Giuseppe A. Ramirez

Circulating platelets as a source of the damage-associated molecular pattern HMGB1 in patients with systemic sclerosis

The link between platelet activation and vascular injury in Systemic Sclerosis (SSc) is poorly characterized. Here we report that platelet activation results in i) the translocation from the cytoplasm to the surface of HMGB1, a prototypical DAMP signal associated with tissue regeneration and ii) the release of platelet derived microparticles (PDμP) expressing HMGB1. Decreased HMGB1 content (334.6 ± 21.2 vs 587.1 ± 11.1 AUF, P < 0.001) and HMGB1 translocation to the outer leaflet of the plasma membrane (17.8 ± 3.5 vs 4.5 ± 0.5%, P < 0.001) characterize circulating platelets of SSc patients (n = 29) when compared with age-matched healthy controls (HC, n = 20). Conversely, a significantly higher fraction of PDμP in the blood of SSc patients, but not of HC, consistently expose (HMGB1 (MFI 62.8 ± 3.95 vs 4.3 ± 0.7). Platelet HMGB1 depletion is significantly associated in SSc patients with degranulation and with expression of P-selectin and of tissue factor as well as with fibrinogen binding to their plasma membrane. These findings indicate that platelets represent a source of HMGB1, an ancestral signal of necrosis, in the vasculature of SSc patients, possible contributing to persistent microvascular injury and endothelial cell activation.

Selective up-regulation of the soluble pattern-recognition receptor pentraxin 3 and of vascular endothelial growth factor in giant cell arteritis: relevance for recent optic nerve ischemia.

OBJECTIVE To assess local expression and plasma levels of pentraxin 3 (PTX3) in patients with giant cell arteritis (GCA). METHODS Plasma and serum samples were obtained from 75 patients with GCA (20 of whom had experienced optic nerve ischemia in the previous 3 weeks and 24 of whom had experienced symptom onset in the previous 6 months and had no history of optic nerve ischemia) and 63 controls (35 age-matched healthy subjects, 15 patients with rheumatoid arthritis, and 13 patients with chronic stable angina). In 9 patients in whom GCA was recently diagnosed, circulating levels of interleukin-1β (IL-1β), IL-2, IL-4, IL-6, IL-7, IL-8, IL-10, IL-12p70, CCL2/monocyte chemotactic protein 1, CCL3/macrophage inflammatory protein 1α (MIP-1α), CCL4/MIP-1β, CCL11/eotaxin, CXCL9/monokine induced by interferon-γ, CXCL10/interferon-γ-inducible 10-kd protein, tumor necrosis factor α (TNFα), interferon-γ, vascular endothelial growth factor (VEGF), granulocyte-macrophage colony-stimulating factor, and FasL were measured via a multiplexed cytometric assay. PTX3 and VEGF concentrations were assessed by enzyme-linked immunosorbent assay. PTX3 and CD68 expression were determined by immunohistochemistry and immunofluorescence on temporal artery samples. RESULTS GCA patients with very recent optic nerve ischemia had significantly higher PTX3 and VEGF levels compared to other GCA patients and controls. GCA patients with a disease duration of <6 months had significantly higher PTX3 levels compared to other GCA patients and controls. Immunohistochemistry revealed selective PTX3 expression in the wall of inflamed arteries. CONCLUSION Our findings indicate that local expression of PTX3 is a feature of vascular inflammation in GCA; elevated circulating levels of PTX3 identify patients with very recent optic nerve ischemia or a recent diagnosis. Optic nerve ischemia is also associated with increased circulating VEGF levels.

Platelet-leukocyte deregulated interactions foster sterile inflammation and tissue damage in immune-mediated vessel diseases

Platelets and leukocytes co-localize and interact at sites of vessel injury, haemorrhage, thrombosis and inflammation. Recent studies have highlighted the role of local cues in the interaction between the two cell populations, including the exposure of anionic phospholipids and the release of Damage Associated Molecular Patterns (DAMPs) by activated platelets, the release of the prototypical tissue pentraxin PTX3 by neutrophils, as well as the generation of polarized clusters of neutrophil ß(2) integrins. In turn, the reciprocal activatory cross-talk between platelets and leukocytes contributes to the generation of thrombo-inflammatory lesions and of vascular injury. Here we will discuss the implications of these results for the pathogenesis and the clinical features of self-sustaining immune-mediated vessel diseases.

Intravascular immunity as a key to systemic vasculitis: a work in progress, gaining momentum

Vascular inflammation contributes to the defence against invading microbes and to the repair of injured tissues. In most cases it resolves before becoming apparent. Vasculitis comprises heterogeneous clinical entities that are characterized by the persistence of vascular inflammation after it has served its homeostatic function. Most underlying mechanisms have so far remained elusive. Intravascular immunity refers to the surveillance of the vasculature by leucocytes that sense microbial or sterile threats to vessel integrity and initiate protective responses that entail most events that determine the clinical manifestations of vasculitis, such as end‐organ ischaemia, neutrophil extracellular traps generation and thrombosis, leucocyte extravasation and degranulation. Understanding how the resolution of vascular inflammation goes awry in patients with systemic vasculitis will facilitate the identification of novel pharmacological targets and bring us a step closer in each patient to the selection of more effective and less toxic treatments.

The role of platelets in the pathogenesis of systemic sclerosis

Systemic sclerosis (SSc) is an inflammatory disease of unknown etiology characterized by widespread organ dysfunction due to fibrosis and ischemia. Its nebulous pathogenic background and the consequent absence of an etiological therapy prevent the adoption of satisfying treatment strategies, able to improve patients’ quality of life and survival and stimulate researchers to identify a unifying pathogenic target. Platelets show a unique biological behavior, lying at the crossroads between vascular function, innate and adaptive immunity, and regulation of cell proliferation. Consequently they are also emerging players in the pathogenesis of many inflammatory diseases, including SSc. In the setting of SSc platelets are detectable in a persistent activated state, which is intimately linked to the concomitant presence of an injured endothelium and to the widespread activation of the innate and adaptive immune system. As a consistent circulating source of bioactive compounds platelets contribute to the development of many characteristic phenomena of SSc, such as fibrosis and impaired vascular tone.

AB0176 Association between Polymorphisms in Beta-Adducin and Sodium/Calcium Exchanger 1 and SLE with and without Nephritis

Background Genes involved in cytoskeletal assembly and water/electrolyte balance have been previously linked to hypertension, but recent evidences suggest a role also in the development of inflammation and autoimmunity [1-2]. Systemic Lupus Erythematosus is a prototypic multi-organ autoimmune disease, characterized by polymorphic clinical features and a complex polygenic background. Renal disease in SLE occurs in 40-70% of lupus patients and is responsible of an high burden of morbidity and mortality. Despite substantial efforts, less is known about the role of specific genetic factors in conferring susceptibility to SLE and its complications, including lupus nephritis (LN) [3]. Objectives With these premises we sought if an association between known hypertension-related polymorphisms and development of SLE and LN existed. Methods 106 patients (96 females, 10 males) diagnosed with SLE (n=51) or LN (n=55), 23 patients with Sjoegrens Syndrome and 62 healthy controls were enrolled. Patients and controls were genotyped for polymorphisms in α-, β- and γ-adducin (ADD1,2,3 respectively), angiotensin converting enzyme, transient receptor potential cation channel-subfamily C, solute carrier family 8 (sodium-calcium exchanger) member 1 (SLC8A1), solute carrier family 24 (sodium/potassium/calcium exchanger) member 3, PKD2 calcium channel and PRKG1 kinase genes. Results Beta-adducin (ADD2) rs4984 CT heterozygosis was significantly more frequent in SLE patients than in LN patients (χ2 =6.154; p=0.013). No patient had the ADD2 rs4984 TT genotype in accordance with a low prevalence of the ADD2 C1797T homozygosity in the population. Seven patients with SLE (n=3) or LN (n=4), but none of the control groups carried the AA variant of sodium/calcium exchanger 1 (SLC8A1) rs11893826 SNP (χ2 =11.771; p=0.019). Conclusions Genes involved in the control of electrolyte/water balance and cytoskeletal plasticity could affect the pathogenic background of SLE/LN. Larger studies are required to confirm these data and attempt correlations between genetic data and specific clinical features. References Tintinger GR, et al., Drug Des Devel Ther, 2009 Kleinewietfeld M, et al., Nature, 2013 Ramos PS, et al., Semin Nephrol, 2010 Disclosure of Interest None declared DOI 10.1136/annrheumdis-2014-eular.3378

Raoultella planticola-associated cholangitis and sepsis: a case report and literature review

### Learning Point for Clinicians Raoultella planticola is a rare and possibly underestimated cause of severe human infection and its presence should be suspected in older patients with a history of cancer, immune-suppression and recent exposure to traumatic injuries or invasive medical procedures. The frequent involvement of the bilio-pancreatic tract suggests the importance of the gut flora as a bacterial reservoir in clinically relevant infections. Raoultella planticola 1 is a Gram-negative anaerobic bacterium and a rare cause of human infection. Twelve cases of clinically relevant human infections (two fatal) have been described so far in the English literature. A 70-year-old male with a history of chronic obstructive pulmonary disease and bronchiectasis was diagnosed with pancreatic adenocarcinoma. Due to significant mass-effect on the biliary …

Parietal and intravascular innate mechanisms of vascular inflammation

Sustained inflammation of the vessel walls occurs in a large number of systemic diseases (ranging from atherosclerosis to systemic vasculitides, thrombotic microangiopathies and connective tissue diseases), which are ultimately characterized by ischemia and end-organ failure. Cellular and humoral innate immunity contribute to a common pathogenic background and comprise several potential targets for therapeutic intervention. Here we discuss some recent advances in the effector and regulatory action of neutrophils and in the outcome of their interaction with circulating platelets. In parallel, we discuss novel insights into the role of humoral innate immunity in vascular inflammation. All these topics are discussed in light of potential clinical and therapeutic implications in the near future.

ANCA-associated vasculitis in childhood: recent advances

Anti-neutrophil cytoplasmic antibody (ANCA)-associated vasculitides are rare systemic diseases that usually occur in adulthood. They comprise granulomatosis with polyangiitis (GPA, Wegener’s), microscopic polyangiitis (MPA) and eosinophilic granulomatosis with polyangiitis (EGPA, Churg-Strauss syndrome). Their clinical presentation is often heterogeneous, with frequent involvement of the respiratory tract, the kidney, the skin and the joints. ANCA-associated vasculitis is rare in childhood but North-American and European cohort studies performed during the last decade have clarified their phenotype, patterns of renal involvement and their prognostic implications, and outcome. Herein, we review the main clinical and therapeutic aspects of childhood-onset ANCA-associated vasculitis, and provide preliminary data on demographic characteristics and organ manifestations of an Italian multicentre cohort.

Drug induced exfoliative dermatitis: state of the art

Drug induced exfoliative dermatitis (ED) are a group of rare and severe drug hypersensitivity reactions (DHR) involving skin and usually occurring from days to several weeks after drug exposure. Erythema multiforme (EM), Stevens–Johnson syndrome (SJS) and toxic epidermal necrolysis (TEN) are the main clinical presentations of drug induced ED. Overall, T cells are the central player of these immune-mediated drug reactions. Here we provide a systematic review on frequency, risk factors, pathogenesis, clinical features and management of patients with drug induced ED.