Killer immunoglobulin-like receptor and human leukocyte antigen-C genotypes in rheumatoid arthritis primary responders and non-responders to anti-TNF-α therapy

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.

The Influence of KIR Gene Polymorphisms and KIR-ligand Binding on Outcomes in Hematologic Malignancies following Haploidentical Stem Cell Transplantation: A Comprehensive Review

Natural killer (NK) cell behavior and function are controlled by a balance between negative or positive signals generated by an extensive array of activating and inhibiting receptors, including killer cell immunoglobulin-like receptor (KIR) proteins, main components of the innate immune system that contribute to initial responses against viral infected-transformed cells through generation of the release of cytokines and cytotoxicity. What is certain is that KIRs are genetically polymorphic and the extent of KIRs diversity within the individuals may have the potential outcomes for hematopoietic stem cell transplantation (HSCT). In this regard, recent studies suggest that KIR is as imperative as its ligand (HLA) in stem cell transplantation for malignant diseases. However, unlike HLA epitope mismatches, which are well-known causes of NK alloreactivity, a complete understanding of KIR genes' role in HSCT remains unclear. Because of genetic variability in KIR gene content, allelic polymorphism, and cell-surface expression among individuals, an appropriate selection of donors based on HLA and KIR profiles is crucial to improve outcomes of stem cell transplantation. In addition, the impact of the KIR/HLA interaction on HSCT outcomes needs to be investigated more comprehensively. The present work aimed to review the NK cell regeneration, KIR gene polymorphisms, and KIRligand binding on outcomes in hematologic malignancies following haploidentical stem cell transplantation. Comprehensive data gathered from the literature can provide new insight into the significance of KIR matching status in transplantations.

Gene Ontology Analysis Highlights Biological Processes Influencing Non-Response to Anti-TNF Therapy in Rheumatoid Arthritis

Anti-TNF therapy has significantly improved disease control in rheumatoid arthritis, but a fraction of rheumatoid arthritis patients do not respond to anti-TNF therapy or lose response over time. Moreover, the mechanisms underlying non-response to anti-TNF therapy remain largely unknown. To date, many single biomarkers of response to anti-TNF therapy have been published but they have not yet been analyzed as a system of interacting nodes. The aim of our study is to systematically elucidate the biological processes underlying non-response to anti-TNF therapy in rheumatoid arthritis using the gene ontologies of previously published predictive biomarkers. Gene networks were constructed based on published biomarkers and then enriched gene ontology terms were elucidated in subgroups using gene ontology software tools. Our results highlight the novel role of proteasome-mediated protein catabolic processes (p = 2.91 × 10⁻¹⁵) and plasma lipoproteins (p = 4.55 × 10⁻¹¹) in anti-TNF therapy response. The results of our gene ontology analysis help elucidate the biological processes underlying non-response to anti-TNF therapy in rheumatoid arthritis and encourage further study of the highlighted processes.

Rheumatoid Arthritis Susceptibility Is Associated with the KIR2DS4-Full of Killer-Cell Immunoglobulin-Like Receptor Genes in the Lur Population of Iran

Background

The pathophysiology underlying the progression and development of autoimmune conditions, such as Rheumatoid Arthritis (RA), is a result of dysregulations of the immune system. Research has explored the genetic alterations present in RA; however, limited studies have examined the role of Killer cell Immunoglobulin-like Receptors (KIR) and Human Leukocyte Antigen (HLA) molecules in RA. Therefore, the aim of this study was to examine KIR genes, their HLA ligands, and KIR-HLA compounds in patients with RA.

Methods

In this case-control study, a total of 50 patients with RA and 100 healthy individuals were enrolled. DNA samples were evaluated using PCR with sequence specific Primers (PCR-SSP). Odds ratio (OR) with a 95% confidence interval (CI) were reported.

Results

Among the KIR genes examined, KIR2DLA (p= 0.0255, OR= 0.389, 95% CI= 0.210-0.722) and KIR2DS4-full (p< 0.0001, OR= 6.163, 95% CI= 3.174-11.968) were observed to have a statistically significant correlation with disease susceptibility to RA. As an inhibitory gene, KIR2DLA was observed to have a protective effect against RA while KIR2DS4-full as an activating gene, was found to increase risk for RA. No significant associations were found between any of the other KIR genotypes, HLA ligands, or KIR-HLA compounds examined in this study to RA susceptibility.

Conclusion

In this study of RA in the Lur population of Iran, KIR2DS4-full was observed to increase susceptibility to RA, while KIR2DL5A was found to act as a protecting factor based on both the cross Table and regression analyses. Further research should focus on repeating this study in additional populations.

Allelic polymorphisms of KIRs and antitumor immunity against chronic myeloid leukemia

The development of BCR-ABL1 tyrosine kinase inhibitors (TKIs) markedly improved the prognosis of patients with chronic myeloid leukemia (CML). Approximately 50% of patients who achieve deep molecular response (DMR) remain in treatment-free remission (TFR) even after discontinuation of TKIs. Although TKIs may achieve clinical "cure" after TKI treatment for specific periods, there are no reliable biomarkers for predicting the response to TKIs and the probability of TFR in CML. An increase in natural killer (NK) cells in the peripheral blood of TKI-treated CML patients is correlated with better outcomes, suggesting that TKIs induce antitumor NK cell immunity against CML cells. Killer immunoglobulin-like receptors (KIRs) are highly polymorphic NK cell receptors that play important roles in the regulation of immune responses. The identification of allelic polymorphisms of KIRs by next-generation sequencing uncovered novel aspects of KIRs. Here we summarize the current knowledge of the genetic and immunological aspects of KIRs and discuss the association between allelic polymorphisms of KIRs and TKI-treated CML.

HLA-C: An Accomplice in Rheumatic Diseases

Human leukocyte antigen c (HLA-C) is a polymorphic membrane protein encoded by the HLA-C gene in the class I major histocompatibility complex. HLA-C plays an essential role in protection against cancer and viruses but has also been implicated in allograft rejection, preeclampsia, and autoimmune disease. This review summarizes reports and proposed mechanisms for the accessory role of HLA-C in rheumatic diseases. Historically, contributions of HLA-C to rheumatic diseases were eclipsed by the stronger association with HLA-DRB1 alleles containing the "shared epitope" with rheumatoid arthritis. Larger genetic association studies and more powerful analytical approaches have revealed independent associations of HLA-C with rheumatic disease-associated phenotypes, including development of anticitrullinated peptide antibodies. HLA-C functions by presenting antigens to T cells and by binding activatory and inhibitory receptors on natural killer (NK) cells, but the exact mechanisms by which the HLA-C locus contributes to autoimmunity are largely undefined. Studies have suggested that HLA-C and NK cell receptor polymorphisms may predict responsiveness to pharmacotherapy. Understanding the mechanisms of the role of HLA-C in rheumatic disease could uncover therapeutic targets or guide precision pharmacologic treatments.

Influence of NKG2D Genetic Variants on Response to Anti-TNF Agents in Patients with Rheumatoid Arthritis

A natural killer group 2 member D (NKG2D) acts as a powerful activating and co-stimulatory receptor on immune effector cells including NK and T cells. Disruptions within the NKG2D signalling pathway may trigger an exacerbated immune response and promote autoimmune reactions. The objective of the study was to evaluate a plausible role of polymorphisms within the NKG2D gene as a predictor of how effective anti-tumor necrosis factor (TNF) therapy is in rheumatoid arthritis (RA) patients. A total of 280 RA patients receiving anti-TNF therapy were genotyped for NKG2D rs2255336 (A > G), rs1049174 (C > G), and rs1154831 (C > A). Clinical response was evaluated according to the European League against Rheumatism (EULAR) criteria at the 12th and 24th week. Both the NKG2D rs225336 and rs1049174 polymorphisms were significantly associated with efficacy of TNF inhibitors. Inefficient therapy was more frequently observed in patients with rs2255336 GG or rs1049174 CC genotype as compared to other genotypes (p-value = 0.003 and p-value = 0.004, respectively). The presence of the rs2255336 G or the rs1049174 C allele correlated with a worse EULAR response (p-value = 0.002, p-value = 0.031, respectively). Moreover, patients carrying the rs2255336 or rs1049174 heterozygous genotype achieved better EULAR responses than patients with homozygous genotypes (p-value = 0.010 and p-value = 0.002, respectively). Data from the present study provides evidence that NKG2D polymorphisms may affect response to anti-TNF inhibitors in RA patients.

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.

KIR2DL2 and KIR2DS2 as genetic markers to the methotrexate response in rheumatoid arthritis patients

CONTEXT

Disease Modifying Anti-Rheumatic Drugs (DMARDs) are aimed to interfere with rheumatoid arthritis (RA) progression and reduce the joint damage; however, not all patients respond alike. Killer-cell immunoglobulin-like receptors (KIR) and their ligands, human leucocyte antigen class I (HLA-I), have been associated with RA pathology; therefore, KIR and HLA genes may influence the treatment response.

MATERIALS AND METHODS

We evaluated the association of KIR genotype and their ligands HLA-C genes with the response to DMARDs in RA patients. We included 69 patients diagnosed with RA and 82 healthy individuals as the reference group. KIR and HLA-C genotyping was performed using SSP-PCR. RA patients were assessed at baseline and under treatment at 6 and 12 months; subsequently classified as responders and non-responders in each time period. We evaluated the association between DMARD response and genes using statistical analysis by using Fisher exact test with Bonferroni correction; results were regarded as statistically significant at p < 0.05.

RESULTS

Significant difference was observed in gene frequencies of patients and the reference group, KIR2DL2 was associated with RA (p = 0.031, OR = 2.119). We also observed an association between KIR2DS2 and the response to methotrexate (MTX), moreover, the combination KIR2DL2+/KIR2DS2+ was more frequent in responders to MTX (p = 0.043).

DISCUSSION AND CONCLUSIONS

In our results, responders and non-responders to DMARDs showed KIR2DS2 and KIR2DL2 different gene frequencies, therefore, these genes could be used as response predictors to DMARDs treatment. Thus, these genes were also associated with disease severity, as well as the treatment response possibly by the immunoregulatory function of NK cells.

Genetic polymorphism and evolutionary differentiation of Eastern Chinese Han: a comprehensive and comparative analysis on KIRs

Killer cell immunoglobulin-like receptor genes, namely KIRs, cluster together within the 160 kb genomic DNA region. In this study, we used PCR-SSP approach and successfully identified the genotype of 17 KIR genes in 123 independent healthy donors residing in the Jiangsu province, China. All individuals were positive at the 7 genes. The observed carrier gene frequencies (OFs) of remaining 10 KIRs ranged from 14.63% (KIR2DS3) to 95.93% (KIR3DL1). We found 27 distinct genotypes excluding KIR1D. The most frequent occurred in 63 individuals (51.22%). The linkage disequilibrium analysis signified 29 positive and 6 negative relations in 45 pairwise comparisons. To study population differentiation, we drew a Heatmap based on the data of KIRs from 59 populations and conducted Hierarchical Clustering by Euclidean distances. We next validated our results by estimating pairwise D_A distances and illustrating a Neighbor-Joining tree, as well as a MDS plot covering 3 additional Chinese Han groups. The phylogenetic reconstruction and cluster analysis strongly indicated a genetically close relationship between Eastern and Jilin Hans. In conclusion, the present study provided a meritorious resource of KIR genotyping for population genetics, and could be helpful to uncover the genetic mechanism of KIRs in immune disease in the future.

Analysis of killer cell immunoglobulin-like receptors (KIRs) and their HLA ligand genes polymorphisms in Iranian patients with systemic sclerosis

Genetic factors have a great role in the pathogenesis of autoimmune diseases by cooperating with environmental stimuli. Killer immunoglobulin-like receptors (KIRs) are cell surface proteins on NK cells whose association with major histocompatibility complex-I regulates their killing function. The aim of this study was to provide information on the possible association between KIR and human leukocyte antigen (HLA) genes with systemic sclerosis disease in Iranian population. A total of 279 systemic sclerosis patients and 451 healthy controls were enrolled in this case-control study in order to determine the presence or absence of 19 KIR genes and 6 specific HLA class I ligands. DNA was analyzed by polymerase chain reaction using the specific sequence primer method (PCR-SSP). Among 11 discovered KIR genotypes, 6 genotypes showed a considerable role and 4 genotypes could preclude the risk of systemic sclerosis (SSc) disease. The gene-gene interactions were also analyzed, and significant confounding effects were seen between involved genes in these two combinations: "KIR3DL1; HLA-BW4-Thr80" and "KIR3DL1 -HLA-BW4-A1." None of single KIR genes showed significant effect on the risk of SSc. We conclude that there is an important relationship between KIR genes and their HLA ligands with incidence rate of systemic sclerosis in Iranian population. The powerful role of a number of discovered KIR/HLA compounds such as activating KIR genotype 3 and HLA-BW4-A1 confirmed the provocative hypothesis of the interplay between activating or inhibitory KIR genes with HLA ligands as a critical index of systemic sclerosis predisposition.

Analysis of killer cell immunoglobulin-like receptors and their human leukocyte antigen-ligands gene polymorphisms in Iranian patients with systemic lupus erythematosus

Objective

Systemic lupus erythematosus (SLE) is an inflammatory autoimmune disease. Natural killer (NK) cells play a critical role in the pathogenesis of autoimmune disorders that mainly express killer cell immunoglobulin-like receptors (KIRs). The present study was undertaken to determine the association of the KIR alleles, genotypes, and KIR–human leukocyte antigen ( HLA) ligand gene combinations with the susceptibility to SLE.

Methods

The genotyping of 17 KIR and 5 HLA loci was performed using the polymerase chain reaction-sequence specific primer (PCR-SSP) method. The study population consisted of 230 SLE patients and 273 ethnical-, age-, and sex-matched healthy controls. The association of the polymorphisms with the prevalence of 11 clinical criteria in patients was analyzed.

Results

The carrier frequency of HLA-A-Bw4 was modestly decreased in the SLE patients. The prevalence of hematological and renal disorders was significantly increased in patients with combination of KIR3DL1+; HLA-B-Bw4Thr80+ and KIR2DS1+; HLA-C2+ genes, respectively. Female patients with combination of KIR2DL2+; HLA-C1− genes were more likely to develop serositis. In addition the prevalence of renal disorders, oral ulcer and serositis was significantly increased in male patients with KIR3DP1+, KIR2DS1+, and KIR2DS3+ genotypes respectively.

Conclusion

Our results showed that the presence of activating KIR receptors alone or in combination with their HLA ligands and the absence of inhibitory KIRs in combination with their HLA ligands may activate NK cells and are significantly correlated with the prevalence of renal disease, hematologic disorders, serositis, and oral ulcer in SLE patients.

Association of Killer Cell Immunoglobulin- Like Receptor Genes in Iranian Patients with Rheumatoid Arthritis

Objectives

Rheumatoid arthritis (RA) is a chronic inflammatory disorder characterized by persistent synovitis, ultimately leading to cartilage and bone degeneration. Natural Killer cells and CD28 null T-cells are suspected as role players in RA pathogenesis. These cells are similar in feature and function, as they both exert their cytotoxic effect via Killer Cell Immunoglobulin- Like Receptors (KIR) on their surface. KIR genes have either an inhibitory or activating effect depending on their intracytoplasmic structure. Herein we genotyped 16 KIR genes, 3 pseudo genes and 6 HLA class І genes as their corresponding ligands in RA patients and control subjects.

Methods

In this case-control study, KIR and HLA genes were genotyped in 400 RA patients and 372 matched healthy controls using sequence-specific primers (SSP-PCR). Differences in the frequency of genes and haplotypes were determined by χ² test.

Results

KIR2DL2, 2DL5a, 2DL5b and activating KIR: KIR2DS5 and 3DS1 were all protective against RA. KIR2DL5 removal from a full Inhibitory KIR haplotype converted the mild protection (OR = 0.56) to a powerful predisposition to RA (OR = 16.47). Inhibitory haplotype No. 7 comprising KIR2DL5 in the absence of KIR2DL1 and KIR2DL3 confers a 14-fold protective effect against RA.

Conclusion

Individuals carrying the inhibitory KIR haplotype No. 6 have a high potential risk for developing RA.

Biomarkers in rheumatic diseases: how can they facilitate diagnosis and assessment of disease activity?

Serological and proteomic biomarkers can help clinicians diagnose rheumatic diseases earlier and assess disease activity more accurately. These markers have been incorporated into the recently revised classification criteria of several diseases to enable early diagnosis and timely initiation of treatment. Furthermore, they also facilitate more accurate subclassification and more focused monitoring for the detection of certain disease manifestations, such as lung and renal involvement. These biomarkers can also make the assessment of disease activity and treatment response more reliable. Simultaneously, several new serological and proteomic biomarkers have become available in the routine clinical setting--for example, a protein biomarker panel for rheumatoid arthritis and a myositis antibody panel for dermatomyositis and polymyositis. This review will focus on commercially available antibody and proteomic biomarkers in rheumatoid arthritis, systemic lupus erythematosus, systemic sclerosis (scleroderma), dermatomyositis and polymyositis, and axial spondyloarthritis (including ankylosing spondylitis). It will discuss how these markers can facilitate early diagnosis as well as more accurate subclassification and assessment of disease activity in the clinical setting. The ultimate goal of current and future biomarkers in rheumatic diseases is to enable early detection of these diseases and their clinical manifestations, and to provide effective monitoring and treatment regimens that are tailored to each patient's needs and prognosis.

Randomised controlled trial of tumour necrosis factor inhibitors against combination intensive therapy with conventional disease-modifying antirheumatic drugs in established rheumatoid arthritis: the TACIT trial and associated systematic reviews

BACKGROUND

Rheumatoid arthritis (RA) is initially treated with methotrexate and other disease-modifying antirheumatic drugs (DMARDs). Active RA patients who fail such treatments can receive tumour necrosis factor inhibitors (TNFis), which are effective but expensive.

OBJECTIVE

We assessed whether or not combination DMARDs (cDMARDs) give equivalent clinical benefits at lower costs in RA patients eligible for TNFis.

DESIGN

An open-label, 12-month, pragmatic, randomised, multicentre, two-arm trial [Tumour necrosis factor inhibitors Against Combination Intensive Therapy (TACIT)] compared these treatment strategies. We then systematically reviewed all comparable published trials.

SETTING

The TACIT trial involved 24 English rheumatology clinics.

PARTICIPANTS

Active RA patients eligible for TNFis.

INTERVENTIONS

The TACIT trial compared cDMARDs with TNFis plus methotrexate or another DMARD; 6-month non-responders received (a) TNFis if in the cDMARD group; and (b) a second TNFi if in the TNFi group.

MAIN OUTCOME MEASURES

The Heath Assessment Questionnaire (HAQ) was the primary outcome measure. The European Quality of Life-5 Dimensions (EQ-5D), joint damage, Disease Activity Score for 28 Joints (DAS28), withdrawals and adverse effects were secondary outcome measures. Economic evaluation linked costs, HAQ changes and quality-adjusted life-years (QALYs).

RESULTS

In total, 432 patients were screened; 104 started on cDMARDs and 101 started on TNFis. The initial demographic and disease assessments were similar between the groups. In total, 16 patients were lost to follow-up (nine in the cDMARD group, seven in the TNFi group) and 42 discontinued their intervention but were followed up (23 in the cDMARD group and 19 in the TNFi group). Intention-to-treat analysis with multiple imputation methods used for missing data showed greater 12-month HAQ score reductions with initial cDMARDs than with initial TNFis [adjusted linear regression coefficient 0.15, 95% confidence interval (CI) -0.003 to 0.31; p = 0.046]. Increases in 12-month EQ-5D scores were greater with initial cDMARDs (adjusted linear regression coefficient -0.11, 95% CI -0.18 to -0.03; p = 0.009) whereas 6-month changes in HAQ and EQ-5D scores and 6- and 12-month changes in joint damage were similar between the initial cDMARD group and the initial TNFi group. Longitudinal analyses (adjusted general estimating equations) showed that the DAS28 was lower in the initial TNFi group in the first 6 months (coefficient -0.63, 95% CI -0.93 to -0.34; p < 0.001) but there were no differences between the groups in months 6-12. In total, 36 patients in the initial cDMARD group and 44 in the initial TNFi group achieved DAS28 remission. The onset of remission did not differ between groups (p = 0.085 on log-rank test). In total, 10 patients in the initial cDMARD group and 18 in the initial TNFi group experienced serious adverse events; stopping therapy because of toxicity occurred in 10 and six patients respectively. Economic evaluation showed that the cDMARD group had similar or better QALY outcomes than TNFi with significantly lower costs at 6 and 12 months. In the systematic reviews we identified 32 trials (including 20-1049 patients) on early RA and 19 trials (including 40-982 patients) on established RA that compared (1) cDMARDs with DMARD monotherapy; (2) TNFis/methotrexate with methotrexate monotherapy; and (3) cDMARDs with TNFis/methotrexate. They showed that cDMARDs and TNFis had similar efficacies and toxicities.

CONCLUSIONS

Active RA patients who have failed methotrexate and another DMARD achieve equivalent clinical benefits at a lower cost from starting cDMARDs or from starting TNFis (reserving TNFis for non-responders). Only a minority of patients achieve sustained remission with cDMARDs or TNFis; new strategies are needed to maximise the frequency of remission.

TRIAL REGISTRATION

Current Control Trials ISRCTN37438295.

FUNDING

This project was funded by the National Institute for Health Research Health Technology Assessment programme and will be published in full in Health Technology Assessment; Vol. 18, No. 66. See the NIHR Journals Library website for further project information.

Current and future trends in biomarker discovery and development of companion diagnostics for arthritis

Musculoskeletal diseases such as rheumatoid arthritis are complex multifactorial disorders that are chronic in nature and debilitating for patients. A number of drug families are available to clinicians to manage these disorders but few tests exist to target these to the most responsive patients. As a consequence, drug failure and switching to drugs with alternate modes of action is common. In parallel, a limited number of laboratory tests are available which measure biological indicators or 'biomarkers' of disease activity, autoimmune status, or joint damage. There is a growing awareness that assimilating the fields of drug selection and diagnostic tests into 'companion diagnostics' could greatly advance disease management and improve outcomes for patients. This review aims to highlight: the current applications of biomarkers in rheumatology with particular focus on companion diagnostics; developments in the fields of proteomics, genomics, microbiomics, imaging and bioinformatics and how integration of these technologies into clinical practice could support therapeutic decisions.

Presence of the full-length KIR2DS4 gene reduces the chance of rheumatoid arthritis patients to respond to methotrexate treatment

Background

KIR genes coding for natural killer cell immunoglobulin-like receptors, KIR, influence the effector and regulatory function of NK cells as well as some subpopulations of T lymphocytes (e.g. CD4+CD28-KIR+) depending on presence of ligands (particularly HLA-C molecules). KIR-KIR ligand interaction may lead to the development of autoimmune disorders, including rheumatoid arthritis (RA). However, their role in the response of RA patients to methotrexate therapy is not known.

Methods

KIR genes and KIR-ligand (HLA-C C1/C2 allomorphs) genotyping was performed using the PCR-SSP method in 312 RA patients (179 classified as good responders and 133 as poor responders using DAS28 criteria). Thus, we evaluated the association of KIR genes and HLA-C allomorphs with the response to methotrexate (MTX) treatment.

Results

We observed that patients possessing the full-length KIR2DS4 (KIR2DS4f) gene had a lower chance of responding in comparison to KIR2DS4f-negative cases. This phenomenon was observed both in erosive disease (ED) and rheumatoid factor (RF) positive and in ED- and RF-negative patients. Interestingly, the observed effect of the KIR2DS4f gene was strongest in individuals possessing medium values (20-33 mm/h) of the erythrocyte sedimentation rate (ESR). Patients with high ESR values had low probability and, in contrast, patients with low ESR had a high probability of MTX response, and the presence of KIR2DS4f did not affect their outcome. Additionally, we show that the KIR2DS4f effect did not depend on the presence of either C1 or C2 allomorphs.

Conclusion

Our results suggest that the response of RA patients with medium ESR values to MTX treatment may be dependent on the full-length KIR2DS4 gene.

One size fits one: pharmacogenetics in gastroenterology

Individual variability in response and development of adverse effects to drugs is a major challenge in clinical practice. Pharmacogenomics refers to the aspect of personalized medicine where the patient's genetic information instructs the selection and dosage of therapy while also predicting its adverse effects profile. Sequencing of the entire human genome has given us the opportunity to study commonly used drugs as well as newer therapeutic agents in a new light, opening up opportunities for better drug efficacy and decreased adverse effects. This article highlights developments in pharmacogenomics, relates these to practice of gastroenterology, and outlines roadblocks in translation of this knowledge into clinical practice.