COVID-19 infection has a heterogenous disease course; it may be asymptomatic or causes only mild symptoms in the majority of the cases, while immunologic complications such as macrophage activation syndrome also known as secondary hemophagocytic lymphohistiocytosis, resulting in cytokine storm syndrome and acute respiratory distress syndrome, may also occur in some patients. According to current literature, impairment of SARS-CoV-2 clearance due to genetic and viral features, lower levels of interferons, increased neutrophil extracellular traps, and increased pyroptosis and probable other unknown mechanisms create a background for severe disease course complicated by macrophage activation syndrome and cytokine storm. Various genetic mutations may also constitute a risk factor for severe disease course and occurrence of cytokine storm in COVID-19. Once, immunologic complications like cytokine storm occur, anti-viral treatment alone is not enough and should be combined with appropriate anti-inflammatory treatment. Anti-rheumatic drugs, which are tried for managing immunologic complications of COVID-19 infection, will also be discussed including chloroquine, hydroxychloroquine, JAK inhibitors, IL-6 inhibitors, IL-1 inhibitors, anti-TNF-α agents, corticosteroids, intravenous immunoglobulin (IVIG), and colchicine. Early recognition and appropriate treatment of immunologic complications will decrease the morbidity and mortality in COVID-19 infection, which requires the collaboration of infectious disease, lung, and intensive care unit specialists with other experts such as immunologists, rheumatologists, and hematologists.

Juvenile hyaline fibromatosis (JHF) and infantile systemic hyalinosis (ISH) are autosomal recessive conditions characterized by multiple subcutaneous skin nodules, gingival hypertrophy, joint contractures, and hyaline deposition. We previously mapped the gene for JHF to chromosome 4q21. We now report the identification of 15 different mutations in the gene encoding capillary morphogenesis protein 2 (CMG2) in 17 families with JHF or ISH. CMG2 is a transmembrane protein that is induced during capillary morphogenesis and that binds laminin and collagen IV via a von Willebrand factor type A (vWA) domain. Of interest, CMG2 also functions as a cellular receptor for anthrax toxin. Preliminary genotype-phenotype analyses suggest that abrogation of binding by the vWA domain results in severe disease typical of ISH, whereas in-frame mutations affecting a novel, highly conserved cytoplasmic domain result in a milder phenotype. These data (1) demonstrate that JHF and ISH are allelic conditions and (2) implicate perturbation of basement-membrane matrix assembly as the cause of the characteristic perivascular hyaline deposition seen in these conditions.

Assessment of the pattern and extent of arterial involvement and measurement of current disease activity are essential for the management of Takayasu arteritis (TA). Since there is no completed, placebo-controlled, randomized clinical trial, the level of evidence for management of TA is low, generally reflecting the results of open studies, case series and expert opinion. The most commonly used agents include corticosteroids and conventional immunosuppressive agents such as MTX, AZA, MMF and LEF. In patients who remain resistant and/or intolerant to these agents, biologic drugs including TNF inhibitors, rituximab and tocilizumab seem to be promising. Antiplatelet treatment may also lower the frequency of ischaemic events in TA. In the presence of short-segment, critical arterial stenosis, balloon angioplasty or stent graft replacement may be useful. On the other hand, long-segment stenosis with extensive periarterial fibrosis or occlusion requires surgical bypass of the affected segment, which is clearly associated with superior results compared with endovascular intervention. As a general rule, both endovascular intervention and surgical procedures should be avoided during the active phase of the disease. Earlier diagnosis, better assessment of disease activity and future clinical trials will obviously improve the management of TA.

Takayasu arteritis is a rare inflammatory disease of large arteries. The etiology of Takayasu arteritis remains poorly understood, but genetic contribution to the disease pathogenesis is supported by the genetic association with HLA-B*52. We genotyped ~200,000 genetic variants in two ethnically divergent Takayasu arteritis cohorts from Turkey and North America by using a custom-designed genotyping platform (Immunochip). Additional genetic variants and the classical HLA alleles were imputed and analyzed. We identified and confirmed two independent susceptibility loci within the HLA region (r(2) < 0.2): HLA-B/MICA (rs12524487, OR = 3.29, p = 5.57 × 10(-16)) and HLA-DQB1/HLA-DRB1 (rs113452171, OR = 2.34, p = 3.74 × 10(-9); and rs189754752, OR = 2.47, p = 4.22 × 10(-9)). In addition, we identified and confirmed a genetic association between Takayasu arteritis and the FCGR2A/FCGR3A locus on chromosome 1 (rs10919543, OR = 1.81, p = 5.89 × 10(-12)). The risk allele in this locus results in increased mRNA expression of FCGR2A. We also established the genetic association between IL12B and Takayasu arteritis (rs56167332, OR = 1.54, p = 2.18 × 10(-8)).

Behçet's disease is an inflammatory disease characterized by recurrent oral and genital ulcers and significant organ involvement. Localizing the genetic association between HLA-B*51 and Behçet's disease and exploring additional susceptibility loci in the human leukocyte antigen (HLA) region are complicated by the strong linkage disequilibrium in this region. We genotyped 8,572 variants in the extended HLA locus and carried out imputation and meta-analysis of 24,834 variants in 2 independent Behçet's disease cohorts from 2 ancestry groups. Genotyped SNPs were used to infer classical HLA alleles in the HLA-A, HLA-B, HLA-C, HLA-DQA1, HLA-DQB1 and HLA-DRB1 loci. Our data suggest that the robust HLA-B*51 association in Behçet's disease is explained by a variant located between the HLA-B and MICA genes (rs116799036: odds ratio (OR) = 3.88, P = 9.42 × 10(-50)). Three additional independent genetic associations within PSORS1C1 (rs12525170: OR = 3.01, P = 3.01 × 10(-26)), upstream of HLA-F-AS1 (rs114854070: OR = 1.95, P = 7.84 × 10(-14)) and with HLA-Cw*1602 (OR = 5.38, P = 6.07 × 10(-18)) were also identified and replicated.

Although inflammation-induced thrombosis is a well-known entity, its pathogenesis remains complicated. There are complex interactions between inflammation and hemostasis, involving proinflammatory cytokines, chemokines, adhesion molecules, tissue factor expression, platelet and endothelial activation, and microparticles. Inflammation increases procoagulant factors, and also inhibits natural anticoagulant pathways and fibrinolytic activity, causing a thrombotic tendency. Besides, chronic inflammation may cause endothelial damage, resulting in the loss of physiologic anticoagulant, antiaggregant and vasodilatory properties of endothelium. However, inflammation- induced venous thrombosis may develop even in the absence of vessel wall damage. On the other hand, coagulation also augments inflammation, causing a vicious cycle. This is mainly achieved by means of thrombin-induced secretion of proinflammatory cytokines and growth factors. Platelets may also trigger inflammation by activating the dendritic cells. There are many systemic inflammatory diseases characterized by thrombotic tendency, including Behçet disease (BD), antineutrophilic cytoplasmic antibody-associated vasculitides, Takayasu arteritis, rheumatoid arthritis, systemic lupus erythematosus, antiphosholipid syndrome, familial Mediterranean fever, thromboangiitis obliterans (TAO) and inflammatory bowel diseases. Inflammation-induced thrombosis may respond to immunosuppressive (IS) treatment, as in the case of BD. However effectiveness of this treatment can not be generalized to all other inflammatory diseases. For instance, IS agents do not have any beneficial role in the management of TAO. Heparin, antiplatelet agents such as aspirin and clopidogrel, colchicine and statins also have some antiinflammatory activity. However, decreased responsiveness to aspirin and clopidogrel treatments may be observed in inflammatory diseases, due to antiplatelet resistance caused by systemic inflammation. In the present review, we aimed to discuss the details of the complex crosstalk between inflammation and hemostasis in the context of available data. We also intended to overview the major inflammatory diseases with thrombotic tendency, as well as to discuss the general principles of the management of inflammation-induced thrombosis.

Objective Takayasu’s arteritis is a rare large vessel vasculitis with incompletely understood etiology. We performed the first unbiased genome-wide association study (GWAS) in Takayasu’s arteritis. Methods Two independent Takayasu’s arteritis cohorts from Turkey and North America were included in our study. The Turkish cohort consisted of 559 patients and 489 controls, and the North American cohort consisted of 134 European-derived patients and 1,047 controls. Genotyping was performed using the Omni1-Quad and Omni2.5 genotyping arrays. Genotyping data were subjected to rigorous quality control measures and subsequently analyzed to discover genetic susceptibility loci for Takayasu’s arteritis. Results We identified genetic susceptibility loci for Takayasu’s arteritis with a genome-wide level of significance in IL6 (rs2069837, OR= 2.07, P= 6.70×10−9), RPS9/LILRB3 (rs11666543, OR= 1.65, P= 2.34×10−8), and an intergenic locus on chromosome 21q22 (rs2836878, OR= 1.79, P= 3.62×10−10). The genetic susceptibility locus in RPS9/LILRB3 is located within the leukocyte receptor complex (LRC) gene cluster on chromosome 19q13.4, and the disease risk variant in this locus correlates with reduced expression of multiple genes including the inhibitory leukocyte immunoglobulin-like receptor gene LILRB3 (P= 2.29×10−8). In addition, we identified candidate susceptibility genes with suggestive levels of association (P <1×10−5) including PCSK5, LILRA3, PPM1G/NRBP1, and PTK2B in Takayasu’s arteritis. Conclusion This study identified novel genetic susceptibility loci for Takayasu’s arteritis and uncovered potentially important aspects in the pathophysiology of this form of vasculitis.

Takayasu arteritis (TAK) is a challenging chronic, granulomatous, large-vessel systemic vasculitis, mostly due to difficulties in early diagnosis and assessing actual disease activity. Since there are no specific diagnostic laboratory tests, biomarkers, or autoantibodies, many patients experience considerable delay in diagnosis. Remembering the possibility of TAK together with the use of acute phase responses and appropriate imaging studies may be helpful for early diagnosis. Since there may be discrepancies between systemic and vascular wall inflammation, using only acute phase responses is not reliable in assessing current disease activity. Therefore, physical examination and new imaging findings should also be used to assess current disease activity. Despite its limitations, the Indian Takayasu Clinical Activity Score (ITAS2010) may also be helpful for this purpose. The rationale of medical treatment is to suppress both vascular and systemic inflammation with appropriate systemic immunosuppression, including corticosteroids and conventional immunosuppressive agents. In cases of refractory disease activity, leflunomide and biologic agents such as TNF inhibitors and tocilizumab may be tried. In selected cases with persistent lesions that cannot be reversed with medical treatment, endovascular interventions including balloon angioplasty, stent and stent graft replacement, or surgery may be tried. However, such procedures should be performed after suppression of inflammation, i.e. during inactive disease. Prognosis of TAK is probably getting better with lower mortality rates reported in recent years, probably due to the use of more effective medical treatments as well as the use of endovascular interventions when necessary and available.