γδ T Cell Therapy Development for Hepatitis C Virus Infections

γδ T cells are one type of innate immune cells, and their functions include cytotoxicity, cytokine secretion, antigen presentation, and crosstalk with other immune cells. In the process of infection, autoimmune reaction, or tumor development, γδ T cells are activated to stimulate, regulate, or even suppress the immune response. As a leader in the research of γδ T cells, Creative Biolabs is driven to provide comprehensive γδ T cells development and engineering services to promote their clinical application in HCV treatment.

Intriguing and Enigmatic T Cell Subset - γδ T Cells

γδ T cells were discovered 30 years ago, although in humans they comprise a small fraction of the total circulating T-lymphocyte pool, they represent an important T-cell subset in tissues such as the liver, with roles bridging the innate and adaptive immune systems. The associations of γδ T cells with chronic liver disease have been explored - however, it is still conflicting whether these T-cells are pathogenic or protective. In patients with some forms of liver disease, their expansion in the periphery and especially in the liver may indeed help pathogen clearance; while in other conditions, their presence may, in contrast, contribute to disease progression.

Fig.1 Immunosuppressive circuits in the liver. (Fisicaro, 2020)

Short Introduction to HCV Infection

Hepatitis C is an infectious disease caused by the HCV that primarily affects the liver. During the initial infection, people often have mild or no symptoms. Occasionally a fever, dark urine, abdominal pain, or yellow-tinged skin occurs. The virus persists in the liver in about 75% to 85% of those initially infected. Early chronic infection typically has no symptoms. Over many years, however, it often leads to liver disease and occasionally cirrhosis. In some cases, those with cirrhosis will develop serious complications such as liver failure, liver cancer, or dilated blood vessels in the esophagus and stomach.

Fig.2 Stages of liver damage. (Allah, 2015)

Why γδ T Cells Is Important in HCV Infection

Many HCV infection results in chronicity and only 10-50% of cases are cleared in the acute phase. Failing cytotoxic T cell activity due to exhaustion of expanded T cells causes chronic viral persistence and continuous activation of liver-infiltrating lymphocytes progressively leading to liver cirrhosis and development of hepatocellular carcinoma. Cytotoxicity of γδ T-cells has been widely studied in the context of tumors. Ex vivo expanded γδ T-cells from healthy volunteers are cytotoxic to high-grade glioblastomas in vitro and in vivo. γδ T-cells have also been shown to mediate the killing of other tumor cells and represent an important effector of the immune system with an anti-tumor peripheral surveillance role.

γδ T Cells and Hepatitis C Virus Infection

The Vδ2 T-cells produce cytokines typical of T helper type (Th)-1, Th-2, or Th-17 cells, cross-talk with dendritic cells (DCs), and also have a direct cytotoxic effect via perforin/granzyme, Fas/Fas Ligand (FasL), Tumor Necrosis Factor (TNF)/TNF-R, and TNF-related apoptosis-inducing ligand (TRAIL)-TRAIL-R pathways. The killing capacity of the Vδ2 T-cells was improved by pre-treatment of tumor target cells with amino bisphosphonates. The role of γδ T-cells in the future of anticancer therapy may be either via adoptive transfer or in vivo stimulation and recruitment through the amino bisphosphonates.

Fig.3 Mechanisms of γδ T cell activation. (Yazdanifar, 2020)

In biopsies from 25 HCV patients, the predominant portal tract infiltrates were found to be αβ T-cells; the lobular infiltration frequencies between αβ and γδ T-cells were approximately equal. These γδ T-cells had high levels of non-major histocompatibility complex (MHC)-restricted cytotoxicity activity against primary hepatocytes and produced high levels of interleukin (IL)-8, interferon (IFN)-γ, and Tumor Necrosis Factor (TNF)-α when activated by anti-CD3. The study revealed increased γδ T-cells in immunohistochemical staining of liver tissue from patients with chronic liver disease. Thus, although not the dominant T-cell infiltrates in the liver, the γδ T-cell population is enriched in the livers of patients with liver disease.

Patients with chronic HCV showed a decreased percentage of Vδ2 cells, as well as reduced perforin-positive T cells compared to controls or to those who had cleared HCV infection. So impaired function and the number of the Vδ2 γδ T-cells (although measured here in the periphery) may be involved in viral persistence.

Scientists monitored peripheral γδ T cells repertoire dynamics in a homogenous cohort of chronic HCV patients before and during direct-acting antiviral (DAA) therapy. During HCV infection, cytokine release (IFN-γ) by Vγ9JP+Vδ2+ and non-Vγ9JP+Vδ2+ may contribute to virus clearance, while HCV persistence is associated with low γδ T cells numbers and impaired cytokine production. Chronic HCV patients with high liver inflammation rather have increased frequencies of cytotoxic γδ T cells when compared with healthy subjects or patients with no liver inflammation. In the study, all chronic HCV patients had no or only mild liver fibrosis and mild liver inflammation, which might explain that they displayed not significantly, elevated numbers of γδ T cells.

Our Services

γδ T-cells play an important role in defense against foreign pathogens, although they are a small non-dominant T-cell subset in the human T-cell lineage. Their role as innate sentinels, guarding against microbial invasion places them as a key T-cell subset in the battle against pathogens. Evidence is emerging that depending on the type of liver disease, γδ T-cells may play a role in disease pathogenesis. In the future, patients with HCV-driven hepatocellular-cancer (HCC) may be amenable to γδ T-cell-based immunotherapy.

Based on the γδ T-cells, we offer a variety of services, including but not limited to the following aspects:

• γδ T cell development (isolation, activation and expansion, characterization, production, cytotoxicity test, etc.) for tumors and cancers, pathogen infections, and autoimmune diseases.
• γδ T cell receptors services (γδ TCR repertoires analysis, γδ TCR transcriptome analysis, etc.).
• γδ T cell engineering services (CAR engineered-, αβ TCR-engineered γδ T cell development, bispecific γδ T cell antibody development, γδ T cell hybridomas development, etc.).

Creative Biolabs is a well-executed partner in the biological field that has won a high reputation worldwide for successfully achieving numerous challenging programs. If you have any unsolved challenges in the treatment or clinical application of γδ T cells, please feel free to contact us for a discussion with our scientists.

References

1. Fisicaro, P.; et al. Pathogenetic mechanisms of T cell dysfunction in chronic HBV infection and related therapeutic approaches. Frontiers in Immunology. 2020, 11.
2. Allah, Nawaz.; et al. Concise review on the insight of hepatitis C. Journal of Taibah University Medical Sciences. 2015, 10(2).
3. Yazdanifar, M.; et al. γδ T cells: the ideal tool for cancer immunotherapy. 2020.
4. Wu, Y. L.; et al. γδ T Cells and their potential for immunotherapy. International Journal of Biological ences. 2014, 10(2): 119-135.
5. Alnaggar, M.; et al. Allogenic Vγ9Vδ2 T cell as new potential immunotherapy drug for solid tumor: a case study for cholangiocarcinoma. Journal for immunotherapy of cancer. 2019, 7(1).