Genetic variant spectrum in 265 Chinese patients with hemophagocytic lymphohistiocytosis: Molecular analyses of PRF1, UNC13D, STX11, STXBP2, SH2D1A, and XIAP

Clinical Characteristics and Treatment of Familial Hemophagocytic Lymphohistiocytosis

Familial hemophagocytic lymphohistiocytosis (fHLH) comprises a group of autosomal recessive disorders characterized by germline loss-of-function variants that negatively impact lymphocyte cytotoxicity. These disorders exhibit variable clinical presentations, most often in association with severe hyperinflammation. fHLH is diagnosed through clinical and laboratory assessments as well as genetic testing and immunologic assays. In the absence of therapy to control the hyperactive immune system, fHLH is generally fatal. Treatment has historically taken the form of cytotoxic chemotherapy and/or immunosuppressive therapy, although targeted inhibitors of inflammatory cytokines and their downstream signaling are increasingly being utilized. Definitive treatment requires allogeneic hematopoietic cell transplantation.

Successful Second CBT for Graft Failure After First CBT for Adult-Onset Familial Hemophagocytic Lymphohistiocytosis Type 3: A Case Report

Familial hemophagocytic lymphohistiocytosis (FHL) is a rare inherited autosomal recessive immune deficiency that usually manifests during infancy or early childhood, rarely occurring in adults. Hematopoietic stem cell transplantation (HSCT) is the only curative treatment for FHL. However, optimal conditioning regimens for adult-onset FHL have not yet been established. Herein, we report a case of adult-onset FHL. A 37-year-old man presented with fever, liver dysfunction, and pancytopenia, which improved temporarily with corticosteroid therapy. However, he later developed encephalitis and myelitis. Genetic analysis revealed rare variants of UNC13D (c.2367+1 g>a and c.2588 g>a), which were compound heterozygous pathogenic mutations. FHL type 3 was diagnosed, and treatment based on the hemophagocytic lymphohistiocytosis (HLH) 1994 protocol was initiated. The patient underwent cord blood transplantation (CBT) with myeloablative conditioning using fludarabine, melphalan, and total-body irradiation (TBI), which resulted in graft rejection. The patient was successfully rescued by a second CBT following reduced-intensity conditioning with fludarabine, cyclophosphamide, and TBI. Although graft failure is an important complication especially in CBT, it could be managed by appropriate treatment, and that cord blood would be a promising alternative source with the advantages of rapidity and avoidance of related donors with a high risk of harboring the same genetic mutation.

Genetic and clinical characteristics of primary hemophagocytic lymphohistiocytosis in children

To analyze the genetic variation and prognosis of primary hemophagocytic lymphohistiocytosis (pHLH) in children and the clinical features of isolated central nervous system HLH (CNS-HLH). We retrospectively analyzed the clinical and genetic data of 480 HLH children admitted to our hospital from September 2017 to September 2022. There were 66 patients (13.75%) with pHLH, and the median age was 3.21 years (0.17-12.92 years). Variants in UNC13D (22/66, 33.33%), PRF1 (20/66, 30.30%) and XIAP (11/66, 16.67%) were the most common. More CNS involvement was observed in pHLH patients than in secondary hemophagocytic lymphohistiocytosis (sHLH) patients (50% vs. 25.3%, P = 0.001). Eight pHLH patients had isolated CNS-HLH at onset, which progressed to systemic HLH within 10-30 days to several years. Among them, five patients who underwent hematopoietic stem cell transplantation (HSCT) survived without CNS sequelae, and the three patients who did not undergo HSCT died of disease progression or recurrence. Determination of natural killer (NK) cell cytotoxicity and CD107a levels had low sensitivity and specificity in the diagnosis of pHLH, especially in patients with PRF1 and XIAP mutations. The 3-year overall survival (OS) was significantly lower in pHLH patients than in sHLH patients (74.5% ± 14.7% vs. 89.2% ± 3.53%, P = 0.021) and in patients with CNS involvement than in those without (53.8% ± 26.07% vs. 94.4% ± 10.58%, P = 0.012). There was a significant difference in OS among pHLH patients with different gene variants (P = 0.032); patients with PRF1 variants had poor 3-year OS, and patients with XIAP variants had good 3-year OS (50% ± 28.22% and 100%, respectively). pHLH patients with distinct variants have different prognoses. Isolated CNS-HLH patients are easily misdiagnosed, and HSCT may be beneficial for these patients. Determination of NK cell cytotoxicity and CD107a levels cannot precisely distinguish pHLH from sHLH.

Hemophagocytic lymphohistiocytosis with a hemizygous PRF1 c.674G>A mutation

Hemophagocytic lymphohistiocytosis(HLH) is a rare highly-fatal disease presenting with fever, hepatosplenomegaly, and pancytopenia and has a poor prognosis. Homozygous or semi-zygous or complex heterozygous variants can cause familial HLH and heterozygous carriers are frequently seen in secondary HLH. A 42-year-old male patient was admitted to the hospital for persistent fever, fatigue, and splenomegaly. Investigations revealed hypertriglyceridemia, hyperlactatemia dehydrogenaseemia, hyperferritinemia, and elevated levels of soluble cluster of differentiation 25. We found a heterozygous mutation of PRF1: c.674G>A (p.R225Q) through next-generation sequencing technology of hemophagocytic-lymphohistiocytosis-related genes. After a brief remission with dexamethasone and etoposide-based therapy, the disease relapsed quickly, and an allogeneic hematopoietic stem cell transplant was performed to achieve complete remission. To date, the patient's condition was in complete remission. Our study detected a rare missense mutation in the PRF1 gene in a patient with HLH disease and the c.674G>A mutation may be rated as a possible pathogenic variant.

[Clinical characteristics of primary hemophagocytic lymphohistiocytosis associated with perforin gene deficiency: a single-center retrospective study]

Objective: This study aimed to investigate the clinical characteristics of patients diagnosed with primary hemophagocytic lymphohistiocytosis (pHLH) associated with perforin gene deficiency. Methods: We retrospectively analyzed the clinical data of 16 pHLH patients associated with perforin gene deficiency at Beijing Friendship Hospital, Capital Medical University, from April 2014 to August 2021. The mutation sites, mutation types, family history, clinical characteristics, and prognosis of the patients were assessed. Results: A total of 16 patients, including ten males and six females, with a median onset age of 17.5 years (range: 4-42 years), were enrolled in this study. Sixteen different mutations were identified, consisting of 11 missense mutations, one nonsense mutation, two frameshift mutations, and two in-frame mutations. All patients harbored at least one deleterious missense mutation, with the most common mutation sites being c.1349C>T (p.T450M) and c.503G>A (p.S168N). Decreased natural killer (NK) cell activity was observed in 11 patients, reduced perforin protein expression in ten patients, concurrent Epstein-Barr virus (EBV) infection at onset in eight patients, a family history in two patients, and central nervous system involvement in four patients. Eleven cases underwent allogeneic hematopoietic stem cell transplantation (allo-HSCT), with eight cases surviving. The median survival time of non-transplanted patients was eight months (range: 4-18 months), while that of transplanted patients was reported as "not reached". Conclusions: Emphasizing the diagnosis of pHLH in adults with perforin gene deficiency. In addition, it should be noted that EBV infection can potentially act as a triggering factor in such disease, and allo-HSCT exerts a substantial effect on the prognosis of patients.

UNC13D inhibits STING signaling by attenuating its oligomerization on the endoplasmic reticulum

Stimulator of interferon genes (STING) is an essential signaling protein that is located on the endoplasmic reticulum (ER) and triggers the production of type I interferons (IFN) and proinflammatory cytokines in response to pathogenic DNA. Aberrant activation of STING is linked to autoimmune diseases. The mechanisms underlying homeostatic regulation of STING are unclear. Here, we report that UNC13D, which is associated with familial hemophagocytic lymphohistiocytosis (FHL3), is a negative regulator of the STING-mediated innate immune response. UNC13D colocalizes with STING on the ER and inhibits STING oligomerization. Cellular knockdown and knockout of UNC13D promote the production of interferon-β (IFN-β) induced by DNA viruses, but not RNA viruses. Moreover, UNC13D deficiency also increases the basal level of proinflammatory cytokines. These effects are diminished by an inhibitor of STING signaling. Furthermore, the domains involved in the UNC13D/STING interaction on both proteins are mapped. Our findings provide insight into the regulatory mechanism of STING, the previously unknown cellular function of UNC13D and the potential pathogenesis of FHL3.

Hemophagocytic Lymphohistiocytosis in Adults: A Retrospective Study in a Belgian Teaching Hospital

Introduction

Hemophagocytic lymphohistiocytosis (HLH) is a life-threatening disease, which can be primary (due to genetic mutation) or secondary to malignancy, infection and rheumatologic diseases. Data concerning Belgian patients with adult HLH are lacking.

Methods

This retrospective study was performed in a teaching hospital in Belgium. All cases of adult HLH, from December 2010 to April 2022, were reviewed. Patients with more than five HLH-2004 criteria and/or HScore >80% were included in the study. The objective of our study was to describe clinical and biological characteristics of patients with HLH and attempt to look for variables associated with mortality.

Results

Fifty-two patients were included in the final analysis. Mean age (SD) of patients was 48 (18) years old, and 29 patients were of male gender (56%). The underlying diseases associated with HLH were malignancy (M-HLH) in 22 patients, infection related HLH in 20 patients, rheumatologic disease related HLH in 7 patients, idiopathic in 2 patients and secondary to pregnancy in 1 patient. Overall mortality, mortality at 30 days and 90 days were 24/52 (46%), 13/52 (25%) and 4/52 (10%), respectively. In univariate analysis, malignancy, male sex, age and disseminated intravascular coagulation (DIC) were associated with mortality (p < 0.05). In multivariate analysis, only age was significantly associated with mortality (odds ratio, 1.053; 95% confidence interval, 1.016–1.092; p 0.005).

Conclusion

In our study, the most frequent triggers were malignancy and infectious agent followed by rheumatologic disease. Risk factors for mortality were age, male sex, malignancy and DIC, but only age remained significant in multivariate analysis. Treatment guidelines are mainly based on pediatric patients, and it is important for physician to describe adult patients’ outcome to better understand this disease and adapt treatment.

RF1 Gene Mutation in Familial Hemophagocytic Lymphohistiocytosis 2: A Family Report and Literature Review

OBJECTIVE

Gene mutation analysis was performed on a family with familial hemophagocytic lymphohistiocytosis (FHL) so as to provide an accurate etiological diagnosis, leading to genetic counseling for the family members.

METHODS

The clinical data of two probands (siblings) with FHL in one family were analyzed, and eight genes related to the onset of the primary hemophagocytic lymphohistiocytosis (pHLH) (PRF1, UNC13D, STX11, STXBP2, SH2D1A, BIRC4/XIAP, Rab27a, LYST) were detected and analyzed in the probands and their parents with whole exome sequencing.

RESULTS

Proband 1 was a two-year-old male with the clinical manifestations of fever, hepatosplenomegaly, and a decreased peripheral blood cell count, sCD25: 12504pg/mL. The results of genetic testing showed that there was a c.1349C>T heterozygous missense mutation and a c.853_855del heterozygous mutation in the PRF1 in proband 1. Proband 2 was an eight-year-old female with the clinical manifestations of convulsions and disturbance of consciousness with fever. The genetic test results were the same as those of proband 1. There was a single heterozygous mutation in the parents of the probands, and both probands had compound heterozygous mutations.

CONCLUSION

According to the clinical manifestations, laboratory tests, and results of the family molecular genetic testing, the probands could be clinically diagnosed as FHL2. The results of gene sequencing revealed that this was an autosomal recessive family with familial hemophagocytic syndrome. A rare pathogenic mutation (c.853_855del) in the PRF1 was discovered in the two patients with HLH.

Phenotype, genotype, treatment, and survival outcomes in patients with X-linked inhibitor of apoptosis deficiency

BACKGROUND

X-linked inhibitor of apoptosis (XIAP) deficiency is a rare, primary immunodeficiency disease caused by XIAP gene mutations. A broad range of phenotype, severity, and age of onset present challenges for patient management.

OBJECTIVE

To characterize the phenotype, treatment, and survival outcomes of XIAP deficiency and assess parameters influencing prognosis.

METHODS

Data published from 2006-2020 were retrospectively analyzed.

RESULTS

167 patients from 117 families with XIAP deficiency were reported with 90 different mutations. A wide spectrum of clinical features were seen, of which hemophagocytic lymphohistiocytosis (HLH) and inflammatory bowel disease (IBD) were the most common. Patients frequently developed multiple features with no clear genotype-phenotype correlation. 117 patients were managed conservatively and 50 underwent hematopoietic stem cell transplantation (HSCT), with respective overall survival probabilities of 90% and 53% at age 16 years. The predominant indication for HSCT was early-onset HLH. Active HLH and myeloablative conditioning regimens increased HSCT-related mortality, although HSCT outcome was much better after 2015 than before. For conservatively managed patients reaching adulthood, survival probabilities were 86% at age 30 years and 37% by age 52 years, with worse outcomes for patients developing the disease before the age of 5 years or with new disease features in adulthood. 9 asymptomatic mutation carriers were identified with a median age of 13.5 years.

CONCLUSIONS

Our study demonstrates the variable nature of XIAP deficiency which evolves over life for individual patients. Better therapeutic strategies and prospective studies are required to reduce morbidity and mortality and improve decision-making and long-term outcomes for patients with XIAP deficiency.

Hemophagocytic Lymphohistiocytosis

CONTEXT.—

Hemophagocytic lymphohistiocytosis (HLH) is a rare, life-threatening disorder of immune regulation that can eventually result in end-organ damage and death. HLH is characterized by uncontrolled activation of cytotoxic T lymphocytes, natural killer cells, and macrophages that can lead to a cytokine storm. The diagnosis of HLH is often challenging due to the diverse clinical manifestations and the presence of several diagnostic mimics. The prognosis is generally poor, warranting rapid diagnosis and aggressive management.

OBJECTIVE.—

To provide a comprehensive review of the pathogenesis, clinical features, diagnosis, and management of HLH.

DATA SOURCES.—

Peer-reviewed literature.

CONCLUSIONS.—

HLH is a condition where a complete understanding of the pathogenesis, early diagnosis, and proper management has an important role in determining patient outcome. Genetic mutations causing impairment in the function of cytotoxic T lymphocytes and natural killer cells have been identified as the root cause of familial HLH; however, the specific pathogenesis of acquired HLH is unclear. The HLH-2004 protocol used in the diagnosis of HLH was originally developed for the pediatric population. The HLH-2004 protocol still forms the basis of the diagnosis of HLH in adults, although its use in adults has not been formally validated yet. Treatment of HLH is primarily based on the HLH-94 protocol, which involves suppressing the inflammatory response, but the treatment needs to be modified in adults depending on the underlying cause and comorbidities.

Spectrum mutations of PRF1, UNC13D, STX11, and STXBP2 genes in Vietnamese patients with hemophagocytic lymphohistiocytosis

INTRODUCTION

The prevalence of gene mutations in hemophagocytic lymphohistiocytosis (HLH) varied between studies. Thus far, data on the genetic background of HLH in Vietnamese patients are limited.

METHODS

We recruited 94 HLH patients and analyzed for the 4 genes using Sanger sequencing technology.

RESULTS

Pathogenic variants were observed in 36 (38.29%) patients, including 27 in UNC13D, 5 in STXBP2, 3 in PRF1, and 2 in STX11 (one patient with digenic variants in both UNC13D and STX11). Monoallelic variants accounted for 77.8% of all cases with mutation. A total of 23 different types of pathogenic variants were documented in the 4 genes tested, including 15 in UNC13D, 3 in PRF1, 3 in STXBP2, and 2 in STX11. Interestingly, the novel splicing variant c.3151G>A in UNC13D was recurrently identified in 8 unrelated patients.

CONCLUSION

Vietnamese patients with HLH showed a distinct genetic variant spectrum, in which UNC13D is the predominant genetic lesion associated with HLH.

Germline variants in UNC13D and AP3B1 are enriched in COVID-19 patients experiencing severe cytokine storms

Critically ill coronavirus disease 2019 (COVID-19) is characterized by severe cytokine storms, a hyperinflammatory condition intimately related to the development of fatal outcomes. Why some individuals seem particularly vulnerable to severe cytokine storms is still unknown. Primary immunodeficiency (PID)-related genes are inherited factors that dysregulate host inflammatory responses to infection, especially hemophagocytic lymphohistiocytosis (HLH)-related genes, established as contributors to the development of excessive cytokine storms. We analyzed the association between PID gene variants with severe cytokine storms in COVID-19. We conducted whole-exome sequencing in 233 hospitalized COVID-19 patients and identified four PID gene (UNC13D, AP3B1, RNF168, DHX58) variants were significantly enriched in COVID-19 patients experiencing severe cytokine storms. The total percentage of COVID-19 patients with variants in UNC13D or AP3B1, two typical HLH genes, was dramatically higher in high-level cytokine group than in low-level group (33.3 vs. 5.7%, P < 0.001). Germline variants in UNC13D and AP3B1 were associated with the development of severe cytokine storms, fatal outcomes in COVID-19. These findings advance the understanding of individual susceptibility to severe cytokine storms and help optimize the current management of COVID-19.

Familial hemophagocytic lymphohistiocytosis type 2 in a female Chinese neonate: A case report and review of the literature

BACKGROUND

Familial hemophagocytic lymphohistiocytosis type 2 (FHL2) is a rare genetic disorder presenting with fever, hepatosplenomegaly, and pancytopenia secondary to perforin-1 (PRF1) mutation. FLH2 has been described in Chinese but usually presents after 1 year old. We describe a female Chinese neonate with FHL2 secondary to compound heterozygous PRF1 mutation with symptom onset before 1 mo old. We review Chinese FHL2 patients in the literature for comparison.

CASE SUMMARY

A 15-d-old female neonate was referred to our hospital for persistent fever and thrombocytopenia with diffuse petechiae. She was born to a G5P3 mother at 39 wk and 4 d via cesarean section secondary to breech presentation. No resuscitation was required at birth. She was described to be very sleepy with poor appetite since birth. She developed a fever up to 39.5°C at 7 d of life. Leukocytosis, anemia, and thrombocytopenia were detected at a local medical facility.

CONCLUSION

A literature review identified 75 Chinese FHL2 patients, with only five presenting in the first year of life. Missense and frameshift mutations are the most common PRF1 mutations in Chinese, with 24.8% having c.1349C>T followed by 11.6% having c.65delC. The c.658G>C mutation has only been reported once in the literature and our case suggests it can be pathogenic, at least in the presence of another pathogenic mutation such as c.1066C>T.

Clinical Management of Relapsed/Refractory Hemophagocytic Lymphohistiocytosis in Adult Patients: A Review of Current Strategies and Emerging Therapies

Introduction

Haemophagocytic lymphohistiocytosis (HLH) is a severe disorder with high mortality. The aim of this review is to update clinical management of relapsed/refractory HLH in adults, with a focus on current and new therapies.

Methods

We searched relevant articles in Embase and PUBMED with the MESH term “hemophagocytic lymphohistiocytosis; refractory; relapsing; adult.”

Results

One hundred eight papers were found; of these, 22 were retained for this review. The treatment of HLH in adult is based on the HLH-94 regimen. The response rate is lower than in pediatric patients, and 20–30% are refractory to this therapy. DEP regimen and allogenic hematopoietic stem cell transplantation (HSCT) are associated with complete response and partial response in 27% and 49.2%, respectively. However, many patients fail to achieve a stable condition before HSCT, and mortality is higher in them. New drugs have been developed, such as emapalumab, ruxolitinib, and alemtuzumab, and they may be used as bridges to the curative HSCT. They are relatively well tolerated and have few or mild side effects. With these agents, the rate of partial response ranges from 14.2% to 100%, while the rate of complete response is highly variable according to study and medication used. The number of patients who achieved HSCT ranged from 44.8% to 77%, with a survival rate of 55.9% to 100%. However, the populations in these studies are mainly composed of mixed-age patients (pediatric and adult patients), and studies including only adult patients are scarce.

Conclusion

Relapsed or refractory HLH in adult patients is associated with poor outcome, and consolidation with HSCT may be required in some cases. Mortality related to HSCT is mainly due to active HLH disease before HSCT and post HSCT complications. New drugs, such as empalumab, ruxolitinib, and alemtuzumab are interesting since these agents may be used as bridges to HSCT with increases in the numbers of patients proceeding to HSCT and survival rate.

Adult onset type 2 familial hemophagocytic lymphohistiocytosis with PRF1 c.65delC/c.163C>T compound heterozygous mutations: A case report

BACKGROUND

Familial hemophagocytic lymphohistiocytosis (FHL) is a primary immunodefici-ency disease caused by gene defects. The onset of FHL in adolescents and adults may lead clinicians to ignore or even misdiagnose the disease. To the best of our knowledge, this is the first report to detail the clinical features of type 2 FHL (FHL2) with compound heterozygous perforin (PRF1) defects involving the c.163C>T mutation, in addition to correlation analysis and a literature review.

CASE SUMMARY

We report a case of a 27-year-old male patient with FHL2, who was admitted with a persistent fever and pancytopenia. Through next-generation sequencing technology of hemophagocytic lymphohistiocytosis (HLH)-related genes, we found compound heterozygous mutations of PRF1: c.65delC (p.Pro22Argfs*29) (frameshift mutation, paternal) and c.163C>T (p.Arg55Cys) (missense mutation, maternal). Although he did not receive hematopoietic stem cell transplantation, the patient achieved complete remission after receiving HLH-2004 treatment protocol. To date, the patient has stopped taking drugs for 15 mo, is in a stable condition, and is under follow-up observation.

CONCLUSION

The delayed onset of FHL2 may be related to the PRF1 mutation type, pathogenic variation pattern, triggering factors, and the temperature sensitivity of some PRF1 mutations. For individual, the detailed reason for the delay in the onset of FHL warrants further investigation.

Use of the JAK Inhibitor Ruxolitinib in the Treatment of Hemophagocytic Lymphohistiocytosis

Hemophagocytic lymphohistiocytosis (HLH) is a rare hyperinflammatory syndrome driven by overactive T cells and macrophages that abundantly secrete numerous pro-inflammatory cytokines, including interferon (IFN)-gamma, interleukin (IL)-1-beta, IL-2, IL-6, IL-10, IL-18, and tumor necrosis factor (TNF). The release of these and other cytokines underlies many of the clinical and pathologic manifestations of HLH, which if left untreated, can lead to multi-organ failure and death. The advent of etoposide-based regimens, such as the Histiocyte Society HLH-94 and HLH-2004 protocols, has substantially decreased the mortality associated with HLH. Nevertheless, the 5-year survival remains low at ~60%. To improve upon these results, studies have focused on the use of novel cytokine-directed therapies to dampen inflammation in HLH. Among the agents being tested is ruxolitinib, a potent inhibitor of the Janus Kinase (JAK) and Signal Transducer and Activation of Transcription (STAT) pathway, which functions downstream of many HLH-associated cytokines. Here, we review the basic biology of HLH, including the role of cytokines in disease pathogenesis, and discuss the use of ruxolitinib in the treatment of HLH.

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.

A retrospective analysis of etiology and outcomes of hemophagocytic lymphohistiocytosis in children and adults

Background

Hemophagocytic lymphohistiocytosis (HLH) is a rare but severe, life-threatening inflammatory condition if untreated. We aimed to investigate the etiologies, outcomes, and risk factors for death in children and adults with HLH.

Methods

The medical records of patients who met the HLH criteria of two regional university hospitals in Korea between January 2001 and December 2019 were retrospectively investigated.

Results

Sixty patients with HLH (35 children and 25 adults) were included. The median age at diagnosis was 7.0 years (range, 0.1–83 years), and the median follow-up duration was 8.5 months (range, 0–204 months). Four patients had primary HLH, 48 patients had secondary HLH (20 infection-associated, 18 neoplasm-associated, and 10 autoimmune-associated HLH), and eight patients had HLH of unknown cause. Infection was the most common cause in children (14/35, 40.0%), whereas neoplasia was the most common cause in adults (13/25, 52.0%). Twenty-eight patients were treated with HLH-2004/94 immunochemotherapy. The 5-year overall survival (OS) rate for all HLH patients was 59.9%. The 5-year OS rates for patients with primary, infection-associated, neoplasm-associated, autoimmune-associated, and unknown cause HLH were 25.0%, 85.0%, 26.7%, 87.5%, and 62.5%, respectively. Using multivariate analysis, neoplasm-induced HLH (p=0.001) and a platelet count <50×10⁹/L (p=0.008) were identified as independent risk factors for poor prognosis in patients with HLH.

Conclusion

Infection was the most common cause of HLH in children, while it was neoplasia in adults. The 5-year OS rate for all HLH patients was 59.9%. HLH caused by an underlying neoplasm or a low platelet count at the time of diagnosis were risk factors for poor prognosis.

Outcomes and prognostic factors associated with 180-day mortality in Taiwanese pediatric patients with Hemophagocytic Lymphohistiocytosis

BACKGROUND/PURPOSE

Hemophagocytic lymphohistiocytosis (HLH), a rarely occurring syndrome with various triggers, is associated with early mortality. Owing to a lack of sufficient corresponding data in Taiwan, this study aimed to identify the outcome and potential factors associated with 180-day mortality in pediatric HLH.

METHODS

This retrospective study analyzed clinical and laboratory data on pediatric patients diagnosed with HLH at our institute (1995-2019). Logistic regression analysis was conducted to determine the associations between various factors and 180-day mortality.

RESULTS

Overall, 48 patients had HLH; their median age at diagnosis was 5 years (interquartile range: 2-11 years). Clinical presentations and laboratory parameters required for diagnosis included fever (98%), splenomegaly (79%), hyperferritinemia (98%), hemophagocytosis (94%), thrombocytopenia (90%), anemia (63%), hypertriglyceridemia (68%), and neutropenia (57%). The 5-year overall survival (OS) rate was 49%. Of 22 patients who had died at the last follow-up, 15 (68%) died within 180 days after diagnosis. In the multivariate analysis, hemoglobin (odds ratio [OR]: 0.564, p = 0.024) and triglyceride (OR: 1.004, p = 0.049) were significantly associated with 180-day mortality. Higher triglyceride levels at diagnosis were related to significantly lower 180-day OS rates (52.9% vs. 86.1%, p = 0.018).

CONCLUSION

The overall outcome in our cohort was similar to that reported in some of the largest international cohorts. Hypertriglyceridemia and anemia may be indicative of poor prognoses in pediatric HLH patients independently and may be used to guide treatment strategy formulations for better outcomes.

Epstein-Barr virus-related hemophagocytic lymphohistiocytosis complicated with coronary artery dilation and acute renal injury in a boy with a novel X-linked inhibitor of apoptosis protein (XIAP) variant: a case report

Background

X-linked lymphoproliferative disease (XLP) is a rare inherited X-linked primary immunodeficiency diseases (PID). One such disease, X-linked inhibitor of apoptosis protein (XIAP) deficiency, is characterized by Epstein–Barr virus-related hemophagocytic lymphohistiocytosis (EBV-HLH). However, EBV-HLH with coronary artery dilation and acute renal injury (AKI) in children is unusual.

Case presentation

We report the case of a young boy aged 17 months with a novel XIAP variant. He was initially diagnosed with EBV-HLH based on the HLH-2004 diagnostic criteria and the condition was accompanied by coronary artery dilation and acute renal injury. The comprehensive genetic analysis of peripheral blood-derived DNA revealed a hemizygous variant of the XIAP gene [c.116G > C(p.G39A)], which was inherited from his mother (heterozygous condition). After combined treatment with rituximab, intravenous immunoglobulin, corticosteroids, antiviral drugs, and mycophenolate mofetil (MMF) in addition to supportive therapy, his clinical manifestations and laboratory indexes were improved. The patient achieved complete remission with MMF treatment in the 8-month follow-up.

Conclusions

We report the [c.116G > C(p.G39A)] variant in the XIAP gene for the first time in a case of XLP-2 associated with EBV-HLH. For male patients with severe EBV-HLH, the possibility of XLP should be considered and molecular genetic testing should be used early in auxiliary diagnosis. Reports of EBV-HLH with coronary artery dilation and AKI in children are rare. In the patients with EBV-HLH, color Doppler echocardiography and urine tests should be monitored regularly. If necessary, renal biopsy can be performed to clarify the pathology. Treatment with rituximab, immunosuppressors and supportive therapy achieved a good effect, but long-term follow-up is required.

Dilemmas in diagnosis and management of hemophagocytic lymphohistiocytosis in children

BACKGROUND

Hemophagocytic lymphohistiocytosis (HLH) is a life-threatening entity which is characterized by severe hyperinflammation. Now the HLH-2004 protocol has been widely accepted and clinically used; however, many questions still remain in clinical practice. In this review, we discuss the dilemmas in the diagnosis and treatment of HLH in children.

DATA SOURCES

Original research for articles and literature reviews published in PubMed was carried out using the key term "hemophagocytic lymphohistiocytosis".

RESULTS

As the gene sequencing technology progresses, the range of causal mutations and primary HLH has been redefined. The monoallelic variants may contribute to the pathogenesis of the disease. Many conditions without defective cytotoxicity of T or NK cells may lead to HLH, such as primary immunodeficiency (PID) and dysregulated immune activation or proliferation (DIAP). HLH shares overlapping clinical and laboratory characteristics with severe sepsis, but usually the single values are more pronounced in HLH than sepsis. H score is another approach to help the diagnosis of secondary HLH. Specific Th1/Th2 cytokine patterns are very helpful tools to differentiate HLH (reactivation of HLH) from sepsis. Moreover, it also has been used successfully to stratify the therapy intensity. The treatment of HLH should consider underlying diseases, triggers and severity. HLH-94 is recommended for patients who need etoposide-based therapy.

CONCLUSIONS

Dramatic progress has been made during the past decades in understanding the pathophysiology of HLH. However, diagnosis and treatment of HLH remain with many dilemmas because of the heterogeneous nature of the disease. Better understanding new gene defects and more effective diagnostic approaches and salvage regimens are goals for the future.

Frequency and spectrum of disease-causing variants in 1892 patients with suspected genetic HLH disorders

This article explores the distribution and mutation spectrum of potential disease-causing genetic variants in hemophagocytic lymphohistiocytosis (HLH)-associated genes observed in a large tertiary clinical referral laboratory. Samples from 1892 patients submitted for HLH genetic analysis were studied between September 2013 and June 2018 using a targeted next-generation sequencing panel approach. Patients ranged in age from 1 day to 78 years. Analysis included 15 genes associated with HLH. A potentially causal genetic finding was observed in 227 (12.0%) samples in this cohort. A total of 197 patients (10.4%) had a definite genetic diagnosis. Patients with pathogenic variants in familial HLH genes tended to be diagnosed significantly younger compared with other genes. Pathogenic or likely pathogenic variants in the PRF1 gene were the most frequent. However, mutations in genes associated with degranulation defects (STXBP2, UNC13D, RAB27A, LYST, and STX11) were more common than previously appreciated and collectively represented >50% of cases. X-linked conditions (XIAP, SH2D1A, and MAGT1) accounted for 17.8% of the 197 cases. Pathogenic variants in the SLC7A7 gene were the least encountered. These results describe the largest cohort of genetic variation associated with suspected HLH in North America. Merely 10.4% of patients were identified with a clearly genetic cause by this diagnostic approach; other possible etiologies of HLH should be investigated. These results suggest that careful thought should be given regarding whether patients have a clinical phenotype most consistent with HLH vs other clinical and disease phenotypes. The gene panel identified known pathogenic and novel variants in 10 HLH-associated genes.

The genetics of macrophage activation syndrome

Macrophage activation syndrome (MAS), or secondary hemophagocytic lymphohistiocytosis (HLH), is a cytokine storm syndrome associated with multi-organ system dysfunction and high mortality rates. Laboratory and clinical features resemble primary HLH, which arises in infancy (1 in 50,000 live births) from homozygous mutations in various genes critical to the perforin-mediated cytolytic pathway employed by NK cells and cytotoxic CD8 T lymphocytes. MAS/secondary HLH is about ten times more common and typically presents beyond infancy extending into adulthood. The genetics of MAS are far less defined than for familial HLH. However, the distinction between familial HLH and MAS/secondary HLH is blurred by the finding of heterozygous perforin-pathway mutations in MAS patients, which may function as hypomorphic or partial dominant-negative alleles and contribute to disease pathogenesis. In addition, mutations in a variety of other pathogenic pathways have been noted in patients with MAS/secondary HLH. Many of these genetically disrupted pathways result in a similar cytokine storm syndrome, and can be broadly categorized as impaired viral control (e.g., SH2P1A), dysregulated inflammasome activity (e.g., NLRC4), other immune defects (e.g., IKBKG), and dysregulated metabolism (e.g., LIPA). Collectively these genetic lesions likely combine with states of chronic inflammation, as seen in various rheumatic diseases (e.g., still disease), with or without identified infections, to result in MAS pathology as explained by the threshold model of disease. This emerging paradigm may ultimately support genetic risk stratification for high-risk chronic and even acute inflammatory disorders. Moving forward, continued whole-exome and -genome sequencing will likely identify novel MAS gene associations, as well as noncoding mutations altering levels of gene expression.

Adult haemophagocytic lymphohistiocytosis: a Review

BACKGROUND

Hemophagocytic lymphohistiocytosis (HLH) is a life-threatening disorder characterized by hyperimmune response. The mortality is high despite progress being made in the diagnosis and treatment of the disease.

AIM

This review aimed to update knowledge on adult HLH pathophysiology, identifiy the numerous causes, and help clinicians make early diagnosis and initiate treatment.

DESIGN AND METHODS

Using Embase, we searched relevant articles published from January 1, 2010 to October 31, 2019, with the MESH term « hemophagocytic lymphohistiocytosis; macrophagic activation syndrome, adult ».

RESULTS

The mean age at presentation is about 50 years, with a male predominance. The most frequent disease associations are haematological diseases, viral or bacterial infections, and autoimmune diseases. The pathophysiologic mechanism is probably the combination of inherited genetic mutations and extrinsic triggers. The mortality rate is 26.5% to 74.8%. H-score is more efficient than HLH-2004 criteria to identify HLH, with diagnostic sensitivity and specificity 90% and 79%, respectively.18F-FDG PET/CT is potentially useful for detecting underlying disease and the extent of secondary HLH. Disease-specific treatment should be given as soon as possible. Treatment with corticosteroids combined or not with etoposide is the mainstay of treatment. Monoclonal antibodies and JAK pathway inhibitors show promise of being effective.

CONCLUSION

In adult HLH, infectious diseases, autoimmune disease and malignancy should be suspected so that disease-specific treatment can be given promptly. Treatment with corticosteroids combined or not with etoposide is the mainstay of treatment, but new therapies show promise of being effective.

X-linked lymphoproliferative syndrome in mainland China: review of clinical, genetic, and immunological characteristic

X-linked lymphoproliferative syndrome (XLP) is a rare primary immunodeficiency disease that can be divided into two types: SAP deficiency (XLP1) and XIAP deficiency (XLP2), caused by mutations in the SH2D1A and XIAP genes, respectively. Few cases of XLP (particularly XIAP deficiency) have been reported in mainland China; hence, little is known about the characteristics of Chinese patients with XLP. We identified 13 and 7 patients with SAP and XIAP deficiency, respectively, in our center. Of our 20 patients, 19/20 (95%) presented with disease symptoms at a very early age: six in infancy and 13 in childhood. One XIAP- and three SAP-deficient patients died, while 3/7(42.9%) and 4/13(30.8%), respectively, developed hemophagocytic lymphohistiocytosis (HLH). Epstein-Barr virus (EBV) infection was significantly more common in SAP-deficient 10/13 (76.9%) than XIAP-deficient 2/7 (28.6%) patients, as was hypogammaglobulinemia (10/13 (76.9%) vs. 1/7 (14.3%)). None of the seven XIAP-deficient patients had colitis or lymphoma. Nine SAP-deficient patients and five XIAP-deficient patients showed markedly deficient SAP and XIAP expression, respectively, in lymphocytes. Significantly reduced levels of switched memory B cells were observed in six SAP-deficient patients with persistent hypogammaglobulinemia. One of 13 (7.7%) SAP-deficient patients and 1 of 7 (12.3%) XIAP-deficient patients have received HSCT treatment and are now alive and well; the other alive patients were waiting for HSCT. We also summarized clinical, genetic, and immunological characteristics of all 55 patients (including our 20 patients) reported in the literature in mainland China today.Conclusion: The overall characteristics of SAP deficiency in mainland China were consistent with those in previous reports, whereas manifestations of XIAP deficiency varied significantly. None of inflammatory bowel disease (IBD) has been reported among XIAP-deficient patients in our center; however, whether Chinese XIAP-deficient patients will develop colitis in the future warrants further investigation. HSCT is the only curative therapy for XLP and this therapy should be urgently considered.What is Known:• SAP and XIAP deficiencies share common clinical feature, HLH, whereas they also have their own specific manifestations.• IBD affects 25-30% of XIAP-deficient patients, which has been reported in other countries especially in European country and Japan.What is New:• This is the largest patient cohort study of XLP in China.• We firstly summarized the clinical features and outcomes of Chinese XIAP-deficient patients and found only 1 in 22 patients developed IBD and diet background may contribute to it; Asian SAP-deficient patients carrying SH2D1A R55X mutation were more prone to HLH.

Recommendations for the management of hemophagocytic lymphohistiocytosis in adults

Hemophagocytic lymphohistiocytosis (HLH) is a severe hyperinflammatory syndrome induced by aberrantly activated macrophages and cytotoxic T cells. The primary (genetic) form, caused by mutations affecting lymphocyte cytotoxicity and immune regulation, is most common in children, whereas the secondary (acquired) form is most frequent in adults. Secondary HLH is commonly triggered by infections or malignancies but may also be induced by autoinflammatory/autoimmune disorders, in which case it is called macrophage activation syndrome (MAS; or MAS-HLH). Most information on the diagnosis and treatment of HLH comes from the pediatric literature. Although helpful in some adult cases, this raises several challenges. For example, the HLH-2004 diagnostic criteria developed for children are commonly applied but are not validated for adults. Another challenge in HLH diagnosis is that patients may present with a phenotype indistinguishable from sepsis or multiple organ dysfunction syndrome. Treatment algorithms targeting hyperinflammation are frequently based on pediatric protocols, such as HLH-94 and HLH-2004, which may result in overtreatment and unnecessary toxicity in adults. Therefore, dose reductions, individualized tailoring of treatment duration, and an age-dependent modified diagnostic approach are to be considered. Here, we present expert opinions derived from an interdisciplinary working group on adult HLH, sponsored by the Histiocyte Society, to facilitate knowledge transfer between physicians caring for pediatric and adult patients with HLH, with the aim to improve the outcome for adult patients affected by HLH.

Treatment of refractory secondary hemophagocytic lymphohistiocytosis with umbilical cord mesenchymal stem cells

Hemophagocytic lymphohistiocytosis (HLH) is an aggressive and life-threatening syndrome of excessive immune activation. Mesenchymal stem cells (MSCs) generate an immunosuppressive microenvironment by secreting cytokines and have been used to treat autoimmune diseases. We report the first case of refractory secondary HLH treated with umbilical cord MSCs. A 52-year-old Chinese female patient with a history of type 2 diabetes was diagnosed with refractory secondary HLH based upon the HLH-2004 protocol and was treated by infusion of third-party umbilical cord MSCs (1.4 × 10⁶ cells/kg of body weight, 70 × 10⁶ cells in total) from the stem cell bank of Hainan Province. Body temperature recovered to normal on the sixth day after infusion with umbilical cord MSCs, and the levels of inflammatory factors macrophage inflammatory protein (MIP)-1α, interleukin (IL)-12p70, stromal cell-derived factor (SDF)-1α, and IL-7 decreased significantly. Blood glucose levels were significantly lower than before treatment, and the amount of insulin needed was significantly reduced. Umbilical cord MSCs can relieve the symptoms of refractory secondary HLH and have a therapeutic effect on insulin resistance in type 2 diabetes mellitus.

Pathogenic Gene Mutations or Variants Identified by Targeted Gene Sequencing in Adults With Hemophagocytic Lymphohistiocytosis

Hemophagocytic lymphohistiocytosis (HLH) can be classified into primary HLH and secondary HLH. Primary HLH usually occurs in infants and children with an underlying genetic defect, and there are also teens and occasional adults with primary HLH. Most cases with secondary HLH are adult patients with secondary triggers including infections, malignancies, and autoimmune diseases. The distinction between primary HLH and secondary HLH seems to be less straightforward, as patients with secondary HLH may also have genetic defects while primary HLH can be triggered by secondary causes. In this study, using amplicon-based targeted gene sequencing (TGS), we sequenced eighteen HLH-related genes in 112 adult HLH cases, which were mostly secondary HLH. Mutations or rare variants were identified in 48 cases (42.9%). All the variants except one were missense variants, and biallelic gene mutations were identified in 3 cases in which only one case harbored homogenous missense mutation. Recurrent variants including UNC13D p.G863D and AP3B1 p.T359A are much more prevalent in our cohort than in normal East Asian population, and in silico analysis predicted pathogenicity of these variants. In conclusion, according to our study, genetic defects may also contribute to the development of adult HLH cases or secondary HLH cases.

Systemic Epstein-Barr Virus-Positive T/NK Lymphoproliferative Diseases With SH2D1A/XIAP Hypomorphic Gene Variants

X-linked lymphoproliferative disease (XLP) is one of the X-linked primary immunodeficiency diseases (PIDs) with defective immune response to Epstein-Barr virus (EBV) infection. Chronic active EBV infection (CAEBV) and EBV-hemophagocytic lymphohistiocytosis (HLH) are recognized as systemic EBV-positive T-cell and natural killer (NK)-cell lymphoproliferative diseases (LPDs) arising from the clonal proliferations of EBV-infected T cells and NK cells. A high incidence of CAEBV in East Asia implies the unknown genetic predisposition. In patients with XLP, EBV-infected cells are generally B cells. No mutation of SH2D1A/XIAP genes has ever been identified in patients with systemic EBV-positive T-cell and NK-cell LPD. We report herewith a male case of NK-cell type CAEBV with SH2D1A hypomorphic mutation (c.7G > T, p.Ala3Ser), two male cases of CAEBV/EBV-HLH with XIAP hypomorphic variant (c.1045_1047delGAG, p.Glu349del), and another female case of CD4⁺CAEBV with the same XIAP variant. The female underwent bone marrow transplantation from an HLA-matched sister with the XIAP variant and obtained a complete donor chimerism and a cure of laryngeal LPD lesion, but then suffered from donor-derived CD4⁺ T cell EBV-LPD. These observations demonstrated that SH2D1A and XIAP genes are critical for the complete regulation of EBV-positive T/NK cell LPD. X-linked lymphoproliferative disease (XLP) is one of the X-linked primary immunodeficiency diseases (PIDs) reported to have a defective immune response to Epstein-Barr virus (EBV) infection. Mutations in SH2D1A and XIAP genes cause XLP. Systemic EBV-positive T-cell and natural killer (NK)-cell lymphoproliferative diseases (LPDs) consist of three major types: EBV-positive hemophagocytic lymphohistiocytosis (HLH), chronic active EBV infection (CAEBV), and EBV-positive T-cell/NK-cell lymphoma. CAEBV is recognized as a poor prognostic disease of EBV-associated T-cell and NK-cell LPD arising from the clonal proliferation of EBV-infected T cells (CD4⁺, CD8⁺, and TCRγδ⁺) and/or NK cells. The majority of cases with CAEBV were reported from East Asia and South America. In Caucasian patients with CAEBV disease, the target of infection is exclusively B cells. These imply a genetic predisposition to EBV-positive T/NK cell LPD according to ethnicity. In reported cases with XLP, EBV-infected cells are B cells. On the other hand, no mutation of SH2D1A/XIAP genes have been determined in patients with T/NK-cell-type (Asian type) CAEBV. We here describe, for the first time, four case series of CAEBV/EBV-HLH patients who carried the hypomorphic variants of XLP-related genes. These cases included a male patient with CAEBV carrying SH2D1A hypomorphic mutation (c.7G > T, p.Ala3Ser) and two male patients with CAEBV/EBV-HLH carrying the XIAP hypomorphic variant (c.1045_1047delGAG, p.Glu349del), along with another female patient with CAEBV carrying the same XIAP variant. The female case underwent bone marrow transplantation from a healthy HLA-matched sister having the same XIAP variant. Although a complete donor chimerism was achieved with the resolution of laryngeal LPD lesions, systemic donor-derived CD4⁺ T-cell EBV-LPD developed during the control phase of intractable graft- vs. -host-disease. These observations demonstrated that SH2D1A and XIAP genes are critical for the complete regulation of systemic EBV-positive T/NK-cell LPD.

A Case of Recurrent Pregnancy-Induced Adult Onset Familial Hemophagocytic Lymphohistiocytosis

Hemophagocytic lymphohistiocytosis (HLH) is a rare and potentially fatal disease primarily of children, characterized by a severe hyperinflammatory state. We describe a case of adult onset familial HLH with a novel exon 19, c.1607G>T (p.Arg536Leu) heterozygous mutation of the UNC13D gene in a 40-year-old woman who developed HLH during her first and second pregnancies, both episodes occurring during the first trimester. Our patient was treated successfully both times with HLH-94 protocol following spontaneous abortions and is currently in the process of getting a bone marrow transplant. We also discuss pregnancy as a potential trigger for late onset familial HLH.