Hemophagocytic lymphohistiocytosis and macrophage activation syndrome: two rare sides of the same devastating coin.

Hemophagocytic lymphohistiocytosis (HLH) is a rare genetic hyperinflammatory syndrome that occurs early in life. Macrophage activation syndrome (MAS) usually refers to a secondary form of HLH associated with autoimmunity, although there are other causes of secondary HLH, such as infections and malignancy. In this article, we reviewed the concepts, epidemiology, clinical and laboratory features, diagnosis, differential diagnosis, prognosis, and treatment of HLH and MAS. We also reviewed the presence of MAS in the most common autoimmune diseases that affect children. Both are severe diseases that require prompt diagnosis and treatment to avoid morbidity and mortality.

Humanization with CD34-positive hematopoietic stem cells in NOG-EXL mice results in improved long-term survival and less severe myeloid cell hyperactivation phenotype relative to NSG-SGM3 mice.

NSG-SGM3 and NOG-EXL mice combine severe immunodeficiency with transgenic expression of human myeloid stimulatory cytokines, resulting in marked expansion of myeloid populations upon humanization with CD34+ hematopoietic stem cells (HSCs). Humanized NSG-SGM3 mice typically develop a lethal macrophage activation syndrome and mast cell hyperplasia that limit their use in long-term studies (e.g., humanization followed by tumor xenotransplantation). It is currently unclear to what extent humanized NOG-EXL mice suffer from the same condition observed in humanized NSG-SGM3 mice. We compared the effects of human CD34+ HSC engraftment in these two strains in an orthotopic patient-derived glioblastoma model. NSG-SGM3 mice humanized in-house were compared to NOG-EXL mice humanized in-house and commercially available humanized NOG-EXL mice. Mice were euthanized at humane or study endpoints, and complete pathological assessments were performed. A semiquantitative multiparametric clinicopathological scoring system was developed to characterize chimeric myeloid cell hyperactivation (MCH) syndrome. NSG-SGM3 mice were euthanized at 16 weeks after humanization because of severe deterioration of clinical conditions. Humanized NOG-EXL mice survived to the study endpoint at 22 weeks after humanization and showed less-severe MCH phenotypes than NSG-SGM3 mice. Major differences included the lack of mast cell expansion and limited tissue/organ involvement in NOG-EXL mice compared to NSG-SGM3 mice. Engraftment of human lymphocytes, assessed by immunohistochemistry, was similar in the two strains. The longer survival and decreased MCH phenotype severity in NOG-EXL mice enabled their use in a tumor xenotransplantation study. The NOG-EXL model is better suited than the NSG-SGM3 model for immuno-oncology studies requiring long-term survival after humanization.

Macrophage immunophenotypes in Jorge Lobo's disease and lepromatous leprosy - a comparative study

Jorge Lobo's disease (JLD) and lepromatous leprosy (LL) share several clinical, histological and immunological features, especially a deficiency in the cellular immune response. Macrophages participate in innate and adaptive inflammatory immune responses, as well as in tissue regeneration and repair. Macrophage function deficiency results in maintenance of diseases. M1 macrophages produce pro-inflammatory mediators and M2 produce anti-inflammatory cytokines. To better understand JLD and LL pathogenesis, we studied the immunophenotype profile of macrophage subtypes in 52 JLD skin lesions, in comparison with 16 LL samples, using a panmacrophage (CD68) antibody and selective immunohistochemical markers for M1 (iNOS) and M2 (CD163, CD204) responses, HAM56 (resident/fixed macrophage) and MAC 387 (recently infiltrating macrophage) antibodies. We found no differences between the groups regarding the density of the CD163, CD204, MAC387+ immunostained cells, including iNOS, considered a M1 marker. But HAM56+ cell density was higher in LL samples. By comparing the M2 and M1 immunomarkers in each disease separately, some other differences were found. Our results reinforce a higher M2 response in JLD and LL patients, depicting predominant production of anti-inflammatory cytokines, but also some distinction in degree of macrophage activation. Significant amounts of iNOS + macrophages take part in the immune milieu of both LL and JLD samples, displaying impaired microbicidal activity, like alternatively activated M2 cells

Hemophagocytic lymphohistiocytosis and macrophage activation syndrome: two rare sides of the same devastating coin

Abstract Hemophagocytic lymphohistiocytosis (HLH) is a rare genetic hyperinflammatory syndrome that occurs early in life. Macrophage activation syndrome (MAS) usually refers to a secondary form of HLH associated with autoimmunity, although there are other causes of secondary HLH, such as infections and malignancy. In this article, we reviewed the concepts, epidemiology, clinical and laboratory features, diagnosis, differential diagnosis, prognosis, and treatment of HLH and MAS. We also reviewed the presence of MAS in the most common autoimmune diseases that affect children. Both are severe diseases that require prompt diagnosis and treatment to avoid morbidity and mortality.

Case report: Multisystem inflammatory syndrome in children associated with COVID-19, macrophage activation syndrome, and incomplete Kawasaki disease.

Background: Multisystem inflammatory syndrome in children (MIS-C), is a severe complication of coronavirus disease 2019 (COVID-19), characterized by persistent fever, systemic inflammatory response, and organ failure. MIS-C with a history of COVID-19 may share clinical features with other well-defined syndromes such as macrophage activation syndrome, Kawasaki disease, hemophagocytic syndrome and toxic shock syndrome. Case 1: An 11-year-old male with a history of hypothyroidism and precocious puberty with positive antibody test for COVID-19 was admitted for fever, poor general condition, severe respiratory distress, refractory shock, and multiple organ failure. His laboratory examination showed elevated inflammatory parameters, and bone marrow aspirate showed hemophagocytosis. Case 2: A 13-year-old male with a history of attention deficit hyperactivity disorder and cognitive delay presented clinical manifestations of Kawasaki disease, fever, conjunctival congestion, exanthema, and hyperemia in oral mucosa, tongue, and genitals, with refractory shock and multiple organ failure. Reverse transcriptase polymerase chain reaction (RT-PCR) and antibodies for COVID-19 were negative, inflammation parameters were elevated, and bone marrow aspirate showed hemophagocytosis. Patients required intensive care with invasive mechanical ventilation, vasopressor support, intravenous gamma globulin, systemic corticosteroids, low molecular weight heparin, antibiotics, and monoclonal antibodies and, patient 2 required renal replacement therapy. Conclusions: Multisystemic inflammatory syndrome in children can have atypical manifestations, and identifying them early is very important for the timely treatment and prognosis of patients.

Polymorphism in cytolytic pathway genes in patients with pediatric inflammatory multisystemic syndrome temporally associated with SARS-CoV-2 / Polimorfismos em genes da via citolítica em pacientes com síndrome inflamatória multissistêmica pediátrica temporariamente associada ao SARS-CoV-2

Introduction: Pediatric inflammatory multisystem syndrome temporally associated with SARS-CoV-2 (PIMS-TS) is a systemic hyperinflammatory disease that occurs in a small number of children after being infected with SARS-CoV-2. Macrophage activation syndrome, an aggressive condition characterized by the excessive inflammation and activation of well-differentiated macrophages, has been shown to occur in patients infected by SARS-CoV-2. Considering the clinical and pathophysiological similarities between these diseases, our main objective was to determine whether gene polymorphisms associated with macrophage activation syndrome were also present in patients with PIMS-TS. Methods: DNA from 10 pediatric patients with PIMS-TS (case group) and ten COVID-19 patients without PIMS-TS (control group) were genotyped by Real-time PCR analysis (TaqMan®) for single nucleotide polymorphisms (SNP) in four genes associated with macrophage activation syndrome: perforin 1 (PRF1), granzyme B (GZMB), syntaxin 11 (STX11), and syntaxin binding protein 2 (STXBP2). The SNP analysis was performed using the additive, dominant, and recessive models. Results: A significantly higher frequency of an SNP (C wild allele in rs6573910) in the GZMB gene was observed in both the additive and dominant models in the PIMS-TS group than controls. A borderline significant difference was also observed for the G allele in rs7764017 of the STX11 gene in the PIMS-TS group in the additive model. Conclusions: This study indicated the presence of two polymorphisms in genes associated with macrophage activation syndrome (GZMB and STX11) in patients who developed PIMS-TS. If the presence of these SNPs is validated in a larger number of PIMS-TS cases, they can be used as potential biomarkers for early identification of pediatric patients with a higher probability of developing PIMS-TS associated with SARS-CoV-2 infection.

Introdução: A síndrome multissistêmica inflamatória pediátrica temporariamente associada ao SARS-CoV-2 (SIMP-TS) é uma doença hiperinflamatória sistêmica que ocorre em um pequeno número de crianças após serem infectadas pelo SARS-CoV-2. A síndrome de ativação de macrófagos (SAM), uma condição agressiva caracterizada pela inflamação excessiva e ativação de macrófagos bem diferenciados, demonstrou ocorrer em pacientes infectados por SARS-CoV-2. Considerando as semelhanças clínicas e fisiopatológicas entre essas doenças, neste estudo o nosso principal objetivo foi determinar se polimorfismos gênicos associados à SAM também estavam presentes em pacientes com SIMP-TS. Métodos: DNA de dez pacientes pediátricos com SIMP (grupo caso) e dez pacientes COVID-19 sem SIMP (grupo controle) foram genotipados por análise de PCR em tempo real (tecnologia TaqMan®) para polimorfismos de nucleotídeo único (SNPs) em quatro genes selecionados associados com SAM: perforina 1 (PRF1), granzima B (GZMB), sintaxina 11 (STX11) e proteína de ligação de sintaxina 2 (STXBP2). A análise dos SNPs foi realizada utilizando o modelo aditivo, dominante e recessivo. Resultados: Uma frequência significativamente maior de um SNP (alelo selvagem C em rs6573910) no gene GZMB foi observada pelos modelos aditivo e dominante no grupo SIMP quando comparado aos controles. Além disso, uma significância limítrofe foi observada para o alelo G em rs7764017 do gene STX11 no grupo SIMP pelo modelo aditivo. Conclusões: Nosso estudo indicou a presença de dois polimorfismos em genes associados à SAM (GZMB e STX11) em pacientes que desenvolveram SIMP-TS. Uma vez validada a presença desses SNPs em um número maior de casos de SIMP-TS, eles podem ser usados como potenciais biomarcadores para a identificação precoce de pacientes pediátricos com maior probabilidade de desenvolver SIMP-TS associado à infecção por SARS-CoV-2.

Splenomegaly in Kawasaki Disease: A Pitfall in Diagnosis.

Among the 365 children diagnosed as having Kawasaki disease (KD), only 5 children (1.4%) presented with splenomegaly: 2 complicated by macrophage activation syndrome and 3 ultimately received a diagnosis of alternative systemic illness. Splenomegaly is atypical in KD and a potential marker of an underling complication, namely macrophage activation syndrome, or diagnosis other than KD.

Variation of Diagnostic Approaches and Treatment Practices for Hemophagocytic Lymphohistiocytosis/Macrophage Activation Syndrome Among Pediatric Subspecialists.

OBJECTIVE: To assess the diagnostic and treatment practices among a variety of subspecialists at pediatric institutions in the US. STUDY DESIGN: Using a web-based survey, we assessed the consultation, diagnostic, and treatment preferences of providers from the different pediatric subspecialties who care for pediatric patients with hemophagocytic lymphohistiocytosis (HLH)/macrophage activating syndrome (MAS). Domains included demographics, provider training level and specialty, experience and comfort level with the diagnosis and treatment of HLH/MAS, and institutional approaches toward the diagnosis and management of HLH/MAS. Participants also were given 2 case scenarios: one describing Epstein-Barr virus-associated HLH and another describing an underlying rheumatologic condition with MAS. RESULTS: Of 263 respondents, 23%, 29%, 39%, and 7% identified as hematology/oncology, rheumatology, general pediatrics/critical care/hospitalist, and allergy/immunology, respectively. For Epstein-Barr virus/HLH, hematology/oncology was the preferred first consultant by most respondents other than rheumatologists, of whom only 47% agreed. For MAS, 92% of respondents from all specialties favored a rheumatology consultation. Preferred diagnostic tests varied by subspecialty, with hematology/oncology more likely than rheumatology to order an infectious workup, natural killer cell function, soluble interleukin-2 receptor, bone marrow biopsy, and genetic testing. First-line therapy also varied, with hematology/oncology preferring dexamethasone and etoposide and rheumatology more often preferring methylprednisolone and anakinra. One-half of respondents were unaware of institutional algorithms for diagnosis and treatment of HLH/MAS. Most (85.6%) favored the development of treatment algorithms for HLH/MAS, and 90% supported a multidisciplinary approach. CONCLUSIONS: Current consulting patterns, diagnostic workup, and treatment approaches of HLH/MAS vary by specialty, highlighting the need for standardized management algorithms and institutional multidisciplinary HLH/MAS teams.

Therapeutic plasma exchange in refractory macrophage activation syndrome complicating systemic juvenile idiopathic arthritis: a case-based review.

Juvenile idiopathic arthritis (JIA) is a heterogeneous group of arthritis of autoimmune aetiology. Systemic-onset juvenile idiopathic arthritis (soJIA) presents with fever, transient erythematous rash, hepatomegaly, splenomegaly, lymphadenopathy, and serositis. SoJIA presents multiple complications, and the most severe is the macrophage activation syndrome (MAS); the timely treatment of MAS must be established early and aggressively to avoid a fatal outcome. Therapeutic plasma exchange has anecdotally been used in refractory cases. A 66-month-old male with a 1-year illness characterized by evening-predominant, intermittent fever, adenomegalies, urticarial-like rash, arthralgia, and arthritis. Biochemical analysis revealed anaemia, leukocytosis, neutrophilia, hypertriglyceridemia, hyperferritinemia, and hypofibrinogenemia; bone marrow aspirate showed hemophagocytosis. He was diagnosed with SoJIA complicated with MAS. He received multiple treatments with IV human gammaglobulin, cyclosporine, dexamethasone, and tocilizumab without improvement. Plasma replacement treatment was performed. Afterwards, he presented significant improvement. After 3-year-follow-up, he remains in good general condition. We present a refractory case of soJIA complicated with MAS successfully treated with plasma exchange.

Macrophage Activation Syndrome as a Complication of Chronic Granulomatous Disease: A Case Report.

Chronic granulomatous disease (CGD) presents with granuloma formation and lethal infections. It is inherited in an autosomal or X-linked recessive pattern. We describe a 10-month-old patient with a fatal secondary HLH as a CGD primary manifestation. We carried out an autopsy and found noncaseating granulomas, an aspergilloma in the lung, and hemophagocytosis. We performed a DHR assay on the patient's mother and grandmother, showing a bimodal pattern conclusive of X-linked CGD. Thus, our definitive diagnosis was CGD complicated by macrophage activation syndrome. CGD is caused by phagocytes' inability to control pathogens, resulting in granulomas. Secondary HLH is a severe complication and could be characterized by the proliferation of macrophages and T lymphocytes and the production of proinflammatory cytokines. The early suspicion of this presentation helps establish a specific treatment, and the study of the carriers helps determine the etiology.

Hemophagocytic lymphohistiocytosis: presentation and outcome of twenty-one patients at a single institution

ABSTRACT Introduction: Hemophagocytic lymphohistiocytosis comprises a systemic hyperactivation of macrophages that requires prompt recognition of symptoms and early treatment. Objective and Method: In this context, we described clinical and laboratory characteristics, therapeutic modality and outcome of 21 patients with HLH treated at a pediatric oncology hospital between January 2000 and February 2019. Results: HLH mainly affected females, fever was the most frequent clinical sign and hyperferritinemia was the most prevalent laboratory abnormality. All patients were admitted to the intensive care unit (ICU) at some point. Fifteen (71.4%) patients presented resolution criteria and eight (53.3%) of them presented reactivation. The mortality rate was 57.1% and the mean time between diagnosis and death was 9.98 months. The 5-year overall survival (OS) was 36.7%. We observed a significant difference in prognosis associated with reactivation of HLH. These patients demonstrated an estimated 5-year OS of 25%, while all patients that did not reactivate were alive until the end of the follow-up. Conclusion: In conclusion, HLH is a rare disease with a high mortality rate, especially in patients with disease reactivation and those with familial- or immunodeficiency-associated forms, which makes early recognition and genetic testing crucial for appropriate management and prompt SCT indication.

Effect of mycobacterial proteins that target mitochondria on the alveolar macrophages activation during Mycobacterium tuberculosis infection.

Purpose of the study: During the early and progressive (late) stages of murine experimental pulmonary tuberculosis, the differential activation of macrophages contributes to disease development by controlling bacterial growth and immune regulation. Mycobacterial proteins P27 and PE_PGRS33 can target the mitochondria of macrophages. This study aims to evaluate the effect of both proteins on macrophage activation during mycobacterial infection. Materials and methods: We assess both proteins for mitochondrial oxygen consumption, and morphological changes, as well as bactericide activity, production of metabolites, cytokines, and activation markers in infected MQs. The cell line MH-S was used for all the experiments. Results: We show that P27 and PE_PGRS33 proteins modified mitochondrial dynamics, oxygen consumption, bacilli growth, cytokine production, and some genes that contribute to macrophage alternative activation and mycobacterial intracellular survival. Conclusions: Our findings showed that these bacterial proteins partially contribute to promoting M2 differentiation by altering mitochondrial metabolic activity.

Hemophagocytic lymphohistiocytosis: presentation and outcome of twenty-one patients at a single institution.

INTRODUCTION: Hemophagocytic lymphohistiocytosis comprises a systemic hyperactivation of macrophages that requires prompt recognition of symptoms and early treatment. OBJECTIVE AND METHOD: In this context, we described clinical and laboratory characteristics, therapeutic modality and outcome of 21 patients with HLH treated at a pediatric oncology hospital between January 2000 and February 2019. RESULTS: HLH mainly affected females, fever was the most frequent clinical sign and hyperferritinemia was the most prevalent laboratory abnormality. All patients were admitted to the intensive care unit (ICU) at some point. Fifteen (71.4%) patients presented resolution criteria and eight (53.3%) of them presented reactivation. The mortality rate was 57.1% and the mean time between diagnosis and death was 9.98 months. The 5-year overall survival (OS) was 36.7%. We observed a significant difference in prognosis associated with reactivation of HLH. These patients demonstrated an estimated 5-year OS of 25%, while all patients that did not reactivate were alive until the end of the follow-up. CONCLUSION: In conclusion, HLH is a rare disease with a high mortality rate, especially in patients with disease reactivation and those with familial- or immunodeficiency-associated forms, which makes early recognition and genetic testing crucial for appropriate management and prompt SCT indication.

Coronavirus Disease 2019 Infection and Early Diagnosis of Macrophage Activation Syndrome: A Case Report of a 62-year-old man

ABSTRACT A 62-year-old man presented with a history of fever, headache, anosmia, ageusia, and diarrhea for 9 days. A clinical and epidemiological diagnosis of infection with the novel coronavirus was made. After symptom refractoriness, the second step involves using human intravenous immunoglobulin. Early diagnosis of macrophage activation syndrome (MAS) involves observation of the refractory nature of clinical support treatment associated with biochemical changes to the patient's baseline characteristics, suggesting the relevance of a favorable clinical outcome of weaning from artificial life support when there is an early suspicion of a diagnosis of MAS secondary to coronavirus disease 2019 infection.

Systemic lupus erythematosus complicated with macrophage activation syndrome mimicking COVID-19 multisystemic inflammatory syndrome in children.

BACKGROUND: Macrophage activation syndrome (MAS) is characterized by excessive activation of macrophages and lymphocytes, leading to multiorgan dysfunction. As the initial manifestation of systemic lupus erythematosus (SLE), MAS is rare in children. Due to the COVID-19 pandemic, it is vital to identify the MAS as it shares similar characteristics with the multisystem inflammatory syndrome in children (MIS-C). CASE REPORT: We report the case of an 11-year-old male adolescent with symptoms of MIS-C. Although with negative results of RT-PCR (reverse transcription-polymerase chain reaction) and serology for SARS-CoV-2, contact with a positive COVID-19 relative was reported. When admitted to a referral hospital center, the patient received standard treatment for MIS-C. Although the same scheme was given on three occasions, the patient showed no response to initial therapy. Thus, the patient was classified as a refractory case. When the study was extended to other differential diagnoses, we found MAS associated with SLE. Therefore, the patient was treated with etoposide, cyclosporine, dexamethasone, and methotrexate and showed a good clinical response. CONCLUSIONS: MAS associated with SLE is rare in the pediatric population. MAS shares inflammatory markers with the MIS-C and is often confused with rheumatologic, infectious, and neoplastic entities. Reporting this case is important to identify differential diagnoses in patients presenting as MIS-C and decide on timely treatment, as it could be harmful or even fatal if a definitive diagnosis is not obtained on time.

INTRODUCCIÓN: El síndrome de activación de macrófagos (SAM) se caracteriza por una activación excesiva de los macrófagos y de los linfocitos que conduce a una disfunción multiorgánica. Como manifestación inicial del lupus eritematoso sistémico (LES), el SAM es poco común en la infancia. Debido a la pandemia de COVID-19, es importante identificar el SAM, ya que comparte características similares con el síndrome inflamatorio multisistémico en niños (MIS-C, por sus siglas en inglés). CASO CLÍNICO: Presentamos el caso de un varón de 11 años con síntomas de MIS-C. Resultó negativo en la prueba de reacción en cadena de la polimerasa con retrotranscriptasa y en la serología para SARS-CoV-2, aunque reportó contacto con un familiar positivo para COVID-19. Ingresó en un centro hospitalario de referencia y recibió tratamiento estandarizado para MIS-C. A pesar de recibir el mismo esquema en tres ocasiones, no mostró respuesta a la terapia inicial, por lo que fue clasificado como caso refractario. Al ampliar el estudio para otros diferenciales, se encontró SAM asociado con LES, por lo que el paciente recibió tratamiento con etopósido, ciclosporina, dexametasona y metotrexato, y mostró buena respuesta clínica. CONCLUSIONES: La asociación entre el SAM y el LES es rara en la población pediátrica. El SAM comparte marcadores inflamatorios con el MIS-C y suele confundirse con enfermedades reumatológicas, infecciosas y neoplásicas. La importancia de reportar este caso es identificar los diagnósticos diferenciales en los pacientes que se presentan como MIS-C, y decidir el tratamiento con prontitud, pues podría ser dañino o incluso fatal si no se obtiene un diagnóstico definitivo a tiempo.

Síndrome de activación macrofágica como desenlace de enfermedades reumatológicas: reporte de 4 casos / Macrophage activation syndrome as a result of rheumatological diseases: Report of 4 cases

RESUMEN El síndrome de activación macrofágica (SAM) es una grave complicación de varias entidades reumáticas entre las que se encuentran la artritis idiopática juvenil sistémica, enfermedad de Still y lupus eritematoso sistémico. Este síndrome forma parte de las linfohistiocitosis hemofagocíticas adquiridas y constituye una enfermedad potencialmente mortal, con difi cultad en su identificación y carencia de consensos en cuanto a su manejo. Describimos una serie de casos de pacientes con SAM, exponiendo su proceso diagnóstico, su relación con las enfermedades reumáticas de base, su seguimiento y tratamiento, así como los resultados de diferentes esquemas de manejo.

ABSTRACT Macrophage activation syndrome (MAS) is a serious complication of several rheumatic disor ders, among which are the systemic juvenile idiopathic arthritis, Still's disease and systemic lupus erythematosus. This syndrome is part of the Acquired Haemophagocytic Lymphohistiocytoses, and is a potentially fatal disease, with difficulty in its identification and a lack of consensus regarding its management. A series of cases are describe of patients with macrophage activation syndrome, explaining their diagnostic process, their relationship with rheumatic diseases, their monitoring, and treatment, as well as the results of different management schemes.

Síndrome de activación de macrofágica como complicación de la artritis idiopática juvenil sistémica / Macrophage activation syndrome as a complication of systemic juvenile idiopathic arthritis

RESUMEN La artritis idiopática juvenil sistémica, también conocida como enfermedad de Still, se considera un trastorno autoinflamatorio y suele ser la más compleja y grave entre todas las formas clínicas de la enfermedad. Cursa generalmente en forma de brotes de actividad repetidos, intercalados por periodos de remisión. Se presenta el caso de una paciente femenina de 4 años de edad, con diagnóstico de enfermedad de Still a los 2 años. Actualmente tiene tratamiento con triple terapia de inducción: cloroquina, metotrexato y salazosulfapiridina con actividad de la enfermedad persistentemente alta por JADAS 27. Acudió a consulta por presentar fiebre, toma del estado general y manifestaciones respiratorias de tres días de evolución que se interpretó como una infección respiratoria baja. Se prescribió tratamiento con antibióticos sin signos de mejoría. A los 7 días se agravó el cuadro clínico y se planteó el diagnóstico de síndrome de activación macrofágica. Se comenzó protocolo de tratamiento con esteroides en combinación con otros fármacos de probada eficacia para esta situación clínica (etopósido, ciclosporina, metotrexato). Se revaloró política de antibióticos sin lograrse respuesta satisfactoria y se decidió introducir el rituximab que aporta excelentes resultados. Después de 3 meses de difícil manejo, la paciente egresó del hospital recuperada de esta complicación y con bajo nivel de actividad de la enfermedad de base.

ABSTRACT Systemic Juvenile Idiopathic Arthritis, also known as Still's disease, is considered an autoinflammatory disorder and is often the most complex and severe of all clinical forms of the disease. It usually takes the form of repeated bouts of activity, interspersed with periods of remission. We present the case of a 4-year-old female patient, diagnosed with Still's disease at 2 years of age. Currently undergoing treatment with triple induction therapy: chloroquine, methotrexate and salazosulfapyridine with persistently high disease activity due to JADAS 27. He comes to the clinic due to fever, general condition, and respiratory manifestations of three days of evolution interpreted as an infectious respiratory process under. Antibiotic treatment is started without signs of improvement. At 7 days the clinical picture worsens, and the diagnosis of Macrophage Activation Syndrome is raised. A steroid treatment protocol is started in combination with other drugs of proven efficacy for this clinical situation (ethopside, cyclosporine, methotrexate). Antibiotic policy was reassessed without achieving a satisfactory response and it was decided to introduce rituximab, which provides excellent results. After three months of difficult management, the patient was released from the hospital recovered from this complication and with a low level of activity of the underlying disease.

Lonomia obliqua Venom Induces NF-κB Activation and a Pro-Inflammatory Profile in THP-1-Derived Macrophage.

Envenomation caused by contact with Lonomia obliqua bristles is characterized by pain, an intense systemic proinflammatory reaction and disturbances in the coagulation cascade that can cause severe clinical manifestations and death. However, the role of immune system components in these effects is still poorly understood. In this study, we evaluated the cytotoxic effect of L. obliqua venom on THP-1-derived macrophages and its ability to modulate inflammatory markers, as well as the cytokine and chemokine release profile. Our results show that L. obliqua venom is able to directly exert a potent pro-inflammatory reaction in macrophages, characterized by the activation of the NF-κB transcription factor pathway, the expression of CD80 and CD83, and the release of pro-inflammatory mediators such as TNF-α, IL-1ß, IL-6, IL-8 and CXCL10. These results suggest that macrophages can play an important role during the orchestration of the inflammatory response present in envenomation caused by Lonomia obliqua caterpillars.

An autopsy series of an oft-missed ante-mortem diagnosis: hemophagocytic lymphohistiocytosis.

Hemophagocytic lymphohistiocytosis (HLH) is a rare and potentially fatal syndrome resulting from a hyperactivated immune system. Diverse patient profiles and clinical presentations often result in misdiagnosis. This article describes the varied clinical presentations and autopsy findings in three patients with this entity. The etiopathogenesis of HLH, its disparate and confounding clinical features, the diagnostic criteria, and management principles are also briefly reviewed.

Thrombotic Microangiopathy Associated with Macrophage Activation Syndrome: A Multinational Study of 23 Patients.

OBJECTIVE: To describe the clinical characteristics, treatment, and outcomes of a multinational cohort of patients with macrophage activation syndrome (MAS) and thrombotic microangiopathy (TMA). STUDY DESIGN: International pediatric rheumatologists were asked to collect retrospectively the data of patients with the co-occurrence of MAS and TMA. Clinical and laboratory features of patients with systemic juvenile idiopathic arthritis (sJIA)-associated MAS and TMA were compared with those of an historical cohort of patients with sJIA and MAS. RESULTS: Twenty-three patients with MAS and TMA were enrolled: 17 had sJIA, 2 systemic lupus erythematosus, 1 juvenile dermatomyositis, 1 mixed connective tissue disease, and 2 undifferentiated connective tissue disease. Compared with the historical cohort of MAS, patients with sJIA with coexistent MAS and TMA had higher frequencies of renal failure and neurologic involvement, hemorrhage, jaundice, and respiratory symptoms, as well as more severe anemia and thrombocytopenia, higher levels of alanine aminotransferase, lactate dehydrogenase, bilirubin and D-dimer, and lower levels of albumin and fibrinogen. They also required admission to the intensive care unit more frequently. Among patients tested, complement abnormalities and reduced ADAMTS13 activity were observed in 64.3% and 44.4% of cases, respectively. All patients received glucocorticoids. Treatment for TMA included plasma-exchange, eculizumab, and rituximab. CONCLUSIONS: The possible coexistence of MAS and TMA in rheumatic diseases may be underrecognized. This association should be considered in patients with MAS who develop disproportionate anemia, thrombocytopenia, and lactate dehydrogenase increase, or have multiorgan failure.