Plasminogen activator-coated nanobubbles targeting cellbound ß2-glycoprotein I as a novel thrombus-specific thrombolytic strategy.

ß2-glycoprotein I (ß2-GPI) is a serum protein widely recognized as the main target of antibodies present in patients with antiphospholipid syndrome (APS). ß2-GPI binds to activated endothelial cells, platelets and leukocytes, key players in thrombus formation. We developed a new targeted thrombolytic agent consisting of nanobubbles (NB) coated with recombinant tissue plasminogen activator (rtPA) and a recombinant antibody specific for cell-bound ß2-GPI. The therapeutic efficacy of targeted NB was evaluated in vitro, using platelet-rich blood clots, and in vivo in three different animal models: i) thrombosis developed in a rat model of APS; ii) ferric chloride-induced mesenteric thrombosis in rats, and iii) thrombotic microangiopathy in a mouse model of atypical hemolytic uremic syndrome (C3-gain-of-function mice). Targeted NB bound preferentially to platelets and leukocytes within thrombi and to endothelial cells through ß2-GPI expressed on activated cells. In vitro, rtPA-targeted NB (rtPA-tNB) induced greater lysis of platelet-rich blood clots than untargeted NB. In a rat model of APS, administration of rtPA-tNB caused rapid dissolution of thrombi and, unlike soluble rtPA that induced transient thrombolysis, prevented new thrombus formation. In a rat model of ferric chloride triggered thrombosis, rtPA-tNB, but not untargeted NB and free rtPA, induced rapid and persistent recanalization of occluded vessels. Finally, treatment of C3-gain-of-function mice with rtPA-tNB, that target ß2-GPI deposited in kidney glomeruli, decreased fibrin deposition, and improved urinalysis data with a greater efficiency than untargeted NB. Our findings suggest that targeting cell-bound ß2-GPI may represent an efficient and thrombus-specific thrombolytic strategy in both APS-related and APS-unrelated thrombotic conditions.

Chromosome 3 cluster rs11385942 variant links complement activation with severe COVID-19.

BACKGROUND: Genetic variation at a multigene cluster at chromosome 3p21.31 and the ABO blood group have been associated with the risk of developing severe COVID-19, but the mechanism remains unclear. Complement activation has been associated with COVID-19 severity. OBJECTIVE: The aim of this study was to examine whether chromosome 3p21.31 and the ABO variants are linked to the activation of the complement cascade in COVID-19 patients. METHODS: We considered 72 unrelated European hospitalized patients with genetic data and evaluation of circulating C5a and soluble terminal complement complex C5b-9 (SC5b-9). Twenty-six (36.1%) patients carried the rs11385942 G>GA variant and 44 (66.1%) non-O blood group associated with increased risk of severe COVID-19. RESULTS: C5a and SC5-b9 plasma levels were higher in rs11385949 GA carriers than in non-carriers (P = 0.041 and P = 0.012, respectively), while C5a levels were higher in non-O group than in O group patients (P = 0.019). The association between rs11385949 and SC5b-9 remained significant after adjustment for ABO and disease severity (P = 0.004) and further correction for C5a (P = 0.018). There was a direct relationship between upper airways viral load and SC5b-9 in carriers of the rs11385949 risk allele (P = 0.032), which was not observed in non-carriers. CONCLUSIONS: The rs11385949 G>GA variant, tagging the chromosome 3 gene cluster variation and predisposing to severe COVID-19, is associated with enhanced complement activation, both with C5a and terminal complement complex, while non-O blood group with C5a levels. These findings provide a link between genetic susceptibility to more severe COVID-19 and complement activation.

Targeting CD34+ cells of the inflamed synovial endothelium by guided nanoparticles for the treatment of rheumatoid arthritis.

Despite the advances in the treatment of rheumatoid arthritis (RA) achieved in the last few years, several patients are diagnosed late, do not respond to or have to stop therapy because of inefficacy and/or toxicity, leaving still a huge unmet need. Tissue-specific strategies have the potential to address some of these issues. The aim of the study is the development of a safe nanotechnology approach for tissue-specific delivery of drugs and diagnostic probes. CD34 + endothelial precursors were addressed in inflamed synovium using targeted biodegradable nanoparticles (tBNPs). These nanostructures were made of poly-lactic acid, poly-caprolactone, and PEG and then coated with a synovial homing peptide. Immunofluorescence analysis clearly demonstrated their capacity to selectively address CD34 + endothelial cells in synovial tissue obtained from human, mouse, and rat. Biodistribution studies in two different animal models of rheumatoid arthritis (antigen-induced arthritis/AIA and collagen-induced arthritis/CIA) confirmed the selective accumulation in inflamed joints but also evidenced the capacity of tBNP to detect early phases of the disease and the preferential liver elimination. The therapeutic effect of methotrexate (MTX)-loaded tBNPs were studied in comparison with conventional MTX doses. MTX-loaded tBNPs prevented and treated CIA and AIA at a lower dose and reduced administration frequency than MTX. Moreover, MTX-loaded tBNP showed a novel mechanism of action, in which the particles target and kill CD34 + endothelial progenitors, preventing neo-angiogenesis and, consequently, synovial inflammation. tBNPs represent a stable and safe platform to develop highly-sensitive imaging and therapeutic approaches in RA targeting specifically synovial neo-angiogenesis to reduce local inflammation.

Lysyl oxidase-a possible role in systemic sclerosis-associated pulmonary hypertension: a multicentre study.

OBJECTIVE: Lysyl oxidase (LOX) is an extracellular enzyme that cross-links collagen fibrils. LOX was found to be increased in serum of SSc patients and was suggested to be related to skin fibrosis, yet a vascular source of LOX has been demonstrated in idiopathic pulmonary arterial hypertension (iPAH). We aimed to validate elevated LOX serum levels in SSc and to study its correlation with clinical characteristics and investigate its main source at the tissue level. METHODS: A total of 86 established SSc patients were compared with 86 patients with very early diagnosis of systemic sclerosis (VEDOSS), 110 patients with primary RP (PRP) and 80 healthy controls. LOX serum levels were determined by ELISA. Five lung and 12 skin biopsies from SSc patients were stained for LOX and compared with controls. RESULTS: Serum levels of LOX in SSc were significantly higher than in VEDOSS, PRP and healthy controls (P < 0.001). LOX inversely correlated with the diffusing capacity of the lung for carbon monoxide diffusing capacity (DLCO) in diffuse SSc (r = -0.376, P = 0.02). Patients with moderate to severe estimated systolic PAH had higher LOX levels (P < 0.01). Lung biopsies demonstrated intense LOX staining in SSc patients with PAH that was predominantly located in the endothelium of the remodelled pulmonary vessels. CONCLUSION: Serum LOX levels are increased in established SSc and inversely correlate with the DLCO. LOX is elevated in patients with moderate to severe PAH and is located in the proliferating endothelium in lung arterioles, suggesting a possible role for LOX in SSc-associated PAH.

Italian consensus recommendations for the management of hepatitis C infection in patients with rheumatoid arthritis.

Objectives: The recent introduction of direct-acting antiviral agents (DAAs) which can eliminate Hepatitis C virus (HCV) had revolutionized the treatment of HCV infections also in a complex clinical setting such as the patients with rheumatoid arthritis (RA). HCV elimination is also opportune due to the availability of more efficient immunosuppressive drugs, whose effect on the course of HCV infection is largely unknown.Methods: Consensus process was endorsed by the Italian Society of Rheumatology (SIR) and the Italian Society of Infectious and Tropical Diseases (SIMIT) to review the available evidence and produce practical, hospital-wide recommendations. The consensus panel consisted of 18 infectious diseases consultants, 20 rheumatologists and one clinical epidemiologist, who used the criteria of the Oxford Centre for Evidence-based Medicine to assess the quality of the evidence and the strength of their recommendations.Results: A core-set of statements about management of patients with RA and infection by HCV have been developed to help clinicians in their clinical practice.Conclusions: A screening for HCV should be performed in all RA patients and it is mandatory before starting an immunosuppressive therapy. Finally, a DAA treatment should be considered in all HCV-infected patients.Significance and InnovationsHCV antibodies should be investigated at the time of diagnosis of RA and, in any case, before starting immunosuppressive therapy with disease-modifying antirheumatic drugs (DMARDs).HCV eradication with DAA should be attempted as soon as possible, depending on patient conditions allowing a continuous oral treatment lasting 8-12 weeksConventional and biological DMARDs are allowed in patients with HCV infection, but they should be used cautiously in presence of advanced liver disease.

IL-22 capacitates dermal fibroblast responses to TNF in scleroderma.

OBJECTIVES: Interleukin (IL) 22 mRNA in systemic sclerosis (SSc) skin and Th22 cells in SSc peripheral blood are increased, but the role of IL-22 in fibrosis development remains poorly understood. METHODS: Biopsies were obtained from the involved skin of 15 SSc, 4 morphea and 8 healthy donors (HD). The presence of IL-22+ cells in the skin was determined by immunostaining. The in vitro response of HD and SSc fibroblasts to IL-22, IL-22 in conjunction with tumour necrosis factor (TNF) or keratinocyte conditioned medium was assessed by ELISA, radioimmunoassay (RIA), real-time PCR and western blot. The in vivo response in mice was assessed by histomorphometry. RESULTS: IL-22+ cells were over-represented in the dermis and epidermis of morphea and in the epidermis of SSc compared with HD. The majority of dermal IL-22+ cells were T cells. Dermal fibroblasts expressed both IL-22 receptor subunits IL-10RB and IL-22RA, expression of which was enhanced by TNF and reduced by transforming growth factor (TGF)-ß. IL-22 induced rapid phosphorylation of p38 and ERK1/2 in fibroblasts, but failed to induce the synthesis of chemokines and extracellular matrix components. However, IL-22 enhanced the production of monocyte chemotactic protein 1, IL-8 and matrix metalloproteinase 1 induced by TNF. Fibroblast responses were maximal in the presence of conditioned medium from keratinocytes activated by IL-22 in conjunction with TNF. Dermal thickness was maximal in mice injected simultaneously with IL-22 and TNF. CONCLUSIONS: IL-22 capacitates fibroblast responses to TNF and promotes a proinflammatory fibroblast phenotype by favouring TNF-induced keratinocyte activation. These results define a novel role for keratinocyte-fibroblast interactions in the context of skin fibrosis.

Prospectively-followed pregnancies in patients with inflammatory arthritis taking biological drugs: an Italian multicentre study.

OBJECTIVES: Information on new drugs does not include their possible effects on pregnancy because pregnant women are excluded from clinical trials. Although not classified as teratogenic in animals, limited data is available on biological anti-rheumatic agents and their safety in human pregnancy. The aim of the study is to evaluate the safety of biological drugs in pregnant patients with chronic arthritis. METHODS: Pregnancy outcome and maternal disease variations were prospectively followed in six Italian Rheumatology Centres. Patients exposed to biological agents during the periconceptional period or during pregnancy were included in the study. The occurrence of congenital malformations as well as the obstetric and neonatal outcomes were assessed. RESULTS: Between 1999 and 2013 we identified 79 exposed pregnancies in 67 women affected by different rheumatic diseases with peripheral chronic arthritis. At the time of the start of pregnancy, 56 patients were taking etanercept, 13 adalimumab, 3 infliximab, 2 each certolizumab-pegol and rituximab, 1 each golimumab, anakinra and abatacept. Biological treatment was stopped after a mean of 41 days since documented pregnancy. Live births were reported in 66% of pregnancies. The rate of spontaneous pregnancy loss was 20%. Only one congenital malformation was reported. CONCLUSIONS: TNF-alpha inhibitors can be considered safe in the periconception period, representing a possible therapeutic choice also in young women affected by an aggressive form of chronic arthritis and hoping for a pregnancy. Reports of exposure during 2nd/3rd trimester are still limited and suggest caution. Experience with abatacept, tocilizumab, anakinra and rituximab in pregnancy is insufficient.

International recommendations for the assessment of autoantibodies to cellular antigens referred to as anti-nuclear antibodies.

Anti-nuclear antibodies (ANA) are fundamental for the diagnosis of autoimmune diseases, and have been determined by indirect immunofluorescence assay (IIFA) for decades. As the demand for ANA testing increased, alternative techniques were developed challenging the classic IIFA. These alternative platforms differ in their antigen profiles, sensitivity and specificity, raising uncertainties regarding standardisation and interpretation of incongruent results. Therefore, an international group of experts has created recommendations for ANA testing by different methods. Two groups of experts participated in this initiative. The European autoimmunity standardization initiative representing 15 European countries and the International Union of Immunologic Societies/World Health Organization/Arthritis Foundation/Centers for Disease Control and Prevention autoantibody standardising committee. A three-step process followed by a Delphi exercise with closed voting was applied. Twenty-five recommendations for determining ANA (1-13), anti-double stranded DNA antibodies (14-18), specific antibodies (19-23) and validation of methods (24-25) were created. Significant differences between experts were observed regarding recommendations 24-25 (p<0.03). Here, we formulated recommendations for the assessment and interpretation of ANA and associated antibodies. Notably, the roles of IIFA as a reference method, and the importance of defining nuclear and cytoplasmic staining, were emphasised, while the need to incorporate alternative automated methods was acknowledged. Various approaches to overcome discrepancies between methods were suggested of which an improved bench-to-bedside communication is of the utmost importance. These recommendations are based on current knowledge and can enable harmonisation of local algorithms for testing and evaluation of ANA and related autoantibodies. Last but not least, new more appropriate terminologies have been suggested.

Rituximab vs mycophenolate and vs cyclophosphamide pulses for induction therapy of active lupus nephritis: a clinical observational study.

OBJECTIVE: We report the first comparison between rituximab (RTX) and either MMF or CYC pulses in the treatment of active LN. METHODS: Fifty-four patients with active LN received three methylprednisolone pulses for 3 consecutive days followed by oral prednisone and RTX 1 g at days 3 and 18 (17 patients) or MMF 2-2.5 g/day (17 patients) or six CYC pulses (0.5 g every fortnight) (20 patients). At 4 months MMF, AZA or ciclosporin were associated to prednisone as a consolidation/maintenance therapy in all groups. The outcomes of the three groups were compared at 3 and 12 months. RESULTS: Patients in the RTX group were older, had a longer duration of SLE and LN, had more renal flares, had higher activity and had higher chronicity indexes at renal biopsy than the other two groups. Four patients in each group had acute renal dysfunction and ∼50% had nephrotic syndrome. At 3 months, proteinuria was reduced by 50% in 58.8% of patients on RTX, in 64.7% on MMF and in 63.1% on CYC. At 12 months, complete remission was present in 70.6% of patients on RTX, in 52.9% on MMF, and in 65% on CYC. Partial remission was reached in 29.4% on RTX, 41.2% on MMF, and 25% on CYC. CONCLUSION: RTX seems to be at least as effective as MMF and CYC pulses in inducing remission. Considering that patients treated with RTX had more negative renal prognostic factors, this drug should be considered a viable alternative for the treatment of active LN.

Interleukin-17A+ cell counts are increased in systemic sclerosis skin and their number is inversely correlated with the extent of skin involvement.

OBJECTIVE: Levels of interleukin-17A (IL-17A) have been found to be increased in synovial fluid from individuals with systemic sclerosis (SSc). This study was undertaken to investigate whether IL-17A-producing cells are present in affected SSc skin, and whether IL-17A exerts a role in the transdifferentiation of myofibroblasts. METHODS: Skin biopsy samples were obtained from the involved skin of 8 SSc patients and from 8 healthy control donors undergoing plastic surgery. Immunohistochemistry and multicolor immunofluorescence techniques were used to identify and quantify the cell subsets in vivo, including IL-17A+, IL-4+, CD3+, tryptase-positive, α-smooth muscle actin (α-SMA)-positive, myeloperoxidase-positive, and CD1a+ cells. Dermal fibroblast cell lines were generated from all skin biopsy samples, and quantitative polymerase chain reaction, Western blotting, and solid-phase assays were used to quantify α-SMA, type I collagen, and matrix metalloproteinase 1 (MMP-1) production by the cultured fibroblasts. RESULTS: IL-17A+ cells were significantly more numerous in SSc skin than in healthy control skin (P = 0.0019) and were observed to be present in both the superficial and deep dermis. Involvement of both T cells and tryptase-positive mast cells in the production of IL-17A was observed. Fibroblasts positive for α-SMA were found adjacent to IL-17A+ cells, but not IL-4+ cells. However, IL-17A did not induce α-SMA expression in cultured fibroblasts. In the presence of IL-17A, the α-SMA expression induced in response to transforming growth factor ß was decreased, while MMP-1 production was directly enhanced. Furthermore, the frequency of IL-17A+ cells was higher in the skin of SSc patients with greater severity of skin fibrosis (lower global skin thickness score). CONCLUSION: IL-17A+ cells belonging to the innate and adaptive immune system are numerous in SSc skin. IL-17A participates in inflammation while exerting an inhibitory activity on myofibroblast transdifferentiation. These findings are consistent with the notion that IL-17A has a direct negative-regulatory role in the development of dermal fibrosis in humans.

In vivo distribution of ß2 glycoprotein I under various pathophysiologic conditions.

In vitro studies have documented ß2 glycoprotein I (ß2GPI) binding to endothelial cells (ECs) and trophoblast using antiphospholipid antibodies. The in vivo binding of ß2GPI to these cells and the conditions that favor their interaction have not been investigated. We analyzed the in vivo distribution of cyanine 5.5-labeled ß2GPI in mice and evaluated the effect of pregnancy and circulating antibodies on its tissue localization. The signal was detected in the liver by whole body scan and ex vivo analysis. The ß2GPI failed to bind to the vascular endothelium and reacted only with the ECs of uterine vessels. In pregnant mice the protein was localized on ECs and trophoblast at the embryo implantation sites. Immunized mice showed a similar ß2GPI biodistribution to naive mice but the immunized pregnant animals exhibited a significant increase in fetal loss associated with C3 and C9 deposition at the implantation sites. Treatment of mice with LPS after ß2GPI-Cy5.5 injection promoted protein localization on gut and brain ECs associated with IgG, C1q, and C9 deposition in immunized mice. These findings indicate that ß2GPI binding to EC requires priming with pro-inflammatory factors which is not needed for uterine and placental localization probably dependent on hormonal changes.

Anti-GalNAcß: a novel anti-glycan autoantibody associated with pregnancy loss in women with antiphospholipid syndrome and in a mouse experimental model.

OBJECTIVES: We evaluated the presence of anti-glycan antibodies (aGA) in patients with antiphospholipid syndrome (APS), and associations between aGA and clinical features of the disease. METHODS: Sera from APS patients and healthy controls were analyzed for aGA levels by ELISA. Analysis of the association of specific aGA with clinical manifestations of APS was performed. Selected aGA were affinity-purified and injected intravenously into naive mice which were tested for fetal loss. Matrigel invasion assay was performed for detection of choriocarcinoma cells (JAR) invasion and proliferation in the presence of selected aGA. Culture fluid of JAR invasion assays was analyzed for the presence of MMP2 and MMP9. RESULTS: High levels of several aGA were found in APS sera, of which anti-GalNAc-ß was significantly associated with recurrent pregnancy loss. Naive mice infused intravenously with anti-GalNAc-ß developed increased fetal loss. Anti-GalNAc-ß significantly inhibited the in-vitro percentage of JAR invasiveness and the secretion of MMP2 and MMP9 by human JAR cells. CONCLUSIONS: APS sera contain significant levels of aGA directed against several glycans. Anti-GalNAc-ß Ab is specifically associated with recurrent pregnancy loss both in human patients and experimental mouse model. The pathogenic effects of anti-GalNAc-ß include inhibition of JAR cells invasiveness accompanied by decreased MMP2 and MMP9 secretion.

Anti-phospholipid induced murine fetal loss: novel protective effect of a peptide targeting the ß2 glycoprotein I phospholipid-binding site. Implications for human fetal loss.

ß2 glycoprotein I (ß2GPI)-dependent anti-phospholipid antibodies (aPL) induce thrombosis and affect pregnancy. The CMV-derived synthetic peptide TIFI mimics the PL-binding site of ß2GPI and inhibits ß2GPI cell-binding in vitro and aPL-mediated thrombosis in vivo. Here we investigated the effect of TIFI on aPL-induced fetal loss in mice. TIFI inhibitory effect on in vitro aPL binding to human trophoblasts was evaluated by indirect immunofluorescence and ELISA. TIFI effect on aPL-induced fetal loss was investigated in pregnant C57BL/6 mice treated with aPL or normal IgG (NHS). Placenta/fetus weight and histology and RNA expression were analyzed. TIFI, but not the control peptide VITT, displayed a dose-dependent inhibition of aPL binding to trophoblasts in vitro. Injection of low doses of aPL at day 0 of pregnancy caused growth retardation and increased fetal loss rate, both significantly reduced by TIFI but not VITT. Consistent with observations in humans, histological analysis showed no evidence of inflammation in this model, as confirmed by the absence of an inflammatory signature in gene expression analysis, which in turn revealed a TIFI-dependent modulation of molecules involved in differentiation and development processes. These findings support the non-inflammatory pathogenic role of aPL and suggest innovative therapeutic approaches to aPL-dependent fetal loss.

Anti-ß2-glycoprotein I IgG antibodies from 1-year-old healthy children born to mothers with systemic autoimmune diseases preferentially target domain 4/5: might it be the reason for their 'innocent' profile?

BACKGROUND: Anti-ß2-glycoprotein-I (anti-ß2GPI) were demonstrated to be pathogenic in the antiphospholipid syndrome (APS). However, they can be detected in patients with no features of APS, especially those affected by systemic autoimmune diseases (SAD), and so in healthy children. It has been suggested that anti-ß2GPI against domain 1 (D1) associate with thrombosis, while those recognising domain 4/5 (D4/5) are present in non-thrombotic conditions. OBJECTIVE: To evaluate the fine specificity of anti-ß2GPI in adults and infants. METHODS: Three groups were examined-group A: 57 1-year-old healthy children born to mothers with SAD; group B: 33 children with atopic dermatitis; group C: 64 patients with APS. SUBJECTS: were selected based on positive anti-ß2GPI IgG results. Serum samples were tested for anti-ß2GPI IgG D1 and D4/5 using research ELISAs containing recombinant ß2GPI domain antigens. RESULTS: Children (A and B) displayed preferential IgG reactivity for D4/5, whereas patients with APS were mainly positive for D1. No thrombotic events were recorded in groups A and B. CONCLUSIONS: The specificity for D4/5 suggests that anti-ß2GPI IgG production in children born to mothers with SAD is a process neither linked to systemic autoimmunity nor related to the maternal autoantibody status. This unusual fine specificity might, at least partially, account for the 'innocent' profile of such antibodies.

Risk factors for a first thrombotic event in antiphospholipid antibody carriers: a prospective multicentre follow-up study.

OBJECTIVES: To assess risk factors for a first thrombotic event in confirmed antiphospholipid (aPL) antibody carriers and to evaluate the efficacy of prophylactic treatments. METHODS: Inclusion criteria were age 18-65 years, no history of thrombosis and two consecutive positive aPL results. Demographic, laboratory and clinical parameters were collected at enrolment, once a year during the follow-up and at the time of the thrombotic event, whenever that occurred. RESULTS: 258 subjects were prospectively observed between October 2004 and October 2008. The mean ± SD follow-up was 35.0 ± 11.9 months (range 1-48). A first thrombotic event (9 venous, 4 arterial and 1 transient ischaemic attack) occurred in 14 subjects (5.4%, annual incidence rate 1.86%). Hypertension and lupus anticoagulant (LA) were significantly predictive of thrombosis (both at p<0.05) and thromboprophylaxis was significantly protective during high-risk periods (p<0.05) according to univariate analysis. Hypertension and LA were identified by multivariate logistic regression analysis as independent risk factors for thrombosis (HR 3.8, 95% CI 1.3 to 11.1, p<0.05, and HR 3.9, 95% CI 1.1 to 14, p<0.05, respectively). CONCLUSIONS: Hypertension and LA are independent risk factors for thrombosis in aPL carriers. Thromboprophylaxis in these subjects should probably be limited to high-risk situations.

Pregnancy and reproduction in autoimmune rheumatic diseases.

Despite evidence for the important role of oestrogens in the aetiology and pathophysiology of chronic immune/inflammatory diseases, the previous view of an unequivocal beneficial effect of oestrogens on RA compared with a detrimental effect on SLE has to be reconsidered. Likewise, the long-held belief that RA remits in the majority of pregnant patients has been challenged, and shows that only half of the patients experience significant improvement when objective disease activity measurements are applied. Pregnancies in patients with SLE are mostly successful when well planned and monitored interdisciplinarily, whereas a small proportion of women with APS still have adverse pregnancy outcomes in spite of the standard treatment. New prospective studies indicate better outcomes for pregnancies in women with rare diseases such as SSc and vasculitis. Fertility problems are not uncommon in patients with rheumatic disease and need to be considered in both genders. Necessary therapy, shortly before or during the pregnancy, demands taking into account the health of both mother and fetus. Long-term effects of drugs on offspring exposed in utero or during lactation is a new area under study as well as late effects of maternal rheumatic disease on children.

Circulating Calprotectin as a Biomarker of COVID-19 Severity.

INTRODUCTION: Coronavirus disease 2019 (COVID-19) is an infectious disease caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection. Although demographic and clinical parameters such as sex, age, comorbidities, genetic background and various biomarkers have been identified as risk factors, there is an unmet need to predict the risk and onset of severe inflammatory disease leading to poor clinical outcomes. In addition, very few mechanistic biomarkers are available to inform targeted treatment of severe (auto)-inflammatory conditions associated with COVID-19. Calprotectin, also known as S100A8/S100A9, MRP8/14 (Myeloid-Related Protein) or L1, is a heterodimer involved in neutrophil-related inflammatory processes. In COVID-19 patients, calprotectin levels were reported to be associated with poor clinical outcomes such as significantly reduced survival time, especially in patients with severe pulmonary disease. AREAS COVERED: Pubmed was searched using the following keywords: Calprotectin + COVID19, S100A8/A9 + COVID19, S100A8 + COVID-19, S100A9 + COVID-19, MRP8/14 + COVID19; L1 + COVID-19 between May 2020 and 8 March 2021. The results summarized in this review provide supporting evidence and propose future directions that define calprotectin as an important biomarker in COVID-19. EXPERT OPINION: Calprotectin represents a promising serological biomarker for the risk assessment of COVID-19 patients.

Multi-organ complement deposition in COVID-19 patients.

BACKGROUND: Increased levels of circulating complement activation products have been reported in COVID-19 patients, but only limited information is available on complement involvement at tissue level. The mechanisms and pathways of local complement activation remain unclear. METHODS: We performed immunofluorescence analyses of autopsy specimens of lungs, kidney and liver from nine COVID-19 patients who died of acute respiratory failure. Snap-frozen samples embedded in OCT were stained with antibodies against complement components and activation products, IgG and spike protein of SARS-CoV-2. FINDINGS: Lung deposits of C1q, C4, C3 and C5b-9 were localized in the capillaries of the interalveolar septa and on alveolar cells. IgG displayed a similar even distribution, suggesting classical pathway activation. The spike protein is a potential target of IgG, but its uneven distribution suggests that other viral and tissue molecules may be targeted by IgG. Factor B deposits were also seen in COVID-19 lungs and are consistent with activation of the alternative pathway, whereas MBL and MASP-2 were hardly detectable. Analysis of kidney and liver specimens mirrored findings observed in the lung. Complement deposits were seen on tubules and vessels of the kidney with only mild C5b-9 staining in glomeruli, and on hepatic artery and portal vein of the liver. INTERPRETATION: Complement deposits in different organs of deceased COVID-19 patients caused by activation of the classical and alternative pathways support the multi-organ nature of the disease. FUNDING: Grants from the Italian Ministry of Health (COVID-2020-12371808) to PLM and National Institutes of Health HL150146 to NP are gratefully acknowledged.