Neutrophils-Important Communicators in Systemic Lupus Erythematosus and Antiphospholipid Syndrome

Risk factors for hospitalization in Mexican patients with systemic lupus erythematosus

INTRODUCTION

Systemic lupus erythematosus (SLE) is an autoimmune disease that often requires hospitalization. Most hospitalizations are due to infections and/or disease activity, for which several risk factors have been described in non-Mestizo patients.

OBJECTIVE

To identify risk factors for hospitalization in patients with systemic lupus erythematosus (SLE).

METHODS

This was an observational case-control study of patients with SLE in San Luis Potosí, Mexico, evaluated from January 2019 to October 2020. We compared hospitalized lupus patients with non-hospitalized lupus patients. We used descriptive statistics and logistic regression to describe potential risk factors.

RESULTS

Of a total of 202 patients, 89 (45.1%) were hospitalized; these patients were younger, had shorter disease duration, higher disease activity scores (systemic lupus erythematosus disease activity index-SLEDAI), and more accumulated damage than non-hospitalized patients. The primary reasons for hospitalization were disease activity (60.7%), kidney disease, infection, and drug toxicity (5.6%). Multivariate analysis revealed several risk factors associated with hospitalization, including elevated creatinine, C-reactive protein, neutrophil levels, and constitutional symptoms, while prolonged international normalized ratio (INR), longer stay in the intensive care unit (ICU), and vasopressor use were associated with mortality. The use of antimalarials was a protective factor against hospitalization. Survival analysis revealed that patients with hospital-acquired infections had a lower probability of survival.

CONCLUSIONS

Disease activity was the most common reason for hospitalization; kidney, constitutional, and hematological factors were associated with hospitalization; and the use of antimalarial was a protective factor for hospitalization.

T cell involvement in antiphospholipid syndrome

Antiphospholipid syndrome (APS) is a systemic autoimmune disorder characterized by arterial and venous thrombosis, and obstetric complications in the presence of antiphospholipid antibodies (aPL), including lupus anticoagulant, anticardiolipin and anti-β2-glycoprotein I antibodies. APS manifests as single, often as recurrent events, and rarely as a catastrophic condition. Most studies of APS pathogenesis to date have focused on the prothrombotic role of aPL, while innate immune responses such as monocyte, complement and neutrophil activation have been also recognized as part of the thrombo-inflammatory cascade in APS. While the presence of autoreactive T cells against β2-glycoprotein I has been long known, less data are available on their pathogenetic role in APS. In this review, we summarize current knowledge on the involvement of T cells in APS pathophysiology, alterations of T cell subsets in peripheral blood, and clinical associations. We also highlight potential therapeutic opportunities by targeting T helper-B cell interactions in these patients.

Inhibitors of Bruton's tyrosine kinase as emerging therapeutic strategy in autoimmune diseases

Bruton's tyrosine kinase (BTK) is a cytoplasmic, non-receptor signal transducer, initially identified as an essential signaling molecule for B cells, with genetic mutations resulting in a disorder characterized by disturbed B cell and antibody development. Subsequent research revealed the critical role of BTK in the functionality of monocytes, macrophages and neutrophils. Various immune cells, among which B cells and neutrophils, rely on BTK activity for diverse signaling pathways downstream of multiple receptors, which makes this kinase an ideal target to treat hematological malignancies and autoimmune diseases. First-generation BTK inhibitors are already on the market to treat hematological disorders. It has been demonstrated that B cells and myeloid cells play a significant role in the pathogenesis of different autoimmune diseases such as multiple sclerosis, rheumatoid arthritis, systemic lupus erythematosus and primary Sjögren's syndrome. Consequently, second-generation BTK inhibitors are currently being developed to treat these disorders. Despite the acknowledged involvement of BTK in various cell types, the focus on B cells often overshadows its impact on innate immune cells. Among these cell types, neutrophils are often underestimated in the pathogenesis of autoimmune diseases. In this narrative review, the function of BTK in different immune cell subsets is discussed, after which an overview is provided of different upcoming BTK inhibitors tested for treatment of autoimmune diseases. Special attention is paid to BTK inhibition and its effect on neutrophil biology.

The prevalence of neutropenia and association with infections in patients with systemic lupus erythematosus: a Swedish single-center study conducted over 14 years

Hematologic abnormalities are common manifestations of SLE, although neutropenia is observed less frequently and is not included in the classification criteria. Nonetheless, neutropenia is a risk factor for infections, especially those caused by bacteria or fungi. We aimed to evaluate the impact of neutropenia in SLE through a systematic investigation of all infections in a large cohort of well-characterized patients, focusing on neutropenia, lymphopenia, and hypocomplementemia. Longitudinal clinical and laboratory parameters obtained at visits to the Rheumatology Unit, Linköping University Hospital, and linked data on all forms of healthcare utilization for all the subjects included in our regional SLE register during 2008-2022 were assessed. Data regarding confirmed infections were retrieved from the medical records. Overall, 333 patients were included and monitored during 3,088 visits to a rheumatologist during the study period. In total, 918 infections were identified, and 94 occasions of neutropenia (ANC < 1.5 × 109/L) were detected in 40 subjects (12%). Thirty neutropenic episodes in 15 patients occurred in association with infections, of which 13 (43%) required in-hospital care, 4 (13%) needed intensive care, and 1 (3%) resulted in death. Bayesian analysis showed that patients with ≥ 1 occasion of neutropenia were more likely to experience one or more infections (OR = 2.05; probability of association [POA] = 96%). Both invasiveness (OR = 7.08; POA = 98%) and severity (OR = 2.85; POA = 96%) of the infections were significantly associated with the present neutropenia. Infections are common among Swedish SLE patients, 12% of whom show neutropenia over time. Importantly, neutropenia is linked to both the invasiveness and severity of infections. Awareness of the risks of severe infections in neutropenic patients is crucial to tailor therapies to prevent severe illness and death.

Single-cell transcriptomics reveals peripheral immune responses in non-segmental vitiligo

Background

Vitiligo is a common autoimmune depigmented dermatology due to destruction of melanocytes. Much evidence suggests that vitiligo is associated with systemic immune activation. Previous studies have focused on immune cell infiltration in and around lesion areas, but few studies have investigated the cell types and function of circulating immune cells in peripheral blood. Here, single cell RNA-sequencing (scRNA-seq) was used to investigate the mechanisms of peripheral immune responses in vitiligo patients.

Methods

Peripheral blood was collected from five patients with progressive non-segmental vitiligo and three healthy controls. Peripheral blood mononuclear cells (PBMCs) were obtained by Ficoll-Paque density gradient centrifugation, and scRNA-seq was performed on isolated cell populations to obtain single cell transcriptomes and characterize important genes and intracellular signaling pathways. The key findings were validated with qPCR and flow cytometry assays.

Results

We identified 10 major cell types by scRNA-seq. Among these cell types, neutrophils were specifically observed in our scRNA-seq data from PBMCs. Peripheral blood effector CD8+ T cells from vitiligo patients did not show significant differences at the transcriptome level compared with healthy controls, whereas regulatory T cells showed pro-inflammatory TH1-like properties. Innate immune cells, including natural killer cells and dendritic cells, showed increased antigen processing and presentation as well as upregulated interferon responses. B cells, monocytes, and neutrophils all showed activation. B cells, especially memory B cells, had upregulated expression of genes related to humoral immunity. Monocytes showed production of proinflammatory cytokines and chemokines. Neutrophils showed strong chemokine ligand-receptor (L-R) pair (CXCR8-CXCR2) autocrine signaling pathway.

Conclusion

This study revealed the genetic profile and signaling pathway characteristics of peripheral blood immune cells in vitiligo patients, providing new insights into its pathogenesis, which may facilitate identification of potential therapeutic targets.

Neutrophils in Inflammatory Diseases: Unraveling the Impact of Their Derived Molecules and Heterogeneity

Inflammatory diseases involve numerous disorders and medical conditions defined by an insufficient level of self-tolerance. These diseases evolve over the course of a multi-step process through which environmental variables play a crucial role in the emergence of aberrant innate and adaptive immunological responses. According to experimental data accumulated over the past decade, neutrophils play a significant role as effector cells in innate immunity. However, neutrophils are also involved in the progression of numerous diseases through participation in the onset and maintenance of immune-mediated dysregulation by releasing neutrophil-derived molecules and forming neutrophil extracellular traps, ultimately causing destruction of tissues. Additionally, neutrophils have a wide variety of functional heterogeneity with adverse effects on inflammatory diseases. However, the complicated role of neutrophil biology and its heterogeneity in inflammatory diseases remains unclear. Moreover, neutrophils are considered an intriguing target of interventional therapies due to their multifaceted role in a number of diseases. Several approaches have been developed to therapeutically target neutrophils, involving strategies to improve neutrophil function, with various compounds and inhibitors currently undergoing clinical trials, although challenges and contradictions in the field persist. This review outlines the current literature on roles of neutrophils, neutrophil-derived molecules, and neutrophil heterogeneity in the pathogenesis of autoimmune and inflammatory diseases with potential future therapeutic strategies.

Association between ambient air pollution exposure in pregnant women with antiphospholipid syndrome in Nanjing, China

Antenatal exposure to air pollutants is thought to be associated with a variety of maternal blood markers as well as adverse birth outcomes. However, the dysgenic influence of air pollutants on the antiphospholipid syndrome (APS) in mothers and their pregnancy outcomes remains unclear. In the current study, 371 mother-infant pairs (189 healthy: 182 APS) from Nanjing Maternal and Child Health Hospital as well as air pollutants concentration from their living environment were used to investigate correlations between air pollution with maternal blood indicators and fetal birth weight in the groups of APS and healthy mothers. Generalized linear model was used to evaluate the contributions of air pollutant exposure during pregnancy to the blood indicators variation. The relationships between birth weight with specific air pollutant and blood index were analyzed using ridge regression. Results showed that APS fetal birth weight was significantly impacted by air pollutant exposure during pregnancy, in particular, the birth weight decreased significantly along with increasing fine particulate matter 2.5 (PM2.5) and fine particulate matter 10 (PM10) exposure concentrations throughout pregnancy. In contrast, birth weight increased significantly with sulfur dioxide (SO2) exposure. In addition, APS-related blood indicators comprised of platelet distribution width (PDW), total bilirubin (TBIL), mean platelet volume (MPV), platelet-larger cell ratio (P_LCR), homocysteine (HCY), alkaline phosphatase (ALP), direct bilirubin (DBIL), basophilic granulocyte (BAS), platelet thrombocytocrit (PCT), preprandial glucose levels (OGTT0), monocytes (MON), and monocytes ratio (MON_ratio) were also strongly related with prenatal exposure to PM2.5 and PM10, in which PDW levels showed most strongly negative impaction on fetal birth weight. Together, we showed that prenatal exposure to air pollutant (PM2.5 and PM10) may exacerbate the poor birth outcomes of low birth weight by impacting APS maternal blood indicators especially for PDW.

The Role of the Oxidative State and Innate Immunity Mediated by TLR7 and TLR9 in Lupus Nephritis

Lupus nephritis (LN) is a severe complication of systemic lupus erythematosus (SLE) and is considered one of the leading causes of mortality. Multiple immunological pathways are involved in the pathogenesis of SLE, which makes it imperative to deepen our knowledge about this disease's immune-pathological complexity and explore new therapeutic targets. Since an altered redox state contributes to immune system dysregulation, this document briefly addresses the roles of oxidative stress (OS), oxidative DNA damage, antioxidant enzymes, mitochondrial function, and mitophagy in SLE and LN. Although adaptive immunity's participation in the development of autoimmunity is undeniable, increasing data emphasize the importance of innate immunity elements, particularly the Toll-like receptors (TLRs) that recognize nucleic acid ligands, in inflammatory and autoimmune diseases. Here, we discuss the intriguing roles of TLR7 and TLR9 in developing SLE and LN. Also included are the essential characteristics of conventional treatments and some other novel and little-explored alternatives that offer options to improve renal function in LN.

The Role of Neutrophil Extracellular Traps (NETs) in the Pathogenesis of Systemic Lupus Erythematosus and Antiphospholipid Syndrome

Systemic lupus erythematosus (SLE) is a systemic autoimmune disease of unknown aetiology [...].

The perspectives of NETosis on the progression of obesity and obesity-related diseases: mechanisms and applications

Obesity is a disease commonly associated with urbanization and can also be characterized as a systemic, chronic metabolic condition resulting from an imbalance between energy intake and expenditure. The World Health Organization (WHO) has identified obesity as the most serious chronic disease that is increasingly prevalent in the world population. If left untreated, it can lead to dangerous health issues such as hypertension, hyperglycemia, hyperlipidemia, hyperuricemia, nonalcoholic steatohepatitis, atherosclerosis, and vulnerability to cardiovascular and cerebrovascular events. The specific mechanisms by which obesity affects the development of these diseases can be refined to the effect on immune cells. Existing studies have shown that the development of obesity and its associated diseases is closely related to the balance or lack thereof in the number and function of various immune cells, of which neutrophils are the most abundant immune cells in humans, infiltrating and accumulating in the adipose tissues of obese individuals, whereas NETosis, as a newly discovered type of neutrophil-related cell death, its role in the development of obesity and related diseases is increasingly emphasized. The article reviews the significant role that NETosis plays in the development of obesity and related diseases, such as diabetes and its complications. It discusses the epidemiology and negative impacts of obesity, explains the mechanisms of NETosis, and examines its potential as a targeted drug to treat obesity and associated ailments.

Low-density granulocytes are related to shorter pregnancy duration but not to interferon alpha protein blood levels in systemic lupus erythematosus

BACKGROUND

An increased risk of pregnancy complications is seen in women with systemic lupus erythematosus (SLE), but the specific immunopathological drivers are still unclear. Hallmarks of SLE are granulocyte activation, type I interferon (IFN) overproduction, and autoantibodies. Here we examined whether low-density granulocytes (LDG) and granulocyte activation increase during pregnancy, and related the results to IFNα protein levels, autoantibody profile, and gestational age at birth.

METHODS

Repeated blood samples were collected during pregnancy in trimesters one, two, and three from 69 women with SLE and 27 healthy pregnant women (HC). Nineteen of the SLE women were also sampled late postpartum. LDG proportions and granulocyte activation (CD62L shedding) were measured by flow cytometry. Plasma IFNα protein concentrations were quantified by single molecule array (Simoa) immune assay. Clinical data were obtained from medical records.

RESULTS

Women with SLE had higher LDG proportions and increased IFNα protein levels compared to HC throughout pregnancy, but neither LDG fractions nor IFNα levels differed during pregnancy compared to postpartum in SLE. Granulocyte activation status was higher in SLE relative to HC pregnancies, and it was increased during pregnancy compared to after pregnancy in SLE. Higher LDG proportions in SLE were associated with antiphospholipid positivity but not to IFNα protein levels. Finally, higher LDG proportions in trimester three correlated independently with lower gestational age at birth in SLE.

CONCLUSION

Our results suggest that SLE pregnancy results in increased peripheral granulocyte priming, and that higher LDG proportions late in pregnancy are related to shorter pregnancy duration but not to IFNα blood levels in SLE.

Markers of NETosis in Patients with Systemic Lupus Erythematosus and Antiphospholipid Syndrome

Neutrophil Extracellular Traps (NETs) have been implicated in systemic lupus erythematosus (SLE) and antiphospholipid syndrome (APS) pathogenesis. The myeloperoxidase-deoxyribonucleic acid (MPO-DNA) complex and nucleosomes are serum markers of NETosis. The aim of this study was to assess these NETosis parameters as markers for SLE and APS diagnosis and their association with clinical features and disease activity. A total of 138 people were included in the cross-sectional study: 30 with SLE without APS, 47 with SLE and APS, 41 patients with primary antiphospholipid syndrome (PAPS), and 20 seemingly healthy individuals. Serum MPO-DNA complex and nucleosome levels were determined via an enzyme-linked immunosorbent assay (ELISA). Informed consent was obtained from all subjects involved in the study. The Ethics Committee of the V.A. Nasonova Research Institute of Rheumatology (Protocol No. 25 dated 23 December 2021) approved the study. In patients with SLE without APS, the levels of the MPO-DNA complex were significantly higher compared to patients with SLE with APS, with PAPS, and healthy controls (p < 0.0001). Among patients with a reliable diagnosis of SLE, 30 had positive values of the MPO-DNA complex, of whom 18 had SLE without APS, and 12 had SLE with APS. Patients with SLE and positive MPO-DNA complex levels were significantly more likely to have high SLE activity (χ² = 5.25, p = 0.037), lupus glomerulonephritis (χ² = 6.82, p = 0.009), positive antibodies to dsDNA (χ² = 4.82, p = 0.036), and hypocomplementemia (χ² = 6.72, p = 0.01). Elevated MPO-DNA levels were observed in 22 patients with APS: 12 with SLE with APS and 10 with PAPS. There were no significant associations between positive levels of the MPO-DNA complex and clinical and laboratory manifestations of APS. The concentration of nucleosomes was significantly lower in the group of SLE patients (±APS) compared to controls and PAPS (p < 0.0001). In SLE patients, the frequency of low nucleosome levels was associated with high SLE activity (χ² = 13.4, p < 0.0001), lupus nephritis (χ² = 4.1, p = 0.043), and arthritis (χ² = 3.89, p = 0.048). An increase in the specific marker of NETosis, the MPO-DNA complex, was found in the blood serum of SLE patients without APS. Elevated levels of the MPO-DNA complex can be regarded as a promising biomarker of lupus nephritis, disease activity, and immunological disorders in SLE patients. Lower levels of nucleosomes were significantly associated with SLE (±APS). Low nucleosome levels were more common in patients with high SLE activity, lupus nephritis, and arthritis.

Study of peripheral blood inflammatory factor levels and their clinical value in patients with lupus nephritis

OBJECTIVE

To explore the effect of traditional Chinese and western medicine on the levels of inflammatory cytokines in the peripheral blood of patients with lupus nephritis (LN).

METHODS

A total of 80 patients with LN admitted to the hospital from August 2016 to August 2017 were retrospectively analyzed. They were equally separated into an experimental group and a control group by the different types of medications. The control group was treated with western medicine, and the experimental group was treated with the combination of traditional Chinese and western medicines. The therapeutic effects were compared.

RESULTS

The levels of IL-6, IL-18 and TNF-α in the experimental group after treatment were (5.47±1.66) pg/ml, (31.66±3.87) pg/ml, and (9.28±3.06) pg/ml, respectively, which were significantly lower than (13.71±3.86) pg/ml, (68.47±4.26) pg/ml, and (22.17±6.54) pg/ml before treatment. The difference was statistically significant (t1 = 12.403, t2 = 40.450, t3 = 11.291, all P<0.001). In the control group after treatment, the levels of IL-6, IL-18 and TNF-α were (12.68±1.32) pg/ml, (68.22±3.42) pg/ml, and (19.78±5.57) pg/ml, respectively. The difference in control and experimental groups was statistically significant (t1 = 21.501, t2 = 44.771, t3 = 10.449, P<0.001). The total effective rate was 95.00% (38/40) in the experimental group and 80.00% (32/40) in control group, (X² = 4.114, P<0.001). There SLEDAI scores of the experimental group were much lower than control after 8 and 12 weeks of treatment (t1 = 8.186, t2 = 20.776, P<0.001). Moreover, the liver and kidney Yin deficiency symptoms in both groups were significantly improved after treatment (P<0.01).

CONCLUSION

The combined treatment of traditional Chinese and western medicine can successfully prevent the secretion of serum IL-6, IL-18 and TNF-α, control the development of disease, boost the therapeutic outcome, and alleviate the immune injury of the body.

Autoinflammatory manifestations in adult patients

Autoinflammatory diseases represent a family of immune-mediated conditions characterized by the unchecked activation of innate immunity. These conditions share common clinical features such as recurrent fever, inflammatory arthritis, and elevation of acute phase reactants, in the absence of an identified infectious etiology, generally without detectable serum autoantibodies, with variable response to glucocorticoids and in some cases colchicine, which represented the mainstay of treatment until cytokine blockade therapies became available. The first autoinflammatory diseases to be described were monogenic disorders caused by missense mutations in inflammasome components and were recognized predominantly during childhood or early adulthood. However, the progress of genetic analyses and a more detailed immunological phenotyping capacity led to the discovery a wide spectrum of diseases, often becoming manifest or being diagnosed in the adult population. The beneficial role of targeting hyperinflammation via interleukin 1 in complex non-immune-mediated diseases is a field of growing clinical interest. We provide an overview of the autoinflammatory diseases of interest to physicians treating adult patients and to analyze the contribution of hyperinflammation in non-immune-mediated diseases; the result is intended to provide a roadmap to orient scientists and clinicians in this broad area.

Proteomics analysis of lysine crotonylation and 2-hydroxyisobutyrylation reveals significant features of systemic lupus erythematosus

INTRODUCTION/OBJECTIVES

To seek significant features of systemic lupus erythematosus (SLE) by utilizing bioinformatics analysis.

METHOD

Liquid chromatography-tandem mass spectrometry (LC-MS/MS) was used to quantify lysine crotonylation (Kcr) and lysine 2-hydroxyisobutyrylation (Khib) in peripheral blood mononuclear cells (PBMCs) of systemic lupus erythematosus (SLE) patients and normal controls.

RESULTS

Seventy-six differentially modified proteins (DMPs) dually modified by Kcr and Khib were identified between SLE patients and healthy people. GO enrichment analysis prompted significant enrichment of seventy-six DMPs in MHC class II protein complex binding and leukocyte migration. KEGG pathways were enriched in antigen processing and presentation pathway and leukocyte transendothelial migration pathway. Six DMPs (CLTC, HSPA1B, HSPA8, HSP90AB1, HSPD1, and PDIA3) were identified in antigen processing and presentation pathway, of which HSPA8 was the core protein. Significant changes of Kcr and Khib in HSPA8 may increase ATP hydrolysis and promote antigen binding to MHC II molecule. In leukocyte transendothelial migration pathway, 7 DMPs (ACTN1, ACTN4, EZR, MSN, RAC1, RHOA, and VCL) were identified. MSN was the protein with the most modification sites in this pathway. In amino terminal ferm region of MSN, Kcr and Khib expression change may lead to the adhesion between leukocytes and endothelial cells, which was an important step of leukocyte migration.

CONCLUSION

Kcr and Khib may promote the antigen presentation and jointly regulate the tissue damage mediated by leukocyte migration in SLE patients, which may play key roles in the pathogenesis of SLE probably. Key Points • Antigen processing and presentation and leukocyte transendothelial migration may play key roles in the pathogenesis of SLE.

Neutrophils in the Pathogenesis of Rheumatic Diseases

Rheumatic diseases, including rheumatoid arthritis (RA), systemic lupus erythematosus (SLE), and anti-neutrophil cytoplasmic antibody (ANCA)-associated vasculitis (AAV), are a group of auto-inflammatory disorders associated with substantial morbidity and mortality. One unifying feature of these diseases is the presence of abnormal neutrophils exhibiting dysregulated neutrophil extracellular trap (NET) release, reactive oxygen species (ROS) production, degranulation, and pro-inflammatory cytokines secretion. Moreover, the release of autoantigens associated with NETs promotes the generation of autoantibodies and a breakdown of self-tolerance, thereby perpetuating inflammation and tissue injury in these patients. In recent years, targeted therapies directed at neutrophilic effector functions have shown promising results in the management of rheumatic diseases. In this review, we will highlight the emerging roles of neutrophils in the onset and progression of rheumatic diseases, and further discuss current and future therapeutic approaches targeting the pathogenic functions of neutrophils, which can modulate inflammation and hence improve patients' survival and quality of life.

SARS-CoV-2 and Skin: New Insights and Perspectives

The SARS-CoV-2 pandemic has disrupted global health systems and brought the entire globe to its knees. Although born as a disease of the respiratory system, COVID-19 can affect different parts of the body, including the skin. Reports of ongoing skin manifestations of COVID-19 have gradually multiplied, pushing researchers to investigate the etiopathogenic mechanisms underlying these phenomena in more depth. In an attempt to investigate the possible association between SARS-CoV-2, ACE2, TMPRSS2 and skin manifestations, we performed immunohistochemical investigations of the ACE2 receptor and TMPRSS2 in nine skin samples from SARS-CoV-2-positive patients compared to a cohort of healthy controls. Furthermore, after consulting public databases regarding ACE2 mRNA expression in various cell populations resident in the skin, we conducted a literature review aimed at outlining the current state of this topic. We did not find statistically different immuno-expression of ACE2 and TMPRSS2 between the group of SARS-CoV-2-positive patients (nine skin biopsies) and the control group. Regarding ACE2, major immunolabeling was present in the epidermal keratinocytes and, rarely, in the fibroblasts and in the adenomeres of the eccrine sweat glands. Regarding the immune expression of TMPRSS2, we found no significant differences between the two groups, with a weak immune staining only in some skin cytotypes. From the review of the literature, we isolated 35 relevant articles according to the inclusion criteria adopted. ACE2 appears to be a target of SARS-CoV-2, although, other receptor molecules may potentially be implicated, such as TMPRSS2. Future studies with large cases and different molecular investigative methods are needed to further elucidate the mechanisms underlying the skin manifestations of SARS-CoV-2.

Placental damage in pregnancies with systemic lupus erythematosus: A narrative review

Systemic lupus erythematosus (SLE) is a chronic inflammatory autoimmune disease of unknown cause, which mainly affects women of childbearing age, especially between 15 and 55 years of age. During pregnancy, SLE is associated with a high risk of perinatal morbidity and mortality. Among the most frequent complications are spontaneous abortion, fetal death, prematurity, intrauterine Fetal growth restriction (FGR), and preeclampsia (PE). The pathophysiology underlying obstetric mortality and morbidity in SLE is still under investigation, but several studies in recent years have suggested that placental dysfunction may play a crucial role. Understanding this association will contribute to developing therapeutic options and improving patient management thus reducing the occurrence of adverse pregnancy outcomes in this group of women. In this review, we will focus on the relationship between SLE and placental insufficiency leading to adverse pregnancy outcomes.

Meta-Analysis and Systematic Review of the Association between a Hypoactive NCF1 Variant and Various Autoimmune Diseases

Genetic association studies have discovered the GTF2I-NCF1 intergenic region as a strong susceptibility locus for multiple autoimmune disorders, with the missense mutation NCF1 rs201802880 as the causal polymorphism. In this work, we aimed to perform a comprehensive meta-analysis of the association of the GTF2I-NCF1 locus with various autoimmune diseases and to provide a systemic review on potential mechanisms underlying the effect of the causal NCF1 risk variants. The frequencies of the two most extensively investigated polymorphisms within the locus, GTF2I rs117026326 and NCF1 rs201802880, vary remarkably across the world, with the highest frequencies in East Asian populations. Meta-analysis showed that the GTF2I-NCF1 locus is significantly associated with primary Sjögren’s syndrome, systemic lupus erythematosus, systemic sclerosis, and neuromyelitis optica spectrum disorder. The causal NCF1 rs201802880 polymorphism leads to an amino acid substitution of p.Arg90His in the p47phox subunit of the phagocyte NADPH oxidase. The autoimmune disease risk His90 variant results in a reduced ROS production in phagocytes. Clinical and experimental evidence shows that the hypoactive His90 variant might contribute to the development of autoimmune disorders via multiple mechanisms, including impairing the clearance of apoptotic cells, regulating the mitochondria ROS-associated formation of neutrophil extracellular traps, promoting the activation and differentiation of autoreactive T cells, and enhancing type I IFN responses. In conclusion, the identification of the association of NCF1 with autoimmune disorders demonstrates that ROS is an essential regulator of immune tolerance and autoimmunity mediated disease manifestations.

Insights into the role of neutrophils in neuropsychiatric systemic lupus erythematosus: Current understanding and future directions

Central nervous system (CNS) involvement of systemic lupus erythematosus (SLE), termed neuropsychiatric SLE (NPSLE), is a major and debilitating manifestation of the disease. While patients with SLE mostly complain of common neuropsychological symptoms such headache and mild mood disorders that may not even be technically attributed to SLE, many SLE patients present with life-threatening NPSLE syndromes such as cerebrovascular disease, seizures and psychosis that are equally challenging in terms of early diagnosis and therapy. While we are just beginning to unravel some mysteries behind the immunologic basis of NPSLE, advancements in the mechanistic understanding of the complex pathogenic processes of NPSLE have been emerging through recent murine and human studies. The pathogenic pathways implicated in NPSLE are multifarious and various immune effectors such as cell-mediated inflammation, autoantibodies and cytokines including type I interferons have been found to act in concert with the disruption of the blood-brain barrier (BBB) and other neurovascular interfaces. Beyond antimicrobial functions, neutrophils are emerging as decision-shapers during innate and adaptive immune responses. Activated neutrophils have been recognized to be involved in ischemic and infective processes in the CNS by releasing neutrophil extracellular traps (NETs), matrix metalloproteinase-9 and proinflammatory cytokines. In the context of NPSLE, these mechanisms contribute to BBB disruption, neuroinflammation and externalization of modified proteins on NETs that serve as autoantigens. Neutrophils that sediment within the peripheral blood mononuclear cell fraction after density centrifugation of blood are generally defined as low-density neutrophils (LDNs) or low-density granulocytes. LDNs are a proinflammatory subset of neutrophils that are increased with SLE disease activity and are primed to undergo NETosis and release cytokines such as interferon-α and tumor necrosis factor. This review discusses the immunopathogenesis of NPSLE with a focus on neutrophils as a core mediator of the disease and potential target for translational research in NPSLE.

Risk Factors and Outcomes of Acute Myocardial Infarction in a Cohort of Antiphospholipid Syndrome

Background

Antiphospholipid syndrome (APS) is a disorder associated with thromboembolic diseases, including acute myocardial infarction (AMI). Given that AMI is a relatively common condition with poor prognostic features, identification of risk factors for AMI in APS is important.

Methods

A retrospective cohort study was performed consisting of 332 patients with APS, and 239 patients with thrombotic APS were finally included. Patients were followed up in the outpatient department for 5 years. Clinical data and laboratory parameters were analyzed to identify the risk factors for AMI in APS. The primary and secondary clinical outcomes were all-cause mortality and recurrence of thrombosis, respectively.

Results

AMI was observed in 12.1% (29/239) of patients with APS. Compared to patients without AMI, patients with AMI had multiple organ thrombosis (55.1 vs. 34.3%, p = 0.029), recurrent thrombosis (58.6 vs. 34.3%, p = 0.011), a higher incidence of atherosclerosis (62.1 vs. 23.8%, p < 0.001), higher neutrophil count (×10⁹/L) [4.68 (3.25, 8.17) vs. 3.71 (2.64, 5.80), p = 0.036], longer QT interval (ms) [438 ms (423, 454) vs. 425 ms (410, 446), p = 0.016], and fewer venous thrombosis events (27.6 vs. 63.3%, p < 0.001). Multivariate logistic regression analysis (adjusted for age and gender) identified several factors that were positively associated with AMI, including multiple organ thrombosis [odds ratio (OR) 8.862, 95% confidence interval (CI): 1.817–43.212, p = 0.007), atherosclerosis (OR 5.397, 95%CI: 1.943–14.994, p = 0.001), and elevated neutrophil count (>6.3 ×10⁹/L) (OR 3.271, 95%CI: 1.268–8.440, p = 0.014). The venous thrombosis was negatively associated with AMI (OR 0.106, 95%CI: 0.036–0.314, p < 0.001). Kaplan–Meier analysis revealed that the recurrence rates of arterial thrombosis differed significantly between patients with AMI and those without AMI [hazard ratio (HR) = 3.307, p = 0.038].

Conclusion

Atherosclerosis, multiple organ thrombosis, an increased number of neutrophils are variables positively associated with AMI in APS, and venous thrombosis had a negative association with AMI. AMI only predicts the subsequent recurrence of arterial thrombosis. These findings suggest that distinct pathophysiological mechanisms may exist and contribute to the development of venous or arterial thrombotic APS.

Impact of Neutrophil Extracellular Traps on Thrombosis Formation: New Findings and Future Perspective

Thrombotic diseases seriously endanger human health, neutrophils and neutrophil extracellular traps (NETs) play an important role in abnormal thrombus formation. NETs are extracellular structures released by neutrophils upon stimulation by pathogens. NETs include neutrophil elastase (NE), myeloperoxidase (MPO), cathepsin G and other active substances. The network structure provided by NETs can prevent the spread of pathogens and effectively kill and eliminate pathogens. However, the components of NETs can also abnormally activate the coagulation pathway and participate in the formation of pathological thrombi. This review aims to summarize the mechanisms of NETs formation in detail; the research progress of NETs in venous thrombosis, arterial thrombosis, acquired disease-associated thrombosis, sepsis coagulation disorder; as well as the strategies to target NETs in thrombosis prevention and treatment.

Beyond Hemostasis: Platelet Innate Immune Interactions and Thromboinflammation

There is accumulating evidence that platelets play roles beyond their traditional functions in thrombosis and hemostasis, e.g., in inflammatory processes, infection and cancer, and that they interact, stimulate and regulate cells of the innate immune system such as neutrophils, monocytes and macrophages. In this review, we will focus on platelet activation in hemostatic and inflammatory processes, as well as platelet interactions with neutrophils and monocytes/macrophages. We take a closer look at the contributions of major platelet receptors GPIb, α_IIbβ₃, TLT-1, CLEC-2 and Toll-like receptors (TLRs) as well as secretions from platelet granules on platelet-neutrophil aggregate and neutrophil extracellular trap (NET) formation in atherosclerosis, transfusion-related acute lung injury (TRALI) and COVID-19. Further, we will address platelet-monocyte and macrophage interactions during cancer metastasis, infection, sepsis and platelet clearance.

Thrombosis and Inflammation—A Dynamic Interplay and the Role of Glycosaminoglycans and Activated Protein C

Hemostasis, thrombosis, and inflammation are tightly interconnected processes which may give rise to thrombo-inflammation, involved in infectious and non-infectious acute and chronic diseases, including cardiovascular diseases (CVD). Traditionally, due to its hemostatic role, blood coagulation is isolated from the inflammation, and its critical contribution in the progressing CVD is underrated, until the full occlusion of a critical vessel occurs. Underlying vascular injury exposes extracellular matrix to deposit platelets and inflammatory cells. Platelets being key effector cells, bridge all the three key processes (hemostasis, thrombosis, and inflammation) associated with thrombo-inflammation. Under physiological conditions, platelets remain in an inert state despite the proximity to the endothelium and other cells which are decorated with glycosaminoglycan (GAG)-rich glycocalyx (GAGs). A pathological insult to the endothelium results in an imbalanced blood coagulation system hallmarked by increased thrombin generation due to losses of anticoagulant and cytoprotective mechanisms, i.e., the endothelial GAGs enhancing antithrombin, tissue factor pathway-inhibitor (TFPI) and thrombomodulin-protein C system. Moreover, the loss of GAGs promotes the release of mediators, such as von Willebrand factor (VWF), platelet factor 4 (PF4), and P-selectin, both locally on vascular surfaces and to circulation, further enhancing the adhesion of platelets to the affected sites. Platelet-neutrophil interaction and formation of neutrophil extracellular traps foster thrombo-inflammatory mechanisms exacerbating the cardiovascular disease course. Therefore, therapies which not only target the clotting mechanisms but simultaneously or independently convey potent cytoprotective effects hemming the inflammatory mechanisms are expected to provide clinical benefits. In this regard, we review the cytoprotective protease activated protein C (aPC) and its strong anti-inflammatory effects thereby preventing the ensuing thrombotic complications in CVD. Furthermore, restoring GAG-like vasculo-protection, such as providing heparin-proteoglycan mimetics to improve regulation of platelet and coagulation activity and to suppress of endothelial perturbance and leukocyte-derived pro-inflammatory cytokines, may provide a path to alleviate thrombo-inflammatory disorders in the future. The vascular tissue-modeled heparin proteoglycan mimic, antiplatelet and anticoagulant compound (APAC), dual antiplatelet and anticoagulant, is an injury-targeting and locally acting arterial antithrombotic which downplays collagen- and thrombin-induced and complement-induced activation and protects from organ injury.

Risk of Thrombosis, Pregnancy Morbidity or Death in Antiphospholipid Syndrome

The antiphospholipid syndrome is an autoimmune disease characterized by thrombosis and pregnancy morbidity. The manifestations are caused by antibodies targeting cell membrane phospholipids and/or associated proteins. The triggers leading to these antibodies' production are unknown but recent work suggests cross-reactivity between the autoantigens and peptides produced by the intestinal microbiome. Work on how the autoantibodies could cause clinical manifestations implicates different mechanisms. Binding to surface proteins of different cell types can induce intracellular signaling leading to cell activation and tissue factor expression. Complement activation and neutrophil extracellular-traps are also involved, and recent evidence implicates endothelial protein C receptor-lysobisphosphatidic acid complex. Pregnancy is a high-risk situation for antiphospholipid syndrome patients due to the increased risk of thrombosis and obstetric complications. Epidemiological and clinical research on APS is hampered by heterogeneity in populations, testing and treatment strategies. About one in 10 to one in fifty APS pregnancies is complicated by thrombosis, despite treatment. Pregnant patients with prior thrombosis are prescribed therapeutic dose heparins and low dose aspirin. Without prior thrombosis a prophylactic dose is used. The most frequent obstetrical manifestation is recurrent early pregnancy loss. The association of APS antibodies with late pregnancy loss is stronger, however. Prevention of recurrence is achieved with aspirin and prophylactic dose heparin, although the evidence is of low certainty. The third obstetrical classifying manifestation comprises preterm delivery due to placenta-mediated complications and is treated in subsequent pregnancies with aspirin with or without prophylactic dose heparin, again based on low quality evidence. New therapies are under investigation.

Cardiovascular disease risk in antiphospholipid syndrome: Thrombo-inflammation and atherothrombosis

Antiphospholipid syndrome (APS) is an autoimmune disorder characterized by the presence of antiphospholipid antibodies (aPL) (lupus anticoagulant, anticardiolipin antibodies and anti-beta2glycoprotein I (anti-β2GPI) antibodies) and a plethora of macro- and micro-vascular manifestations, affecting predominantly young adults. Cardiovascular events are the leading causes of morbidity and mortality in APS. APL-mediated thrombo-inflammation and atherothrombosis are emerging pathogenetic mechanisms of cardiovascular disease (CVD) in APS, involving endothelial cell and monocyte activation, cytokines and adhesion molecules expression, complement and neutrophils activation, neutrophil extracellular traps formation, platelet cell activation and aggregation, and subsequent thrombin generation, in parallel with an oxidized low-density lipoprotein (oxLDL)-β2GPI complex induced macrophage differentiation to foam cells. High risk aPL profile, especially the presence of lupus anticoagulant and triple aPL positivity (all three aPL subtypes), co-existence with Systemic Lupus Erythematosus (SLE), as well as traditional risk factors such as smoking, hypertension, hyperlipemia and obesity are associated with both subclinical atherosclerosis and cardiovascular events in APS. Increased awareness of CVD risk by the physicians and patients, regular assessment and strict control of traditional risk factors, and lifestyle modifications are recommended. Use of low-dose aspirin should be considered for cardiovascular prevention in asymptomatic aPL carriers or SLE patients with high-risk aPL profile. The role of older agents such as hydroxychloroquine and statins or new potential targeted treatments against immuno- and athero-thrombosis has been demonstrated by experimental and some clinical studies and needs to be further evaluated by randomized controlled studies. This review summarizes the available evidence about the pathogenetic mechanisms and prevalence of cardiovascular events and subclinical atherosclerosis, the interrelationship between traditional and disease-related CVD risk factors, and the cardiovascular risk assessment and management in APS.

Cancer and Autoimmune Diseases: A Tale of Two Immunological Opposites?

The present article compares, side-by-side, cancer and autoimmune diseases in terms of innate and adaptive immune cells involvement, MHC Class I and Class II expression, TGFβ effect, immune modulating drugs effect and the effect of reactive oxygen species. The change in the inflammatory immune reaction during the progress of cancer and the effect of this change on the comorbidity of autoimmune diseases and cancer are discussed. The similar inflammatory properties of autoimmune diseases and early cancer, and the contrasting inflammatory properties of autoimmune diseases and advanced cancer elucidate the increased incidence of many types of cancer in patients with pre-existing autoimmune diseases and the decreased cancer-specific mortality of these patients. Stage-dependent effects of reactive oxygen-species on tumor proliferation are an additional probable cause for these epidemiological observations. The relationship: {standardized incidence ratio (SIR)} > {cancer-specific hazard ratio (HR)} for cancer patients with a history of autoimmune diseases is substantiated and rationalized.

Humanized Mouse Models of Systemic Lupus Erythematosus: Opportunities and Challenges

Animal models have played a crucial role in the understanding of the mechanisms and treatments of human diseases; however, owing to the large differences in genetic background and disease-specific characteristics, animal models cannot fully simulate the occurrence and progression of human diseases. Recently, humanized immune system mice, based on immunodeficient mice, have been developed that allow for the partial reconstruction of the human immune system and mimic the human in vivo microenvironment. Systemic lupus erythematosus (SLE) is a complex disease characterized by the loss of tolerance to autoantigens, overproduction of autoantibodies, and inflammation in multiple organ systems. The detailed immunological events that trigger the onset of clinical manifestations in patients with SLE are still not well known. Two methods have been adopted for the development of humanized SLE mice. They include transferring peripheral blood mononuclear cells from patients with SLE to immunodeficient mice or transferring human hematopoietic stem cells to immunodeficient mice followed by intraperitoneal injection with pristane to induce lupus. However, there are still several challenges to be overcome, such as how to improve the efficiency of reconstruction of the human B cell immune response, how to extend the lifespan and improve the survival rate of mice to extend the observation period, and how to improve the development of standardized commercialized models and use them. In summary, there are opportunities and challenges for the development of humanized mouse models of SLE, which will provide novel strategies for understanding the mechanisms and treatments of SLE.

OUP accepted manuscript

Objectives

Clinical phenotyping and predicting treatment responses in SLE patients is challenging. Extensive blood transcriptional profiling has identified various gene modules that are promising for stratification of SLE patients. We aimed to translate existing transcriptomic data into simpler gene signatures suitable for daily clinical practice.

Methods

Real-time PCR of multiple genes from the IFN M1.2, IFN M5.12, neutrophil (NPh) and plasma cell (PLC) modules, followed by a principle component analysis, was used to identify indicator genes per gene signature. Gene signatures were measured in longitudinal samples from two childhood-onset SLE cohorts (n = 101 and n = 34, respectively), and associations with clinical features were assessed. Disease activity was measured using Safety of Estrogen in Lupus National Assessment (SELENA)-SLEDAI. Cluster analysis subdivided patients into three mutually exclusive fingerprint-groups termed (1) all-signatures-low, (2) only IFN high (M1.2 and/or M5.12) and (3) high NPh and/or PLC.

Results

All gene signatures were significantly associated with disease activity in cross-sectionally collected samples. The PLC-signature showed the highest association with disease activity. Interestingly, in longitudinally collected samples, the PLC-signature was associated with disease activity and showed a decrease over time. When patients were divided into fingerprints, the highest disease activity was observed in the high NPh and/or PLC group. The lowest disease activity was observed in the all-signatures-low group. The same distribution was reproduced in samples from an independent SLE cohort.

Conclusions

The identified gene signatures were associated with disease activity and were indicated to be suitable tools for stratifying SLE patients into groups with similar activated immune pathways that may guide future treatment choices.

Update on treatment strategies for vasculitis affecting the central nervous system

Vasculitis affecting the nervous system is a rare disease that can not only present with nonspecific initial symptoms, but also run a severe course without accurate treatment. Although improvements have been achieved, diagnosis of vasculitis remains challenging, because many classification criteria are unspecific or inconclusive with regard to central nervous system (CNS) manifestations. Currently, beside an isolated primary CNS vasculitis, several systemic types of vasculitis are known to affect the nervous system. In this review, we provide an overview of the pathophysiology, current therapeutic guidelines, and highlight novel treatment strategies for CNS vasculitis.

The Roles of Neutrophils in Cytokine Storms

A cytokine storm is an abnormal discharge of soluble mediators following an inappropriate inflammatory response that leads to immunopathological events. Cytokine storms can occur after severe infections as well as in non-infectious situations where inflammatory cytokine responses are initiated, then exaggerated, but fail to return to homeostasis. Neutrophils, macrophages, mast cells, and natural killer cells are among the innate leukocytes that contribute to the pathogenesis of cytokine storms. Neutrophils participate as mediators of inflammation and have roles in promoting homeostatic conditions following pathological inflammation. This review highlights the advances in understanding the mechanisms governing neutrophilic inflammation against viral and bacterial pathogens, in cancers, and in autoimmune diseases, and how neutrophils could influence the development of cytokine storm syndromes. Evidence for the destructive potential of neutrophils in their capacity to contribute to the onset of cytokine storm syndromes is presented across a multitude of clinical scenarios. Further, a variety of potential therapeutic strategies that target neutrophils are discussed in the context of suppressing multiple inflammatory conditions.

Cardiovascular disease in systemic lupus erythematosus

There is a well-known increased risk for cardiovascular disease that contributes to morbidity and mortality in systemic lupus erythematosus (SLE). Major adverse cardiovascular events and subclinical atherosclerosis are both increased in this patient population. While traditional cardiac risk factors do contribute to the increased risk that is seen, lupus disease-related factors, medications, and genetic factors also impact the overall risk. SLE-specific inflammation, including oxidized lipids, cytokines, and altered immune cell subtypes all are likely to play a role in the pathogenesis of atherosclerotic plaques. Research is ongoing to identify biomarkers that can help clinicians to predict which SLE patients are at the greatest risk for cardiovascular disease (CVD). While SLE-specific treatment regimens for the prevention of cardiovascular events have not been identified, current strategies include minimization of traditional cardiac risk factors and lowering of overall lupus disease activity.

Thrombosis and thrombocytopenia in antiphospholipid syndrome: their association with mean platelet volume and hematological ratios

OBJECTIVE

To assess the mean platelet volume (MPV), platelet-to-lymphocyte ratio (PLR), the neutrophil-to-lymphocyte ratio (NLR) and the MPV-to-lymphocyte ratio, and to test them according to the clinical/serological status, shift through time and other comorbidities in APS.

METHODS

We included 96 primary APS patients according to the Sydney classification criteria and/or patients with thrombocytopenia and/or autoimmune hemolytic anemia who also fulfilled the serological criteria. We tested aCL, anti-β2GP-I and aPS/PT antibodies and LA. We first registered the MPV and the aforementioned ratios within at least 6 months after an event of thrombosis or thrombocytopenia/AIHA (baseline determination), and during thrombosis/thrombocytopenia/AIHA onset when available (acute event).

RESULTS

A lower baseline MPV and a higher PLR characterized the thrombotic group (n = 74). The AUC for baseline PLR was 0.82 (p < 0.001): SE of 69%, SP 91%, PPV 96%, NPV 74%, LR+ 13.67 and LR- 0.19. During the acute event, both variables increased. The thrombocytopenic group (n = 66) had a higher baseline MPV and a lower PLR, and during an acute event the PLR decreased more deeply. The AUC for MPV was 0.64 (p = 0.02): SE 44%, SP 92%, PPV 86%, NPV 40%, LR+ 3.3 and LR- 0.85. These findings were not related with the aPL antibody profile status, titers or comorbidities.

CONCLUSION

Basal MPV and PLR might help to identify APS patients according to their thrombotic or thrombocytopenic phenotype. These variables change during the acute events and might be the reflex of physiopathological or compensatory mechanisms in APS.

Neutrophils: Need for Standardized Nomenclature

Neutrophils are the most abundant innate immune cell with critical anti-microbial functions. Since the discovery of granulocytes at the end of the nineteenth century, the cells have been given many names including phagocytes, polymorphonuclear neutrophils (PMN), granulocytic myeloid derived suppressor cells (G-MDSC), low density neutrophils (LDN) and tumor associated neutrophils (TANS). This lack of standardized nomenclature for neutrophils suggest that biologically distinct populations of neutrophils exist, particularly in disease, when in fact these may simply be a manifestation of the plasticity of the neutrophil as opposed to unique populations. In this review, we profile the surface markers and granule expression of each stage of granulopoiesis to offer insight into how each stage of maturity may be identified. We also highlight the remarkable surface marker expression profiles between the supposed neutrophil populations.

Type I Interferons in Systemic Autoimmune Diseases: Distinguishing Between Afferent and Efferent Functions for Precision Medicine and Individualized Treatment

A sustained increase in type I interferon (IFN-I) may accompany clinical manifestations and disease activity in systemic autoimmune diseases (SADs). Despite the very frequent presence of IFN-I in SADs, clinical manifestations are extremely varied between and within SADs. The present short review will address the following key questions associated with high IFN-I in SADs in the perspective of precision medicine. 1) What are the mechanisms leading to high IFN-I? 2) What are the predisposing conditions favoring high IFN-I production? 3) What is the role of IFN-I in the development of distinct clinical manifestations within SADs? 4) Would therapeutic strategies targeting IFN-I be helpful in controlling or even preventing SADs? In answering these questions, we will underlie areas of incertitude and the intertwined role of autoantibodies, immune complexes, and neutrophils.

Synovial fluid neutrophils in oligoarticular juvenile idiopathic arthritis have an altered phenotype and impaired effector functions

Background

Neutrophils are the most prevalent immune cells in the synovial fluid in inflamed joints of children with oligoarticular juvenile idiopathic arthritis (JIA). Despite this, little is known about neutrophil function at the site of inflammation in JIA and how local neutrophils contribute to disease pathogenesis. This study aimed to characterize the phenotype and function of synovial fluid neutrophils in oligoarticular JIA.

Methods

Neutrophils obtained from paired blood and synovial fluid from patients with active oligoarticular JIA were investigated phenotypically (n = 17) and functionally (phagocytosis and oxidative burst, n = 13) by flow cytometry. In a subset of patients (n = 6), blood samples were also obtained during inactive disease at a follow-up visit. The presence of CD206-expressing neutrophils was investigated in synovial biopsies from four patients by immunofluorescence.

Results

Neutrophils in synovial fluid had an activated phenotype, characterized by increased CD66b and CD11b levels, and most neutrophils had a CD16^hi CD62L^lowaged phenotype. A large proportion of the synovial fluid neutrophils expressed CD206, a mannose receptor not commonly expressed by neutrophils but by monocytes, macrophages, and dendritic cells. CD206-expressing neutrophils were also found in synovial tissue biopsies. The synovial fluid neutrophil phenotype was not dependent on transmigration alone. Functionally, synovial fluid neutrophils had reduced phagocytic capacity and a trend towards impaired oxidative burst compared to blood neutrophils. In addition, the effector functions of the synovial fluid neutrophils correlated negatively with the proportion of CD206⁺ neutrophils.

Conclusions

Neutrophils in the inflamed joint in oligoarticular JIA were altered, both regarding phenotype and function. Neutrophils in the synovial fluid were activated, had an aged phenotype, had gained monocyte-like features, and had impaired phagocytic capacity. The impairment in phagocytosis and oxidative burst was associated with the phenotype shift. We speculate that these neutrophil alterations might play a role in the sustained joint inflammation seen in JIA.

New insights into the pathogenic mechanisms and treatment of arterial thrombosis in antiphospholipid syndrome

Antiphospholipid syndrome (APS) is a systemic disorder clinically characterized by widespread thrombosis and obstetric complications associated with the persistent presence of antiphospholipid antibodies (aPLs). The persistent presence of aPLs represents a thrombotic risk in APS, which can be stratified according to the aPL profile. Thrombosis occurs in both arteries and veins. Notably, arterial thromboses have a higher recurrence compared with venous thromboses and a tendency for recurrence in the same vascular (arterial) site. Secondary prevention of arterial thrombosis requires more intensive treatment than prevention of venous thrombosis. Data from randomized clinical trials indicated that factor Xa inhibitors should not be recommended for APS. Recurrent thromboses in patients with APS treated with factor Xa inhibitors were mainly arterial, with a high rate of stroke. Dual antiplatelet therapy may have some benefit for preventing the recurrence of arterial thrombosis in patients with APS. This review article describes pathogenic mechanisms, clinical features, risk assessment, and management of arterial thrombosis in patients with APS. Particularly, we discuss how secondary prophylaxis may be a useful approach to reduce the occurrence of arterial thrombosis.

Activated low-density granulocytes in peripheral and intervillous blood and neutrophil inflammation in placentas from SLE pregnancies

OBJECTIVE

Women with SLE face an increased risk of adverse pregnancy outcomes compared with healthy women, but the underlying immunological mechanisms are unknown. Given the recognised association of neutrophil activation with SLE pathogenesis, we examined whether there is increased neutrophil activation and inflammation in blood and placenta in SLE relative to healthy pregnancy.

METHODS

At delivery, peripheral blood, maternal-derived intervillous blood and placentas were collected from 12 SLE and 10 healthy control pregnancies. The proportion of low-density granulocytes (LDGs) and the activation status of LDG and normal-density granulocytes were examined with flow cytometry. The chemokines CXCL8 and CXCL1 were quantified with a cytometric bead-based assay and interferon alpha (IFNα) protein levels with a Simoa method. IFNα-stimulated maternal-derived decidual stromal cells were examined for CXCL8 gene expression with qPCR. A pathologist, blinded to the patient background, examined all placentas.

RESULTS

Women with SLE had significantly higher proportions of LDG in peripheral blood compared with controls (p=0.02), and LDG in both peripheral and intervillous blood were more activated in SLE relative to healthy pregnancies (peripheral blood: p=0.002 and intervillous blood: p=0.05). There were higher levels of CXCL8 and CXCL1 in intervillous compared with peripheral blood in women with SLE (p=0.004 and p=<0.0001, respectively) but not in controls. In SLE pregnancy, IFNα was detectable in 6 out of 10 intervillous blood samples but only in one control. Stimulation with IFNα upregulated CXCL8 gene expression in decidual stromal cells from both SLE and healthy pregnancy. Histological chorioamnionitis was present in 6 out of 12 placentas from women with SLE and in 1 out of 10 controls.

CONCLUSIONS

In women with SLE, locally produced chemokines in the placenta are increased and may attract and activate neutrophils. This in turn could contribute to placental inflammation and dysfunction and increased risk of placenta-related pregnancy complications.

Neonatal low-density granulocytes internalize and kill bacteria but suppress monocyte function using extracellular DNA

Low-density granulocytes (LDGs) are found abundantly in neonatal blood; however, there is limited mechanistic understanding of LDG interactions with bacteria and innate immune cells during acute infection. We aimed to determine how human neonatal LDGs may influence control of the bacterial burden at sites of infection, both individually and in the presence of mononuclear phagocytes. LDGs from human umbilical cord blood do phagocytose Escherichia coli O1:K1:H7 and traffic bacteria into acidic compartments. However, LDGs were significantly less efficient at bacterial uptake and killing compared to monocytes, and this activity was associated with a reduced inflammatory cytokine response. The presence of bacteria triggered the release of DNA (eDNA) from LDGs into the extracellular space that resembled neutrophil extracellular traps, but had limited anti-bacterial activity. Instead, eDNA significantly impaired monocyte control of bacteria during co-culture. These results suggest that LDG recruitment to sites of bacterial infection may compromise host protection in the neonate. Furthermore, our findings reveal novel insights into LDG activity during infection, clarify their inflammatory contributions relative to monocytes, and identify a novel LDG mechanism of immunosuppression.This article has an associated First Person interview with the first author of the paper.

Immunosuppressive Treatment in Antiphospholipid Syndrome: Is It Worth It?

The antiphospholipid syndrome (APS) is characterized by the development of venous and/or arterial thrombosis and pregnancy morbidity in patients with persistent antiphospholipid antibodies (aPL). Catastrophic antiphospholipid syndrome (CAPS) is a life-threatening form of APS occurring in about 1% of cases. Lifelong anticoagulation with vitamin K antagonists remains the cornerstone of the therapy for thrombotic APS, but frequently the use of anticoagulation may be problematic due to the increased risk of bleeding, drug interactions, or comorbidities. Immunosuppressant drugs are widely used to treat several autoimmune conditions, in which their safety and effectiveness have been largely demonstrated. Similar evidence in the treatment of primary APS is limited to case reports or case series, and studies on a large scale lack. Immunomodulatory drugs may be an emerging tool in managing such particular situations, like refractory obstetrical complications, CAPS, or so-called APS non-criteria manifestations. In addition, immunomodulatory drugs may be useful in patients experiencing recurrent thromboembolic events despite optimized anticoagulant therapy. We did a comprehensive review of literature analyzing the possible role of immunomodulation in primary APS to provide a broad overview of potentially safe and effective target treatments for managing this devastating disease.

SARS-CoV-2 infection and thrombotic complications: a narrative review

The current, global situation regarding the severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) pandemic and its potentially devastating clinical manifestations, i.e. coronavirus disease 2019 (COVID-19), took the world by storm, as millions of people have been infected worldwide and more than 1,600,000 patients have succumbed. Infection induced by various respiratory viruses may lead to thrombotic complications. Infection-elicited thrombosis may involve a repertoire of distinct, yet interconnected pathophysiological mechanisms, implicating a hyperinflammatory response, platelet activation and triggering of the coagulation cascade. In the present review, we present current knowledge on the pathophysiological mechanisms that may underlie thrombotic complications in SARS-CoV-2 infection. Furthermore, we provide clinical data regarding the incidence rate of thrombotic events in several viral respiratory infections that cause acute respiratory distress syndrome, including SARS-CoV-2 infection and finally we summarize current recommendations concerning thromboprophylaxis and antithrombotic therapy in patients with thrombotic complications related to SARS-CoV-2 infection.

Lessons from dermatology about inflammatory responses in Covid-19

The SARS‐Cov‐2 is a single‐stranded RNA virus composed of 16 non‐structural proteins (NSP 1‐16) with specific roles in the replication of coronaviruses. NSP3 has the property to block host innate immune response and to promote cytokine expression. NSP5 can inhibit interferon (IFN) signalling and NSP16 prevents MAD5 recognition, depressing the innate immunity. Dendritic cells, monocytes, and macrophages are the first cell lineage against viruses' infections. The IFN type I is the danger signal for the human body during this clinical setting. Protective immune responses to viral infection are initiated by innate immune sensors that survey extracellular and intracellular space for foreign nucleic acids. In Covid‐19 the pathogenesis is not yet fully understood, but viral and host factors seem to play a key role. Important points in severe Covid‐19 are characterized by an upregulated innate immune response, hypercoagulopathy state, pulmonary tissue damage, neurological and/or gastrointestinal tract involvement, and fatal outcome in severe cases of macrophage activation syndrome, which produce a ‘cytokine storm’. These systemic conditions share polymorphous cutaneous lesions where innate immune system is involved in the histopathological findings with acute respiratory distress syndrome, hypercoagulability, hyperferritinemia, increased serum levels of D‐dimer, lactic dehydrogenase, reactive‐C‐protein and serum A amyloid. It is described that several polymorphous cutaneous lesions similar to erythema pernio, urticarial rashes, diffuse or disseminated erythema, livedo racemosa, blue toe syndrome, retiform purpura, vesicles lesions, and purpuric exanthema or exanthema with clinical aspects of symmetrical drug‐related intertriginous and flexural exanthema. This review describes the complexity of Covid‐19, its pathophysiological and clinical aspects.

In vivo evidence for extracellular DNA trap formation

Extracellular DNA trap formation is a cellular function of neutrophils, eosinophils, and basophils that facilitates the immobilization and killing of invading microorganisms in the extracellular milieu. To form extracellular traps, granulocytes release a scaffold consisting of mitochondrial DNA in association with granule proteins. As we understand more about the molecular mechanism for the formation of extracellular DNA traps, the in vivo function of this phenomenon under pathological conditions remains an enigma. In this article, we critically review the literature to summarize the evidence for extracellular DNA trap formation under in vivo conditions. Extracellular DNA traps have not only been detected in infectious diseases but also in chronic inflammatory diseases, as well as in cancer. While on the one hand, extracellular DNA traps clearly exhibit an important function in host defense, it appears that they can also contribute to the maintenance of inflammation and metastasis, suggesting that they may represent an interesting drug target for such pathological conditions.

Are the cutaneous manifestations during or due to SARS-CoV-2 infection/COVID-19 frequent or not? Revision of possible pathophysiologic mechanisms

BACKGROUND

SARS-Cov-2 is a single-stranded RNA virus, a Betacoronavirus, composed of 16 non-structural proteins, with specific roles in replication of coronaviruses. The pathogenesis of COVID-19 is not yet fully understood. The virus and host factors interplay among distinct outcomes of infected patients.

METHODS

Using MeSH (Medical Subject Headings) in PubMed, authors searched for articles cotaining information on COVID-19 and the skin.

RESULTS

The pathophysiology of the disease is multifactorial: association with innate immune response, hypercoagulability state, lung tissue damage, neurological and/or gastrointestinal tract involvement, monocytic/macrophage activation syndrome, culminating in exaggerated cytokine secretion, called "cytokine storm", which leads to worsening and death. These systemic conditions may be associated with cutaneous lesions, that have polymorphic aspects, where at histopathological level show involvement in different skin changes. These lesions may be associated with multisystemic manifestations that could occur due to angiotensin-converting enzyme 2 receptor and transmembrane serine protease action, allowing the pulmonary infection and possibly skin manifestation. Several reports in literature show cutaneous lesions similar to chilblain, urticarial eruptions, diffuse or disseminated erythema, livedo racemosa, blue toe syndrome, retiform purpura, vesicle trunk, purpuric exanthema or exanthema with clinical aspects of symmetrical drug-related intertriginous and flexural exanthema (SDRIFE) and others.

CONCLUSIONS

This review describes the complexity of Covid-19, pathophysiological and clinical aspects, dermatological finding and other dermatological conditions associated with SARS-CoV-2 infection or COVID-19.