Reduction of mortality, cardiac damage, and cerebral damage by IL-1 inhibition in a murine model of TTP.

ABSTRACT: Thrombotic thrombocytopenic purpura (TTP), a rare but fatal disease if untreated, is due to alteration in von Willebrand factor cleavage resulting in capillary microthrombus formation and ischemic organ damage. Interleukin-1 (IL-1) has been shown to drive sterile inflammation after ischemia and could play an essential contribution to postischemic organ damage in TTP. Our objectives were to evaluate IL-1 involvement during TTP and to test the efficacy of the recombinant IL-1 receptor antagonist, anakinra, in a murine TTP model. We retrospectively measured plasma IL-1 concentrations in patients with TTP and controls. Patients with TTP exhibited elevated plasma IL-1α and -1ß concentrations, which correlated with disease course and survival. In a mouse model of TTP, we administered anakinra (IL-1 inhibitor) or placebo for 5 days and evaluated the efficacy of this treatment. Anakinra significantly reduced mortality of mice (P < .001). Anakinra significantly decreased TTP-induced cardiac damage as assessed by blood troponin concentrations, evaluation of left ventricular function by echocardiography, [18F]fluorodeoxyglucose positron emission tomography of myocardial glucose metabolism, and cardiac histology. Anakinra also significantly reduced brain TTP-induced damage evaluated through blood PS100b concentrations, nuclear imaging, and histology. We finally showed that IL-1α and -1ß trigger endothelial degranulation in vitro, leading to the release of von Willebrand factor. In conclusion, anakinra significantly reduced TTP mortality in a preclinical model of the disease by inhibiting both endothelial degranulation and postischemic inflammation, supporting further evaluations in humans.

Immune-mediated thrombotic thrombocytopenic purpura plasma induces calcium- and IgG-dependent endothelial activation: correlations with disease severity.

Immune-mediated thrombotic thrombocytopenic purpura (iTTP) is characterized by a severe ADAMTS13 deficiency due to the presence of anti-ADAMTS13 auto-antibodies, with subsequent accumulation of circulating ultra-large von Willebrand factor (VWF) multimers. The role of endothelial cell activation as a trigger of the disease has been suggested in animal models but remains to be demonstrated in humans. We prospectively obtained plasma from the first plasma exchange of 25 patients during iTTP acute phase. iTTP but not control plasma, induced a rapid VWF release and P-selectin exposure on the surface of dermal human micro-vascular endothelial cell (HMVEC-d), associated with angiopoietin-2 and endothelin-1 secretion, consistent with Weibel-Palade bodies exocytosis. Calcium (Ca2+) blockade significantly decreased VWF release, whereas iTTP plasma induced a rapid and sustained Ca2+ flux in HMVEC-d which correlated in retrospect, with disease severity and survival in 62 iTTP patients. F(ab)'2 fragments purified from the immunoglobulin G fraction of iTTP plasma mainly induced endothelial cell activation with additional minor roles for circulating free heme and nucleosomes, but not for complement. Furthermore, two anti-ADAMTS13 monoclonal antibodies purified from iTTP patients' B cells, but not serum from hereditary TTP, induced endothelial Ca2+ flux associated with Weibel-Palade bodies exocytosis in vitro, whereas inhibition of endothelial ADAMTS13 expression using small intering RNA, significantly decreased the stimulating effects of iTTP immunoglobulin G. In conclusion, Ca2+-mediated endothelial cell activation constitutes a "second hit" of iTTP, is correlated with the severity of the disease and may constitute a possible therapeutic target.

Early IL-1 receptor blockade in severe inflammatory respiratory failure complicating COVID-19.

Around the tenth day after diagnosis, ∼20% of patients with coronavirus disease 2019 (COVID-19)-associated pneumonia evolve toward severe oxygen dependence (stage 2b) and acute respiratory distress syndrome (stage 3) associated with systemic inflammation often termed a "cytokine storm." Because interleukin-1 (IL-1) blocks the production of IL-6 and other proinflammatory cytokines, we treated COVID-19 patients early in the disease with the IL-1 receptor antagonist, anakinra. We retrospectively compared 22 patients from three different centers in France with stages 2b and 3 COVID-19-associated pneumonia presenting with acute severe respiratory failure and systemic inflammation who received either standard-of-care treatment alone (10 patients) or combined with intravenous anakinra (12 patients). Treatment started at 300 mg⋅d-1 for 5 d, then tapered with lower dosing over 3 d. Both populations were comparable for age, comorbidities, clinical stage, and elevated biomarkers of systemic inflammation. All of the patients treated with anakinra improved clinically (P < 0.01), with no deaths, significant decreases in oxygen requirements (P < 0.05), and more days without invasive mechanical ventilation (P < 0.06), compared with the control group. The effect of anakinra was rapid, as judged by significant decrease of fever and C-reactive protein at day 3. A mean total dose of 1,950 mg was infused with no adverse side effects or bacterial infection. We conclude that early blockade of the IL-1 receptor is therapeutic in acute hyperinflammatory respiratory failure in COVID-19 patients.

Mast cells drive pathologic vascular lesions in Takayasu arteritis.

BACKGROUND: Takayasu arteritis (TAK) is a large vessel vasculitis resulting in artery wall remodeling with segmental stenosis and/or aneurysm formation. Mast cells (MCs) are instrumental in bridging cell injury and inflammatory response. OBJECTIVES: This study sought to investigate the contribution of MCs on vessel permeability, angiogenesis, and fibrosis in patients with TAK. METHODS: MC activation and their tissue expression were assessed in sera and in aorta from patients with TAK and from healthy donors (HDs). In vivo permeability was assessed using a modified Miles assay. Subconfluent cultured human umbilic vein endothelial cells and fibroblasts were used in vitro to investigate the effects of MC mediators on angiogenesis and fibrogenesis. RESULTS: This study found increased levels of MC activation markers (histamine and indoleamine 2,3-dioxygenase) in sera of patients with TAK compared with in sera of HDs. Marked expression of MCs was shown in aortic lesions of patients with TAK compared with in those of noninflammatory aorta controls. Using Miles assay, this study showed that sera of patients with TAK significantly increased vascular permeability in vivo as compared with that of HDs. Vessel permeability was abrogated in MC-deficient mice. MCs stimulated by sera of patients with TAK supported neoangiogenesis (increased human umbilic vein endothelial cell proliferation and branches) and fibrosis by inducing increased production of fibronectin, type 1 collagen, and α-smooth muscle actin by fibroblasts as compared to MCs stimulated by sera of HD. CONCLUSIONS: MCs are a key regulator of vascular lesions in patients with TAK and may represent a new therapeutic target in large vessel vasculitis.

Predictors of Relapses or Recurrences in Patients With Giant Cell Arteritis: A Medical Records Review Study.

OBJECTIVE: Giant cell arteritis (GCA) is the most common systemic vasculitis in individuals aged ≥50 years. Its course is marked by a high relapse rate requiring long-term glucocorticoid use with its inherent adverse effects. We aimed to identify factors associated with relapses or recurrences in GCA at diagnosis. METHODS: We reviewed the medical records of consecutive patients with GCA diagnosed between 2009 and 2019 and followed for at least 12 months. We recorded their characteristics at onset and during follow-up. Factors associated with relapses or recurrences were identified using multivariable analysis. RESULTS: We included 153 patients, among whom 68% were female with a median age of 73 (47-98) years and a median follow-up of 32 (12-142) months. Seventy-four patients (48.4%) had at least 1 relapse or recurrence. Headache and polymyalgia rheumatica were the most frequent manifestations of relapses. The first relapse occurred at a median time of 13 months after the diagnosis, with a median dose of 5.5 (0-25) mg/d of glucocorticoids.In multivariable analysis, patients with relapses or recurrences had a higher frequency of cough and scalp tenderness at diagnosis (20.3% vs 5.1%; odds ratio [OR], 4.73; 95% confidence interval [CI], 1.25-17.94; p = 0.022; and 41.9% vs 29.1%; OR, 2.4; 95% CI, 1.07-5.39; p = 0.034, respectively). Patients with diabetes mellitus at diagnosis had fewer relapses or recurrences during follow-up (5.4% vs 19%; OR, 0.24; 95% CI, 0.07-0.83; p = 0.024). CONCLUSIONS: Cough and scalp tenderness at diagnosis were associated with relapses or recurrences, whereas patients with diabetes experienced fewer relapses or recurrences.

Factors associated with dexamethasone efficacy in COVID-19. A retrospective investigative cohort study.

Dexamethasone has demonstrated efficacy in reducing mortality in COVID-19. However, its practical use is badly defined. We aimed to investigate factors associated with dexamethasone efficacy in real life. Our retrospective study was conducted in two university hospitals between September and November 2020 and included all the consecutive hospitalized patients with a laboratory-confirmed SARS-CoV-2 infection assessed by RT-PCR, treated with intravenous dexamethasone (6 mg/day). Among 111 patients, 10.6% necessitated a transfer into the intensive care unit (ICU) and the 28-day mortality rate was 17.1%. The 28-day mortality rate was significantly lower in patients who demonstrated improvement at 48 h (hazard ratio [HR]: 0.17, 95% confidence interval [CI]: 0.04-0.78, p = 0.02) and 96 h (HR: 0.07, 95% CI: 0.02-0.31, p = 0.0005) after dexamethasone initiation. Apart from well-known risk factors (age, hypertension, active cancer, severe lesions on chest computed tomography [CT] scan), we found that a high viral load in nasopharyngeal swab (Cycle threshold <30) at dexamethasone initiation was associated with higher 28-day mortality (66.6% vs. 36.7%, p = 0.03). Patients who did not receive antibiotics at dexamethasone initiation had a higher rate of transfer into the ICU (55.6% vs. 23.5%, p = 0.045) with a trend towards higher mortality in case of severe or critical lesions on CT scan (75.0% vs. 25.0%, p = 0.053). Patients who did not improve within 2-4 days after steroid initiation have a bad prognosis and should receive additional anti-inflammatory drugs. Our data suggest better efficacy of dexamethasone in patients with a low or negative viral load, receiving broad-spectrum antibiotics.

Functional and genetic testing in adults with HLH reveals an inflammatory profile rather than a cytotoxicity defect.

Hemophagocytic lymphohistiocytosis (HLH) is a life-threatening hyperinflammatory condition. Primary HLH occurs early in life as a result of monogenic biallelic mutations affecting lymphocyte cytotoxicity. Secondary HLH occurs mostly in adults secondary to infection, lymphoma, or rheumatic disease. In this latter setting, lymphocyte cytotoxicity status is not known. We conducted a systematic evaluation of natural killer (NK) cell cytotoxicity in adult patients with secondary HLH. Adult patients with secondary HLH were prospectively studied ex vivo for total lymphocyte count and subtype, NK cell phenotype, perforin expression and degranulation, and natural or antibody-dependent cell cytotoxicity, in comparison with patients affected by the same underlying disease without HLH (disease controls [DCs]) and with healthy controls (HCs). Screening for variants of cytotoxity genes was systematically performed. 68 patients were included in the HLH group and 34 each in the DC and HC groups. In HLH patients, severe and transient lymphopenia, activated NK cell phenotype (eg, increased CD69, ICAM-1, HLADR, and CCR5 expression), and decreased capacity of interferon γ production were observed; mean perforin expression was normal; and degranulation tests and NK cell cytotoxicity were not different from those in DCs. A monoallelic variant of uncertain significance affecting a lymphocyte cytotoxicity gene or the perforin variant A91V was observed in almost 50% of the patients. We detected no major intrinsic cytotoxicity dysfunction in secondary HLH patients compared with DCs and no predicted pathogenic gene variant. The activated NK phenotype profile associated with decreased interferon γ production seems similar to those of other hyperinflammatory diseases such as sepsis or systemic juvenile idiopathic arthritis.

Open ADAMTS13, induced by antibodies, is a biomarker for subclinical immune-mediated thrombotic thrombocytopenic purpura.

Recently, we showed that ADAMTS13 circulates in an open conformation during the acute phase of immune-mediated thrombotic thrombocytopenic purpura (iTTP). Although the cause of this conformational change remains elusive, ADAMTS13 is primarily closed in iTTP patients in remission with ADAMTS13 activity >50% and undetectable anti-ADAMTS13 autoantibodies, as well as after rituximab treatment, suggesting a role for anti-ADAMTS13 autoantibodies. Therefore, immunoglobulin G from 18 acute iTTP patients was purified and added to closed ADAMTS13 in healthy donor plasma. This resulted in open ADAMTS13 in 14 of 18 (78%) samples, proving that anti-ADAMTS13 autoantibodies can induce an open ADAMTS13 conformation. To further elucidate the conformation of ADAMTS13 in iTTP patients, we studied a novel iTTP patient cohort (n = 197) that also included plasma samples from iTTP patients in remission in whom ADAMTS13 activity was <50%. The open ADAMTS13 conformation was found during acute iTTP, as well as in patients in remission with ADAMTS13 activity <50% and in half of the patients with ADAMTS13 activity >50%, although free anti-ADAMTS13 autoantibodies were not always detected. Thus, open ADAMTS13 is a hallmark of acute iTTP, as well as a novel biomarker that can be used to detect subclinical iTTP in patients in remission. Finally, a long-term follow-up study in 1 iTTP patient showed that the open conformation precedes a substantial drop in ADAMTS13 activity. In conclusion, we have shown that anti-ADAMTS13 autoantibodies from iTTP patients induce an open ADAMTS13 conformation. Most importantly, an open ADAMTS13 conformation is a biomarker for subclinical iTTP and could become an important tool in TTP management.

Aortitis is an under-recognized manifestation of antiphospholipid syndrome: A case report and literature review.

Aortitis is a classic manifestation of large vessel vasculitis. Antiphospholipid syndrome (APS), sometimes known as Hughes syndrome, is an acquired autoimmune disorder that manifests clinically as recurrent venous or arterial thrombosis. Patients with APS may also suffer from various underlying diseases, most frequently systemic lupus erythematosus (SLE). Catastrophic antiphospholipid syndrome (CAPS) is a rare but serious complication of APS characterized by failure of several organs due to diffuse microcirculatory thrombi. Its main manifestations involve the kidneys, lungs, heart and central nervous system, and require early diagnosis and rapid therapeutic management. While APS can affect virtually any blood vessel, aortitis is not a known symptom of APS. We report the case of a 36-year-old patient with APS and SLE who presented with CAPS during pregnancy, with no concomitant SLE flare. The first manifestation of CAPS was aortitis, preceding renal, cardiac and haematological manifestations. The outcome was favourable with combined treatment including corticosteroids, anticoagulants, plasma exchange and rituximab. We then carried out a literature search for papers describing the presence of aortitis in APS and/or SLE. In the cases of aortic involvement identified in the literature, including another case of CAPS, the occurrence of aortitis in SLE, often associated with the presence of antiphospholipid antibodies/APS, suggests that aortitis should be considered as an under-recognized manifestation and potential non-criterion feature of APS.

Pericardial effusion in giant cell arteritis is associated with increased inflammatory markers: a retrospective cohort study.

OBJECTIVE: Giant cell arteritis (GCA) is the most frequent vasculitis affecting adults aged > 50 years. Cardiac involvement in GCA is considered rare, and only a few cases of pericarditis have been reported. The aim of this study was to determine the characteristics and prognosis of GCA patients suffering from pericardial involvement at diagnosis. METHODS: We conducted a single-centre, retrospective chart review of patients with GCA in internal medicine departments (from 2000 to 2020). Patients were identified through a centralized hospital database. We retrospectively collected demographic, clinicobiological, histological, imaging, treatment and outcome data. Patients with pericardial effusion, defined as an effusion visible on the CT-scan performed at GCA diagnosis were compared to those without pericardial involvement. RESULTS: Among the 250 patients with GCA, 23 patients (9.2%) had pericardial effusion on CT-scan. The comparison between the groups revealed similar distribution of age, gender, cranial symptoms and ocular ischaemic complications. Patients with pericardial effusion had a higher frequency of weight loss. They also had lower haemoglobin levels and higher platelet levels (p = 0.006 and p = 0.002, respectively), and they more frequently had positive temporal artery biopsy. There were no differences concerning the treatment, relapses, follow-up duration or deaths. CONCLUSIONS: This case series sheds light on GCA as a cause of unexplained pericardial effusion or symptomatic pericarditis among adults aged > 50 years and elevated inflammatory biological markers. Fortunately, pericardial involvement is a benign GCA manifestation. In that context, the search for constitutional symptoms, cranial symptoms and associated signs of polymyalgia rheumatica is crucial for rapidly guiding GCA diagnosis.

Interleukin-18: Biological properties and role in disease pathogenesis.

Initially described as an interferon (IFN)γ-inducing factor, interleukin (IL)-18 is indeed involved in Th1 and NK cell activation, but also in Th2, IL-17-producing γδ T cells and macrophage activation. IL-18, a member of the IL-1 family, is similar to IL-1ß for being processed by caspase 1 to an 18 kDa-biologically active mature form. IL-18 binds to its specific receptor (IL-18Rα, also known as IL-1R7) forming a low affinity ligand chain. This is followed by recruitment of the IL-18Rß chain. IL-18 then uses the same signaling pathway as IL-1 to activate NF-kB and induce inflammatory mediators such as adhesion molecules, chemokines and Fas ligand. IL-18 also binds to the circulating high affinity IL-18 binding protein (BP), such as only unbound free IL-18 is active. IL-18Rα may also bind IL-37, another member of the IL-1 family, but in association with the negative signaling chain termed IL-1R8, which transduces an anti-inflammatory signal. IL-18BP also binds IL-37 and this acts as a sink for the anti-inflammatory properties of IL-37. There is now ample evidence for a role of IL-18 in various infectious, metabolic or inflammatory diseases such as influenza virus infection, atheroma, myocardial infarction, chronic obstructive pulmonary disease, or Crohn's disease. However, IL-18 plays a very specific role in the pathogenesis of hemophagocytic syndromes (HS) also termed Macrophage Activation Syndrome. In children affected by NLRC4 gain-of-function mutations, IL-18 circulates in the range of tens of nanograms/mL. HS is treated with the IL-1 Receptor antagonist (anakinra) but also specifically with IL-18BP. Systemic juvenile idiopathic arthritis or adult-onset Still's disease are also characterized by high serum IL-18 concentrations and are treated by IL-18BP.

Anti-NuMA antibodies: clinical associations and significance in patients with primary Sjögren's syndrome or systemic lupus erythematosus.

OBJECTIVE: To determine the clinical significance of anti-nuclear mitotic apparatus (NuMA) antibodies (AC-26 or AC-25) in patients with primary Sjögren's syndrome (pSS) and SLE. METHODS: Between 2013 and 2018, clinical and immunological features of pSS and SLE patients with anti-NuMA antibodies were compared with anti-NuMA antibodies-negative pSS and SLE cohorts. RESULTS: Among 31 284 sera positive for antinuclear antibodies, 90 patients (0.29%) had anti-AC-26 (anti-NuMA1) and AC-25 (anti-HsEg5) antibodies (73.3% and 26.7%, respectively). Autoimmune diseases, mainly consisting in pSS (28.9%) and SLE (21.1%), were found in 67.8%. Anti-NuMA antibodies represented the unique ANA in 60% and 50% of patients with pSS and SLE patients, respectively. Compared with 137 anti-NuMA-negative pSS patients, 20 anti-NuMA-positive pSS presented with less frequent ocular sicca syndrome (70.0% vs 89.1%, P=0.031), dryness complications (15.0% vs 39.4%, P=0.045), or detectable anti-SSa and/or anti-SSb antibodies (40.0% vs 66.4%, P=0.027). Compared with 80 anti-NuMA-negative SLE patients, 14 anti-NuMA-positive SLE patients had no lupus nephritis (0.0% vs 28.8%, P=0.049), less frequent dsDNA antibodies (42.9% vs 75.0%, P=0.025) and complement consumption (21.4% vs 53.8%, P=0.040). Anti-NuMA-positive pSS and SLE patients less frequently required treatments compared with anti-NuMA-negative patients. CONCLUSION: Although rare, anti-NuMA antibodies are mainly associated with pSS and SLE and may be useful for diagnosis when other auto-antibodies are negative. PSS and SLE patients with anti-NuMA antibodies have less severe clinical and biological profiles, suggesting that anti-NuMA antibodies may constitute a good prognosis marker in both autoimmune diseases.

Clinical characteristics and outcomes of patients with haematologic malignancies and COVID-19 suggest that prolonged SARS-CoV-2 carriage is an important issue.

Specificities of COVID-19 disease course in patients with haematologic malignancies are still poorly studied. So, we aimed to compare patients with haematologic malignancies to patients without malignancies, matched by sex and age and hospitalised for COVID-19 at the same time and in the same centre. Among 25 patients with haematologic malignancies, we found that mortality (40% versus 4%, p < 0.01), number of days with RT-PCR positivity (21.2 ± 15.9 days [range, 3-57] versus 7.4 ± 5.6 days [range, 1-24], p < 0.01), maximal viral load (mean minimal Ct, 17.2 ± 5.2 [range, 10-30] versus 26.5 ± 5.1 [range, 15-33], p < 0.0001) and the delay between symptom onset and clinical worsening (mean time duration between symptom onset and first day of maximum requirement in inspired oxygen fraction, 14.3 ± 10.7 days versus 9.6 ± 3.7 days, p = 0.0485) were higher than in other patients. COVID-19 course in patients with haematologic malignancies has a delayed onset and is more severe with a higher mortality, and patients may be considered as super-spreaders. Clinicians and intensivists need to be trained to understand the specificity of COVID-19 courses in patients with haematological malignancies.

Circulating Endothelial Cells as a Marker of Endothelial Injury in Severe COVID -19.

Beside the commonly described pulmonary expression of the coronavirus disease 2019 (COVID-19), major vascular events have been reported. The objective of this study was to investigate whether increased levels of circulating endothelial cells (CECs) might be associated with severe forms of COVID-19. Ninety-nine patients with COVID-19 were enrolled in this retrospective study. Patients in the intensive care units (ICU) had significantly higher CEC counts than non-ICU patients and the extent of endothelial injury was correlated with putative markers of disease severity and inflammatory cytokines. Together, these data provide in vivo evidence that endothelial injury is a key feature of COVID-19.

Co(III)-NTA Mediated Antigen Immobilization on a Fiber Optic-SPR Biosensor for Detection of Autoantibodies in Autoimmune Diseases: Application in Immune-Mediated Thrombotic Thrombocytopenic Purpura.

Autoantibodies are key biomarkers in clinical diagnosis of autoimmune diseases routinely detected by enzyme-linked immunosorbent assays (ELISAs). However, the complexity of these assays is limiting their use in routine diagnostics. Fiber optic-surface plasmon resonance (FO-SPR) can overcome these limitations, but improved surface chemistries are still needed to guarantee detection of autoantibodies in complex matrices. In this paper, we describe the development of an FO-SPR immunoassay for the detection of autoantibodies in plasma samples from immune-mediated thrombotic thrombocytopenic purpura (iTTP) patients. Hereto, hexahistidine-tagged recombinant ADAMTS13 (rADAMTS13-His6) was immobilized on nitrilotriacetic acid (NTA)-coated FO probes chelated by cobalt (Co(III)) and exposed to anti-ADAMTS13 autoantibodies. Initial studies were performed to optimize rADAMTS13-His6 immobilization and to confirm the specificity of the immunoassay for detection of anti-ADAMTS13 autoantibodies with FO-SPR. The performance of the immunoassay was then evaluated by comparing Co(III)- and nickel (Ni(II))-NTA stabilized surfaces, confirming the stable immobilization of the antigen in Co(III)-NTA-functionalized FO probes. A calibration curve was prepared with a dilution series of a cloned human anti-ADAMTS13 autoantibody in ADAMTS13-depleted plasma resulting in an average interassay coefficient of variation of 7.1% and a limit of detection of 0.24 ng/mL. Finally, the FO-SPR immunoassay was validated using seven iTTP patient plasma samples, resulting in an excellent correlation with an in-house-developed ELISA (r = 0.973). In summary, the specificity and high sensitivity in combination with a short time-to-result (2.5 h compared to 4-5 h for a regular ELISA) make the FO-SPR immunoassay a powerful assay for routine diagnosis of iTTP and with extension for any other autoimmune disease.

Neutrophil extracellular traps are associated with the pathogenesis of diffuse alveolar hemorrhage in murine lupus.

Diffuse alveolar hemorrhage (DAH) is a life-threatening complication of systemic lupus erythematosus (SLE) and systemic vasculitis. Although initially described to have antibacterial properties, increasing evidence suggests that neutrophil extracellular traps (NETs) have a detrimental role in both autoimmune diseases and acute lung injury. We investigated whether NETs could be detected in a murine model of pristane-induced lupus DAH and contribute to lung injury. Such NETs might constitute a therapeutic target. NETs were characterized by immunofluorescence staining of DNA, neutrophil elastase and citrullinated histones. Evaluation of lung injury was performed by haematoxylin-eosin staining and a quantification program. Clinical status of the mice was assessed by measurement of arterial oxygen saturation and survival curves after recombinant human deoxyribonuclease-1 (Rh-DNase-1) inhalations or polymorphonuclear neutrophil (PMN) depletion. Pristane was found to promote NETs formation in vitro and in vivo. Treatment of mice with Rh-DNase-1 inhalations cleared NETs and reduced lung injury. Clinical status improved significantly, with increased arterial oxygenation and survival. Following PMN depletion, NETs were absent with a subsequent reduction of lung injury and improved arterial oxygenation. These results support a pathogenic role of PMNs and NETs in lung injury during pristane-induced DAH. Targeting NETs with Rh-DNase-1 inhalations could constitute an interesting adjuvant therapy in human DAH.

Elevated serum Krebs von den Lungen-6 in systemic sclerosis: a marker of lung fibrosis and severity of the disease.

OBJECTIVES: We aimed to assess the clinical significance of Krebs von den Lungen-6 (KL-6) in the diagnosis and severity of interstitial lung disease (ILD) in a French cohort of patients with systemic sclerosis (SSc). METHODS: Serum KL-6 concentrations were measured with chemiluminescent enzyme immunoassay (CLEIA) in 75 SSc patients. Patients were divided into two groups according to the presence of interstitial lung disease (SSc-ILD versus SSc-without ILD) on chest High-Resolution Computed Tomography. Pulmonary function tests, main manifestations and severity of the lung disease (Medsger's severity scale) were collected. RESULTS: KL-6 serum concentrations were significantly higher in SSc-ILD patients than in those without ILD (p < 10-4) and were inversely correlated with forced vital capacity, total lung capacity and diffuse lung capacity of carbon monoxide. Serum KL-6 level superior to 872 U/ml appeared as the optimal cut-off value associated with ILD. Patients with a restrictive pulmonary syndrome and dyspnoea had significant higher KL-6 serum concentrations. SSc patients with anti-topoisomerase 1 antibodies had higher KL-6 serum levels than patients with anti-centromere antibodies (p < 10- 4). ILD and anti-topoisomerase 1 antibodies were independent factors associated with KL-6 in multivariate analysis. Interestingly, KL-6 serum concentrations positively increased with the patient lung severity. CONCLUSIONS: Our study confirms that KL-6 is an accurate biomarker for the diagnosis of SSc-ILD in a French cohort of patients. High KL-6 levels should prompt physicians to assess ILD with pulmonary imaging and pulmonary functions tests. Prospective clinical studies are still required to determine whether levels of KL-6 might predict progression of ILD as well as its usefulness in the timing of therapeutic intervention.