Visceral leishmaniasis, hypertriglyceridemia and secondary hemophagocytic lymphohistiocytosis

Secondary hemophagocytic lymphohistiocytosis in pediatric patients with visceral leishmaniasis and Epstein-Barr virus infection

Visceral leishmaniasis-associated hemophagocytic lymphohistiocytosis (VL-HLH) is indistinguishable from those of HLH of other etiologies due to the overlap symptoms, posing a serious threat to life. In this study, we aimed to provide insights for early diagnosis and improve outcomes in pediatric patients with VL-HLH. We retrospectively analyzed the clinical and laboratory data of 10 pediatric patients with VL-HLH and 58 pediatric patients with Epstein-Barr virus-associated hemophagocytic lymphohistiocytosis (EBV-HLH). The median time from symptom onset to cytopenia in patients with VL-HLH and EBV-HLH was 11 days (interquartile range, 7-15 days) and five days (interquartile range, 3.75-9.25 days) (P = 0.005). Both groups showed liver injury and increased lactate dehydrogenase levels; however the levels of aspartate aminotransferase, alanine aminotransferase, direct bilirubin, and lactate dehydrogenase in patients with VL-HLH were significantly lower than those in patients with EBV-HLH (P < 0.05). The fibrinogen and triglyceride levels were almost normal in VL-HLH patients but were significantly altered in EBV-HLH cases ( P < 0.05). The positive rate of first bone marrow microscopy examination, anti-rK39 IgG detection, and blood metagenomic next-generation sequencing was 50%, 100%, and 100%, respectively. After VL diagnosis, eight patients were treated with sodium stibogluconate and two were treated with liposomal amphotericin B. All the patients with VL-HLH recovered. Our study demonstrates that regular triglyceride and fibrinogen levels in pediatric patients with VL-HLH may help in differential diagnosis from EBV-HLH. VL-HLH is milder than EBV-HLH, with less severe liver injury and inflammatory responses, and timely treatment with antileishmanial agents is essential to improve the outcomes of pediatric patients with VL-HLH.

Leishmania Infection-Induced Proteolytic Processing of SIRPα in Macrophages

The shedding of cell surface receptors may bring synergistic outcomes through the loss of receptor-mediated cell signaling and competitive binding of the shed soluble receptor to its ligand. Thus, soluble receptors have both biological importance and diagnostic importance as biomarkers in immunological disorders. Signal regulatory protein α (SIRPα), one of the receptors responsible for the 'don't-eat-me' signal, is expressed by myeloid cells where its expression and function are in part regulated by proteolytic cleavage. However, reports on soluble SIRPα as a biomarker are limited. We previously reported that mice with experimental visceral leishmaniasis (VL) manifest anemia and enhanced hemophagocytosis in the spleen accompanied with decreased SIRPα expression. Here, we report increased serum levels of soluble SIRPα in mice infected with Leishmania donovani, a causative agent of VL. Increased soluble SIRPα was also detected in a culture supernatant of macrophages infected with L. donovani in vitro, suggesting the parasite infection promotes ectodomain shedding of SIRPα on macrophages. The release of soluble SIRPα was partially inhibited by an ADAM proteinase inhibitor in both LPS stimulation and L. donovani infection, suggesting a shared mechanism for cleavage of SIRPα in both cases. In addition to the ectodomain shedding of SIRPα, both LPS stimulation and L. donovani infection induced the loss of the cytoplasmic region of SIRPα. Although the effects of these proteolytic processes or changes in SIRPα still remain unclear, these proteolytic regulations on SIRPα during L. donovani infection may explain hemophagocytosis and anemia induced by infection, and serum soluble SIRPα may serve as a biomarker for hemophagocytosis and anemia in VL and the other inflammatory disorders.

Two Infectious Agents Causing Hemophagocytic Lymphohistiocytosis

Hemophagocytic lymphohistiocytosis (HLH) is a life-threatening immune activation syndrome that should be recognized earlier for effective treatment. Adults usually have secondary HLH. An uncommon cause of secondary HLH is AIDS and simultaneous opportunistic infections. Acute human immunodeficiency virus (HIV) and opportunistic infections are also independent causes of HLH, so the presence of both should raise suspicion, especially if patients fulfill the criteria. HLH secondary to severe babesiosis is a rare entity as well. Some patients might not meet the full criteria of HLH on presentation, especially when some specific lab test results are still pending. A delay in diagnosis can happen in those cases. Here, we present two cases. The first case is of a 35-year-old homosexual male who presented with constitutional symptoms of one-week duration. He was diagnosed and started on the treatment of HIV. His fever was not resolving and further investigations led to a diagnosis of disseminated histoplasma infection. The patient fulfilled the criteria of HLH as well. Prompt therapy resulted in the improvement of clinical and laboratory parameters. The second case is of a 72-year-old female presenting with fever. A diagnosis of severe babesiosis and secondary HLH was made. Treatment of babesia resulted in the improvement of clinical and biochemical parameters.

Clinical, immunological and genetic findings in patients with UNC13D deficiency (FHL3): A systematic review

BACKGROUND

Familial hemophagocytic lymphohistiocytosis (FHL) is a rare autosomal recessive immune disorder that is caused by mutations in 6 different genes related to the formation and function of secretory lysosomes within cytotoxic T lymphocytes and natural killer (NK) cells. Thus, defect in these genes is associated with the accumulation of antigens due to defective cytotoxic function. FHL type 3 (FHL3) accounts for nearly 30-40% of FHL, and its underlying reason is mutation in UNC13D gene which encodes Munc13-4 protein.

METHODS

For the first time, we aimed to systematically review clinical features, immunologic data, and genetic findings of patients with FHL3. We conducted electronic searches for English-language articles in PubMed, Web of Science, EMBASE, and Scopus databases to collect comprehensive records related to patients with UNC13D mutations.

RESULTS

A total of 279 abstracts were initially reviewed for inclusion. Among them, 57 articles corresponding to 322 individual FHL3 patients fulfilled our selection criteria. Finally, 73 and 249 patients were considered as severe and mild feature groups, respectively. Our results confirmed that fever, hepatosplenomegaly, and hemophagocytosis are common clinical features in the disease. Moreover, reduced fibrinogen and NK cell activity, as well as increased ferritin and triglycerides, are important markers for early diagnosis of the FHL3 disease. Investigation of genotype showed that the most prevalent type and zygosity of UNC13D are splice-site errors and compound heterozygous, respectively.

CONCLUSION

FHL3 patients have a wide range of clinical manifestations, which makes it difficult to diagnose. Therefore, it seems that the sequencing of the entire UNC13D gene (coding and non-coding regions) is the most appropriate way to accurate diagnosis of FHL3 patients.

Hemophagocytic lymphohistiocytosis associated with Leishmania: A hidden passenger in endemic areas

INTRODUCTION

Hemophagocytic lymphohistiocytosis (HLH) is an aggressive and life-threatening syndrome characterized by excessive immune activation. We analyzed the presentation, diagnosis and prognosis of our cohort of HLH-Leishmania cases.

METHODS

We studied HLH cases in patients over 14 years of age in the province of Granada (Spain), from January 2008 to November 2019.

RESULTS

In this study, Leishmania was the predominant trigger of adult HLH in our region. There were no differences in the clinical-analytical presentation between HLH triggered by Leishmania and those initiated by a different cause. RT-PCR was the best tool to identify Leishmania as the trigger of HLH, given that the other microbiological tests showed low sensitivity to detect the parasite in our HLH-Leishmania cases.

CONCLUSION

A comprehensive search for Leishmania is mandatory in HLH cases. Based on our findings, we propose that RT-PCR for Leishmania in bone marrow samples must be included in HLH differential diagnostic protocols.

A case of pediatric visceral leishmaniasis-related hemophagocytic lymphohistiocytosis diagnosed by mNGS

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Atypical clinical features make it hard to identify VL in HLH in non-epidemic area.

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VL is difficult to diagnose when traditional tests are ineffective, while mNGS is.

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mNGS can be used as a detection method of HLH in children caused by rare pathogens.

Background

Visceral leishmaniasis-related hemophagocytic lymphohistiocytosis (VL-HLH) is a secondary hemophagocytic syndrome, which can be life-threatening, caused by leishmania and transmitted by infected sandflies. Rapid and accurate identification of leishmania is crucial for clinical strategies.

Case report

Here, we report an infantile infection in a non-epidemic area of China. The infant was a 9.5-month-old girl with fever, pancytopenia and hepatosplenomegaly, which meet the HLH-2004 standard, and the negative gene results exclude congenital HLH. However, chemotherapy is ineffective and is accompanied by severe infection. Fortunately, she is diagnosed with VL-HLH (visceral leishmaniasis-related hemophagocytic lymphohistiocytosis), as leishmania is detected by next-generation meta-genome sequencing (mNGS) and quickly relieved after treatment with libosomal amphotericin B (L-AMB).

Conclusion

mNGS can detect leishmania in pediatric HLH, and should be performed as a new detection for VL-HLH, particularly for infants, who may not respond to HLH-2004 regimen.

Epidemiological and clinical features of visceral leishmaniasis in children in Alicante Province, Spain

BACKGROUND

Visceral leishmaniasis (VL) is endemic to the Mediterranean basin. In children, VL often presents with non-specific symptoms and can be life-threatening without proper treatment.

AIM

To describe the epidemiological and clinical features of pediatric VL in children in Alicante, Spain.

METHODS

The study included all paediatric (<15 years) cases admitted to three hospitals in the province of Alicante from May 1992 to May 2015 with diagnosis of VL (detection was either by anti-Leishmania antibodies in serology or Leishmania in blood and/or bone marrow aspirates).

RESULTS

There were 38 cases of pediatric VL (18 aged <24 months, 15 aged 24-59 months and 5 aged ≥5 years). The main symptoms were fever (97.4%), followed by pallor (75.0%) and loss of appetite (46.4%). Eighty-seven per cent of patients were anaemic (haemoglobin < 9 g/dL), 73.7% had neutropenia and 68.4% had thrombocytopenia. Before 2004, 92.3% of patients were treated with meglumine antimoniate (MA) and 7.7% with liposomal amphotericin B (LAmB); after 2004, 84% were treated with LAmB and just one (16%) with MA (p < 0.001). LAmB performed better than MA in terms of mean treatment length (7.4 days vs 25.9 days, p < 0.001), time to becoming afebrile (1.7 vs 13.7 days, p < 0.001), and length of hospital stay (10.9 vs 19.4 days, p = 0.001).

CONCLUSION

Paediatric VL in Alicante mainly affects children under five. Children aged ≤24 months present with a lower haemoglobin and white blood cell count. Treatment with LAmB reduces treatment length, time to becoming afebrile and length of hospital stay.

Acute HIV infection presenting as hemophagocytic lymphohistiocytosis: case report and review of the literature

Background

Hemophagocytic lymphohistiocytosis (HLH) is an uncommon systemic inflammatory condition that can result from infections, autoimmune diseases and malignancies. It is a rarely reported life threatening complication of an acute HIV infection, with only ten documented case reports per our literature search. We present a case of HLH secondary to acute HIV infection with a negative HIV antibody-based assay and high plasma viral load.

Case presentation

A 45 year old male with a past medical history of well controlled hypertension presented with fever, dizziness and non-bloody diarrhea. Initial lab work revealed a new thrombocytopenia, marked renal failure and an elevated creatine kinase, ferritin, lactate dehydrogenase and D-dimer. A bone marrow biopsy revealed HLH. As part of the work up for thrombocytopenia, a rapid HIV antibody based assay was done and was negative. The sample was later routinely tested with a fourth generation antigen/antibody assay as per local protocol and was strongly positive. The plasma RNA viral load was >10,000,000 copies /mL confirming the diagnosis of an acute HIV infection. The patient was urgently started on antiretroviral therapy and recovered.

Conclusion

This case illustrates a diagnostic approach to HLH which is an uncommon but life threatening multisystem disease, requiring the involvement of a multidisciplinary team of experts. Following any diagnosis of HLH, rapid identification and treatment of the underlying condition is critical. A negative rapid HIV antibody test can be misleading in the context of early HIV infection and the additional use of fourth generation antigen/antibody test or plasma RNA viral load may be required within the right clinical context for diagnosis.

Hemophagocytic Lymphohistiocytosis

Hemophagocytic lymphohistiocytosis is a life-threatening disorder characterized by unbridled activation of cytotoxic T lymphocytes, natural killer (NK) cells, and macrophages resulting in hypercytokinemia and immune-mediated injury of multiple organ systems. It is seen in both children and adults and is recognized as primary (driven by underlying genetic mutations that abolish critical proteins required for normal function of cytotoxic T cells and NK cells) or secondary (resulting from a malignant, infectious, or autoimmune stimulus without an identifiable underlying genetic trigger). Clinical and laboratory manifestations include fever, splenomegaly, neurologic dysfunction, coagulopathy, liver dysfunction, cytopenias, hypertriglyceridemia, hyperferritinemia, hemophagocytosis, and diminished NK cell activity. It is treated with immune suppressants, etoposide, and allogeneic hematopoietic stem cell transplantation; more than 50% of children who undergo transplant survive, but adults have quite poor outcomes even with aggressive management. Newer agents directed at subduing the uncontrolled immune response in a targeted fashion offer promise in this highly morbid disease.