Exploring Macrophage Activation Syndrome Secondary to Systemic Lupus Erythematosus in Adults: A Systematic Review of the Literature

Among the autoimmune (AI) diseases, systemic lupus erythematosus (SLE) is known to mimic various disease processes and this can lead to under-diagnosis of macrophage activation syndrome (a dire complication). We aimed at performing a systematic review to identify trigger factors that could lead to the development of macrophage activation syndrome (MAS) in patients with SLE as well as identify factors that can affect mortality. We searched the following databases to extract relevant articles: PubMed, ScienceDirect, Cochrane library, Pro-Quest, and Google Scholar. We used search terms including but not limited to hemophagocytic syndromes OR hemophagocytic lymphohistiocytosis OR macrophage activation syndrome OR HLH OR secondary hemophagocytic lymphohistiocytosis AND systemic lupus erythematosus OR SLE. We screened the articles first by titles and abstracts and later by full text. After the application of our eligibility criteria, we identified eight studies to include in our final synthesis. The studies showed that lupus flare itself, as well as, time to onset and high systemic lupus erythematosus disease activity index (SLEDAI) scores, were major risk factors that led to the development of MAS. In addition, infections followed by drugs, underlying malignancy, and pregnancy were other potential trigger factors identified. Studies also detected that MAS development led to high intensive care unit (ICU) admissions and in-hospital mortalities with C-reactive protein (CRP) levels, age, presence of infection, leukopenia, thrombocytopenia, MAS throughout the hospital stay, and high liver function tests (LFTs) as signs of poor prognosis. Additionally, ferritin levels, LFTs, and triglyceride levels formed an important part of diagnostic criteria. However, our review was limited due to the absence of prospective studies and heterogeneity in the studies seen. More studies need to be done to identify various factors leading to hemophagocytic lymphohistiocytosis (HLH) in autoimmune diseases with validated criteria for MAS secondary to autoimmune diseases.

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.

The Accidental Pathologist: A Curiosity-Driven Journey from Plant Evolution to Innate Immunity

I have had the singular opportunity to perform research and to participate in medical education. Not unexpectedly, people have asked me which of the two was more important to me. My answer has always been and remains that I am equally passionate about research and teaching. My research has been curiosity driven and not purposeful; hence, I was willing to take risks. That my research led to the discovery of natural killer cells and the unraveling of the molecular basis of a human disease was an unexpected reward. By contrast, my interest in medical education was purposeful, with the goal of improving healthcare by teaching pathology as the scientific foundation of medicine. It started with participation in Robbins pathology texts but progressed toward development of technology-based tools for medical education. This was driven by the belief that technology, by providing equal access to knowledge across the world, can be a powerful democratizing force.

[CME: Acquired Hemophagocytic Lymphohistiocytosis]

CME: Acquired Hemophagocytic Lymphohistiocytosis Abstract. Acquired hemophagocytic lymphohistiocytosis comprises a heterogenous group of hyperinflammatory immunoreactions often resulting in uncontrolled immune responses, mainly throughout proliferation of cytotoxic T cells and hemophagocytosis by macrophages. Hemophagocytic lymphohistiocytosis is often underdiagnosed, contributing to its high morbidity and mortality. A systematic diagnostic approach and the use of established diagnostic criteria should lead to an early diagnosis, which is crucial for any therapeutic attempt to achieve a curative state of the disease.

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‐1β 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‐18Rβ 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.