Role of natural killer cells and killer immunoglobulin-like receptor polymorphisms: association of HLA and KIRs

Diversity of KIRs in invasive breast cancer patients and healthy controls along with the clinical significance in ER/PR/HER2+ patients

Killer cell immunoglobulin-like receptors (KIR) consists of activating and inhibitory genes are essential for natural killer cell education. To determine the association of KIRs with susceptibility to invasive Breast cancer (BC), genotyping of 16 KIRs was performed by sequence-specific primers-polymerase chain reaction in 226 confirmed cases of BC with defined estrogen receptor (ER), progesterone receptor (PR), and human epidermal growth factor 2 (HER2) status and 226 healthy controls (CNs). We observed a lower frequency of 2DL1 and 2DS4del along with increased frequency of 2DS4fl in cases compared to CNs. Further analysis revealed a higher frequency of KIR2DL2, 2DS1, 2DS2,3DS1 in ER+ cases, 2DL2, 2DL5 in PR+ and 2DL1 in HER2+ cases compared to CNs. The detrimental role of KIR2DS4fl was observed in ER+ and PR+ cases whereas 2DS4del confers protection against ER+, PR+, and HER2+ cases. We noted the predisposing role of Bx genotype, KIR2DS1, 2DS2, 2DS5, 2DL2, 2DL5 for lymphatic invasion in ER+ cases along with a higher rate of lymph node metastasis (LNM) in carriers of Bx genotype and KIR2DS1 in ER+ cases. We suggest a link between B haplotype associated genes with the increased risk of lymphatic invasion and LNM, particularly in ER+ cases of BC.

Killer immunoglobulin-like receptors/human leukocyte antigen class-I, a crucial immune pathway in cancer

Natural killer cells (NK cells) play a crucial role in tumor immunity. The function of the NK cells is regulated by various receptors expressed on the surface. Among them, the killer immunoglobulin-like receptor (KIR) is one of the most important. The ligand of KIR is major histocompatibility complex class-I (MHC class-I), which is also called human leukocyte antigen class-I (HLA class-I). The combination of HLA class-I and inhibitory KIRs could inhibit NK cells and induce autoimmune tolerance. Inhibitory KIRs were highly expressed on malignant tumor patients, which were related to poor prognosis. KIR/HLA class-I pathway affected the clinical outcomes of cancer through several mechanisms, and inhibitory KIRs could be an ideal target of immunotherapy strategy.

Impact of "Killer Immunoglobulin-Like Receptor /Ligand" Genotypes on Outcome following Surgery among Patients with Colorectal Cancer: Activating KIRs Are Associated with Long-Term Disease Free Survival

Approximately 30 % of patients with stage II/III colorectal cancer develop recurrence following surgery. How individual regulation of host mediated anti-tumor cytotoxicity is modified by the killer-cell immunoglobulin-like receptor (KIRs) genotype is essential for prediction of outcome. We analyzed the frequency of KIR and KIR ligand Human Leukocyte Antigen Class I genotypes, and their effects on recurrence and disease-free survival (DFS). Out of randomly selected 87 colorectal cancer patients who underwent R0 resection operations between 2005 and 2008, 29 patients whose cancers progressed within a median five-year follow-up period were compared with 58 patients with no recurrence within the same time period. Recurrent cases shared similar tumor stages with non-recurrent cases, but had different localizations. We used DNA isolated from pathological archival lymphoid and tumor tissues for KIR and KIR ligand (HLA-C, group C1, group C2, and HLA-A-Bw4) genotyping. Among cases with recurrence, KIR2DL1 (inhibitory KIR) and A-Bw4 (ligand for inhibitory KIR3DL1) were observed more frequently (p=0.017 and p=0.024); and KIR2DS2 and KIR2DS3 (both activating KIRs) were observed less frequently (p=0.005 and p=0.043). Similarly, in the non-recurrent group, inhibitory KIR-ligand combinations 2DL1-C2 and 2DL3-C1 were less frequent, while the activating combination 2DS2-C1 was more frequent. The lack of KIR2DL1, 2DL1-C2, and 2DL3-C1 improved disease-free survival (DFS) (100% vs. 62.3%, p=0.05; 93.8% vs. 60.0%, p=0.035; 73.6% vs. 55.9%, p=0.07). The presence of KIR2DS2, 2DS3, and 2DS2-C1 improved DFS (77.8% vs. 48.5%, p=0.01; 79.4% vs. 58.5%, p=0.003; 76.9% vs. 51.4%, p=0.023). KIR2DS3 reduced the risk of recurrence (HR=0.263, 95% CI = 0.080-0.863, p=0.028). The number of activating KIRs are correlated strongly with DFS, none/ one/ two KIR : 54/77/98 months (p=0.004). In conclusion the inheritance of increasing numbers of activating KIRs and lack of inhibitory KIRs, independent of tumor localization or stage, is associated with long-term DFS.

Infectious diseases and Type 1 diabetes in children

Type 1 diabetes (T1D) is an autoimmune disease triggered by environmental factors. Among those of infectious origin, viruses mostly associated to T1D are rubella virus, enteroviruses (Rotavirus, Coxackie B), Cytomegalovirus and mumps virus. The role of bacterial infections is still controversial, acting either as modulators or precipitating factors of an already started autoimmune process. Polymorphic genes of innate immunity, such as Toll-like receptors, nucleotide-binding oligomerization domain (NOD) 1 and NOD2 and mannose-binding lectin (MBL) genes, did not show a strict association with T1D onset, while protein tyrosine phosphatase (PTPN22), cytotoxic T-lymphocyte antigen (CTLA)4 and natural killer cells immunoglobulin-like receptor (KIR) genes appear to play an important role. However, the adaptive immune response genes (HLA) still provide the major contribution to T1D susceptibility. Here, we review the mechanism by which microorganisms might induce autoimmunity.