EBV susceptibility

EBV susceptibility
Pornsiri Sae-lim , MD
Pediatric Allergy and Immunology Department
King Chulalongkorn Memorial Hospital

Outline
• Introduction
• X-linked lymphoproliferative disease (XLP) type 1
• X-linked lymphoproliferative disease (XLP) type 2/XIAP deficiency
• Other diseases with susceptibility to EBV
• X-linked immunodeficiency with magnesium defect, EBV infection, and
neoplasia (XMEN) due to mutations in MAGT1
• ITK deficiency
• Mutations in CTPS1
• Mutations in RASGRP1
• CD27 deficiency
• CD70 deficiency

Epstein–Barr virus (EBV)
• Human herpesvirus 4
• Spread via saliva and primarily infects the oropharyngeal epithelium and
B cells
• Approximately 90% of adults. After infection, EBV remains latent in B cells
for the remainder of the life of the host, and although most people remain
asymptomatic
• clinical consequences:
• Children : mostly asymptomatic
• teenager and adult : 10% >> develop infectious mononucleosis (IM)
• Oncogenic virus : B, T, and NK cell lymphoma, Hodgkin lymphoma, smooth
muscle tumors, nasopharyngeal and gastric carcinomas
Tangye, Stuart G., Blood, The Journal of the American Society of Hematology 135.9 (2020): 644-655
Panchal, Neelam, et al. Frontiers in immunology 9 (2018): 666..

• Inborn errors of immunity : extreme susceptibility to EBV-induced
disease
• severe & fatal infectious mononucleosis
• hemophagocytic lymphohistiocytosis
• lymphoproliferative disease
• and/or EBV1 B-cell lymphoma
• Acquired or genetic disruptions to host defense that tip the balance in
favor of EBV can have catastrophic effects
Tangye, Stuart G., Blood, The Journal of the American Society of Hematology 135.9 (2020): 644-655.

Regulation of EBV infection by innate and
adaptive immunity
• innate immunity : NK and NKT cells restrain EBV mediated B-cell
transformation
• Adaptive immunity: peripheral blood T cell numbers increase
dramatically

Model of Epstein–Barr Virus (EBV) Infection in Humans
Cohen, Jeffrey I. "Epstein–Barr virus infection." New England Journal of Medicine 343.7 (2000): 481-492.

Molecular and biochemical requirements
for inducing CD81 T cell-mediated EBV-specific immunity

X-linked lymphoproliferative disease (XLP)
type 1
• First report 1975
• known as Purtilo syndrome
• X-linked disorder characterized by EBV-associated HLH, lymphoma
and humoral immune defects
• mutations in SH2D1A, which resides at the Xq25 chromosomal locus
• SH2D1A encodes the SLAM-Associated Protein (SAP)

SAP
• 128 amino acid SH2 domain containing signaling protein that is
expressed abundantly in all T, natural killer, and invariant natural
killer (iNKT) cells
• The SH2 domain of SAP mediates its interaction with members of the
SLAM family of receptors
• SLAM-family receptors : on hematopoietic cells with downstream
intracellular signaling pathways to regulate effector functions of T and
NK cells and NKT cell development

Genetics and pathophysiology
• SH2D1A
• comprised of 4 exons
• Mutation :
• lead to reduced levels or absence of SAP protein
• Exon 2 generally being the most common
• 50% of patients: single nucleotide changes leading to missense or
nonsense mutations
• 25% - 50% of patients: gross deletions involving one or more exons
• Small insertions, deletions, and splice site mutations have less commonly
been identified

Putative mechanism of SAP signaling
Panchal, Neelam, et al. Frontiers in immunology 9 (2018): 666

Cellular defects in SAP deficiency and their
potential contribution to the phenotypes of XLP1
Panchal, Neelam, et al. Frontiers in immunology 9 (2018): 666

Clinical manifestations
• Most commonly presents with one or more of the classic triad of
manifestations
• EBV-associated HLH
• Lymphoma
• progressive hypo- or dysgammaglobulinemia
• Manifestations may arise concurrently, or can develop sequentially
• EBV-HLH occurring in 50% of patients, hypogammaglobulinemia in 30% -
70%, and lymphoma in 20% - 30%
• Less common manifestation :
• AA , vasculitis, lymphomatoid granulomatosis, encephalitis, gastritis,
colitis, and interstitial pneumonitis, approximately 3% - 6%

Diagnostics
• SAP deficiency should be suspected
• Male patient presents with
• EBV-induced HLH
• Hypogammaglobulinemia
• Primary or recurrent Burkitts-type lymphomas
• Aplastic anemia (particularly when it occurs in the setting of a prior EBV
infection)
• Vasculitis
• Atypical herpes group virus-associated lymphoproliferative processes
• Asymptomatic patients with a confirmed or suspected family history of the
disorder
• Rapid flow cytometric screening >> to evaluate for T cell and NK cell expression of
SAP

• Confirmatory sequencing of the SH2D1A gene should be performed
• Patients with reduced or absent SAP expression.
• High clinical suspicion despite normal flow cytometric ( pathologic missense
mutations occasionally result in normal levels of SAP protein )
• Additional laboratory studies
• measurement of the percentage of peripheral blood
• invariant natural killer T cells (iNKTs) :reduction or absence of iNKT cells (
supportive of an XLP1 diagnosis)
• Reduced peripheral blood CD27 memory B cell populations can also be
observed
• Analysis of TCR restimulation-induced cell death (RICD) often reveals impaired
apoptosis of CD4+ and CD8+ T cells

Management
• Curative treatment with allogeneic HSCT should be consider
• HLH :
• chemo-immunotherapeutic regimens consisting of dexamethasone and
etoposide, or alternatively anti-thymocyte globulin (ATG)
• Rituximab : strongly considered as a component of treatment >> rapidly
reduces EBV load and serum ferritin levels
• Refractory HLH : alemtuzumab, anakinra, infliximab can be considered
• Prophylaxis against opportunistic : Pneumocystis jirovecii, fungal and viral
infections

• Hypogammaglobulinemia :
• Immunoglobulin replacement
• closely monitored and aggressively treated for infections
• analogous to patients with other forms of hypogammaglobulinemia
• Lymphoma: protocols based on histology and staging
• Aplastic anemia : transfusions and consideration for allogeneic HSCT
• Vasculitis :
• notoriously difficult to treat
• Immunosuppressive therapy & steroids >> efforts made to treat any
underlying infectious triggers such as EBV

• Allogeneic hematopoietic stem cell transplantation (HSCT)
• Based on factors such as patient age, previous and current complications,
current organ function, status of HLH, availability of a suitably matched donor
• The largest series describing outcomes of transplanted versus non-
transplanted patients
• Survival at the time of publication was 81.4% (n = 43) for transplanted
patients, versus 62.5% (n = 48) for non-transplanted patients
• deaths following transplant were related to sepsis, HLH progression, or presence of
veno-occlusive disease, multi-organ failure, or renal toxicity
• Allogeneic HSCT ( reduced-intensity or with myeloablative conditioning
regimens ) appears to be on the order of 70%- 92%
• Allogeneic HSCT should ideally be performed in patients prior to the
development of HLH, or after remission

Survival
• in 1995, the majority of patients had died before the age of 10 years
• Mortality was highest for HLH (96%), followed by lymphoma (65%)
• Recent reports (2011,2012)
• Mortality rate 29% - 66%.
• Mortality rates range between
• 61% - 89% for HLH
• 9% - 43% for LPD/lymphoma
• 0% - 36% for hypogammaglobulienemia
• Almost 1/3 of EBV-negative untransplanted patients develop fatal complications
• Milder phenotype at the time of diagnosis does not necessarily portend a better
outcome
• Poor overall prognosis >> allogeneic HSCT be strongly considered for SAP
deficient patients ( tolerate the procedure and a suitable donor is available)

X-linked lymphoproliferative disease (XLP)
type 2/XIAP deficiency
• mutations in X-linked Inhibitor of Apoptosis
• Localization to the X chromosome
• Frameshift and nonsense mutations, as well as large deletions
encompassing a single or multiple exons are common abnormalities
• Most female carriers are healthy:
• female patients have been reported to develop inflammatory bowel disease
Kim E, Chapter 25 EBV susceptibility, Stiehm’s Immune Deficiencies 2020

XIAP
• 497-amino acid protein
• Functions :
• regulation of apoptosis
• promotion of intracellular signaling during innate immunity
• regulation of TNF receptor signaling and ultimately NLRP3 inflammasome
activity
• contains 3 BIR domains, a UBA, E3 ubiquitin ligase

Role of XIAP
• Regulator of apoptosis
• Regulation of innate immunity
• TNF receptor signaling and NLRP3 inflammasome activity

Regulator of apoptosis
• Via the BIR2 and BIR3 domains, XIAP binds to and inhibits caspases 3,
7, and 9 >> promotes cell survival
• Absence of XIAP : infected cells might die more easily and promote
systemic dissemination of pathogen
• Lower numbers of peripheral blood mucosal associated invariant T
(MAIT) cells, an innate type of T cell similar to iNKTs
• reduction in MAIT cells in the intestine might play a role in the
pathogenesis of colitis in XIAP deficient patients

Regulation of innate immunity
• Regulate intracellular signaling pathways leading to activation of NFkB
• Activation of NFkB : paramount for the proper function of pattern recognition
receptors (PRRs)
• required for proper function of the PRRs known as NOD-like receptors
(NOD1 and NOD2)
• Defects in NOD2 are also linked to Crohn’s disease
• speculated that defective clearance of intestinal bacteria might lead to
exaggerated inflammation via other PRRs, such as the Toll-like receptors

XIAP and the other IAP family proteins
participate in NOD receptor signaling.

TNF receptor signaling & NLRP3 inflammasome activity
• IAP family proteins serve to negatively regulate signaling mediated by
TNF receptors and NLRP3 activation
• NLRP3 inflammasome >> activates caspase 1>> cleaves and activates
the pro-inflammatory cytokines IL-1b and IL-18
• Genetic deletion of XIAP : overactive inflammasome activity
• explain many of the inflammatory complications, HLH and
inflammatory bowel disease
• emerging NLRP3 inhibitors, may have particular relevance in the
treatment of patients with XIAP deficiency

XIAP regulates NLRP3 inflammasome activity

Clinical manifestations
• 3 manifestations : HLH, hypo or dysgammaglobulinemia, and colitis
• Do not develop lymphoma

HLH:
Approximately 40% - 90% of patients with XIAP deficiency
• Trigger : EBV, CMV, HSV-1 and HHV-6 (without any trigger identify)
• Splenomegaly & Cytopenia : following MMR vaccine, norovirus
infection
• Unlike SAP deficiency: often recurrent HLH or symptoms of recurrent
fevers and/or cytopenias
Suspected XIAP deficiency : male patients of any age who present with HLH or
an HLH-like disease, regardless of the trigger

Humoral immune defects
• Approximately 20% - 25% of patients with XIAP deficiency
• Hypo or dysgammaglobulinemia
• May develop prior to or without HLH manifestations , may be
transient

Enterocolitis
• Approximately 20% - 30% of of patients with XIAP deficiency
• present concurrently or following other phenotypes of XLP2, or as an
initial manifestation
• Symptoms : abdominal pain, diarrhea, or rectal bleeding
• Reported who presented with poor weight gain, peri-rectal abscess and
perineal fistulae
• Lead to life-threatening bleeding
• Pathologic examination of the colon often shows :
• mononuclear inflammatory infiltration of the lamina propria with ulceration,
• apoptotic crypt cells, and rare crypt abscesses

Other manifestations
• Kawasaki syndrome
• Recurrent fevers, uveitis, and fistulating skin abscesses
• Granulomatous hepatitis
• Granulomatous lymphocytic interstitial lung disease
• Isolated splenomegaly

Diagnostics : definitive genetic diagnosis
Considered in male patients who present with
(1) an initial episode of HLH
(2) recurrent HLH
(3) recurrent episodes of fever, cytopenia and splenomegaly
(4) hypogammaglobulinemia
(5) recurrent infections
(6) enterocolitis or Crohn’s disease, especially if associated with
recurrent infections, HLH or hypogammaglobulinemia
(7) any symptom of dysregulated inflammation including
rare complications like uveitis

• Rapid flow cytometric screening for XIAP deficiency is available, has greater than 80%e90% sensitivity
• Confirmatory sequencing of the XIAP gene : absent or low expression of XIAP , high clinical suspicion
despite normal flow cytometric results
Shaded histograms represent isotype staining, and unshaded black histograms represent XIAP

Additional laboratory studies
• iNKT cell numbers are typically low, also be normal, especially in EBV
naïve individuals
• Other innate T cell populations : MAIT cells can also be considered as
these cells may be reduced in XIAP deficiency
• T cell RICD may be increased (not decreased as is the case with XLP1)
• IL-18 levels are notably high
• Flow cytometric interrogation of NOD2 signaling

Management
• Focus on the presenting manifestation
• Definitive treatment : allogeneic HSCT (made on a case-by-case basis)
• HLH :
• standard treatment schemas consisting of dexamethasone, etoposide and/ or
anti-thymocyte globulin
• aggressively search for infectious triggers
• appropriate antibiotics or anti-viral therapies: EBV- rituximab
• Inflammasomopathy : anti-IL-1b
• a recombinant human IL-18 binding protein

Management
• Hypogammaglobulinemia: a should receive IgG replacement.
Aggressive screening and treatment of infection
• Enterocolitis:
• Immunosuppressive agents such as 5-amino salicylic acid, azathioprine,
steroids, cyclosporine, and anti-TNF therapies including adalimumab or
infliximab
• Surgical interventions have been made in refractory cases but poor wound
healing
• Allogeneic HSCT is curative for IBD associated with XIAP deficiency

Management
• Allogeneic HSCT : choice of conditioning regimen
• high incidence of toxicities associated with traditional myeloablative
conditioning regimens
• 1 year probability of survival was only 14%
• XIAP deficiency may increase susceptibility to damage induced by chemotherapeutic
agents,
• Survival was 57% for patients receiving reduced intensity conditioning
regimens
• considered for younger XIAP deficient patients who have displayed severe or
recalcitrant phenotypes, who have matched sibling or well-matched
unrelated donors.
• Only reduced-intensity conditioning approaches should be considered.

Survival
• overall mortality among patients with XIAP deficiency ranges from
22% to 43%
• Enterocolitis seems to have a high risk of mortality
• not clear whether hypogammaglobulinemia contributes a significant
risk
• Mortality following HLH appears to be lower than for patients with
SAP deficiency

Other diseases with susceptibility to EBV
• Genetic lesions in regulators of TCR signaling predispose to EBV-
induced disease
• mutations in MAGT1
• ITK deficiency
• Mutations in CTPS1
• Mutations in RASGRP1
• TNF receptor (TNFR)/TNF superfamily members have critical roles in
initiating EBV-specific CD81 T cell responses
• CD27 deficiency
• CD70 deficiency

Mutations in MAGT1
• XMEN disease (X-linked immunodeficiency with magnesium defect, EBV
infection, neoplasia)
• Mutations in MAGT1 : encodes a magnesium transporter protein
• MAGT1 deficiency :
• Disrupts normal regulation of intracellular Mg flux
• Impaired NKG2D mediated killing contributes to disease pathogenesis
• Impairs T cell PLC-g1 activation and Ca influx following TCR stimulation
• Decreased expression of NKG2D
NKG2D is an important activating receptor on CD8 T cell and NK cells

Mutations in MAGT1
• Management :
• related to EBV complication
• EBV viremia, CAEBV, and LPD which should include consideration for
rituximab
• immune suppression for associated hyperinflammatory manifestation
• immunologic testing should be done to gauge the severity of cellular and
humoral abnormalities
• routine monitoring for complications such as cytopenia and hepatitis should
be performed
• immunoglobulin replacement

• Mg supplementation : Unique potential therapeutic option
• increase surface expression of NKG2D
• clinical trial is ongoing
• Allogeneic HSCT can be considered
Mutations in MAGT1

ITK deficiency
• Biallelic mutations in ITK
• Deficiency of IL-2-inducible tyrosine kinase
• Defective cytotoxic T cell expansion and cytolytic capacity
• Essentially , EBV-associated lymphoproliferative disease including
predominantly Hodgkin lymphoma, but also DLBCL and Burkitt
lymphoma
• Lung involvement seems particularly common
• HLH-spectrum disease has occurred
• Hypogammaglobulinemia is also common
ITK is expressed in T cells and NK cells. It is known to be involved in TCR and CXCR4 signaling

• Monitoring and treatment of EBV and complications as for MAGT1
deficiency
• Routine immunologic investigations to interrogate cellular and
humoral immunity
• Consideration of appropriate anti-microbial prophylaxis and immunoglobulin
replacement
• Allogeneic HSCT can be considered.
ITK deficiency

Mutations in CTPS1
• Homozygous mutations in CTPS1
• Encodes CTP Synthase 1 (CTPS1 or Cytidine 5-prime Triphosphate
Synthetase 1)
• CTP is a critical precursor in nucleic acid metabolism
• Lack of adequate CTP can limit DNA synthesis
• CTP Synthase 1 is strongly upregulated in T cells following TCR
activation, and is required for normal proliferative responses
• impaired proliferative capacity of T cells leads to inadequate T cell
expansion and control of EBV infection

• Present : EBV viremia, severe infectious mononucleosis, and
lymphoma
• Invasive encapsulated bacterial infections are especially troublesome
(including meningitis
• poor pneumococcal antibody responses have been documented in
some patients
• Eczema was reported
Mutations in CTPS1

• immunologic testing : cellular and humoral abnormalities
• appropriate anti-microbial prophylaxis and IVIG replacement
• majority of patients reported to date have been treated with
allogeneic HSCT
• In a series of 11 patients transplanted at a single center, survival was 72%
Mutations in CTPS1

Mutations in RASGRP1
• First report 2016
• RASGRP1 encodes RASGRP1, a diacylglycerol-regulated guanidine
exchange factor that is involved in the activation of RAS
• RASGRP1-deficient T cells
• reduced ERK1/2 phosphorylation and impaired MAP-kinase pathway signaling
• associated with a variety of defects in T cell activation, proliferation, migration, and
function
• also fail to normally upregulate CTPS1

• Normal, increased, and low levels of immunoglobulins
• responses to vaccines were reported to be abnormal
• Abnormal NK cell cytotoxicity was reported
• EBV-associated lymphomas appear common. EBV smooth muscle
tumors and adrenal leiomyomas have also occurred
• A variety of infections
• bacteria such as Moraxella Catarrhalis, Hemophilus Influenza, and
Staphylococcus
• Fungal infections with aspergillus and P. jirovecii have been reported.

• little experience with the management of patients with RASGRP1
deficiency
• appropriate anti-microbial prophylaxis with or without IVIG
replacement
• monitored for the development of complications such as
autoimmune cytopenias, and any clinical indication of infection or
malignancy

CD27 deficiency
• Biallelic mutations in CD27
• encodes the CD27 cell surface protein (a member of the TNF superfamily of
receptors)
• CD27 on T cells interacts with CD70 which is upregulated on activated B
cells (EBV-infected B cells)
• Co stimulatory signaling through CD27 >> normal T cell proliferation and
triggering of cytotoxicity against EBV infected B cells
• Variety of EBV-associated B cell lymphoproliferative disorders : Hodgkin
Lymphoma and DLBCL
• Other common manifestation : severe EBV infection, HLH, hypo/dys-
gammaglobulinemia and recurrent respiratory tract and other infections
• prone to development of oral and other ulcers, and uveitis

• investigation of cellular and humoral immunity, routine screening for
cytopenias and other complications
• treatment of malignancies, treatment of EBV, treatment of other
infections and complications,
• immunoglobulin replacement when needed,
• consideration of allogeneic HSCT.
• Ophthalmologic examination should be performed for any eye
symptoms suggestive of uveitis
CD27 deficiency

CD70 deficiency
• biallelic mutations in CD70
• like CD27, belongs to the TNF super family of receptors
• CD70 expression is upregulated on activated B cells >> CD70 interacts
with CD27 on T cells and serves as a co-stimulatory signal
• Without CD70-CD27 interaction, EBV-specific T cells do not proliferate
normally or kill EBV-infected B cells
• CD8þ memory T cells in patients with CD70 deficiency have reduced
expression of 2B4 and NKG2D

• Most patients with CD70 deficiency develop Hodgkin Lymphoma
• Other manifestations hypogammaglobulinemia, severe varicella
infection, recurrent fever, lymphadenopathy, and
hepatosplenomegaly
• also developed nonerosive oligoarthritis and alopecia areata, and like
patients
• prone to aphthous ulcers and uveitis.
• evaluate the extent of deficiencies in cellular and humoral immunity.
• Management is analogous to that mentioned above for CD27
deficiency.
CD70 deficiency

Clinical features of inborn errors of immunity predisposing to
EBV-induced disease
Proportions of patients with
mutations in the indicated
genes developing :
• lymphoproliferative disease
(LPD)/malignancy
• severe IM
• HLH

EBV-induced disease
Breakdown of
lymphoproliferative
disease and the types of
malignancies

EBV-induced disease
Age of onset of initial presenting
clinical features for the indicated
genotypes.
• Data for 25 individual patients with
XLP1 (SH2D1A mutations)
• The average for these 25 patients
(4.9 years)

EBV-induced disease
Survival post-HSCT.
• Data for XLP1 patients is based on the study by
Booth et al
• Data for the other genotypes are from
individual case reports
• Apart from XLP1 due to SH2D1A mutations,
relatively few patients with other monogenic
mutations have undergone HSCT.

EBV susceptibility

Recommended

Recommended

More Related Content

What's hot

What's hot (20)

Similar to EBV susceptibility

Similar to EBV susceptibility (20)

More from Chulalongkorn Allergy and Clinical Immunology Research Group

More from Chulalongkorn Allergy and Clinical Immunology Research Group (20)

Recently uploaded

Recently uploaded (20)

EBV susceptibility