Grant S. Schulert

Pathogenesis of Macrophage Activation Syndrome and Potential for Cytokine- Directed Therapies

Macrophage activation syndrome (MAS) is an acute episode of overwhelming inflammation characterized by activation and expansion of T lymphocytes and hemophagocytic macrophages. In rheumatology, it occurs most frequently in patients with systemic juvenile idiopathic arthritis (SJIA) and systemic lupus erythematosus. The main clinical manifestations include cytopenias, liver dysfunction, coagulopathy resembling disseminated intravascular coagulation, and extreme hyperferritinemia. Clinically and pathologically, MAS bears strong similarity to hemophagocytic lymphohistiocytosis (HLH), and some authors prefer the term secondary HLH to describe it. Central to its pathogenesis is a cytokine storm, with markedly increased levels of numerous proinflammatory cytokines including IL-1, IL-6, IL-18, TNFα, and IFNγ. Although there is evidence that IFNγ may play a central role in the pathogenesis of MAS, the role of other cytokines is still not clear. There are several reports of SJIA-associated MAS dramatically benefiting from anakinra, a recombinant IL-1 receptor antagonist, but the utility of other biologics in MAS is not clear. The mainstay of treatment remains corticosteroids; other medications, including cyclosporine, are used in patients who fail to respond.

Whole-Exome Sequencing Reveals Mutations in Genes Linked to Hemophagocytic Lymphohistiocytosis and Macrophage Activation Syndrome in Fatal Cases of H1N1 Influenza

BACKGROUND Severe H1N1 influenza can be lethal in otherwise healthy individuals and can have features of reactive hemophagocytic lymphohistiocytosis (HLH). HLH is associated with mutations in lymphocyte cytolytic pathway genes, which have not been previously explored in H1N1 influenza. METHODS Sixteen cases of fatal influenza A(H1N1) infection, 81% with histopathologic hemophagocytosis, were identified and analyzed for clinical and laboratory features of HLH, using modified HLH-2004 and macrophage activation syndrome (MAS) criteria. Fourteen specimens were subject to whole-exome sequencing. Sequence alignment and variant filtering detected HLH gene mutations and potential disease-causing variants. Cytolytic function of the PRF1 p.A91V mutation was tested in lentiviral-transduced NK-92 natural killer (NK) cells. RESULTS Despite several lacking variables, cases of influenza A(H1N1) infection met 44% and 81% of modified HLH-2004 and MAS criteria, respectively. Five subjects (36%) carried one of 3 heterozygous LYST mutations, 2 of whom also possessed the p.A91V PRF1 mutation, which was shown to decrease NK cell cytolytic function. Several patients also carried rare variants in other genes previously observed in MAS. CONCLUSIONS This cohort of fatal influenza A(H1N1) infections confirms the presence of hemophagocytosis and HLH pathology. Moreover, the high percentage of HLH gene mutations suggests they are risk factors for mortality among individuals with influenza A(H1N1) infection.

11-Month-Old Infant With Periodic Fevers, Recurrent Liver Dysfunction, and Perforin Gene Polymorphism

History of the present illness This patient was a former 32-week premature female infant, born by elective cesarean section due to concern for hydrops. After delivery she was found to have ascites and ultimately conjugated hyperbilirubinemia, but was without other congenital abnormalities. She had a normal newborn screening and no family history of congenital or metabolic disorders. An extensive evaluation for biliary atresia, perinatal iron storage disorders, Wilson’s disease, a1-antitrypsin, and metabolic diseases was unrevealing. Liver biopsy findings on day of life 25 showed mild chronic hepatitis with portal and periportal fibrosis and mild persistence of extramedullary hematopoiesis. She had a prolonged neonatal intensive care unit stay secondary to respiratory insufficiency, and remained on supplemental oxygen at the time of discharge. Throughout her hospitalization she had a persistently elevated C-reactive protein (CRP) level, as well as aminotransferases and direct bilirubin, although these had stabilized prior to discharge. Starting at 2 months of age, she developed recurrent episodes of fever, respiratory distress, abdominal distension, and feeding intolerance, lasting 5–7 days and occurring every 3–5 weeks, and beginning shortly after her first round of immunizations. During episodes she developed transient hepatosplenomegaly and ascites, elevated aminotransferases and CRP level, anemia, and thrombocytopenia. Empiric antibiotics were typically started, but all cultures were negative. With her third episode she required mechanical ventilation for 5 weeks. During this prolonged hospitalization an extensive diagnostic evaluation was pursued, summarized in Table 1. Repeat liver biopsy was performed showing chronic hepatitis with moderate periportal and pericellular fibrosis. Bone marrow biopsy findings showed mild granulocytic hyperplasia, mild dyserythropoiesis, and increased interstitial histiocytes without hemophagocytic activity. Ultimately, due to suspected autoimmune process, methylprednisolone 2 mg/kg/day was administered, after which she was weaned off all respiratory support. However, as steroids were weaned she continued to have febrile episodes lasting several days, which were managed with increasing steroids and empiric antibiotics. Due to a finding of reduced transitional B cells and concern for B cell immunodeficiency, at age 9 months she was started on monthly intravenous immunoglobulin (IVIG) therapy; however, this did not alter the frequency of her febrile episodes.

Effect of Biologic Therapy on Clinical and Laboratory Features of Macrophage Activation Syndrome Associated With Systemic Juvenile Idiopathic Arthritis

To assess performance of the 2016 macrophage activation syndrome (MAS) classification criteria for patients with systemic juvenile idiopathic arthritis (JIA) who develop MAS while treated with biologic medications.

Monocyte MicroRNA Expression in Active Systemic Juvenile Idiopathic Arthritis Implicates MicroRNA-125a-5p in Polarized Monocyte Phenotypes.

Systemic juvenile idiopathic arthritis (JIA) is an inflammatory disease of childhood in which cells of the monomyelocytoid lineage are thought to be key effector cells. Monocytes from patients with systemic JIA have a distinct phenotype, with features of both M1 and M2 alternative activation. MicroRNAs are critical regulators of monocyte polarization and function, but cellular microRNAs in systemic JIA have not been examined systematically.

MEVALONATE KINASE DEFICIENCY ASSOCIATED WITH RECURRENT LIVER DYSFUNCTION, MACROPHAGE ACTIVATION SYNDROME AND PERFORIN GENE POLYMORPHISM

History of the present illness This patient was a former 32-week premature female infant, born by elective cesarean section due to concern for hydrops. After delivery she was found to have ascites and ultimately conjugated hyperbilirubinemia, but was without other congenital abnormalities. She had a normal newborn screening and no family history of congenital or metabolic disorders. An extensive evaluation for biliary atresia, perinatal iron storage disorders, Wilson’s disease, a1-antitrypsin, and metabolic diseases was unrevealing. Liver biopsy findings on day of life 25 showed mild chronic hepatitis with portal and periportal fibrosis and mild persistence of extramedullary hematopoiesis. She had a prolonged neonatal intensive care unit stay secondary to respiratory insufficiency, and remained on supplemental oxygen at the time of discharge. Throughout her hospitalization she had a persistently elevated C-reactive protein (CRP) level, as well as aminotransferases and direct bilirubin, although these had stabilized prior to discharge. Starting at 2 months of age, she developed recurrent episodes of fever, respiratory distress, abdominal distension, and feeding intolerance, lasting 5–7 days and occurring every 3–5 weeks, and beginning shortly after her first round of immunizations. During episodes she developed transient hepatosplenomegaly and ascites, elevated aminotransferases and CRP level, anemia, and thrombocytopenia. Empiric antibiotics were typically started, but all cultures were negative. With her third episode she required mechanical ventilation for 5 weeks. During this prolonged hospitalization an extensive diagnostic evaluation was pursued, summarized in Table 1. Repeat liver biopsy was performed showing chronic hepatitis with moderate periportal and pericellular fibrosis. Bone marrow biopsy findings showed mild granulocytic hyperplasia, mild dyserythropoiesis, and increased interstitial histiocytes without hemophagocytic activity. Ultimately, due to suspected autoimmune process, methylprednisolone 2 mg/kg/day was administered, after which she was weaned off all respiratory support. However, as steroids were weaned she continued to have febrile episodes lasting several days, which were managed with increasing steroids and empiric antibiotics. Due to a finding of reduced transitional B cells and concern for B cell immunodeficiency, at age 9 months she was started on monthly intravenous immunoglobulin (IVIG) therapy; however, this did not alter the frequency of her febrile episodes.

Interferon-gamma (IFNy) in macrophage activation syndrome (MAS) associated with systemic juvenile idiopathic arthritis (sJIA). High levels in patients and a role in a murine mas model

Interferon-gamma (IFNg) in macrophage activation syndrome (MAS) associated with systemic juvenile idiopathic arthritis (sJIA). High levels in patients and a role in a murine mas model Claudia Bracaglia, Ivan Caiello, Kathy De Graaf, Giovanni D’Ario, Florence Guilhot, Walter Ferlin, Lidia Melli, Giusi Prencipe, Sergio Davi, Grant Schulert, Angelo Ravelli, Alexei Grom, Cristina De Min, Fabrizio De Benedetti

Convergent pathways of the hyperferritinemic syndromes

Hyperferritinemia and pronounced hemophagocytosis help distinguish a subset of patients with a particularly inflammatory and deadly systemic inflammatory response syndrome. Two clinically similar disorders typify these hyperferritinemic syndromes: hemophagocytic lymphohistiocytosis (HLH) and macrophage activation syndrome (MAS). HLH is canonically associated with a complete disturbance of perforin/granzyme-mediated cytotoxicity, whereas MAS occurs in the context of the related rheumatic diseases systemic juvenile idiopathic arthritis and adult-onset Stills disease, with associated IL-1 family cytokine activation. In practice, however, there are accumulating lines of evidence for innate immune dysregulation in HLH as well as partial impairments of cytotoxicity in MAS, and these mechanisms likely represent only a fraction of the host and environmental factors driving hyperferritinemic inflammation. Herein, we present new findings that highlight the pathogenic differences between HLH and MAS, two conditions that present with life-threatening hyperinflammation, hyperferritinemia and hemophagocytosis.

High levels of interferon-gamma (IFNγ) in macrophage activation syndrome (MAS) and CXCL9 levels as a biomarker for IFNγ production in MAS

Objectives Given the similarities between primary and secondary HLH (sec-HLH), including MAS, we measured levels of IFNg, IFNg-related chemokines (CXCL9, CXCL10, CXLC11), and IL-6 in patients with sec-HLH, and in patients with systemic Juvenile Idiopathic Arthritis (sJIA) with or without MAS at sampling and evaluated their relation to disease activity. In addition, we evaluated the correlation between serum levels of IFNg and of the three IFNg related chemokines with themselves and with laboratory parameters of disease activity in patients with active MAS.

Brief Report: Novel UNC13D Intronic Variant Disrupting an NF-κB Enhancer in a Patient With Recurrent Macrophage Activation Syndrome and Systemic Juvenile Idiopathic Arthritis

Macrophage activation syndrome (MAS) is a life‐threatening complication of systemic juvenile idiopathic arthritis (JIA) and has pathologic similarity to hemophagocytic lymphohistiocytosis (HLH). Intronic variants in UNC13D are found in patients with familial HLH type 3 (FHLH3), but the role of noncoding variants in MAS is unknown. The objective of this study was to identify deep intronic UNC13D variants in patients with MAS.