γδ T cells and their potential for immunotherapy

γδ T cells regulate the expression of cytokines but not the manifestation of fungal keratitis

As an important immunoregulatory cell type, the role of γδ T cells in fungal keratitis (FK) is unclear. We observed the distribution of γδ T cells in infected corneas in vivo by two-photon microscopy. The γδ T cells were depleted by neutralizing antibodies. The cytokine expression profile was obtained by protein arrays to determine the cytokines regulated by γδ T cells. ICAM-1, MIP-2 and IL-17A were evaluated by ELISA assays to confirm the role of γδ T cells in FK. We counted the number of neutrophils, evaluated the volume of fungal hyphae and analyzed the manifestation of the disease. The γδ T cells increased significantly at 36 h and 72 h post fungal infection (P < 0.05) and migrated from the limbus to the infection site. The neutralizing antibodies completely depleted the γδ T cells in 24 h. The depletion of γδ T cells led to up regulation of 25 cytokines and down regulation of 3 cytokines. ICAM-1, MIP-2 and IL-17A changed significantly because of the depletion of γδ T cells (P < 0.05). However, the number of neutrophils, volume of fungal hyphae and manifestation of the disease was not affected by the depletion of γδ T cells. Our results demonstrated that γδ T cells have a role in FK via regulation of some cytokines but did not affect the manifestation of this disease, suggesting that γδ T cells are not the key regulator cells in this disease.

Modulation of human gamma/delta T-cell activation and phenotype by histone deacetylase inhibitors

Histone deacetylase inhibitors have been shown to possess therapeutic potential in various pathophysiological conditions. Valproic acid (VPA), a known histone deacetylase class I inhibitor, has been studied for its influence on immune cell functions. However, the potential impact of VPA on human γδ T-cells remains unknown. Here we investigated the effects of VPA on the proliferation and the immunophenotype of human γδ T-cells. We observed dose-dependent inhibition of proliferation, associated with significant cell death as revealed by flow cytometry. The cellular response to VPA clearly showed differential modulation of cell surface markers on γδ T-cells when compared to αβ T-cells. Furthermore, histone H3 acetylation was detected in γδ T-cells even at toxic concentrations of VPA. Our investigations focusing on the impact of VPA on human γδ T-cells will be helpful in understanding its safety profile in clinical application, particularly in the context of γδ T-cell-targeted immunotherapy.

Immune response of γδT cells in Schistosome japonicum-infected C57BL/6 mouse liver

Systematic evaluation of the role of γδT cells during the Schistosoma japonicum infection has not been reported, despite the fact that γδT cells contribute to many infectious diseases in innate immunity. Therefore, the aim of this study was to observe the properties of γδT cells in the liver of C57BL/6 mice infected by S. japonicum. In this report, using immuno-fluorescent histological analysis, γδT cells were found around hepatic granulomatous. Moreover, the flow cytometry results revealed that the percentage of hepatic γδT cells increased significantly after S. japonicum infection. More interestingly, a subset of CD3(-)γδTCR(+) cells were found and markedly increased after infection. Furthermore, expression of activation markers (CD25 and CD69) and cytokine profiles were detected in these hepatic CD3(+)γδTCR(+) and CD3(-)γδTCR(+) cells. The significantly higher level of CD69, IL-4 and IL-17 were observed in CD3(+)γδTCR(+) cells after infection, suggesting that CD3(+)γδTCR(+) cells instead of CD3(-)γδTCR(+) cells might play a predominant role during the infection. Finally, our results indicated that the expression of NKG2D on CD3(+)γδTCR(+) cells was higher than that on CD3(-)γδTCR(+) cells. Collectively, γδT cells could play an important role in the liver of C57BL/6 mouse during japonicum infection.

Dismicrobism in inflammatory bowel disease and colorectal cancer: Changes in response of colocytes

Patients with inflammatory bowel disease (IBD) have an increased risk of 10%-15% developing colorectal cancer (CRC) that is a common disease of high economic costs in developed countries. The CRC has been increasing in recent years and its mortality rates are very high. Multiple biological and biochemical factors are responsible for the onset and progression of this pathology. Moreover, it appears absolutely necessary to investigate the environmental factors favoring the onset of CRC and the promotion of colonic health. The gut microflora, or microbiota, has an extensive diversity both quantitatively and qualitatively. In utero, the intestine of the mammalian fetus is sterile. At birth, the intestinal microbiota is acquired by ingesting maternal anal or vaginal organisms, ultimately developing into a stable community, with marked variations in microbial composition between individuals. The development of IBD is often associated with qualitative and quantitative disorders of the intestinal microbial flora (dysbiosis). The healthy human gut harbours about 10 different bacterial species distributed in colony forming units which colonize the gastrointestinal tract. The intestinal microbiota plays a fundamental role in health and in the progression of diseases such as IBD and CRC. In healthy subjects, the main control of intestinal bacterial colonization occurs through gastric acidity but other factors such as endoluminal temperature, competition between different bacterial strains, peristalsis and drugs can influence the intestinal microenvironment. The microbiota exerts diverse physiological functions to include: growth inhibition of pathogenic microorganisms, synthesis of compounds useful for the trophism of colonic mucosa, regulation of intestinal lymphoid tissue and synthesis of amino acids. Furthermore, mucus seems to play an important role in protecting the intestinal mucosa and maintaining its integrity. Changes in the microbiota composition are mainly influenced by diet and age, as well as genetic factors. Increasing evidence indicates that dysbiosis favors the production of genotoxins and metabolites associated with carcinogenesis and induces dysregulation of the immune response which promotes and sustains inflammation in IBD leading to carcinogenesis. A disequilibrium in gut microflora composition leads to the specific activation of gut associated lymphoid tissue. The associated chronic inflammatory process associated increases the risk of developing CRC. Ulcerative colitis and Crohn’s disease are the two major IBDs characterized by an early onset and extraintestinal manifestations, such as rheumatoid arthritis. The pathogenesis of both diseases is complex and not yet fully known. However, it is widely accepted that an inappropriate immune response to microbial flora can play a pivotal role in IBD pathogenesis.

Monitoring Circulating γδ T Cells in Cancer Patients to Optimize γδ T Cell-Based Immunotherapy

The success of γδ T cell-based immunotherapy, where the cytotoxic activity of circulating γδ T lymphocytes is activated by nitrogen-containing bisphosphonates (n-BP), or possibly by bispecific antibodies or the combination of both, requires a profound knowledge of patients' γδ T cells. A possible influence of radio- or chemotherapy on γδ T cells as well as their reported exhaustion after repetitive treatment with n-BP or their lack of response to various cancers can be easily determined by the monitoring assays described in this perspective article. Monitoring the absolute cell numbers of circulating γδ T cell subpopulations in small volumes of whole blood from cancer patients and determining γδ T cell cytotoxicity using the Real-Time Cell Analyzer can give a more comprehensive assessment of a personalized tumor treatment. Possible future directions such as the combined usage of n-BP or phosphorylated antigens together with bispecific antibodies that selectively target γδ T cells to tumor-associated antigens, will be discussed. Such strategies induce expansion and enhance γδ T cell cytotoxicity and might possibly avoid their exhaustion and overcome the immunosuppressive tumor microenvironment.