Natural Killer Cell Function, an Important Target for Infection and Tumor Protection, Is Impaired in Type 2 Diabetes

• Published in: PloS one Vol. 8; no. 4; p. e62418
• Main Authors: Berrou, Jeannig, Fougeray, Sophie, Venot, Marion, Chardiny, Victor, Gautier, Jean-François, Dulphy, Nicolas, Toubert, Antoine, Peraldi, Marie-Noëlle
• Format: Journal Article
• Language: English
• Published: United States Public Library of Science 25.04.2013; Public Library of Science (PLoS)
• Subjects: Adult; Aged; Bacterial infections; Biology; Blood donation; Blood donors; Comparative analysis; Complications; Defects; Degranulation; Development and progression; Diabetes; Diabetes mellitus; Diabetes Mellitus, Type 2 - genetics; Diabetes Mellitus, Type 2 - immunology; Diabetes Mellitus, Type 2 - metabolism; Diabetics; Diseases; Endoplasmic reticulum; Endoplasmic Reticulum Stress - immunology; Female; Glycosylated hemoglobin; Health aspects; Humans; Hyperglycemia; Hyperglycemia - immunology; Immune system; Infection control; Infections; Infections - immunology; Interleukin 15; Killer cells; Killer Cells, Natural - immunology; Killer Cells, Natural - metabolism; Kinases; Ligands; Lymphocytes; Male; Medicine; Middle Aged; Natural Cytotoxicity Triggering Receptor 1 - genetics; Natural Cytotoxicity Triggering Receptor 1 - metabolism; Natural killer cells; Neoplasms - immunology; NK Cell Lectin-Like Receptor Subfamily K - genetics; NK Cell Lectin-Like Receptor Subfamily K - metabolism; NKG2 antigen; Oxidative stress; Patients; Phenotype; Protein folding; Proteins; Receptors; Signal transduction; Transcription, Genetic - immunology; Transplants & implants; Tumors; Tunicamycin; Type 2 diabetes; Viral infections; Young Adult; France
• ISSN: 1932-6203; 1932-6203
• DOI: 10.1371/journal.pone.0062418

Patients with Type 2 diabetes (T2D) are highly susceptible to infection and have an increased incidence of some tumors, possibly due to immune system dysfunction. In the innate cellular immune system, Natural Killer (NK) lymphocytes are important effectors responsible for controlling infections and combating tumor development. We analyzed NK cell subsets in 51 patients with long-standing T2D. Compared with healthy blood donors, diabetic patients showed a profound decrease in both NKG2D-positive NK cells (44% vs. 55.5%, P<0.01) and NKp46-positive cells (26% vs. 50%, P<0.01). Decreased expression of these receptors was associated with functional defects, such as reduced NK degranulation capacity when challenged with the tumor target cell line K562 (10.3 vs. 15.8%, P<0.05). This defect could be restored in vitro by stimulating NK cells from T2D patients with IL-15 (P<0.05). NKG2D expression was found to be negatively correlated with HBA1c level (r=-0.50; P=0.009), suggesting that sustained hyperglycemia could directly influence NK cell defects. We demonstrated that endoplasmic reticulum (ER) stress, an important mediator in diabetes-associated complications, was inducible in vitro in normal NK cells and that tunicamycin treatment resulted in a significant decrease in NKG2D expression (P<0.05). Furthermore, markers of the Unfolded Protein Response (UPR) BiP, PDI and sXBP1 mRNAs were significantly increased in NK cells from T2D patients (P<0.05, P<0.01, P<0.05, respectively), indicating that ER stress is activated in vivo through both PERK and IRE1 sensors. These results demonstrate for the first time defects in NK cell-activating receptors NKG2D and NKp46 in T2D patients, and implicate the UPR pathway as a potential mechanism. These defects may contribute to susceptibility to infections and malignancies and could be targetted therapeutically.