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Objective: The aim of this study was to investigate whether a shared genetic susceptibility exists between individuals with rheumatoid arthritis (RA) and individuals with myocardial infarction (MI)—including major MI risk factors—and to quantify the degree of any such overlap. Methods: Genome‐wide association study (GWAS) data for individuals with RA were constructed from a sample of 26,637 Swedish patients with RA and controls without RA. For patients with MI, GWAS data were obtained from a previously published meta‐analysis. Genome‐wide genetic correlation was estimated via linkage disequilibrium score regression. LAVA was employed to estimate local genetic correlations in ~2,500 nonoverlapping loci, including the major histocompatibility complex. The controls without RA were used for reference panel data. We also assessed stratified estimates of both genome‐wide and local genetic correlation based on subsamples of individuals with seropositive RA and those with seronegative RA. Furthermore, genome‐wide genetic correlation was estimated between RA and selected cardiovascular risk factors to elucidate pleiotropic relationships. Results: Following quality control, our GWAS of patients with RA consisted of 25,826 individuas. Genome‐wide genetic correlation between patients with RA and MI was estimated to 0.13 (95% confidence interval –0.03 to 0.29). Six regions exhibited significant local genetic correlation, though none harbored any known risk single‐nucleotide polymorphisms for either of the two traits. Estimates were similar in both individuals with seropositive RA and those with seronegative RA. No statistically significant genetic correlations were observed between RA risk factors and any of the MI risk factors. Conclusion: Our findings indicate that genetic overlap between patients with RA and MI is minor. Furthermore, genetic overlap between RA and MI risk factors seem unlikely to provide a major contribution to the increased risk of MI observed in patients with RA. [ABSTRACT FROM AUTHOR]

Human neutrophils are components of the innate immune system and are the most abundant white blood cells in the circulation. They are professional phagocytes and express several G protein‐coupled receptors (GPCRs), which are essential for proper neutrophil functions. So far, the two formyl peptide receptors, FPR1 and FPR2, have been the most extensively studied group of neutrophil GPCRs, but recently, a new group, the free fatty acid (FFA) receptors, has attracted growing attention. Neutrophils express two FFA receptors, GPR84 and FFA2, which sense medium‐ and short‐chain fatty acids respectively, and display similar activation profiles. The exact pathophysiological role of GPR84 is not yet fully understood, but it is generally regarded as a pro‐inflammatory receptor that mediates neutrophil activation. In this review, we summarize current knowledge of how GPR84 affects human neutrophil functions and discuss the regulatory mechanisms that control these responses, focusing on the similarities and differences in comparison to the two FPRs and FFA2. LINKED ARTICLES: This article is part of a themed issue GPR84 Pharmacology. To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v181.10/issuetoc [ABSTRACT FROM AUTHOR]

Summary: Neutrophils, the most abundant white blood cell in human blood, express receptors that recognize damage/microbial associated pattern molecules of importance for cell recruitment to sites of inflammation. Many of these receptors belong to the family of G protein coupled receptors (GPCRs). These receptor‐proteins span the plasma membrane in expressing cells seven times and the down‐stream signaling rely in most cases on an activation of heterotrimeric G proteins. The GPCRs expressed in neutrophils recognize a number of structurally diverse ligands (activating agonists, allosteric modulators, and inhibiting antagonists) and share significant sequence homologies. Studies of receptor structure and function have during the last 40 years generated important information on GPCR biology in general; this knowledge aids in the overall understanding of general pharmacological principles, governing regulation of neutrophil function and inflammatory processes, including novel leukocyte receptor activities related to ligand recognition, biased/functional selective signaling, allosteric modulation, desensitization, and reactivation mechanisms as well as communication (receptor transactivation/cross‐talk) between GPCRs. This review summarizes the recent discoveries and pharmacological hallmarks with focus on some of the neutrophil expressed pattern recognition GPCRs. In addition, unmet challenges, including recognition by the receptors of diverse ligands and how biased signaling mediate different biological effects are described/discussed. [ABSTRACT FROM AUTHOR]

The article focuses on a study which investigated whether serum amyloid A (SAA) in the plasma of patients with rheumatoid arthritis (RA) possesses proinflammatory properties and activates neutrophils in a manner similar to that of the recombinant protein. To monitor neutrophil activation based on L-selectin shedding from cell surfaces, the researchers used flow cytometry. Potent induction of cleavage of L-selection from neutrophils and in whole blood samples due to recombinant SAA was observed.

The authors reflect on the role of neutrophils or phagocyte-derived reactive oxygen species (ROS) in inflammatory diseases. They contend that chronic granulomatous disease (CGD) is associated more with hyperinflammatory syndrome. Furthermore, they enumerate techniques to determine the cellular production of ROS in or from neutrophils. The relevance of the article by P. J. Ferguson in inflammatory responses following diminished or absent ROS production is also presented.