CD8dim but not CD8bright cells positive to CD56 dominantly express KIR and are cytotoxic during visceral leishmaniasis

Causal relationship between immune cell signatures and colorectal cancer: a bi-directional, two-sample mendelian randomization study

BACKGROUND

Prior studies have demonstrated the association between immune cells and colorectal cancer (CRC). However, the causal link to specific immunophenotypes is limited. This study intends to elucidate the causal relationship of immune cell signatures on CRC.

METHODS

We performed a bi-directional and two-sample mendelian randomization (MR) study, utilizing GWAS summary data of 731 immune cell traits (n = 3,757) and CRC statistics (n = 470,002). The primary MR methodology was inverse-variance weighted (IVW) method. Furthermore, heterogeneity was evaluated by Cochran's Q test. MR-PRESSO and MR-Egger were employed to assess horizontal and vertical pleiotropy respectively. Sensitivity analysis and FDR correction were conducted in our results. These results were validated in both the UK Biobank and FinnGen cohorts. We also extracted transcriptomic data of CRC and adjacent non-tumor tissues from TCGA, and used CIBERSORT to compare the infiltration patterns of 22 immune cell panels between normal tissues and the tumor microenvironment (TME).

RESULTS

Our study indicated nine immune cell signatures had significant causality with the risk of CRC after sensitivity analysis and FDR correction. The positive results covered four panels: B cell, CD8 + T cell, Treg, and monocyte. IgD- CD38br and IgD + CD38br B cell, CD8dim and CD28 + CD45RA- CD8dim T cell, and CD14 on CD14 + CD16- monocyte were the protective factors of CRC. However, CD39 + resting Treg, CX3CR1 on CD14- CD16 + monocyte, FSC-A on HLA DR + T cell, and BAFF-R on B cell increased the risk of CRC. The results were validated in the UK Biobank data and FinnGen cohorts. The data from the TCGA database also confirmed the infiltration of B cell, CD8 + T cell, Treg, and monocyte panels in the TME.

CONCLUSION

This study highlights the causal link between specific immune cell phenotypes and CRC, providing valuable insights into the immune microenvironment's role in CRC. The validation of our findings using large-scale datasets (UK Biobank, FinnGen) and TCGA underscores the robustness of our results, offering new potential therapeutic targets for CRC treatment.

Chemokines Signature and T Cell Dynamics in Leishmaniasis: Molecular insight and therapeutic application

Leishmaniasis, caused by obligate intracellular Leishmania parasites, poses a significant global health burden. The control of Leishmania infection relies on an effective T cell-dependent immune response; however, various factors impede the host’s ability to mount a successful defence. Alterations in the chemokine profile, responsible for cell trafficking to the infection site, can disrupt optimal immune responses and influence the outcome of pathogenesis by facilitating parasite persistence. This review aims to emphasize the significance of the chemokine system in T cell responses and to summarize the current knowledge on the dysregulation of chemokines and their receptors associated with different subsets of T lymphocytes during Leishmaniasis. A comprehensive understanding of the dynamic nature of the chemokine system during Leishmaniasis is crucial for the development of successful immunotherapeutic approaches.

Leishmaniasis: Immune Cells Crosstalk in Macrophage Polarization

Leishmaniasis is a complex infectious parasitic disease caused by protozoa of the genus Leishmania, belonging to a group of neglected tropical diseases. It establishes significant global health challenges, particularly in socio-economically disadvantaged regions. Macrophages, as innate immune cells, play a crucial role in initiating the inflammatory response against the pathogens responsible for this disease. Macrophage polarization, the process of differentiating macrophages into pro-inflammatory (M1) or anti-inflammatory (M2) phenotypes, is essential for the immune response in leishmaniasis. The M1 phenotype is associated with resistance to Leishmania infection, while the M2 phenotype is predominant in susceptible environments. Notably, various immune cells, including T cells, play a significant role in modulating macrophage polarization by releasing cytokines that influence macrophage maturation and function. Furthermore, other immune cells can also impact macrophage polarization in a T-cell-independent manner. Therefore, this review comprehensively examines macrophage polarization's role in leishmaniasis and other immune cells' potential involvement in this intricate process.

Changing roles of CD3 + CD8 low T cells in combating HIV-1 infection

BACKGROUND

Cluster of differentiation 8 (CD8 T) cells play critical roles in eradicating human immunodeficiency virus (HIV)-1 infection, but little is known about the effects of T cells expressing CD8 at low levels (CD8 low ) or high levels (CD8 high ) on HIV-1 replication inhibition after HIV-1 invasion into individual.

METHODS

Nineteen patients who had been acutely infected with HIV-1 (AHI) and 20 patients with chronic infection (CHI) for ≥2 years were enrolled in this study to investigate the dynamics of the quantity, activation, and immune responses of CD3 + CD8 low T cells and their counterpart CD3 + CD8 high T cells at different stages of HIV-1 infection.

RESULTS

Compared with healthy donors, CD3 + CD8 low T cells expanded in HIV-1-infected individuals at different stages of infection. As HIV-1 infection progressed, CD3 + CD8 low T cells gradually decreased. Simultaneously, CD3 + CD8 high T cells was significantly reduced in the first month of AHI and then increased gradually as HIV-1 infection progressed. The classical activation of CD3 + CD8 low T cells was highest in the first month of AHI and then reduced as HIV-1 infection progressed and entered the chronic stage. Meanwhile, activated CD38 - HLA-DR + CD8 low T cells did not increase in the first month of AHI, and the number of these cells was inversely associated with viral load ( r = -0.664, P = 0.004) but positively associated with the CD4 T-cell count ( r = 0.586, P = 0.014). Increased programmed cell death protein 1 (PD-1) abundance on CD3 + CD8 low T cells was observed from the 1st month of AHI but did not continue to be enhanced, while a significant T cell immunoreceptor with immunoglobulin and immunoreceptor tyrosine-based inhibition motif (ITIM) domains (TIGIT) abundance increase was observed in the 12th month of infection. Furthermore, increased PD-1 and TIGIT abundance on CD3 + CD8 low T cells was associated with a low CD4 T-cell count (PD-1: r = -0.456, P = 0.043; TIGIT: r = -0.488, P = 0.029) in CHI. Nonetheless, the nonincrease in PD-1 expression on classically activated CD3 + CD8 low T cells was inversely associated with HIV-1 viremia in the first month of AHI ( r = -0.578, P = 0.015). Notably, in the first month of AHI, few CD3 + CD8 low T cells, but comparable amounts of CD3 + CD8 high T cells, responded to Gag peptides. Then, weaker HIV-1-specific T-cell responses were induced in CD3 + CD8 low T cells than CD3 + CD8 high T cells at the 3rd and 12th months of AHI and in CHI.

CONCLUSIONS

Our findings suggest that CD3 + CD8 low T cells play an anti-HIV role in the first month of infection due to their abundance but induce a weak HIV-1-specific immune response. Subsequently, CD3 + CD8 low T-cell number decreased gradually as infection persisted, and their anti-HIV functions were inferior to those of CD3 + CD8 high T cells.

Type I Natural Killer T Cells as Key Regulators of the Immune Response to Infectious Diseases

The immune system must work in an orchestrated way to achieve an optimal response upon detection of antigens. The cells comprising the immune response are traditionally divided into two major subsets, innate and adaptive, with particular characteristics for each type. Type I natural killer T (iNKT) cells are defined as innate-like T cells sharing features with both traditional adaptive and innate cells, such as the expression of an invariant T cell receptor (TCR) and several NK receptors. The invariant TCR in iNKT cells interacts with CD1d, a major histocompatibility complex class I (MHC-I)-like molecule. CD1d can bind and present antigens of lipid nature and induce the activation of iNKT cells, leading to the secretion of various cytokines, such as gamma interferon (IFN-γ) and interleukin 4 (IL-4). These cytokines will aid in the activation of other immune cells following stimulation of iNKT cells. Several molecules with the capacity to bind to CD1d have been discovered, including α-galactosylceramide. Likewise, several molecules have been synthesized that are capable of polarizing iNKT cells into different profiles, either pro- or anti-inflammatory. This versatility allows NKT cells to either aid or impair the clearance of pathogens or to even control or increase the symptoms associated with pathogenic infections. Such diverse contributions of NKT cells to infectious diseases are supported by several publications showing either a beneficial or detrimental role of these cells during diseases. In this article, we discuss current data relative to iNKT cells and their features, with an emphasis on their driving role in diseases produced by pathogenic agents in an organ-oriented fashion.