An increased frequency of NK cell receptor and HLA-C group 1 combinations in early-onset type 1 diabetes

Fifty years of HLA-associated type 1 diabetes risk: history, current knowledge, and future directions

More than 50 years have elapsed since the association of human leukocyte antigens (HLA) with type 1 diabetes (T1D) was first reported. Since then, methods for identification of HLA have progressed from cell based to DNA based, and the number of recognized HLA variants has grown from a few to tens of thousands. Current genotyping methodology allows for exact identification of all HLA-encoding genes in an individual's genome, with statistical analysis methods evolving to digest the enormous amount of data that can be produced at an astonishing rate. The HLA region of the genome has been repeatedly shown to be the most important genetic risk factor for T1D, and the original reported associations have been replicated, refined, and expanded. Even with the remarkable progress through 50 years and over 5,000 reports, a comprehensive understanding of all effects of HLA on T1D remains elusive. This report represents a summary of the field as it evolved and as it stands now, enumerating many past and present challenges, and suggests possible paradigm shifts for moving forward with future studies in hopes of finally understanding all the ways in which HLA influences the pathophysiology of T1D.

Single-cell RNAseq identifies clonally expanded antigen-specific T-cells following intradermal injection of gold nanoparticles loaded with diabetes autoantigen in humans

Gold nanoparticles (GNPs) have been used in the development of novel therapies as a way of delivery of both stimulatory and tolerogenic peptide cargoes. Here we report that intradermal injection of GNPs loaded with the proinsulin peptide C19-A3, in patients with type 1 diabetes, results in recruitment and retention of immune cells in the skin. These include large numbers of clonally expanded T-cells sharing the same paired T-cell receptors (TCRs) with activated phenotypes, half of which, when the TCRs were re-expressed in a cell-based system, were confirmed to be specific for either GNP or proinsulin. All the identified gold-specific clones were CD8+, whilst proinsulin-specific clones were both CD8+ and CD4+. Proinsulin-specific CD8+ clones had a distinctive cytotoxic phenotype with overexpression of granulysin (GNLY) and KIR receptors. Clonally expanded antigen-specific T cells remained in situ for months to years, with a spectrum of tissue resident memory and effector memory phenotypes. As the T-cell response is divided between targeting the gold core and the antigenic cargo, this offers a route to improving resident memory T-cells formation in response to vaccines. In addition, our scRNAseq data indicate that focusing on clonally expanded skin infiltrating T-cells recruited to intradermally injected antigen is a highly efficient method to enrich and identify antigen-specific cells. This approach has the potential to be used to monitor the intradermal delivery of antigens and nanoparticles for immune modulation in humans.

The dysfunction of natural killer cells is essential for the development of type 1 diabetes

Type 1 diabetes (T1D) is characterized by destruction of pancreatic insulin-producing beta cells by immune cells. In general, environmental and genetic factors can lead to immunological self-tolerance in TID. It is clear that the innate immune system, especially natural killer (NK) cells, is involved in the pathogenesis of T1D. Aberrant NK cell frequencies associated with dysregulation of inhibitory and activating receptors contribute to the initiation and progression of T1D. As T1D is incurable and the metabolic disturbances caused by T1D severely impact patients, a better understanding of NK cell behavior in T1D may facilitate disease treatment strategies. The current review focuses on the role of NK cell receptors in T1D and also highlights ongoing efforts to manipulate key checkpoints in NK cell-targeted therapies.

Association of Killer Cell Immunoglobulin-Like Receptors and Their HLA-Ligands with Type 1 Diabetes Among South Indian Population

BACKGROUND

Type 1 diabetes (T1D) is a multifactorial autoimmune disease, involving strong genetic components with familial predisposition. Killer cell immunoglobulin-like receptors (KIRs) found on the surface of NK cells have ligands of human leukocyte antigen (HLA) class I that are associated with T1D. The present study evaluates the influence of KIR genes and their HLA-ligands in the aetiology of T1D among the South Indian population.

METHODS

A total of 125 T1D patients, along with their parents (n = 126) and siblings (n = 52) were recruited. PCR-based genotyping was performed for KIR genes and HLA class I ligands. The gene frequencies were compared between patients and siblings/parents. Linkage-disequilibrium (LD) analysis was performed to assess the genetic association between KIR gene pairs.

RESULTS

The results show significant differences in HLA-ligands of KIR genes between patients and parents. The HLA-C1C1 homozygosity was found to be a predisposing risk factor, and HLA-C1C2 heterozygosity was protective towards T1D along with either the activating KIR2DS2 or inhibitory KIRs 2DL1, 2DL2, 2DL3. However, the frequency of inhibitory KIR3DL1 significantly increased in the presence of HLA-B Bw4 Ile80 in parents when compared to patients showing a protective effect on T1D. Two pairs of KIR genes, 2DS4-3DL1 and 2DS1-2DL5, showed strong LD in patients, siblings and parents.

CONCLUSION

The KIR-HLA ligand combinations have a significant effect on T1D aetiology among the South Indian population. This study defines a pattern for family-based association studies with genotypic information about KIR genes and their HLA-ligands, providing the first evidence towards T1D among the South Indian population.

Expression of Killer Immunoglobulin Receptor Genes among HIV-Infected Individuals with Non-AIDS Comorbidities

Combined antiretroviral therapy (cART) increased the life expectancy of people living with HIV (PLHIV) and remarkably reduced the morbidity and mortality associated with HIV infection. However, non-AIDS associated comorbidities including diabetes, hypertension, hyperlipidemia, and cardiovascular diseases (CVD) are increasingly reported among PLHIV receiving cART. Killer cell immunoglobulin receptors (KIRs) expressed on the surface of natural killer (NK) cells have been previously implicated in controlling HIV disease progression. The aim of this study is to investigate the role of KIRs in developing non-AIDS associated comorbidities among PLHIV. Demographic and behavioral data were collected from voluntary participants using a standardized questionnaire. Whole blood samples were collected for KIR genotyping. Hypertension (29.5%) and hyperlipidemia (29.5%) followed by diabetes (23.7%) and CVD (9.7%) were mainly reported among our study participants with higher rate of comorbid conditions observed among $\text{participants}>40$ years old. The observed KIR frequency (OF) was ≥90% for inhibitory KIR2DL1 and KIR3DL1, activating KIR2DS4 and the pseudogene KIR2DP1 among study participants. We detected significant differences in the expression of KIR3DS4 and KIR3DL1 ( $p=0.038$ ) between diabetic and nondiabetic and in the expression of KIR2DL3 between hypertensive and normotensive HIV-infected individuals ( $p=0.047$ ). Moreover, KIR2DL1 and KIR2DP1 were associated with significantly reduced odds of having CVD (OR 0.08; 95% CI: 0.01-0.69; $p=0.022$ ). Our study suggests the potential role of KIR in predisposition to non-AIDS comorbidities among PLHIV and underscores the need for more studies to further elucidate the role of KIRs in this population.

Single nucleotide polymorphism rs 2070874 at Interleukin-4 is associated with increased risk of type 1 diabetes mellitus independently of human leukocyte antigens

Introduction

Type 1 diabetes mellitus (T1DM) is characterized by autoimmune destruction of insulin-producing pancreatic beta (β-) cells. Previous studies suggested an imbalance between and pro- and anti-inflammatory cytokines exacerbates T1DM development.

Objectives

We aimed to test the hypothesis that patients with T1DM carry a higher frequency of regulatory genes associated with low levels of the anti-inflammatory cytokines interleukin-4 (IL-4), its receptor (IL-4R), and interleukin-10 (IL-10).

Methods

Accordingly, we compared frequencies of five different single nucleotide polymorphisms (SNPs) in T1DM patients and healthy controls who had been typed for HLA-DRB1, HLA-DQA1, and HLA-DQB1 genes.

Results

The frequencies of rs2070874 (IL-4) alleles C and T differed between T1DM patients and controls (^cp = 0.0065), as did their codominant (^cp = 0.026) and recessive (^cp = 0.015) models. Increased frequencies were observed in T1DM patients for HLA alleles: DRB1*03 (pc < 0.0013), DRB1*04 (^cp = 0.0169), DQA1*03 (^cp = 0.0222), DQA1*05 (^cp < 0.0006), DQB1*02 (^cp = 0.0005), and DQB1*06 (^cp < 0.0005). And lower frequencies were observed for: DRB1*07 (^cp = 0.0078), DRB1*11 (^cp = 0.0013), DRB1*13 (^cp < 0.0364), DRB1*15 (^cp < 0.0013), DQA1*01 (^cp < 0.0006), and DQA1*02 (^cp = 0.0348). Certain DRB1: DQA1: DQB1 haplotypes showed greater frequencies, including, 03:05:02 (p < 0.0001) and 04:03:03 (p = 0.0017), whereas others showed lower frequencies, including, 07:02:02 (p = 0.0032), 11:05:03 (p = 0.0007), and 15:01:06 (p = 0.0002). Stratification for the above HLA haplotypes with rs2070874 C/C exhibited no significant differences between T1DM patients overall and controls. However, when stratified for the vulnerable HLA haplotype (03:05:02/04:03:03), young patients in whom T1DM began at ≤13 years had a higher frequency of the SNP (rs2070874 C/C); a gene associated with low IL-4 production (p < 0.024).

Conclusion

This study suggests that possession of the rs2070874 C/C genotype, which is associated with low production of IL-4, increases the risk of T1DM in young individuals carrying vulnerable HLA alleles/haplotypes.

Innate immunity in latent autoimmune diabetes in adults

Latent autoimmune diabetes in adults (LADA) is an autoimmune disease that shares some genetic, immunological and clinical features with both type 1 diabetes and type 2 diabetes. Immune cells including CD4⁺ T cells, CD8⁺ T cells, B cells, macrophages and dendritic cells (DCs) have been detected in the pancreas of patients with LADA and a rat model of LADA. Therefore, similar to type 1 diabetes, the pathogenesis of LADA may be caused by interactions between islet β-cells and innate and adaptive immune cells. However, the role of the immunity in the initiation and progression of LADA remains largely unknown. In this review, we have summarized the potential roles of innate immunity and immune-modulators in LADA development. Furthermore, we have examined the evidence and discussed potential innate immunological reasons for the slower development of LADA compared with type 1 diabetes. More in-depth mechanistic studies are needed to fully elucidate the roles of innate immune-associated genes, molecules and cells in their contributions to LADA pathogenesis. Undertaking these studies will greatly enhance the development of new strategies and optimization of current strategies for the diagnosis and treatment of the disease.

Association of KIR gene polymorphisms with Type 1 Diabetes: a meta-analysis

Purpose

Type 1 Diabetes (T1D) is a T cell-mediated disease, in which autoimmune destruction of insulin-producing β-cells in pancreatic islets occurs. In recent decades, the role of Killer cell immunoglobulin-like receptor (KIR) gene polymorphisms in susceptibility to T1D has been demonstrated in an increased number of studies. Nonetheless, inconsistency has been observed in the results of performed association studies. To comprehensively clarify the association among KIR gene polymorphisms and the risk of T1D, this meta-analysis on the previously published association studies was carried out via incorporating multiple research.

Methods

No publication has been recorded from Nov 2017 until July 2020 about the KIR genes and T1D. The PubMed/MEDLINE and Scopus databases were systematically searched up to November 2017 to identify investigations on the impact of the polymorphisms of KIR genes on susceptibility to T1D. The odds ratio (OR) with a 95% confidence interval (95% CI) was calculated. Funnel plot and Egger test were used to assess the publication bias. Thirteen qualified published case-control articles were found for evaluation in this meta-analysis.

Results

Our results show statistical significance between the genetic variations in the KIR2DL1 (OR = 0.42, 95% CI = 0.23-0.77; P = 0.005), KIR2DL2 (OR = 1.15, 95% CI = 1.00-1.32; P = 0.048), and KIR2DL5 (OR = 0.86, 95% CI = 0.75-0.98; P = 0.03) with susceptibility to T1D.

Conclusions

This meta-analysis study provides reliable evidence that KIR gene polymorphisms may contribute to T1D risk. KIR 2DL1 and 2DL5 genes might be considered as a protective factor for T1D, while 2DL2 seemed to be a susceptibility factor.

Activating killer cell immunoglobulin-like receptors: Detection, function and therapeutic use

Killer cell immunoglobulin-like receptors (KIRs) have a central role in the control of natural killer (NK) cell function. The functions of the activating KIRs, as compared to those of the inhibitory KIR, have been more difficult to define due to difficulties in antibody-mediated identification and their apparent low affinities for HLA class I. Immunogenetic studies have shown associations of activating KIRs with the outcome of autoimmune diseases, pregnancy-associated disorders, infectious diseases and cancers. Activating KIR are thus thought to have important roles in the control of natural killer cell functions and their role in disease. In this review, we discuss current knowledge on activating KIR, their ligands and, their roles in the pathogenesis and potential therapy of human diseases.

Diversity and association of HLA/KIR receptors with type 2 diabetes in South India

The present study was undertaken to delineate the association(s) of KIR-HLA combination in South Indian Type 2 diabetes mellitus (T2DM) patients. The T2DM patients (n = 343) and healthy controls (n = 309) were genotyped for KIR/HLA ligands by PCR-SSP method. The increased frequency of activatory KIR (aKIR) 2DS2 (OR = 1.91; p < 2.91 × 10^-4 ) was observed in patients suggesting a susceptible association. The frequencies of iKIR 2DL2 (OR = 0.38; p < 1.55 × 10^-5 ) and aKIRs 2DS1 (OR = 0.60; p < 0.001) and 3DS1 (OR = 0.52; p < 5.83 × 10^-5 ) were decreased in patients suggesting protective associations. The C1/C2 combinatorial analysis has revealed an increased frequency of C1⁺ /C2^- in T2DM patients (OR = 1.62; p < 0.014). The KIR "AB" genotype (OR = 2.41; p < 3.87 × 10^-5 ) was observed to be higher in patients. However, the "BB" genotype (OR = 0.32; p < 4.71 × 10^-7 ) was increased in controls. The KIR motifs, "Tel-B/B" (OR = 1.84; p < 0.007), were observed higher among patients. However, the frequency of "Tel-A/B" motif genotype was decreased in patients (OR = 0.56; p < 3.13 × 10^-4 ). The iKIR/HLA combinations such as 2DL2/3 +C1 and 3DL2+A3/A11 were increased in patients (OR = 3.90; p < 7.5 × 10^-5 ) suggesting susceptible associations. On the contrary, the aKIR+HLA combinations such as 2DS2+C1, 2DS1+C2 and 3DS1+Bw4 were less frequent in patients (OR = 0.32; p < 4.2 × 10^-4 ) suggesting protective associations. Thus, the present study clearly establishes the positive and negative associations of different KIR-HLA receptor combinations with T2DM in South India.

Association between KIR gene polymorphisms and type 1 diabetes mellitus (T1DM) susceptibility: A PRISMA-compliant meta-analysis

BACKGROUND

Type 1 diabetes mellitus (T1DM) is a T-cell mediated autoimmune disease with a complex genetic and immunological background. Evidence suggests that killer cell immunoglobulin-like receptor (KIR) genes are associated with T1DM, but the results are inconsistent. Here, we conducted a meta-analysis to comprehensively evaluate the effect of KIR genes on the risk of T1DM.

METHODS

The PubMed, Web of Science, the Chinese Biomedical Database, and Chinese National Knowledge Infrastructure databases were systematically searched to select studies on the association between KIR polymorphisms and T1DM. The quality of each study was scoring in term of the Newcastle-Ottawa Scale. Pooled odds ratios (ORs) and 95% confidence intervals (CIs) were used to assess the strength of this association. Subgroup analysis stratified by ethnicity was also conducted. Funnel plot and Egger test were conducted to assess the publication bias.

RESULTS

A total of 13 independent case-control studies comprising 2076 T1DM cases and 1967 controls were included in this meta-analysis. We found a negative association between the KIR2DL1 polymorphism and susceptibility to T1DM in the overall population (OR = 0.71, 95%CI = 0.51-0.98, P = .038), but not in ethnic-specific analysis. Additionally, a negative association between the KIR2DS1 polymorphism and susceptibility to T1DM was found in the Asians (OR = 0.76, 95%CI = 0.63-0.92, P = .004), but not in the Caucasians. However, the associations could not withstand Bonferroni correction. Conversely, no association between the other KIRs genes (KIR2DL2, KIR2DL3, KIR2DL4, KIR2DL5, KIR2DS2, KIR2DS3, KIR2DS4, KIR2DS5, KIR3DL1, KIR3DL2, KIR3DL3, and KIR3DS1) and T1DM susceptibility was found in overall and subgroup ethnicity. No publication bias was detected in all comparisons.

CONCLUSIONS

In summary, this meta-analysis suggested that the KIR2DL1 and 2DS1 polymorphism might be a potential protective factor for T1DM in the specific ethnicity. Further subtle design studies with more sample size are still needed for a definitive conclusion.

Decreased percentage of NKG2D+NK cells in patients with incident onset of Type 1 Diabetes

Type 1 diabetes mellitus (T1DM) is characterized by absolute insulin deficiency owing to autoimmune destruction of the pancreatic β cells. A significant decrease in natural killer (NK) cells in peripheral blood has been observed in patients with untreated T1DM. In the present study, we aimed to explore the role of NK cells and their subsets in young T1DM patients. A total of 30 children and adolescents with untreated T1DM and 27 healthy controls (HC) were recruited in this study. Flow cytometry analysis indicated that the percentage of peripheral blood CD3-CD56+ NK cells and NK cells subsets (CD56bright, CD56dim and CD56neg), were significantly decreased in the T1DM patients compared to healthy controls. In addition, the percentage of inducible CD107a+ and IFN-γ-secreting NK cells was significantly decreased compared to HC. Interestingly, the percentage of NKG2D+ NK cells negatively correlated with the level of serum TCHOL and TG in T1DM patients. Our data indicate that decreased number and impaired function of NK cells may have a role in the pathogenesis of T1DM.

Interactions between maternal killer cell immunoglobulin receptor genes and foetal HLA ligand genes contribute to type 1 diabetes susceptibility in Han Chinese

In this study, we aimed to test the hypothesis that KIR haplotypes (that interact with HLA class I molecules) are associated with susceptibility in patients with T1DM in utero through maternal-foetal interaction of KIR and their HLA class I ligands in Han Chinese population. We determined the KIR genes and KIR/ligand gene combination frequencies in 59 Han Chinese children with T1D and their mothers and compared it with 159 healthy control children and their mothers. The absence of KIR-2DS1 in the mother and the presence of HLA-C2 ligand in the child were negatively associated with type 1 diabetes in the child. Our results indicate that maternal KIR genes and their interaction with foetal HLA-C2 may contribute to the risk of type 1 diabetes among Han Chinese children.

Investigation of activating and inhibitory killer cell immunoglobulin-like receptors and their putative ligands in type 1 diabetes (T1D)

Genetic and environmental factors play important roles in predisposing an individual to the development of type 1 diabetes (T1D). Several studies have investigated the role of killer cell immunoglobulin-like receptors (KIRs) and their HLA-class I ligands in susceptibility to T1D development, but only some of these studies have demonstrated an association. KIRs and their corresponding HLA class I ligands were investigated in Saudi patients with T1D compared with healthy controls. No significant differences in KIR gene distribution were observed between T1D patients and healthy controls. However, the homozygous C1/C1 ligand was considered a risk factor in predisposing individuals to T1D, whereas C2/C2 and HLA-Bw4 were considered protective factors against T1D. KIR2DL2/2DS2-C1C1 and KIR2DL3-C1C1 were significantly associated with T1D, and KIR2DS1-C2C2 and KIR2DL1-C2C2 were significantly less frequent in T1D patients. Stratification of KIR-HLA class I ligands in terms of the absence/presence of specific genotypes has different indications for susceptibility to T1D.

Immunogenetics of type 1 diabetes: A comprehensive review

Type 1 diabetes (T1D) results from the autoimmune destruction of insulin-producing beta cells in the pancreas. Prevention of T1D will require the ability to detect and modulate the autoimmune process before the clinical onset of disease. Genetic screening is a logical first step in identification of future patients to test prevention strategies. Susceptibility to T1D includes a strong genetic component, with the strongest risk attributable to genes that encode the classical Human Leukocyte Antigens (HLA). Other genetic loci, both immune and non-immune genes, contribute to T1D risk; however, the results of decades of small and large genetic linkage and association studies show clearly that the HLA genes confer the most disease risk and protection and can be used as part of a prediction strategy for T1D. Current predictive genetic models, based on HLA and other susceptibility loci, are effective in identifying the highest-risk individuals in populations of European descent. These models generally include screening for the HLA haplotypes "DR3" and "DR4." However, genetic variation among racial and ethnic groups reduces the predictive value of current models that are based on low resolution HLA genotyping. Not all DR3 and DR4 haplotypes are high T1D risk; some versions, rare in Europeans but high frequency in other populations, are even T1D protective. More information is needed to create predictive models for non-European populations. Comparative studies among different populations are needed to complete the knowledge base for the genetics of T1D risk to enable the eventual development of screening and intervention strategies applicable to all individuals, tailored to their individual genetic background. This review summarizes the current understanding of the genetic basis of T1D susceptibility, focusing on genes of the immune system, with particular emphasis on the HLA genes.

Association of killer cell immunoglobulin-like receptor and human leucocyte antigen-Cw gene combinations with systemic lupus erythematosus

Killer cell immunoglobulin-like receptors (KIRs) are a diverse family of activating and inhibitory receptors expressed on natural killer (NK) cells and T cells, the genes of which show extreme polymorphism. Some KIRs bind to human leucocyte antigen (HLA) class I subgroups, and genetic interactions between KIR genes and their ligand HLA have been shown to be associated with several autoimmune diseases. The present study aimed to investigate whether the combinations of KIR genes and HLA-Cw ligands associate with the susceptibility of systemic lupus erythematosus (SLE). Polymerase chain reaction using sequence-specific primers was used to determine the genotypes of KIR genes and HLA-Cw alleles. We found that the frequencies of HLA-Cw07 were statistically significantly higher in the patient group than those in the control group (P = 0·009). KIR2DS1(+) HLA(-) Cw(Lys) was more common in subjects with SLE compared to control subjects (P = 0·015). In addition, the frequency of KIR2DS1 was increased in SLE when KIR2DL1/HLA-Cw are absent, and the difference was significant (P = 0·001). KIR genotype and HLA ligand interaction may potentially influence the threshold for NK (and/or T) cell activation mediated through activating receptors, thereby contributing to the pathogenesis of SLE.

Killer cell immunoglobulin-like receptor (KIR) gene diversity in a population naturally exposed to malaria in Porto Velho, Northern Brazil

Killer cell immunoglobulin-like receptors (KIR) are expressed mainly in natural killer cells and specifically recognize human leukocyte antigen (HLA) class I molecules. The repertoire of KIR genes and KIR-HLA pairs is known to play a key role in the susceptibilities to and the outcomes of several diseases, including malaria. The aim of this study was to investigate the distribution of KIR genes, KIR genotypes and KIR-HLA pair combinations in a population naturally exposed to malaria from Brazilian Amazon. All 16 KIR genes investigated were present in the studied population. Overall, 46 KIR genotypes were defined. The two most common genotypes in the Porto Velho communities, genotypes 1 and 2, were present at similar frequencies as in the Americas. Principal component analysis based on the frequencies of the KIR genes placed the Porto Velho population closer to the Venezuela Mestizos, USA California hispanic and Brazil Paraná Mixed in terms of KIR gene frequencies. This analysis highlights the multi-ethnic profile of the Porto Velho population. Most of the individuals were found to have at least one inhibitory KIR-HLA pair. Seventy-five KIR-HLA pair combinations were identified. The KIR-2DL2/3_HLA-C1, KIR3DL1_HLA-Bw4 and KIR2DL1_HLA-C2 pairs were the most common. There was no association between KIR genes, KIR genotypes or KIR-HLA pair combinations and malaria susceptibility in the studied population. This is the first report on the distribution of KIR and known HLA ligands in the Porto Velho population. Taken together, these results should provide baseline information that will be relevant to population evolutionary history, malaria and other diseases studies in populations of the Brazilian Amazon.

Human NK cells licensed by killer Ig receptor genes have an altered cytokine program that modifies CD4+ T cell function

NK cells are innate immune cells known for their cytolytic activities toward tumors and infections. They are capable of expressing diverse killer Ig-like receptors (KIRs), and KIRs are implicated in susceptibility to Crohn's disease (CD), a chronic intestinal inflammatory disease. However, the cellular mechanism of this genetic contribution is unknown. In this study, we show that the "licensing" of NK cells, determined by the presence of KIR2DL3 and homozygous HLA-C1 in host genome, results in their cytokine reprogramming, which permits them to promote CD4(+) T cell activation and Th17 differentiation ex vivo. Microfluidic analysis of thousands of NK single cells and bulk secretions established that licensed NK cells are more polarized to proinflammatory cytokine production than unlicensed NK cells, including production of IFN-γ, TNF-α, CCL-5, and MIP-1β. Cytokines produced by licensed NK augmented CD4(+) T cell proliferation and IL-17A/IL-22 production. Ab blocking indicated a primary role for IFN-γ, TNF-α, and IL-6 in the augmented T cell-proliferative response. In conclusion, NK licensing mediated by KIR2DL2/3 and HLA-C1 elicits a novel NK cytokine program that activates and induces proinflammatory CD4(+) T cells, thereby providing a potential biologic mechanism for KIR-associated susceptibility to CD and other chronic inflammatory diseases.

A hybrid qPCR/SNP array approach allows cost efficient assessment of KIR gene copy numbers in large samples

Background

Killer Immunoglobulin-like Receptors (KIRs) are surface receptors of natural killer cells that bind to their corresponding Human Leukocyte Antigen (HLA) class I ligands, making them interesting candidate genes for HLA-associated autoimmune diseases, including type 1 diabetes (T1D). However, allelic and copy number variation in the KIR region effectively mask it from standard genome-wide association studies: single nucleotide polymorphism (SNP) probes targeting the region are often discarded by standard genotype callers since they exhibit variable cluster numbers. Quantitative Polymerase Chain Reaction (qPCR) assays address this issue. However, their cost is prohibitive at the sample sizes required for detecting effects typically observed in complex genetic diseases.

Results

We propose a more powerful and cost-effective alternative, which combines signals from SNPs with more than three clusters found in existing datasets, with qPCR on a subset of samples. First, we showed that noise and batch effects in multiplexed qPCR assays are addressed through normalisation and simultaneous copy number calling of multiple genes. Then, we used supervised classification to impute copy numbers of specific KIR genes from SNP signals. We applied this method to assess copy number variation in two KIR genes, KIR3DL1 and KIR3DS1, which are suitable candidates for T1D susceptibility since they encode the only KIR molecules known to bind with HLA-Bw4 epitopes. We find no association between KIR3DL1/3DS1 copy number and T1D in 6744 cases and 5362 controls; a sample size twenty-fold larger than in any previous KIR association study. Due to our sample size, we can exclude odds ratios larger than 1.1 for the common KIR3DL1/3DS1 copy number groups at the 5% significance level.

Conclusion

We found no evidence of association of KIR3DL1/3DS1 copy number with T1D, either overall or dependent on HLA-Bw4 epitope. Five other KIR genes, KIR2DS4, KIR2DL3, KIR2DL5, KIR2DS5 and KIR2DS1, in high linkage disequilibrium with KIR3DL1 and KIR3DS1, are also unlikely to be significantly associated. Our approach could potentially be applied to other KIR genes to allow cost effective assaying of gene copy number in large samples.

Early onset of diabetes in the proband is the major determinant of risk in HLA DR3-DQ2/DR4-DQ8 siblings

Islet autoimmunity is initiated in infancy, and primary prevention trials require children at high genetic risk to be identified before autoantibodies appear. To inform screening strategies, we evaluated risks of autoimmunity and diabetes associated with HLA DR3-DQ2/DR4-DQ8 in U.K. families. Extended HLA haplotypes were determined in 2,134 siblings from the Bart's-Oxford Study followed to a median age of 22 years. Risks of diabetes and islet autoimmunity (more than two antibodies) were estimated by survival analysis. Of 138 informative DR3-DQ2/DR4-DQ8 siblings, 63% shared both haplotypes with their diabetic proband, 29% shared one, and 8% shared neither. In HLA-identical DR3-DQ2/DR4-DQ8 siblings, the cumulative risk of diabetes by age 15 was 17% (vs. 6% in those sharing one haplotype or none; P = 0.095). Risk varied, however, with the age at the onset of diabetes in the proband; the cumulative risk of autoimmunity and/or diabetes by age 15 was 61% in siblings of probands diagnosed when younger than 10 years old compared with only 4.7% in those diagnosed after age 10 years (P < 0.001). The age of the proband at diagnosis, but not HLA haplotype sharing, was an independent determinant of sibling risk. This suggests that non-HLA genes or epigenetic/environmental factors that accelerate the progression of type 1 diabetes in the proband strongly affect risk in siblings.

High prevalence of HHV8 infection and specific killer cell immunoglobulin-like receptors allotypes in Sardinian patients with type 2 diabetes mellitus

The development of type 2 diabetes is thought to involve both environmental, possibly infectious, and genetic factors. Recently, a high prevalence of human herpesvirus 8 (HHV8) infection was observed in type 2 diabetes patients, and specific killer cell immunoglobulin-like receptors (KIR) allotypes were associated to both increased susceptibility to herpesvirus infection and risk to develop diabetes. However, no clear gene-disease or virus-disease associations have been established. To investigate the possible interplay between HHV8 infection, KIR allotype and type 2 diabetes, virus prevalence and KIR genotype were analyzed by PCR in 168 patients affected by type 2 diabetes and 108 control individuals belonging to the Sardinian population. Results showed a significant increase of HHV8 prevalence in type 2 diabetes patients versus controls (57% vs. 17%, P < 0.001), and a significant increase of KIR2DL2/DS2 homozygosity in diabetes patients infected with HHV8 compared to uninfected ones (64% vs. 14%, P < 0.0001), resulting in a significant OR of 11.31. In addition, the analysis of the frequency of the KIR2DL2/DS2 receptor and its HLA-C1 ligand, accordingly to the status of HHV8 infection, showed a significant increased correlation between KIR2DL2/DS2, type 2 diabetes and HLA-C1C1 genotype in the type 2 diabetes patients infected with HHV8 compared to uninfected ones (62% vs. 15%, P < 0.0001, OR = 8.64). These findings provide preliminary evidence that HHV8 infection might be a cofactor for type 2 diabetes in a specific subset of genetically susceptible individuals, and suggest the possibility that such patients might have an impaired immune-mediated component contributing to the development of type 2 diabetes.

Type 1 diabetes therapy beyond T cell targeting: monocytes, B cells, and innate lymphocytes

Recent clinical trials, investigating type 1 diabetes (T1D), have focused mainly on newly diagnosed individuals who have developed diabetes. We need to continue our efforts to understand disease processes and to rationally design interventions that will be safe and specific for disease, but at the same time not induce undesirable immunosuppression. T cells are clearly involved in the pathogenesis of T1D, and have been a major focus for both antigen-specific and non-antigen-specific therapy, but thus far no single strategy has emerged as superior. As T1D is a multifactorial disease, in which multiple cell types are involved, some of these pathogenic and regulatory cell pathways may be important to consider. In this review, we examine evidence for whether monocytes, B cells, and innate lymphocytes, including natural killer cells, may be suitable targets for intervention.