Hemophagocytic Syndrome and COVID-19: A Comprehensive Review.

Hemophagocytic lymphohistiocytosis (HLH), a hyperinflammatory hyperferritinemic syndrome, is triggered by various etiologies and diseases and can lead to multiorgan dysfunction and death. There are two types of HLH: primary and secondary. Primary HLH (pHLH) is caused by a genetic mutation resulting in dysfunction in cytotoxic T lymphocytes (CTLs), natural killer (NK) cells, hyperactivated immune cells, and hypercytokinemia. In secondary HLH (sHLH), an underlying etiology is the cause of the disease. Infections, malignancy, and autoimmune diseases are well-known triggers for sHLH. Infectious triggers for sHLH are most frequently viruses, where different mechanisms, including dysregulated CTLs and NK cell activity and persistent immune system stimulation, have been reported. Similarly, in severe coronavirus disease 2019 (COVID-19) patients, a hyperinflammatory mechanism leading to hypercytokinemia and hyperferritinemia has been demonstrated. A similar dysfunction in CTLs and NK cells, persistent immune system stimulation with increased cytokines production, and severe end-organ damage have been reported. Therefore, a significant overlap is present between the clinical and laboratory features seen in COVID-19 and sHLH. However, SARS-CoV-2, similar to other viruses, can trigger sHLH. Hence, a diagnostic approach is needed in severe COVID-19 patients presenting with multiorgan failure, in whom sHLH should be considered.

Case report: Virus-induced hemophagocytic lymphohistiocytosis in a patient with APECED.

Autoimmune polyendocrinopathy-candidiasis-ectodermal dystrophy (APECED), also known as autoimmune polyglandular syndrome type 1 (APS-1) is a rare autosomal recessive inborn error of immunity (IEI), which is accompanied by immune dysregulation. Hypoparathyroidism, adrenocortical failure and candidiasis are its typical manifestations. Here we report about recurrent COVID-19 in a 3-year-old boy with APECED, who developed retinopathy with macular atrophy and autoimmune hepatitis after the first episode of SARS-CoV-2 infection. Primary Epstein-Barr virus infection and a new episode of SARS-CoV-2 infection with COVID pneumonia triggered the development of severe hyperinflammation with signs of hemophagocytic lymphohistiocytosis (HLH): progressive cytopenia (thrombocytopenia, anemia, lymphopenia), hypoproteinemia, hypoalbuminemia, high levels of liver enzymes, hyperferritinemia, increased triglycerides levels; and coagulopathy with a low level of fibrinogen. Treatment with corticosteroids and intravenous immunoglobulins did not lead to a significant improvement. The progression of HLH and COVID-pneumonia resulted in a fatal outcome. The rarity and varied presentation of the HLH symptoms led to diagnostic difficulties and diagnosis delay. HLH should be suspected in a patient with immune dysregulation and impaired viral response. Treatment of infection-HLH is a major challenge due to the difficulties in balancing immunosuppression and management of underlying/triggering infection.

Use of rituximab in SARS-CoV-2-positive renal transplant recipient with EBV reactivation and probable haemophagocytic lymphohistiocytosis.

We present a case of a rapid clinical recovery in a critically ill kidney transplant recipient with SARS-CoV-2 positivity, Epstein-Barr virus (EBV) reactivation and probable secondary hemophagocytic lymphohistiocytosis (HLH) treated with etoposide-free regimen, based on dexamethasone and a single dose of rituximab. Although rituximab is often a part of EBV-HLH treatment strategy, its use in simultaneous Coronavirus 2019 disease (COVID-19) and solid-organ transplantation has not been reported yet. We review the current evidence for the potential of SARS-CoV-2 to trigger EBV reactivation, leading to a severe clinical illness. Finally, we compare the clinical features of hyper-inflammatory response typical for severe COVID-19 and classical secondary HLH and discuss the benefits of therapeutic B-cell depletion in both conditions.

Drugs for paediatric hyperinflammatory syndromes.

Background: Many syndromes are associated with exaggerated inflammation. Children with hyperinflammatory syndromes often present with vague and non-specific symptoms that pose diagnostic and management challenges. The recent literature seems biased towards referring these syndromes only to the multisystem inflammatory syndrome in children (MIS-C) that is associated with COVID-19. The purpose of this paper is to provide an updated narrative review on the pathophysiology, manifestations and management approaches for common hyperinflammatory syndromes. Methods: An extensive PubMed search of all publications in the English literature was performed with Clinical Queries for various hyperinflammatory syndromes and conditions using the undermentioned Medical Subject Headings: "hyperinflammation", "hyperinflammatory syndromes", "sepsis syndrome", "severe inflammatory response syndrome" and "acute respiratory distress syndrome". Categories were limited to reviews and clinical trials for the age range from birth to 18 years. Results: The criteria, presentation and management of these hyperinflammatory syndromes are described. Hyperinflammatory syndromes refer to a basket of inflammatory syndromes often associated with multisystem involvement and aberrant cytokine release and should be differentiated from autoinflammatory, autoimmune and hyperimmune syndromes. The major subtypes of hyperinflammatory syndromes, including macrophage activation syndrome, haemophagocytic lymphohistiocytosis, cytokine release syndrome and cytokine storm syndrome, are described. MIS-C associated with SARS-CoV-2 represents the latest addition. It must be understood that the syndrome is not exclusive to COVID-19 but could be caused by various viral infections. Early recognition, prompt and proactive treatment can reduce potential complications and improve outcomes and survival rates in paediatric patients. Anti-inflammatory medications for the management of these syndromes are described. Conclusion: The incidence of these hyperinflammatory conditions is generally low in comparison to other disease conditions. Except for paediatric inflammatory multisystem syndrome/MIS-C, the mortality is high and the hospital stay is prolonged in affected patients. Acute and critical care physicians must be aware of these conditions and their initial management. Corticosteroids are often used in the initial phrase but various disease-specific drugs and biologics are needed in subsequent management and expert management of these often-difficult conditions is crucial.

Cytokine storm after heart transplantation in COVID-19-related haemophagocytic lymphohistiocytosis (HLH).

While severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection primarily causes inflammation in the respiratory system, there is growing evidence of extrapulmonary tissue damage mediated by the host innate immune system in children and adults. A cytokine storm can manifest as a viral-induced haemophagocytic lymphohistiocytosis (HLH). Here, we present a previously healthy 8-year-old boy with newly diagnosed cardiac injury and COVID-19-related HLH syndrome with haemophagocytosis in bone marrow biopsy. After remission of inflammation, the patient underwent a heart transplant due to persistent cardiac failure. The histology of the explanted heart showed only a focal subtle subendocardial inflammation. Three days after transplant, he developed progressive acute respiratory distress syndrome (ARDS) with the rise of inflammatory markers. He unfortunately died after 20 days because of disseminated intravascular coagulation (DIC). For the first time, we described a child with COVID-19-related HLH and severe cardiac failure, which had a poor prognosis despite a heart transplant.

Perforin, COVID-19 and a possible pathogenic auto-inflammatory feedback loop.

During COVID-19 infection, reduced function of natural killer (NK) cells can lead to both compromised viral clearance and dysregulation of the immune response. Such dysregulation leads to overproduction of cytokines, a raised neutrophil/lymphocyte ratio and monocytosis. This in turn increases IL-6 expression, which promotes scar and thrombus formation. Excess IL-6 also leads to a further reduction in NK function through downregulation of perforin expression, therefore forming a pathogenic auto-inflammatory feedback loop. The perforin/granzyme system of cytotoxicity is the main mechanism through which NK cells and cytotoxic T lymphocytes eliminate virally infected host cells, as well as being central to their role in regulating immune responses to microbial infection. Here, we present epidemiological evidence suggesting an association between perforin expression and resistance to COVID-19. In addition, we outline the manner in which a pathogenic auto-inflammatory feedback loop could operate and the relationship of this loop to genes associated with severe COVID-19. Such an auto-inflammatory loop may be amenable to synergistic multimodal therapy.

Secondary haemophagocytic lymphohistiocytosis in hospitalised COVID-19 patients as indicated by a modified HScore is infrequent and high scores do not associate with increased mortality.

A significant proportion of COVID-19 patients show evidence of hyperinflammation (HI), of which secondary haemophagocytic lymphohistiocytosis (sHLH) is the most severe manifestation and diagnosed with HScore. Using a COVID-relevant modification of the HScore (%HScore), we set out to determine the prevalence of sHLH in 567 COVID-19 inpatient cases.The overall incidence of individuals with an 80% probability of sHLH in our COVID-19 cohort was 1.59% on admission and only rose to 4.05% if calculated at any time during admission. This small cohort as defined by %HScore showed no excess mortality compared with the whole cohort. Overall, %HScores were lower in older patients (p<0.0001) and did not reliably predict outcome at any cut-off value (AUROC 0.533, p=0.211, odds ratio 0.99).Our study demonstrates that a modified version (%HScore) of the conventional sHLH scoring system (HScore) does not enable risk stratification in people hospitalised with COVID. We propose further work is needed to develop novel approaches to predict HI and improve trial stratification for HI directed therapy in people with COVID-19.

Cytokine Storms in the Course of COVID-19 and Haemophagocytic Lymphohistiocytosis in Pregnant and Postpartum Women.

The term 'cytokine storm' (CS) applies to a pathological autoimmune reaction when the interactions that lead to cytokine production are destabilised and may even lead to death. CS may be induced by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection. In this study, we present our analysis of certain pathological processes that induce a CS in pregnant and postpartum women. We draw our attention to the similarities between the severe course of Coronavirus Disease 2019 (COVID-19) and haemophagocytic lymphohistiocytosis (HLH). It is noteworthy that many of the criteria used to diagnose HLH are described as COVID-19 mortality predictors. Cytokine storms are considered to be an important cause of death in patients with the severe course of SARS-CoV-2 infection. Due to the fact that pregnant women are in an immunosuppressive state, viral pulmonary infections are more perilous for them-possible risks include miscarriage, intrauterine growth restriction or birth before the term; sometimes ventilation support is needed. HLH should be considered in pregnant and puerperal women suffering from moderately severe to severe COVID-19 and presenting with: fever unresponsive to antibiotic therapy, cytopenia, hepatitis and hyperferritinaemia. The HLH disorder is rare and difficult to diagnose; however, its early detection could reduce patient mortality.

Continuous intravenous anakinra for treating severe secondary haemophagocytic lymphohistiocytosis/macrophage activation syndrome in critically ill children.

The cytokine storm of secondary haemophagocytic lymphohistiocytosis (sHLH)/macrophage activation syndrome (MAS) can cause life-threatening multiorgan failure. Interleukin-1 (IL-1) receptor blockade with anakinra can be effective in the management of sHLH/MAS. Subcutaneous (SC) dosing regimens are widely described; however, intravenous (IV) dosing is advantageous where time-critical intervention is vital and where SC oedema and/or hypoperfusion limits absorption. We review three critically ill children (aged 9, 11 and 17) with sHLH and rapidly progressive multiorgan dysfunction, successfully treated with continuous IV anakinra infusion. This case series significantly enhances the incipient knowledge regarding the safety and efficacy of IV anakinra for life-threatening sHLH.

A fine line between macrophage activation syndrome and multisystem inflammatory syndrome in children - literature review based on two case reports.

Multisystem inflammatory syndrome in children is a newly described condition temporarily associated with severe acute respiratory syndrome coronavirus 2. The primary observations indicated coronavirus disease 2019 infection in children to be mild. However, recent reports have revealed a correlation between multisystem inflammatory symptoms and coronavirus infection. The manifestation of the disease is similar to Kawasaki disease, toxic shock syndrome and macrophage activation syndrome. Treatment includes intravenous corticosteroids, immunoglobulin and biological therapy (anakinra, tocilizumab, infliximab). In this article we compare world reports of multisystem inflammatory syndrome in children to case reports of two patients who were hospitalized recently at the Department of Paediatric Cardiology and Rheumatology. In the course of diagnostics they presented numerous symptoms which required differentiation from multisystem inflammatory syndrome in children.

Bone marrow haemophagocytosis indicates severe infection with severe acute respiratory syndrome coronavirus 2.

AIMS: Haemophagocytosis in the bone marrow of patients who have succumbed to coronavirus disease 19 (COVID-19) has not been widely studied. The aims of the present study were to perform morphological analyses and morphometry of haemophagocytosis in the bone marrow of patients with severe COVID-19, and to correlate the findings with the clinical course of the disease. METHODS AND RESULTS: In this single-centre study performed at the University Hospital Jena, bone marrow specimens of 15 deceased patients who had experienced a severe course of COVID-19 were sampled from the vertebral column during autopsy. Slides of the bone marrow were stained with routine stains or immunohistochemically, and further examined for haemophagocytosis by the use of light microscopy. To substantiate the morphological findings, additional slides were stained for CD163 and morphometry was performed. In all bone marrow samples, an increase in cellularity was found. Haemophagocytes with erythrophagocytosis were detected in 67% of the deceased patients. In tissues with low numbers of haemophagocytes or ill-defined haemophagocytes, an increase in iron deposits was frequently seen. Morphological findings were then correlated with several important clinical data, and the HScore (probability of having a reactive hemophagocytic syndrome) was calculated to posthumously confirm the diagnosis of secondary haemophagocytic lymphohistiocytosis. The median duration of disease and the hospitalisation time were lower in patients with haemophagocytosis (n = 10) than in patients without haemophagocytosis (n = 5). In addition, patients with haemophagocytes showed increased inflammatory parameters 2-5 days prior to death, in contrast to patients without haemophagocytes. CONCLUSIONS: Haemophagocytosis is a common finding in the bone marrow of deceased individuals with severe COVID-19, and may indicate fatal severe acute respiratory syndrome coronavirus 2 infections.

Hereditary haemochromatosis, haemophagocytic lymphohistiocytosis and COVID-19.

BACKGROUND: Syndromes of iron overload have been shown to increase the risk of severe clinical disease in viral infections. Immune dysfunction is similarly described in hereditary haemochromatosis (HH). We present here the case of a 51-year-old man who developed severe coronavirus disease 2019 (COVID-19) complicated by suspected haemophagocytic lymphohistiocytosis (HLH). He was found to have HH post-mortem and we propose a link between his iron overload and the development of severe COVID-19. CASE REPORT: The initial clinical presentation consisted of cough, shortness of breath and fever. Pancytopenia, markedly elevated ferritin and d-dimer were present. Computed tomography (CT) showed bilateral ground glass changes consistent with COVID-19, widespread lymphadenopathy and splenomegaly. A subsequent combined nose and throat swab was positive for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). HLH was suspected based upon the H-score and Anakinra, an IL-1 receptor antagonist, was commenced. Liver function acutely worsened and magnetic resonance cholangiopancreatography (MRCP) revealed hepatic haemosiderosis. Intense splenic and cervical lymph node uptake were seen on a positron emission tomography (PET) scan and high doses of intravenous steroids were administered due to concerns over haematological malignancy. RESULTS: Day fourteen of admission heralded the start of progressive clinical deterioration with rapid increase in oxygen demands. Continuous positive airway pressure (CPAP) was trialled without success and the patient unfortunately died seventeen days into admission. Results returned after his death showed homozygous C282Y mutation of the HFE gene consistent with a diagnosis of HH. Post-mortem examination revealed widespread haemosiderin deposition in the liver along with lung pathology in keeping with severe COVID-19 and widespread splenic infarctions. CONCLUSION: An association between HH and COVID-19 is not currently described in the literature. What does exist, however, is an evidence base for the detrimental impacts iron overload has on viral infections in general and the negative effects of HH on the immune system. We therefore postulate that the underlying metabolic and immune disturbances seen in HH should be considered a potential risk factor for the development of severe COVID-19. This case also adds to the evidence that hyperinflammation appears to be a unique and interesting characteristic of this novel viral disease.

Safety of intravenous anakinra in COVID-19 with evidence of hyperinflammation, a case series.

OBJECTIVES: Anakinra is a selective IL-1 inhibitor, which has been used in the context of secondary haemophagocytic lymphohistiocytosis. Although usually given in the s.c. form, previous anecdotal reports have emphasized its utility when given i.v. Our aim is to report our experience on the beneficial effects of anakinra i.v. in patients with SARS-CoV-2 and evidence of hyperinflammation. METHODS: We report four patients with severe COVID-19 infection requiring intensive care admission and ventilatory support. RESULTS: All four patients showed evidence of deterioration, with hyperferritinaemia and increasing oxygen requirements and with superadded bacterial infections. Upon commencement of anakinra i.v., there was subsequent improvement in the patients clinically, with reduction in ventilatory support and inotropic support, and biochemically, with rapid improvement in inflammatory markers. CONCLUSION: Anakinra is safe to use i.v. in patients with COVID-19 and evidence of superadded bacterial infection. Although its utility has not been confirmed in a randomized trial, current research in the COVID-19 pandemic aims to establish the utility of immunosuppression, including IL-1 blockade, on the outcomes of patients with moderate to severe disease. Our case series supports its use in patients with severe, life-threatening COVID-19 and evidence of hyperinflammation.

Severe COVID-19, Another Piece in the Puzzle of the Hyperferritinemic Syndrome. An Immunomodulatory Perspective to Alleviate the Storm.

The coronavirus disease 2019 (COVID-19), an acute respiratory disease caused by severe acute respiratory syndrome-coronavirus-2 (SARS-CoV-2), has been declared as a worldwide public health emergency. Interestingly, severe COVID-19 is characterized by fever, hyperferritinemia, and a hyper-inflammatory process with a massive release of pro-inflammatory cytokines, which may be responsible for the high rate of mortality. These findings may advocate for a similarity between severe COVID-19 and some challenging rheumatic diseases, such as adult onset Still's disease, secondary hemophagocytic lymphohistiocytosis, and catastrophic anti-phospholipid syndrome, which have been included in the "hyperferritinemic syndrome" category. Furthermore, as performed in these hyper-inflammatory states, severe COVID-19 may benefit from immunomodulatory therapies.