Modulation of Structural and Functional Properties of Human Lymphocytes by Reactive Oxygen Species

Mechanisms of UV-induced human lymphocyte apoptosis

The article reviews the results of the studies of marker parameters (indicators) of various pathways and mechanisms of apoptosis of lymphocytes in donor peripheral blood induced by UV light (240-390 nm) in doses of 151, 1510, and 3020 J/m2. The article analyses the processes of DNA fragmentation, distortion of the structural asymmetry of the cell membranes, changes in the degree of DNA damage (single-strand breaks), transcriptional factor р53, cytochrome с, Fas receptors (CD95), caspase-3, caspase-8, and caspase-9, reactive oxygen species, and calcium ions in UV modified cells. The study determined that programmed cell death of lymphocytes after UV irradiation with 1510 J/m2 involves the р53-dependent pathway of the nuclear mechanism, as well as receptor-mediated caspase mechanism, mitochondrial mechanism, and the mechanism associated with the defects in calcium homeostasis. Cell death is mediated by reactive oxygen and calcium ions. The article suggests a scheme of possible intracellular events resulting in the apoptotic death of lymphocytes after UV irradiation.

Altered expressions of CXCR4 and CD26 on T-helper lymphocytes in hereditary hemorrhagic telangiectasia

Background

Hereditary hemorrhagic telangiectasia (HHT) is a rare genetic disease characterized by a deregulated neo-angiogenesis. Besides a mainly vascular phenotype (muco-cutaneous telangiectases, arteriovenous malformations), a specific risk of infection is suggested by case series of severe and atypical infections as well as by reports of decreased T and natural killer (NK) lymphocyte counts. As some evidence supports a dysregulation of the CXCR4/CXCL12 chemotactic axis of HHT endothelial cells, we hypothesized that a similar phenomenon could occur on lymphocytes.

Methods

Eighteen HHT patients with history of severe infection (HSI) were matched in age and sex with 18 HHT without HSI and 18 healthy control subjects (HC). We assessed the cell count and the surface expression of CXCR4 and CD26 (CXCL12 inactivating peptidase) of circulating T-helper and T-cytotoxic lymphocytes (including naive, memory and activated subsets) and NK cells.

Results

The overall HHT group of 36 patients exhibited a reduction of circulating T-helper lymphocytes compared to HC (median: 517 vs. 1026 cells/mm³, p < 0.0001), correlated with age (r =  − 0.46, p = 0.005), requirement of intravenous iron or blood transfusions (median: 291 vs. 627 cells/mm³, p = 0.03) and CXCR4 surface expression (r = 0.353, p = 0.0345). CXCR4 and CD26 membrane expression were both decreased on HHT T-helper lymphocytes (median MFI ratio: 4.49 vs. 5.74 for CXCR4 and 3.21 vs. 4.33 for CD26, p = 0.03 and 0.0018 respectively) with an unchanged CXCR4/CD26 ratio. The HHT group with HSI had a higher CXCR4/CD26 ratio on the total T-lymphocyte population, as well as on the T-helper population and its naive subset (median on naive T-helper cells: 2.34 vs. 1.32, p = 0.0002).

Conclusions

Our findings support a dysregulation of the CXCL12/CXCR4 chemotaxis of T-helper lymphocytes in HHT patients, potentially linked to their T-helper lymphopenia and susceptibility to infection.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13023-021-02139-y.