encounter, whereas antigen-experienced T cells may survive and persist as long-lived clones. Thus far, little is known about the homeostasis, antigenic specificity, and clonal diversity of long-lived T-cell clones in peripheral lymphoid organs under healthy living conditions. To identify long-lived T-cell clones in mice, we designed a lineage-tracing method to label a wave of T cells produced in the thymus of young mice. After aging the mice for 1.5 y, we found that lineage-tracked T cells consisted of primarily memory-like T cells and T regulatory cells. T-cell receptor repertoire analysis revealed that the lineage-tracked CD4 memory-like T cells and T regulatory cells exhibited age-dependent enrichment of shared clonotypes. Furthermore, these shared clonotypes were found across different mice maintained in the same housing condition. These findings suggest that nonrandom and shared antigens are involved in controlling selection, retention, and immune tolerance of long-lived T-cell clones under healthy living conditions.

Programmed death ligand 1 expression and CD8+ tumor-infiltrating lymphocyte density differences between paired primary and brain metastatic lesions in non-small cell lung cancer

Immunotherapy targeting the programmed cell death-1/programmed death ligand 1(PD-L1) pathway has shown promising antitumor activity in brain metastases (BMs) of non-small cell lung cancer (NSCLC) patients with an acceptable safety profile; however, the response rates often differ between primary lesions and intracranial lesions. Studies are necessary to identify detailed characterizations of the response biomarkers. In this study, we aimed to compare the differences of PD-L1 expression and CD8+ tumor-infiltrating lymphocyte (TIL) density, two major response biomarkers of PD-1/PD-L1 blockade, between paired primary and brain metastatic lesions in advanced NSCLC. We observed that among primary lesions or BMs, only a small number of patients harbored common PD-L1 expression on both tumor cells and tumor-infiltrating immune cells. Additionally, we found that the numbers of CD8+ TILs were significantly fewer in BMs than in primary lung cancers. Low stromal CD8+ TIL numbers in BMs were associated with significantly shorter overall survival compared to high stromal CD8+ TIL counts. Notably, we demonstrated a discrepancy in PD-L1 expression and CD8+ TIL density between primary lung cancers and their corresponding BMs. Such heterogeneities are significantly associated with the time at which BMs occurred. Our study emphasizes the spatial and temporal heterogeneity of biomarkers for anti-PD-1/PD-L1 therapy, which should be concerned in clinical practice.

Late-stage tumors induce anemia and immunosuppressive extramedullary erythroid progenitor cells

Impaired immunity in patients with late-stage cancer is not limited to antitumor responses, as demonstrated by poor vaccination protection and high susceptibility to infection1–3. This has been largely attributed to chemotherapy-induced impairment of innate immunity, such as neutropenia2, whereas systemic effects of tumors on hematopoiesis and adoptive immunity remain incompletely understood. Here we observed anemia associated with severe deficiency of CD8+ T cell responses against pathogens in treatment-naive mice bearing large tumors. Specifically, we identify CD45+ erythroid progenitor cells (CD71+TER119+; EPCs) as robust immunosuppressors. CD45+ EPCs, induced by tumor growth–associated extramedullary hematopoiesis, accumulate in the spleen to become a major population, outnumbering regulatory T cells (Tregs) and myeloid-derived suppressor cells (MDSCs). The CD45+ EPC transcriptome closely resembles that of MDSCs, and, like MDSCs, reactive oxygen species production is a major mechanism underlying CD45+ EPC–mediated immunosuppression. Similarly, an immunosuppressive CD45+ EPC population was detected in patients with cancer who have anemia. These findings identify a major population of immunosuppressive cells that likely contributes to the impaired T cell responses commonly observed in patients with advanced cancer.Large tumors induce anemia and expansion of CD45+ immature erythroid cells, which represent a major immunosuppressive population in the spleen, contributing to systemic suppression of T cell immunity in late-stage cancer.