Long-term outcome and prognosis of mixed histiocytosis (Erdheim-Chester disease and Langerhans Cell Histiocytosis).

Background: Erdheim-Chester disease (ECD) is a rare histiocytosis that may overlap with Langerhans Cell Histiocytosis (LCH). This "mixed" entity is poorly characterized. We here investigated the clinical phenotype, outcome, and prognostic factors of a large cohort of patients with mixed ECD-LCH. Methods: This retrospective study was performed at two referral centers in France and Italy (Pitié-Salpêtrière Hospital, Paris; Meyer Children's Hospital, Florence). We included children and adults with ECD diagnosed in 2000-2022 who had biopsy-proven LCH, available data on clinical presentation, treatment and outcome, and a minimum follow-up of one year. Outcomes included differences in clinical presentation and survival between mixed ECD-LCH and isolated ECD; we also investigated response to treatments and predictors of survival in the mixed cohort. Survival was analyzed using the Kaplan-Maier method and differences in survival with the long-rank test. Cox regression models were used to evaluate the potential impact of age and gender on survival and to identify predictors of non-response and survival. Findings: Out of a cohort of 502 ECD patients, 69 (14%) had mixed ECD-LCH. Compared to isolated ECD, mixed ECD-LCH occurred more frequently in females (51 vs. 26%, p < 0.001) and in patients with multisystem disease (≥4 sites). Mixed ECD-LCH more frequently involved long bones (91 vs. 79%, p = 0.014), central nervous system (51 vs. 34%, p = 0.007), facial/orbit (52 vs. 38%, p = 0.031), lungs (43 vs. 28%, p = 0.009), hypothalamic/pituitary axis (51 vs. 26%, p < 0.001), skin (61 vs. 29%, p < 0.001), and lymph nodes (15 vs. 7%, p = 0.028); the BRAFV600E mutation was also more frequent in mixed ECD-LCH (81 vs. 59%, p < 0.001). Targeted treatments (BRAF and/or MEK inhibitors) induced response more frequently than conventional therapies (interferon-α, chemotherapy), either as first-line (77 vs. 29%, p < 0.001) or as any line (75 vs. 24%, p < 0.001). After a median follow-up of 71 months, 24 patients (35%) died. Survival probability was comparable between ECD alone and mixed ECD-LCH (log-rank p = 0.948). At multivariable analysis, age at diagnosis (HR 1.052, 95% CI 1.008-1.096), associated hematologic conditions (HR 3.030, 95% CI 1.040-8.827), and treatment failure (HR 9.736, 95% CI 2.919-32.481) were associated with an increased risk of death, while lytic bone lesions with a lower risk (HR 0.116, 95% CI 0.031-0.432). Interpretation: Mixed ECD-LCH is a multisystem disease driven by the BRAFV600E mutation and targeted treatments are effective. Age at diagnosis, bone lesion patterns, associated hematologic conditions, and treatment failure are the main predictors of death in mixed ECD-LCH. Funding: None.

Extracorporeal membrane oxygenation (ECMO) during aplasia: A bridge towards myopericarditis recovery after autologous hematopoietic stem cell transplant for systemic sclerosis and recent Coronarovirus disease (COVID-19) vaccination.

Systemic sclerosis (SSc) is a rare autoimmune disease (AD), characterised by early diffuse vasculopathy, activation of the immune response and progressive skin and internal organ fibrosis. In severe progressive diffuse SSc (dSSc), autologous hematopoietic stem cell transplantation (aHSCT) improves survival, despite its own risk of complications and transplant related mortality (TRM). We present herein the case of a dSSc patient undergoing aHSCT with low dose cyclophosphamide conditioning and sudden acute myopericarditis and cardiogenic shock, four weeks after a second mRNA SARS-CoV-2 vaccine (Pfizer) injection. Four days of extracorporeal membrane oxygenation (ECMO) support during the aplasia period, allowed to observe full cardiac function recovery and progressive SSc rehabilitation with sustained disease response at 30 months follow-up. This report illustrates, for the first time to our knowledge, that ECMO can be indicated despite aplasia during aHSCT and successfully used as a bridge towards heart function recovery in highly selected and fragile AD patients. We review the factors that may contribute to endothelial and myocardial stunning and acute reversible cardiac failure in SSc and aggravate intrinsic endothelial injury during the aHSCT procedure. These classically include: cyclophosphamide drug toxicity, viral infections and autoimmune activation with disease flair per se. In the COVID-19 pandemic times, acute myocarditis due to recent viral infection or mRNA vaccine per se, must also be considered.

Neurological outcomes in immune checkpoint inhibitor-related neurotoxicity.

While the spectrum of neurological immune checkpoint inhibitor-related adverse events is expanding, patients' outcomes are not well documented. This study aimed to assess outcomes of neurological immune-related adverse events and to identify prognostic factors. All patients experiencing grade ≥2 neurological immune-related adverse events identified at two clinical networks (French Reference Center for Paraneoplastic Neurological Syndromes, Lyon; and OncoNeuroTox, Paris) over five years were included. Modified Rankin scores were assessed at onset, 6, 12, 18 months, and last visit. A multi-state Markov model was used to estimate the transition rates between minor disability (mRS <3), severe disability (mRS 3-5), and death (mRS 6), over the study period. The state-to-state transition rates were estimated using maximum likelihood and variables were introduced into the different transitions to study their effects. A total of 147 patients were included out of 205 patients with a suspicion of neurological immune-related adverse events. The median age was 65 years (range 20-87) and 87/147 patients (59.2%) were male. Neurological immune-related adverse events involved the peripheral nervous system in 87/147 patients (59.2%), the central nervous system in 51/147 (34.7%), and both systems in 9/147 (6.1%). Paraneoplastic-like syndromes were observed in 30/147 patients (20.4%). Cancers included lung cancers (36.1%), melanoma (30.6%), urological cancers (15.6%), and others (17.8%). Patients were treated with programmed cell death protein (ligan) 1 (PD(L)1) inhibitors (70.1%), CTLA4 inhibitors (3.4%) or both (25.9%). Severe disability was reported in 108/144 patients (75.0%) at onset and in 33/146 patients (22.6%) at last visit (median follow-up duration: 12 months, range 0.5-50); 48/147 (32.7%) patients died, from cancer progression (17/48, 35.4%), neurological toxicity (15/48, 31.2%), other causes (10/48, 20.8%) or unknown causes (6/48, 12.5%). The rate of transition from severe to minor disability independently increased with melanoma [compared to lung cancer, hazard ratio = 3.26, 95%CI (1.27; 8.41)] and myositis/neuromuscular junction disorders [hazard ratio = 8.26, 95%CI (2.90; 23.58)], and decreased with older age [hazard ratio = 0.68, 95%CI (0.47; 0.99)] and paraneoplastic-like syndromes [hazard ratio = 0.29, 95%CI (0.09; 0.98)]. In patients with neurological immune-related adverse events, myositis/neuromuscular junction disorders and melanoma increase the transition rate from severe to minor disability, while older age and paraneoplastic-like syndromes result in poorer neurological outcomes; future studies are needed to optimize the management of such patients.

Remdesivir in combination with dexamethasone for patients hospitalized with COVID-19: A retrospective multicenter study.

BACKGROUND: Dexamethasone is standard of care for the treatment of patients with COVID-19 requiring oxygen. The objective is to assess the clinical benefit of adding remdesivir to dexamethasone. PATIENTS AND METHODS: A retrospective cohort study of hospitalized patients with COVID-19 pneumonia requesting low-flow oxygen who received dexamethasone. Patients admitted to infectious diseases wards also received remdesivir. Primary outcome was duration of hospitalization after oxygen initiation. Secondary outcomes were in-hospital death, and death and/or transfer to the intensive care unit. To handle potential confounding by indication bias, outcome comparison was performed on propensity score-matched populations. Propensity score was estimated by a multivariable logistic model including prognostic covariates; then 1:1 matching was performed without replacement, using the nearest neighbor algorithm with a caliper of 0.10 fold the standard deviation of the propensity score as the maximal distance. Balance after matching was checked on standardized mean differences. RESULTS: From August 15th 2020, to February 28th, 2021, 325 patients were included, 101 of whom received remdesivir. At admission median time from symptoms onset was 7 days, median age: 68 years, male sex; 61%, >1 comorbidity: 58.5%. Overall 180 patients matched on propensity score were analyzed, 90 each received remdesivir plus dexamethasone or dexamethasone alone. Median duration of hospitalization was 9 (IQR: 7-13) and 9 (IQR: 5-18) days with and without remdesivir, respectively (p = 0.37). In-hospital death rates and rates of transfer to the intensive care unit or death were 8.9 and 17.8% (HR: 0.46, 95% CI: 0.21-1.02, p = 0.06) and 20.0 and 35.6% with and without remdesivir, respectively (HR: 0.45, 95% CI: 0.23-0.89, p = 0.015). CONCLUSION: In hospitalized patients with COVID-19 pneumonia receiving low-flow oxygen and dexamethasone, the addition of remdesivir was not associated with shorter hospitalization or lower in-hospital mortality but may have reduced the combined outcome of death and transfer to the intensive care unit.

Anti-PD-1 immune-related adverse events are associated with high therapeutic antibody fixation on T cells.

Immune checkpoint inhibitors (ICI) widely improved the treatment of solid and hematologic malignancies. Yet, a remarkable proportion of patients receiving ICI develop immune related adverse events (irAEs) which are difficult to define as treatment-related. This underlines the need to develop a biomarker to guide irAE diagnosis. We developed a novel flow cytometry assay combining measurement of anti-PD-1 (programmed cell death protein-1) occupancy and evaluation of remaining PD-1 receptor availability with anti-IgG4 PE and anti-PD-1 BV421. We prospectively collected blood and biological fluids samples from patients treated by IgG4 anti-PD-1 therapy (nivolumab or pembrolizumab), with (n=18) or without (n=12) current irAE. We analyzed PD-1+ and IgG4+ staining pattern and MFI values of these parameters on CD4 and CD8 T cells, and IgG4+/PD-1+ MFI ratios are calculated. A higher mean fluorescence intensity IgG4+/PD-1+ ratio was measured on peripheral CD4+ T cells of irAE cases, when compared to controls (p=0.003). ICI-related toxicity is therefore associated with increased therapeutic antibody occupancy of PD-1 receptors on CD4+ T cells. Furthermore, in one case of ICI-related pneumonitis, binding of therapeutic antibody was stronger on lung CD4+ T cell than in blood. In another case of ICI-related encephalitis, the PD-1 receptor occupancy was total on CSF CD4 T cells, but only partial on peripherical CD4 T cells. Our results suggest that flow cytometry monitoring of ICI occupancy can be used in patients treated with monoclonal ICI to guide irAE diagnosis.

Treatment strategies and safety of rechallenge in the setting of immune checkpoint inhibitors-related myositis: a national multicentre study.

OBJECTIVES: The occurrence of immune-related myositis (irM) is increasing, yet there are no therapeutic guidelines. We sought to analyse the current therapeutic strategies of irM and evaluate the outcomes of immune checkpoint inhibitors (ICIs) rechallenge. METHODS: We conducted a nationwide retrospective study between April 2018 and March 2020 including irM without myocardial involvement. Depending on the presence of cutaneous signs or unusual histopathological features, patients were classified into two groups: typical or atypical irM. Therapeutic strategies were analysed in both groups. The modalities and outcomes of ICI rechallenge were reviewed. RESULTS: Among the 20 patients, 16 presented typical irM. Regardless of severity, most typical irM were treated with steroid monotherapy (n = 14/16) and all had a complete response within ≤3 weeks. The efficacy of oral steroids for non-severe typical irM (n = 10) was the same with low-dose (≤0.5 mg/kg/day) or high-dose (1 mg/kg/day). Severe typical irM were successfully treated with intravenous methylprednisolone. Atypical irM (n = 4) had a less favourable evolution, including one irM-related death, and required heavy immunosuppression. ICIs were safely reintroduced in nine patients presenting a moderate (n = 6) or a severe (n = 3) irM. CONCLUSION: Our data highlight that steroid monotherapy is an effective treatment for typical irM, either with prednisone or with intravenous methylprednisone pulses depending on the severity. The identification of unusual features is important in determining the initial therapeutic strategy. The outcomes of rechallenged patients are in favour of a safe reintroduction of ICI following symptom resolution and creatin kinase (CK) normalization in moderate and severe forms of irM.

Different phenotypes in dermatomyositis associated with anti-MDA5 antibody: Study of 121 cases.

OBJECTIVES: The predominance of extramuscular manifestations (e.g., skin rash, arthralgia, interstitial lung disease [ILD]) as well as the low frequency of muscle signs in anti-melanoma differentiation-associated gene 5 antibody-positive (anti-MDA5+) dermatomyositis caused us to question the term myositis-specific antibody for the anti-MDA5 antibody, as well as the homogeneity of the disease. METHODS: To characterize the anti-MDA5+ phenotype, an unsupervised analysis was performed on anti-MDA5+ patients (n = 83/121) and compared to a group of patients with myositis without anti-MDA5 antibody (anti-MDA5-; n = 190/201) based on selected variables, collected retrospectively, without any missing data. RESULTS: Within anti-MDA5+ patients (n = 83), 3 subgroups were identified. One group (18.1%) corresponded to patients with a rapidly progressive ILD (93.3%; p < 0.0001 across all) and a very high mortality rate. The second subgroup (55.4%) corresponded to patients with pure dermato-rheumatologic symptoms (arthralgia; 82.6%; p < 0.01) and a good prognosis. The third corresponded to patients, mainly male (72.7%; p < 0.0001), with severe skin vasculopathy, frequent signs of myositis (proximal weakness: 68.2%; p < 0.0001), and an intermediate prognosis. Raynaud phenomenon, arthralgia/arthritis, and sex permit the cluster appurtenance (83.3% correct estimation). Nevertheless, an unsupervised analysis confirmed that anti-MDA5 antibody delineates an independent group of patients (e.g., dermatomyositis skin rash, skin ulcers, calcinosis, mechanic's hands, ILD, arthralgia/arthritis, and high mortality rate) distinct from anti-MDA5- patients with myositis. CONCLUSION: Anti-MDA5+ patients have a systemic syndrome distinct from other patients with myositis. Three subgroups with different prognosis exist.

Granulomatosis-associated myositis: High prevalence of sporadic inclusion body myositis.

OBJECTIVE: To refine the predictive significance of muscle granuloma in patients with myositis. METHODS: A group of 23 patients with myositis and granuloma on muscle biopsy (granuloma-myositis) from 8 French and Belgian centers was analyzed and compared with (1) a group of 23 patients with myositis without identified granuloma (control-myositis) randomly sampled in each center and (2) a group of 20 patients with sporadic inclusion body myositis (sIBM) without identified granuloma (control-sIBM). RESULTS: All but 2 patients with granuloma-myositis had extramuscular involvement, including signs common in sarcoidosis that were systematically absent in the control-myositis and the control-sIBM groups. Almost half of patients with granuloma-myositis matched the diagnostic criteria for sIBM. In these patients, other than the granuloma, the characteristics of the myopathy and its nonresponse to treatment were similar to the control-sIBM patients. Aside from 1 patient with myositis overlapping with systemic sclerosis, the remaining patients with granuloma-myositis did not match the criteria for a well-defined myositis subtype, suggesting pure sarcoidosis. Matching criteria for sIBM was the sole feature independently associated with nonresponse to myopathy treatment in patients with granuloma-myositis. CONCLUSION: Patients with granuloma-myositis should be carefully screened for sIBM associated with sarcoidosis in order to best tailor their care.

NK Cells in the Human Lungs.

The lung offers one of the largest exchange surfaces of the individual with the elements of the environment. As a place of important interactions between self and non-self, the lung is richly endowed in various immune cells. As such, lung natural killer (NK) cells play major effector and immunoregulatory roles to ensure self-integrity. A better understanding of their abilities in health and diseases has been made possible over the past decade thanks to tremendous discoveries in humans and animals. By precisely distinguishing the different NK cell subsets and dissecting the ontogeny and differentiation of NK cells, both blood and tissue-resident NK populations now appear to be much more pleiotropic than previously thought. In light of these recent findings in healthy individuals, this review describes the different lung NK cell populations quantitatively, qualitatively, phenotypically, and functionally. Their identification, immunological diversity, and adaptive capacities are also addressed. For each of these elements, the impact of the mutual interactions of lung NK cells with environmental and microenvironmental factors are questioned in terms of functionality, competence, and adaptive capacities. As pulmonary diseases are major causes of morbidity and mortality worldwide, special attention is also given to the involvement of lung NK cells in various diseases, including infectious, inflammatory, autoimmune, and neoplastic lung diseases. In addition to providing a comprehensive overview of lung NK cell biology, this review also provides insight into the potential of NK cell immunotherapy and the development of targeted biologics.

Juvenile temporal arteritis: A clinicopathological multicentric experience.

INTRODUCTION: Juvenile temporal arteritis (JTA) is a recently-described and little-known inflammatory disease and its etiology is undetermined. Less than forty cases have been published. This paper is aimed at reporting the largest JTA series and to compare it to literature data to better evaluate its characteristics at diagnosis, its evolution and treatment options. MATERIAL AND METHODS: We conducted a retrospective and descriptive multicentric study in France by identifying adult patients under the age of 50 which had a pathological temporal artery biopsy owing to the presence of a temporal arteritis. Patients with temporal arteritis as a manifestation of systemic vasculitis were excluded. RESULTS: We included 12 patients and the literature review identified 32 cases described in 27 articles, thus a total of 44 patients - 34 men and 10 women - with a median age of 30 and a maximum of 44. All patients presented either a lump in the temporal region or prominent temporal arteries, and 47.7% of patients suffered from headaches. Only 11.4% of patients presented general symptoms and 6.8% a biological inflammatory syndrome; 34.1% had peripheral blood eosinophilia; 83.7% presented a single episode and complete excision without further treatment was documented for 72.7%. Pathology analysis revealed infiltrate of inflammatory cells in the arterial wall in 97.6% of patients but also sparse giant cells for 25% and granuloma for 22.9%, perivascular extension of the inflammation for 82.6%, and presence of lymphoid follicles or germinal centres for 60%. Clinical relapses were present in 16.3% of cases. CONCLUSION: JTA is a rare, localized and benign disease. The majority of cases have only one episode which is cured by local surgery.

Management of immune-related adverse events resulting from immune checkpoint blockade.

INTRODUCTION: Immune checkpoint inhibitors (ICI) are now a standard of care in the treatment of many cancers leading to durable responses in patients with metastatic disease. These agents are generally well tolerated but may lead to the occurrence of immune-related adverse events (irAEs). As any organ may be affected, clinicians should be aware of the broad range of clinical manifestations and symptoms and keep in mind that toxicities may occur late, at any point along a patient's treatment course. Although the most common irAEs are rarely severe, some of them may be associated with great morbidity and even become life-threatening. The rate of occurrence, type and severity of irAEs may vary with the type of ICI; thus, grade 3 and 4 irAEs are reported in more than 55% of patients treated with the combination of ipilimumab 3 mg/kg and nivolumab 1 mg/kg. Area covered: This review presents the management of irAEs resulting from checkpoint blockade, with a focus on rare irAEs. Expert commentary: With the development of immuno-oncology and the expanding role of ICI, physicians have learnt to diagnose and treat most of the irAEs that can occur. This review provides an overview of current guidelines, previously published studies and our multidisciplinary team based practices.

Immune checkpoint inhibitor-related myositis and myocarditis in patients with cancer.

OBJECTIVE: To report the clinicopathologic features and outcome of myositis in patients treated with immune checkpoint inhibitors (ICIs) (irMyositis). METHODS: We retrospectively analyzed patients diagnosed with irMyositis in tertiary centers in Paris, France, and Berlin, Germany, from January 2015 to July 2017. The main outcomes were clinical manifestations and muscle histology, which included major histocompatibility complex class I (MHC-I), C5b-9, CD3, CD4, CD8, CD20, CD68, programmed cell death protein 1 (PD-1), programmed cell death 1 ligand 1 (PD-L) 1, and programmed cell death 1 ligand 2 (PD-L2). RESULTS: Ten patients with metastatic cancer were included; median age was 73 (range 56-87) years. Median follow-up duration was 48 (range 16-88) weeks. Six patients developed myositis during nivolumab therapy, 1 patient during pembrolizumab, 1 patient during durvalumab, and 2 patients during combined nivolumab and ipilimumab. Median delay between ICI initiation and myositis onset was 25 (range 5-87) days. Clinical manifestations were dominated by acute or subacute myalgia (8 patients) and limb-girdle (7), axial (7), and oculomotor (7) weakness. Four patients had evidence of myocarditis. In all patients, creatine kinase levels were elevated (median 2,668, range 1,059-16,620 U/L), while anti-acetylcholine receptor and myositis-associated antibodies were negative. Electrodiagnostic studies showed myopathic process without decrement in all patients. Muscle biopsy constantly showed multifocal necrotic myofibers, sarcolemmal MHC-I, and endomysial inflammation, consisting mainly of CD68+ cells expressing PD-L1 and CD8+ cells expressing PD-1. ICI treatment was withdrawn in all patients; 9 patients received immunosuppressive therapy, which consistently led to marked clinical improvement. CONCLUSIONS: irMyositis presents with remarkably homogeneous and unique clinicopathologic features, expanding the nosologic spectrum of inflammatory myopathies in patients with cancer. ICI withdrawal and treatment with corticosteroids improve outcome.

Symptomatic muscular sarcoidosis: Lessons from a nationwide multicenter study.

OBJECTIVES: To describe clinicopathologic features of muscular sarcoidosis and the associated sarcoidosis phenotype through a nationwide multicenter study. METHODS: Patients were included if they had histologically proven sarcoidosis and symptomatic muscular involvement confirmed by biological, imaging, or histologic examinations. RESULTS: Forty-eight patients (20 males) were studied, with a median age at muscular symptoms onset of 45 years (range 18-71). Four patterns were identified: a nodular pattern (27%); smoldering phenotype (29%); acute, subacute, or progressive myopathic type (35%); and combined myopathic and neurogenic pattern (10%). In all patterns, sarcoidosis was multivisceral with a median of 3 extramuscular organs involved (mostly lungs, lymph nodes, eyes, and skin) and a prolonged course with long-term use of corticosteroids and immunosuppressive drugs. Muscular patterns differed according to clinical presentation (myalgia, nodules, or weakness), electromyographic findings, muscular MRI, and response to sarcoidosis treatment. The myopathic and neuromuscular patterns were more severe. CONCLUSION: This nationwide study of muscular sarcoidosis allowed the identification of 4 patterns of granulomatous myositis, which differed by phenotypes and the clinical course.

Cerebrovascular events in Takayasu arteritis: a multicenter case-controlled study.

OBJECTIVES: Takayasu arteritis (TA) is a giant cell arteritis usually affecting young women and characterized by inflammatory and ischemic signs of large vessel involvement, including extracranial cerebral arteries. The impact of stroke on TA prognosis has not been well evaluated. METHODS: We performed a retrospective multicenter review of patients with definite TA who experienced at least one stroke and compared the findings to 17 matched patients with TA diagnosis without neurological involvement. RESULTS: Seventeen patients (15 women, median age at stroke diagnosis 44 years) receiving a diagnosis of TA and stroke between 2002 and 2016 in our institution were included, from a cohort of 126 patients suffering from TA (13.5%). At diagnosis, patients from both groups had comparable cardiovascular risk factors. The first cerebrovascular event was ischemic stroke (n = 15) or transient ischemic attack (n = 2). In eight patients, stroke occurred after the TA diagnosis was made. In four patients, stroke occurred after carotid surgery. At the end of follow-up, 59% of patients had a neurological impairment, 35% had a recurrence of stroke, and 24% suffered from epilepsy. CONCLUSIONS: Stroke is a major cause of disability in TA patients. Internal carotid surgery may be performed with caution because of the risk of stroke after the procedure.

High prevalence of myeloid neoplasms in adults with non-Langerhans cell histiocytosis.

Erdheim-Chester disease (ECD) is a rare non-Langerhans cell histiocytosis that most commonly affects adults and is driven by a high frequency of mutations in BRAF, MAP2K1, and kinases promoting MAPK signaling. Because of the relative rarity of ECD, key clinical features of the disease may not be well defined. Across a multi-institutional cohort of 189 patients with ECD and ECD overlapping with Langerhans cell histiocytosis (so-called mixed histiocytosis [MH]), we identified an unexpected and heretofore undescribed frequent occurrence of myeloid neoplasms among patients with ECD and MH. Some 10.1% (19/189) of patients with ECD have an overlapping myeloid neoplasm, most commonly occurring as a myeloproliferative neoplasm (MPN), myelodysplastic syndrome (MDS), or mixed MDS/MPN overlap syndrome (including chronic myelomonocytic leukemia). Consistent with this, molecular analysis frequently detected hallmark driver mutations of myeloid neoplasms (such as JAK2V617F and CALR mutations) coexisting with those characteristic of histiocytosis (such as BRAFV600E and MAP2K1 mutations). Histiocytosis patients diagnosed with a concomitant myeloid malignancy were significantly older at diagnosis and more commonly presented with MH than those without a myeloid malignancy. In some cases, the presence of distinct kinase mutations in the histiocytosis and myeloid neoplasm resulted in discordant and adverse responses to kinase-directed targeted therapies. These data highlight the clinical importance of evaluating adults with histiocytosis for a concomitant myeloid neoplasm.

Involvement of NK Cells and NKp30 Pathway in Antisynthetase Syndrome.

Antisynthetase syndrome (aSS) is characterized by the association of interstitial lung disease and myositis with anti-tRNA synthetase autoantibodies. Immune mechanisms leading to aSS could be initiated in the lungs, but the role of NK cells has not yet been studied. Both extensive NK cell phenotype and functions were compared between 33 patients and 26 controls. Direct and redirected polyfunctionality assays (degranulation and intracellular production of TNF-α and IFN-γ) were performed spontaneously or after IL-12 plus IL-18 stimulation in the presence of K562 or P815 target cells, respectively. NK cells from inactive patients showed normal phenotype, whereas active aSS revealed a differentiated NK cell profile, as indicated by increased CD57 and Ig-like transcript 2 and an inability to produce IFN-γ (p = 0.002) compared with controls. Importantly, active aSS was more specifically associated with a significant NKp30 decrease (p = 0.009), although levels of mRNA and intracellular protein were similar in aSS and healthy controls. This NKp30 decrease was strongly correlated with reduced NK cell polyfunctionality in both direct and redirected killing assays with anti-NKp30 Abs (p = 0.009 and p = 0.03, respectively), confirming its important impact in aSS. Histological studies revealed massive infiltrations of NK cells inside the lungs of aSS patients (148 versus 11/mm(2)). Taken together, these data suggest that NK cells and NKp30 could play a role in aSS pathogenesis.

Systemic Lupus Erythematosus and Antineutrophil Cytoplasmic Antibody-Associated Vasculitis Overlap Syndrome in Patients With Biopsy-Proven Glomerulonephritis.

The aim of the study was to report the clinical, biological, and pathological characteristics of patients with glomerulonephritis (GN) secondary to systemic lupus erythematosus (SLE)/antineutrophil cytoplasmic antibodies (ANCA)-associated vasculitis (AAV) overlap syndrome.A nationwide survey was conducted to identify cases of SLE/AAV overlap syndrome. Data were collected from SLE and AAV French research groups. Inclusion criteria were diagnosis of both SLE and AAV according to international classification criteria and biopsy-proven GN between 1995 and 2014. Additional cases were identified through a systematic literature review. A cohort of consecutive biopsy-proven GN was used to study the prevalence of overlapping antibodies and/or overlap syndrome.The national survey identified 8 cases of SLE/AAV overlap syndrome. All patients were female; median age was 40 years. AAV occurred before SLE (n = 3), after (n = 3), or concomitantly (n = 2). Six patients had rapidly progressive GN and 3/8 had alveolar hemorrhage. All patients had antinuclear antibodies (ANA); 7/8 had p-ANCA antimyeloperoxidase (MPO) antibodies. Renal biopsies showed lupus nephritis (LN) or pauci-immune GN. Remission was obtained in 4/8 patients. A literature review identified 31 additional cases with a similarly severe presentation. In the GN cohort, ANCA positivity was found in 30% of LN, ANA positivity in 52% of pauci-immune GN, with no correlation with pathological findings. The estimated prevalence for SLE/AAV overlap syndrome was 2/101 (2%).In patients with GN, SLE/AAV overlap syndrome may occur but with a low prevalence. Most patients have an aggressive renal presentation, with usually both ANA and anti-MPO antibodies. Further studies are needed to assess shared pathogenesis and therapeutic options.