Impaired Control of Epstein-Barr Virus Infection in B-Cell Expansion with NF-κB and T-Cell Anergy Disease

Risk prediction for liver injury in Epstein-Barr virus infection in pediatric respiratory tract infections

BACKGROUND

Epstein-Barr virus (EBV) infection is likely to co-occur in pediatric respiratory tract infections (RTIs). Liver injury is the common complication of EBV infection. The detailed risk factors for liver injury in EBV infection remain elusive. We aimed to investigate the incidence, characteristics and potential risk factors for liver injury in EBV infection for early risk prediction.

METHODS

We retrospectively recruited the pediatric RTIs cases with EBV infection according to a predefined criteria from our hospital between January 2015 and December 2017. We extracted the clinical and laboratory data from the electronical medical records. The impact of age, gender, and various parameters on the liver injury risk was investigated. Univariate logistic regression analysis was performed to analyse the association between clinical/laboratory parameters and liver injury. The related indexes were enrolled in the multivariate logistic regression analysis. Decision curve analysis was used to yield the value of related parameters in predicting liver injury. Receiver operating curve (ROC) analysis was applied to produce the C-index of white blood cell (WBC) count for liver injury. We also tested the non-linear association between WBC count and alanine aminotransferase (ALT).

RESULTS

A total of 216 pediatric RTIs with EBV infection were enrolled. EBV infection is more likely to occur during the winter season. Cytomegalovirus infection was independently associated with liver injury in EBV infection (OR = 6.972, 95% CI = 1.648-29.490, p = 0.008). WBC count was independently associated with liver injury in EBV infection (OR = 1.169, 95% CI = 1.051-1.301, p = 0.004). The P interaction value between WBC count and cytomegalovirus was 0.149. The decision curve analysis showed that WBC count had larger area under curve compared with platelet (PLT) and birthweight (BW). ROC analysis yielded the c-index of WBC count: 0.75 and cut-point of 8.3. The turning point of WBC count in its association with ALT was 16.8. The p value before and after the turning point was < 0.001 and 0.123, respectively.

CONCLUSIONS

Cytomegalovirus co-infection demonstrated 5.972 more times of liver injury risk in EBV infection. WBC count was an independent biomarker for liver injury before the turning point of 16.8 in EBV infection. More attention should be paid to the risk of EBV infection in the winter. Cytomegalovirus infection and WBC count merit attention in the monitoring of possible liver injury in EBV infection among pediatric RTIs.

The Role of NK Cells in EBV Infection and Related Diseases: Current Understanding and Hints for Novel Therapies

The Epstein-Barr virus (EBV) is a ubiquitous herpesvirus most often transmitted during infancy and infecting the vast majority of human beings. Usually, EBV infection is nearly asymptomatic and results in life-long persistency of the virus in a latent state under the control of the host immune system. Yet EBV can cause an acute infectious mononucleosis (IM), particularly in adolescents, and is associated with several malignancies and severe diseases that pose a serious threat to individuals with specific inborn error of immunity (IEI). While there is a general consensus on the requirement for functional CD8 T cells to control EBV infection, the role of the natural killer (NK) cells of the innate arm of immunity is more enigmatic. Here we provide an overview of the interaction between EBV and NK cells in the immunocompetent host as well as in the context of primary and secondary immunodeficiencies. Moreover, we report in vitro data on the mechanisms that regulate the capacity of NK cells to recognize and kill EBV-infected cell targets and discuss the potential of recently optimized NK cell-based immunotherapies for the treatment of EBV-associated diseases.

Expanding spectrum, intrafamilial diversity, and therapeutic challenges from 15 patients with heterozygous CARD11-associated diseases: A single center experience

CARD11-associated diseases are monogenic inborn errors of immunity involving immunodeficiency, predisposition to malignancy and immune dysregulation such as lymphoproliferation, inflammation, atopic and autoimmune manifestations. Defects in CARD11 can present as mutations that confer a complete or a partial loss of function (LOF) or contrarily, a gain of function (GOF) of the affected gene product. We report clinical characteristics, immunophenotypes and genotypes of 15 patients from our center presenting with CARD11-associated diseases. Index cases are pediatric patients followed in our immunology division who had access to next generation sequencing studies. Variant significance was defined by functional analysis in cultured cells transfected with a wild type and/or with mutated hCARD11 constructs. Cytoplasmic aggregation of CARD11 products was evaluated by immunofluorescence. Nine index patients with 9 unique heterozygous CARD11 variants were identified. At the time of the identification, 7 variants previously unreported required functional validation. Altogether, four variants showed a GOF effect as well a spontaneous aggregation in the cytoplasm, leading to B cell expansion with NF-κB and T cell anergy (BENTA) diagnosis. Additional four variants showing a LOF activity were considered as causative of CARD11-associated atopy with dominant interference of NF-kB signaling (CADINS). The remaining variant exhibited a neutral functional assay excluding its carrier from further analysis. Family segregation studies expanded to 15 individuals the number of patients presenting CARD11-associated disease. A thorough clinical, immunophenotypical, and therapeutic management evaluation was performed on these patients (5 BENTA and 10 CADINS). A remarkable variability of disease expression was clearly noted among BENTA as well as in CADINS patients, even within multiplex families. Identification of novel CARD11 variants required functional studies to validate their pathogenic activity. In our cohort BENTA phenotype exhibited a more severe and expanded clinical spectrum than previously reported, e.g., severe hematological and extra hematological autoimmunity and 3 fatal outcomes. The growing number of patients with dysmorphic facial features strengthen the inclusion of extra-immune characteristics as part of the CADINS spectrum. CARD11-associated diseases represent a challenging group of disorders from the diagnostic and therapeutic standpoint, especially BENTA cases that can undergo a more severe progression than previously described.

A novel CARD11 germline mutation in a Chinese patient of B cell expansion with NF-κB and T cell anergy (BENTA) and literature review

Germline gain-of-function (GOF) mutations in the CARD11 gene lead to a rare primary immunodeficiency disease known as B cell expansion with NF-κB and T cell anergy (BENTA). Affected patients present with a polyclonal expansion of B cells, lymphadenopathy, and splenomegaly. Herein, we report a novel germline in-frame three base-pair deletion (c.1030_1032del, p.K344del) in the CARD11 gene in a patient with atypical BENTA, presenting with a recurrent fever and B cell lymphocytosis. This mutation was inherited from his mother, who is clinically asymptomatic and had a recurrent respiratory tract infection in her childhood. In vitro functional analysis demonstrated that this variant decreased the expression level of the CARD11 protein and activated the NF-κB signal pathway, leading to a higher expression of several NF-κB target gene transcripts in HCT116 cells transfected with mutant CARD11 (K344del-CARD11) as revealed by RNA sequencing analysis. To our knowledge, only 23 BENTA patients have been identified and carried seven distinct GOF mutations in CARD11. The clinical manifestations of patients are highly heterogeneous and there was no significant correlation between genotype and phenotype. In summary, we identified a novel in-frame three base-pair deletion that may be responsible for the pathogenesis of atypical BENTA in a Chinese family. Our study expands the mutational spectrum of the CARD11 gene and may be helpful in the understanding of diseases caused by CARD11 mutations and the clinical management of BENTA.

Lymphoproliferation in Inborn Errors of Immunity: The Eye Does Not See What the Mind Does Not Know

Inborn errors of immunity (IEIs) are a group of heterogeneous disorders characterized by a broad clinical spectrum of recurrent infections and immune dysregulation including autoimmunity and lymphoproliferation (LP). LP in the context of IEI may be the presenting feature of underlying immune disorder or may develop during the disease course. However, the correct diagnosis of LP in IEI as benign or malignant often poses a diagnostic dilemma due to the non-specific clinical features and overlapping morphological and immunophenotypic features which make it difficult to treat. There are morphological clues to LP associated with certain IEIs. A combination of ancillary techniques including EBV-associated markers, flow cytometry, and molecular assays may prove useful in establishing a correct diagnosis in an appropriate clinical setting. The present review attempts to provide comprehensive insight into benign and malignant LP, especially the pathogenesis, histological clues, diagnostic strategies, and treatment options in patients with IEIs.

Mechanistic impact of oligomer poisoning by dominant-negative CARD11 variants

The CARD11 scaffold controls antigen receptor signaling to NF-κB, JNK, and mTOR. Three classes of germline mutations in CARD11 cause Primary Immunodeficiency, including homozygous loss-of-function (LOF) mutations in CARD11 deficiency, heterozygous gain-of-function (GOF) mutations in BENTA disease, and heterozygous dominant-negative LOF mutations in CADINS. Here, we characterize LOF CARD11 mutants with a range of dominant-negative activities to identify the mechanistic properties that cause these variants to exert dominant effects when heterozygous. We find that strong dominant negatives can poison signaling from mixed wild-type:mutant oligomers at two steps in the CARD11 signaling cycle, at the Opening Step and at the Cofactor Association Step. Our findings provide evidence that CARD11 oligomer subunits cooperate in at least two steps during antigen receptor signaling and reveal how different LOF mutations in the same oligomeric signaling hub may cause disease with different inheritance patterns.

Germline CBM-opathies: From immunodeficiency to atopy

Caspase recruitment domain (CARD) protein-B cell CLL/lymphoma 10 (BCL10)-MALT1 paracaspase (MALT1) [CBM] complexes are critical signaling adaptors that facilitate immune and inflammatory responses downstream of both cell surface and intracellular receptors. Germline mutations that alter the function of members of this complex (termed CBM-opathies) cause a broad array of clinical phenotypes, ranging from profound combined immunodeficiency to B-cell lymphocytosis. With an increasing number of patients being described in recent years, the clinical spectrum of diseases associated with CBM-opathies is rapidly expanding and becoming unexpectedly heterogeneous. Here we review major discoveries that have shaped our understanding of CBM complex biology, and we provide an overview of the clinical presentation, diagnostic approach, and treatment options for those carrying germline mutations affecting CARD9, CARD11, CARD14, BCL10, and MALT1.

A Novel, Heterozygous Three Base-Pair Deletion in CARD11 Results in B Cell Expansion with NF-κB and T Cell Anergy Disease

Germline gain-of-function mutations in CARD11 lead to the primary immunodeficiency, B cell expansion with NF-κB, and T cell anergy (BENTA). Herein, we report the case of a girl, presenting at 2 years of age with lymphocytosis and splenomegaly in whom a novel, in-frame, three base pair deletion in CARD11 was identified resulting in the deletion of a single lysine residue (K215del) from the coiled-coil domain. In vitro functional assays demonstrated that this variant leads to a subtle increase in baseline NF-κB signaling and impaired proliferative responses following T cell receptor and mitogenic stimulation. Previously reported immunological defects associated with BENTA appear mild in our patient who is now 6 years of age; a B cell lymphocytosis and susceptibility to upper respiratory tract infections persist; however, she has broad, sustained responses to protein-polysaccharide conjugate vaccines and displays normal proliferative responses to ex vivo T cell stimulation.

Human inborn errors of immunity to herpes viruses

Infections with any of the nine human herpes viruses (HHV) can be asymptomatic or life-threatening. The study of patients with severe diseases caused by HHVs, in the absence of overt acquired immunodeficiency, has led to the discovery or diagnosis of various inborn errors of immunity. The related inborn errors of adaptive immunity disrupt α/β T-cell rather than B-cell immunity. Affected patients typically develop HHV infections in the context of other infectious diseases. However, this is not always the case, as illustrated by inborn errors of SAP-dependent T-cell immunity to EBV-infected B cells. The related inborn errors of innate immunity disrupt leukocytes other than T and B cells, non-hematopoietic cells, or both. Patients typically develop only a single type of infection due to HHV, although, again, this is not always the case, as illustrated by inborn errors of TLR3 immunity resulting in HSV1 encephalitis in some patients and influenza pneumonitis in others. Most severe HHV infections in otherwise healthy patients remains unexplained. The forward human genetic dissection of isolated and syndromic HHV-driven illnesses will establish the molecular and cellular basis of protective immunity to HHVs, paving the way for novel diagnosis and management strategies.

Coordinated regulation of scaffold opening and enzymatic activity during CARD11 signaling

The activation of key signaling pathways downstream of antigen receptor engagement is critically required for normal lymphocyte activation during the adaptive immune response. CARD11 is a multidomain signaling scaffold protein required for antigen receptor signaling to NF-κB, c-Jun N-terminal kinase, and mTOR. Germline mutations in the CARD11 gene result in at least four types of primary immunodeficiency, and somatic CARD11 gain-of-function mutations drive constitutive NF-κB activity in diffuse large B cell lymphoma and other lymphoid cancers. In response to antigen receptor triggering, CARD11 transitions from a closed, inactive state to an open, active scaffold that recruits multiple signaling partners into a complex to relay downstream signaling. However, how this signal-induced CARD11 conversion occurs remains poorly understood. Here we investigate the role of Inducible Element 1 (IE1), a short regulatory element in the CARD11 Inhibitory Domain, in the CARD11 signaling cycle. We find that IE1 controls the signal-dependent Opening Step that makes CARD11 accessible to the binding of cofactors, including Bcl10, MALT1, and the HOIP catalytic subunit of the linear ubiquitin chain assembly complex. Surprisingly, we find that IE1 is also required at an independent step for the maximal activation of HOIP and MALT1 enzymatic activity after cofactor recruitment to CARD11. This role of IE1 reveals that there is an Enzymatic Activation Step in the CARD11 signaling cycle that is distinct from the Cofactor Association Step. Our results indicate that CARD11 has evolved to actively coordinate scaffold opening and the induction of enzymatic activity among recruited cofactors during antigen receptor signaling.

Hypomorphic caspase activation and recruitment domain 11 (CARD11) mutations associated with diverse immunologic phenotypes with or without atopic disease

BACKGROUND

Caspase activation and recruitment domain 11 (CARD11) encodes a scaffold protein in lymphocytes that links antigen receptor engagement with downstream signaling to nuclear factor κB, c-Jun N-terminal kinase, and mechanistic target of rapamycin complex 1. Germline CARD11 mutations cause several distinct primary immune disorders in human subjects, including severe combined immune deficiency (biallelic null mutations), B-cell expansion with nuclear factor κB and T-cell anergy (heterozygous, gain-of-function mutations), and severe atopic disease (loss-of-function, heterozygous, dominant interfering mutations), which has focused attention on CARD11 mutations discovered by using whole-exome sequencing.

OBJECTIVES

We sought to determine the molecular actions of an extended allelic series of CARD11 and to characterize the expanding range of clinical phenotypes associated with heterozygous CARD11 loss-of-function alleles.

METHODS

Cell transfections and primary T-cell assays were used to evaluate signaling and function of CARD11 variants.

RESULTS

Here we report on an expanded cohort of patients harboring novel heterozygous CARD11 mutations that extend beyond atopy to include other immunologic phenotypes not previously associated with CARD11 mutations. In addition to (and sometimes excluding) severe atopy, heterozygous missense and indel mutations in CARD11 presented with immunologic phenotypes similar to those observed in signal transducer and activator of transcription 3 loss of function, dedicator of cytokinesis 8 deficiency, common variable immunodeficiency, neutropenia, and immune dysregulation, polyendocrinopathy, enteropathy, X-linked-like syndrome. Pathogenic variants exhibited dominant negative activity and were largely confined to the CARD or coiled-coil domains of the CARD11 protein.

CONCLUSION

These results illuminate a broader phenotypic spectrum associated with CARD11 mutations in human subjects and underscore the need for functional studies to demonstrate that rare gene variants encountered in expected and unexpected phenotypes must nonetheless be validated for pathogenic activity.

A Unique Heterozygous CARD11 Mutation Combines Pathogenic Features of Both Gain- and Loss-of-Function Patients in a Four-Generation Family

CARD11 is a lymphocyte-specific scaffold molecule required for proper activation of B- and T-cells in response to antigen. Germline gain-of-function (GOF) mutations in the CARD11 gene cause a unique B cell lymphoproliferative disorder known as B cell Expansion with NF-κB and T cell Anergy (BENTA). In contrast, patients carrying loss-of-function (LOF), dominant negative (DN) CARD11 mutations present with severe atopic disease. Interestingly, both GOF and DN CARD11 variants cause primary immunodeficiency, with recurrent bacterial and viral infections, likely resulting from impaired adaptive immune responses. This report describes a unique four-generation family harboring a novel heterozygous germline indel mutation in CARD11 (c.701-713delinsT), leading to one altered amino acid and a deletion of 4 others (p.His234_Lys238delinsLeu). Strikingly, affected members exhibit both moderate B cell lymphocytosis and atopic dermatitis/allergies. Ectopic expression of this CARD11 variant stimulated constitutive NF-κB activity in T cell lines, similar to other BENTA patient mutations. However, unlike other GOF mutants, this variant significantly impeded the ability of wild-type CARD11 to induce NF-κB activation following antigen receptor ligation. Patient lymphocytes display marked intrinsic defects in B cell differentiation and reduced T cell responsiveness in vitro. Collectively, these data imply that a single heterozygous CARD11 mutation can convey both GOF and DN signaling effects, manifesting in a blended BENTA phenotype with atopic features. Our findings further emphasize the importance of balanced CARD11 signaling for normal immune responses.

Mechanisms of Regulated and Dysregulated CARD11 Signaling in Adaptive Immunity and Disease

CARD11 functions as a key signaling scaffold that controls antigen-induced lymphocyte activation during the adaptive immune response. Somatic mutations in CARD11 are frequently found in Non-Hodgkin lymphoma, and at least three classes of germline CARD11 mutations have been described as the basis for primary immunodeficiency. In this review, we summarize our current understanding of how CARD11 signals, how its activity is regulated, and how mutations bypass normal regulation to cause disease.

The CBM-opathies-A Rapidly Expanding Spectrum of Human Inborn Errors of Immunity Caused by Mutations in the CARD11-BCL10-MALT1 Complex

The caspase recruitment domain family member 11 (CARD11 or CARMA1)-B cell CLL/lymphoma 10 (BCL10)-MALT1 paracaspase (MALT1) [CBM] signalosome complex serves as a molecular bridge between cell surface antigen receptor signaling and the activation of the NF-κB, JNK, and mTORC1 signaling axes. This positions the CBM complex as a critical regulator of lymphocyte activation, proliferation, survival, and metabolism. Inborn errors in each of the CBM components have now been linked to a diverse group of human primary immunodeficiency diseases termed "CBM-opathies." Clinical manifestations range from severe combined immunodeficiency to selective B cell lymphocytosis, atopic disease, and specific humoral defects. This surprisingly broad spectrum of phenotypes underscores the importance of "tuning" CBM signaling to preserve immune homeostasis. Here, we review the distinct clinical and immunological phenotypes associated with human CBM complex mutations and introduce new avenues for targeted therapeutic intervention.

Clinical, Immunological, and Molecular Findings in Four Cases of B Cell Expansion With NF-κB and T Cell Anergy Disease for the First Time From India

B cell expansion with NF-κB and T cell anergy (BENTA) is a rare primary immunodeficiency disorder caused by mutations in the CARD11 gene and results in constitutive NF-κB activation in B and T cells. Affected patients present with polyclonal expansion of B cells at an early age with splenomegaly, lymphadenopathy, and mild autoimmunity. Here, we discuss four BENTA cases with unusual clinical manifestations not previously reported. All patients showed previously reported gain-of-function mutations (G123S, G123D, and C49Y) in the CARD11 gene. Severe autoimmune manifestations were noted for the first time in all our patients.