Two siblings presenting with novel ADA2 variants, lymphoproliferation, persistence of large granular lymphocytes, and T-cell perturbations

The complex relationship between large granular lymphocyte leukemia and rheumatic disease

INTRODUCTION

Large granular lymphocytic (LGL) leukemia is a rare lymphoproliferative disorder characterized by an expansion of clonal T or NK lymphocytes. Neutropenia-related infections represent the main clinical manifestation. Even if the disease follows an indolent course, most patients will ultimately need treatment in their lifetime. Interestingly, LGL leukemia is characterized by a high frequency of autoimmune disorders with rheumatoid arthritis being the most frequent.

AREAS COVERED

This review covers the pathophysiology, clinic-biological features and the advances made in the treatment of LGL leukemia. A special focus will be made on the similarities in the pathophysiology of LGL leukemia and the frequently associated rheumatic disorders.

EXPERT OPINION

Recent advances in the phenotypic and molecular characterization of LGL clones have uncovered the key role of JAK-STAT signaling in the pathophysiology linking leukemic cells expansion and autoimmunity. The description of the molecular landscape of T- and NK-LGL leukemia and the improved understanding of the associated rheumatic disorders open the way to the development of new targeted therapies effective on both conditions.

Review of T cell proliferation regulatory factors in treatment and prognostic prediction for solid tumors

T cell proliferation regulators (Tcprs), which are positive regulators that promote T cell function, have made great contributions to the development of therapies to improve T cell function. CAR (chimeric antigen receptor) -T cell therapy, a type of adoptive cell transfer therapy that targets tumor cells and enhances immune lethality, has led to significant progress in the treatment of hematologic tumors. However, the applications of CAR-T in solid tumor treatment remain limited. Therefore, in this review, we focus on the development of Tcprs for solid tumor therapy and prognostic prediction. We summarize potential strategies for targeting different Tcprs to enhance T cell proliferation and activation and inhibition of cancer progression, thereby improving the antitumor activity and persistence of CAR-T. In summary, we propose means of enhancing CAR-T cells by expressing different Tcprs, which may lead to the development of a new generation of cell therapies.

A wide spectrum of phenotype of deficiency of deaminase 2 (DADA2): a systematic literature review

INTRODUCTION

Deficiency of adenosine deaminase 2 (DADA2) is a rare monogenic autoinflammatory disease, whose clinical phenotype was expanded since the first cases, originally described as mimicker of polyarteritis nodosa, with immunodeficiency and early-onset stroke.

METHODS

A systematic review according to PRISMA approach, including all articles published before the 31st of August 2021 in Pubmed and EMBASE database was performed.

RESULTS

The search identified 90 publications describing 378 unique patients (55.8% male). To date 95unique mutations have been reported. The mean age at disease onset was 92.15 months (range 0-720 months), 32 (8.5%) showed an onset of the first signs/symptoms after 18 years old and 96 (25.4%) after 10 years old. The most frequent clinical characteristics described were cutaneous (67.9%), haematological manifestations (56.3%), recurrent fever (51.3%), neurological as stroke and polyneuropathy (51%), immunological abnormalities (42.3%), arthralgia/arthritis (35.4%), splenomegaly (30.6%), abdominal involvement (29.8%), hepatomegaly (23.5%), recurrent infections (18.5%), myalgia (17.9%), kidney involvement (17.7%) etc. Patients with skin manifestations were older than the others (101.1 months SD ± 116.5, vs. 75.3 SD ± 88.2, p 0.041), while those with a haematological involvement (64.1 months SD ± 75.6 vs. 133.1 SD ± 133.1, p < 0.001) and immunological involvement (73.03 months SD ± 96.9 vs. 103.2 SD ± 112.9, p 0.05) are younger than the others. We observed different correlations among the different clinical manifestations. The use of anti-TNFα and hematopoietic cell stems transplantation (HCST) has improved the current history of the disease.

CONCLUSION

Due to this highly variable phenotype and age of presentation, patients with DADA2 may present to several type of specialists. Given the important morbidity and mortality, early diagnosis and treatment are mandatory.

Large granular lymphocyte leukemia: An indolent clonal proliferative disease associated with an array of various immunologic disorders

Large granular lymphocyte leukemia (LGLL) is a chronic lymphoproliferative disorder characterized by the proliferation of T or NK cytotoxic cells in the peripheral blood, the spleen and the bone marrow. Neutropenia leading to recurrent infections represents the main manifestation of LGLL. One specificity of LGLL is its frequent association with auto-immune disorders, among them first and foremost rheumatoid arthritis, and other hematologic diseases, including pure red cell aplasia and bone marrow failure. The large spectrum of manifestations and the classical indolent course contribute to the diagnosis difficulties and the frequency of underdiagnosed cases. Of importance, the dysimmune manifestations disappear with the treatment of LGLL as the blood cell counts normalize, giving a strong argument for a pathological link between the two entities. The therapeutic challenge results from the high rate of relapses following the first line of immunosuppressive drugs. New targeted agents, some of which are currently approved in autoimmune diseases, appear to be relevant therapeutic strategies to treat LGLL, by targeting key activated pathways involved in the pathogenesis of the disease, including JAK-STAT signaling.

Case Report: Consistent disease manifestations with a staggered time course in two identical twins affected by adenosine deaminase 2 deficiency

Deficiency of adenosine deaminase 2 (DADA2) is an autosomal recessive disease associated with a highly variable clinical presentation, including vasculitis, immunodeficiency, and hematologic manifestations, potentially progressing over time. The present study describes the long-term evolution of the immuno-hematological features and therapeutic challenge of two identical adult twin sisters affected by DADA2. The absence of plasmatic adenosine deaminase 2 (ADA2) activity in both twins suggested the diagnosis of DADA2, then confirmed by genetic analysis. Exon sequencing revealed a missense (p.Leu188Pro) mutation on the paternal ADA2 allele. While, whole genome sequencing identified an unreported deletion (IVS6_IVS7del*) on the maternal allele predicted to produce a transcript missing exon 7. The patients experienced the disease onset during childhood with early strokes (Patient 1 at two years, Patient 2 at eight years of age), subsequently followed by other shared DADA2-associated features, including neutropenia, hypogammaglobulinemia, reduced switched memory B cells, inverted CD4:CD8 ratio, increased naïve T cells, reduced follicular regulatory T cells, the almost complete absence of NK cells, T-large granular cell leukemia, and osteoporosis. Disease evolution differed: clinical manifestations presented several years earlier and were more pronounced in Patient 1 than in Patient 2. Due to G-CSF refractory life-threatening neutropenia, Patient 1 successfully underwent an urgent hematopoietic stem cell transplantation (HSCT) from a 9/10 matched unrelated donor. Patient 2 experienced a similar, although delayed, disease evolution and is currently on anti-TNF therapy and anti-infectious prophylaxis. The unique cases confirmed that heterozygous patients with null ADA2 activity deserve deep investigation for possible structural variants on a single allele. Moreover, this report emphasizes the importance of timely recognizing DADA2 at the onset to allow adequate follow-up and detection of disease progression. Finally, the therapeutic management in these identical twins raises significant concerns as they share a similar phenotype, with a delayed but almost predictable disease evolution in one of them, who could benefit from a prompt definitive treatment like elective allogeneic HSCT. Additional data are required to assess whether the absence of enzymatic activity at diagnosis is associated with hematological involvement and is also predictive of bone marrow dysfunction, encouraging early HSCT to improve functional outcomes.

ELISA based assays to measure adenosine deaminases concentration in serum and saliva for the diagnosis of ADA2 deficiency and cancer

Adenosine deaminases (ADAs) are enzymes of purine metabolism converting adenosine to inosine. There are two types of ADAs in humans ADA1 and ADA2. While both ADA1 and ADA2 share the same substrate, they differ in expression, cellular localization, and catalytic properties. The genetic deficiency of ADA1 results in severe combined immunodeficiency (SCID), while lack in ADA2 (DADA2) results in multiple phenotypes ranging from systemic inflammation to vascular pathology. Clinical studies have shown that the levels of ADAs in biological fluids are altered in pathophysiological conditions, suggesting that ADA activity could be a convenient marker for the diagnosis of immune diseases and cancer. Here, we describe sensitive and straightforward ELISA assays to measure ADA1 and ADA2 concentrations in biological fluids. Analysis of the serum and saliva samples from the healthy controls and DADA2 patients revealed that ADA2 enzyme concentration is significantly lower in patients than in healthy controls. In contrast, the concentration of ADA2 increases in the serum of patients with large granular leukocyte leukemia (LGLL) and patients’ saliva with head and neck cancer. Thus, this simple, non-invasive method allows for distinguishing healthy controls from the affected patient. It can be implemented in screening and diagnosis of DADA2 and follow up the treatment of LGLL and several types of head and neck cancer.

Adenosine Deaminase 2 Deficiency (DADA2): A Crosstalk Between Innate and Adaptive Immunity

Deficiency of Adenosine deaminase 2 (DADA2) is a monogenic autoinflammatory disorder presenting with a broad spectrum of clinical manifestations, including immunodeficiency, vasculopathy and hematologic disease. Biallelic mutations in ADA2 gene have been associated with a decreased ADA2 activity, leading to reduction in deamination of adenosine and deoxyadenosine into inosine and deoxyinosine and subsequent accumulation of extracellular adenosine. In the early reports, the pivotal role of innate immunity in DADA2 pathogenic mechanism has been underlined, showing a skewed polarization from the M2 macrophage subtype to the proinflammatory M1 subtype, with an increased production of inflammatory cytokines such as TNF-α. Subsequently, a dysregulation of NETosis, triggered by the excess of extracellular Adenosine, has been implicated in the pathogenesis of DADA2. In the last few years, evidence is piling up that adaptive immunity is profoundly altered in DADA2 patients, encompassing both T and B branches, with a disrupted homeostasis in T-cell subsets and a B-cell skewing defect. Type I/type II IFN pathway upregulation has been proposed as a possible core signature in DADA2 T cells and monocytes but also an increased IFN-β secretion directly from endothelial cells has been described. So far, a unifying clear pathophysiological explanation for the coexistence of systemic inflammation, immunedysregulation and hematological defects is lacking. In this review, we will explore thoroughly the latest understanding regarding DADA2 pathophysiological process, with a particular focus on dysregulation of both innate and adaptive immunity and their interacting role in the development of the disease.

Large Granular Lymphocyte Expansion in Myeloid Diseases and Bone Marrow Failure Syndromes: Whoever Seeks Finds

Large granular lymphocytes (LGL) are lymphoid cells characterized by either a T-cell or a natural killer phenotype whose expansion may be reactive to toxic, infectious, and neoplastic conditions, or result from clonal selection. Recently, the higher attention to LGL clones led to their detection in many clinical conditions including myeloid neoplasms and bone marrow failures. In these contexts, it is still unclear whether LGL cells actively contribute to anti-stem cell autoimmunity or are only a reaction to dysplastic/leukemic myelopoiesis. Moreover, some evidence exists about a common clonal origin of LGL and myeloid clones, including the detection of STAT3 mutations, typical of LGL, in myeloid precursors from myelodysplastic patients. In this article we reviewed available literature regarding the association of LGL clones with myeloid neoplasms (myelodysplastic syndromes, myeloproliferative neoplasms, and acute myeloid leukemias) and bone marrow failures (aplastic anemia and pure red cell aplasia, PRCA) focusing on evidence of pathogenic, clinical, and prognostic relevance. It emerged that LGL clones may be found in up to one third of patients, particularly those with PRCA, and are associated with a more cytopenic phenotype and good response to immunosuppression. Pathogenically, LGL clones seem to expand after myeloid therapies, whilst immunosuppression leading to LGL depletion may favor leukemic escape and thus requires caution.

Intrinsic Defects in B Cell Development and Differentiation, T Cell Exhaustion and Altered Unconventional T Cell Generation Characterize Human Adenosine Deaminase Type 2 Deficiency

PURPOSE

Deficiency of adenosine deaminase type 2 (ADA2) (DADA2) is a rare inborn error of immunity caused by deleterious biallelic mutations in ADA2. Clinical manifestations are diverse, ranging from severe vasculopathy with lacunar strokes to immunodeficiency with viral infections, hypogammaglobulinemia and bone marrow failure. Limited data are available on the phenotype and function of leukocytes from DADA2 patients. The aim of this study was to perform in-depth immunophenotyping and functional analysis of the impact of DADA2 on human lymphocytes.

METHODS

In-depth immunophenotyping and functional analyses were performed on ten patients with confirmed DADA2 and compared to heterozygous carriers of pathogenic ADA2 mutations and normal healthy controls.

RESULTS

The median age of the patients was 10 years (mean 20.7 years, range 1-44 years). Four out of ten patients were on treatment with steroids and/or etanercept or other immunosuppressives. We confirmed a defect in terminal B cell differentiation in DADA2 and reveal a block in B cell development in the bone marrow at the pro-B to pre-B cell stage. We also show impaired differentiation of CD4⁺ and CD8⁺ memory T cells, accelerated exhaustion/senescence, and impaired survival and granzyme production by ADA2 deficient CD8⁺ T cells. Unconventional T cells (i.e. iNKT, MAIT, Vδ2⁺ γδT) were diminished whereas pro-inflammatory monocytes and CD56^bright immature NK cells were increased. Expression of the IFN-induced lectin SIGLEC1 was increased on all monocyte subsets in DADA2 patients compared to healthy donors. Interestingly, the phenotype and function of lymphocytes from healthy heterozygous carriers were often intermediate to that of healthy donors and ADA2-deficient patients.

CONCLUSION

Extended immunophenotyping in DADA2 patients shows a complex immunophenotype. Our findings provide insight into the cellular mechanisms underlying some of the complex and heterogenous clinical features of DADA2. More research is needed to design targeted therapy to prevent viral infections in these patients with excessive inflammation as the overarching phenotype.

A Novel Germline Mutation of ADA2 Gene in Two "Discordant" Homozygous Female Twins Affected by Adenosine Deaminase 2 Deficiency: Description of the Bone-Related Phenotype

Adenosine Deaminase 2 Deficiency (DADA2) syndrome is a rare monogenic disorder prevalently linked to recessive inherited loss of function mutations in the ADA2/CECR1 gene. It consists of an immune systemic disease including autoinflammatory vasculopathies, with a frequent onset at infancy/early childhood age. DADA2 syndrome encompasses pleiotropic manifestations such as stroke, systemic vasculitis, hematologic alterations, and immunodeficiency. Although skeletal abnormalities have been reported in patients with this disease, clear information about skeletal health, with appropriate biochemical-clinical characterization/management, its evolution over time and any appropriate clinical management is still insufficient. In this paper, after a general introduction shortly reviewing the pathophysiology of Ada2 enzymatic protein, its potential role in bone health, we describe a case study of two 27 year-old DADA2 monozygotic female twins exhibiting bone mineral density and bone turnover rate abnormalities over the years of their clinical follow-up.

Plasma Adenosine Deaminase (ADA)-1 and -2 Demonstrate Robust Ontogeny Across the First Four Months of Human Life

Background

Human adenosine deaminases (ADAs) modulate the immune response: ADA1 via metabolizing adenosine, a purine metabolite that inhibits pro-inflammatory and Th1 cytokine production, and the multi-functional ADA2, by enhancing T-cell proliferation and monocyte differentiation. Newborns are relatively deficient in ADA1 resulting in elevated plasma adenosine concentrations and a Th2/anti-inflammatory bias compared to adults. Despite the growing recognition of the role of ADAs in immune regulation, little is known about the ontogeny of ADA concentrations.

Methods

In a subgroup of the EPIC002-study, clinical data and plasma samples were collected from 540 Gambian infants at four time-points: day of birth; first week of life; one month of age; and four months of age. Concentrations of total extracellular ADA, ADA1, and ADA2 were measured by chromogenic assay and evaluated in relation to clinical data. Plasma cytokines/chemokine were measured across the first week of life and correlated to ADA concentrations.

Results

ADA2 demonstrated a steady rise across the first months of life, while ADA1 concentration significantly decreased 0.79-fold across the first week then increased 1.4-fold by four months of life. Males demonstrated significantly higher concentrations of ADA2 (1.1-fold) than females at four months; newborns with early-term (37 to <39 weeks) and late-term (≥41 weeks) gestational age demonstrated significantly higher ADA1 at birth (1.1-fold), and those born to mothers with advanced maternal age (≥35 years) had lower plasma concentrations of ADA2 at one month (0.93-fold). Plasma ADA1 concentrations were positively correlated with plasma CXCL8 during the first week of life, while ADA2 concentrations correlated positively with TNFα, IFNγ and CXCL10, and negatively with IL-6 and CXCL8.

Conclusions

The ratio of plasma ADA2/ADA1 concentration increased during the first week of life, after which both ADA1 and ADA2 increased across the first four months of life suggesting a gradual development of Th1/Th2 balanced immunity. Furthermore, ADA1 and ADA2 were positively correlated with cytokines/chemokines during the first week of life. Overall, ADA isoforms demonstrate robust ontogeny in newborns and infants but further mechanistic studies are needed to clarify their roles in early life immune development and the correlations with sex, gestational age, and maternal age that were observed.

Expanding spectrum of DADA2: a review of phenotypes, genetics, pathogenesis and treatment

Deficiency of adenosine deaminase 2 (DADA2) is a monogenic disease caused by biallelic mutations in ADA2 gene (previously CECR1). The aim of this review was to describe the clinical phenotypes, genetics, pathogenesis and treatment of DADA2. ADA2 is highly expressed on myeloid cells and deficiency leads to polarisation of macrophages to an M1 inflammatory type and activation of neutrophils. The pathogenesis of immunological and haematological manifestations is less clear. The spectrum of clinical presentations varies widely from asymptomatic individual to severe vasculitis, several autoinflammatory, immunological and haematological manifestations. Initially considered a childhood disease, the first presentation is now being reported well into adulthood. Vasculitis closely resembles polyarteritis nodosa. Livedoid reticularis/racemosa like skin rash and central nervous system involvement in the form of ischemic or haemorrhagic stroke are dominant manifestations. Immunological manifestations include hypogammaglobulinemia and recurrent infections. Lymphopenia is the most common haematological manifestation; pure red cell aplasia and bone marrow failure has been reported in severe cases. The disease is extremely heterogeneous with variable severity noted in patients with the same mutation and even within family members. Tumour necrosis factor inhibitors are currently the treatment of choice for vasculitic and inflammatory manifestations and also prevent strokes. Haematopoietic stem cell transplantation is a curative option for severe haematological manifestations like pure red cell aplasia, bone marrow failure and immunodeficiency. Further research is required to understand pathogenesis and all clinical aspects of this disease to enable early diagnosis and prompt treatment. Key Points • Deficiency of adenosine deaminase 2 (DADA2) is a monogenic disease caused by biallelic mutations in ADA2 gene. • The clinical features include vasculitis resembling polyarteritis nodosa, autoinflammation, haematological manifestations and immunodeficiency. • The severity varies widely from mild to fatal even in patients within a family and with the same mutation. • The treatment of choice for inflammatory and vasculitic disease is tumour necrosis factor α blockers. Bone marrow transplant may be considered for severe haematological disease.

Case Report: Hypomorphic Function and Somatic Reversion in DOCK8 Deficiency in One Patient With Two Novel Variants and Sclerosing Cholangitis

DOCK8 deficiency is a combined immunodeficiency due to biallelic variants in dedicator of cytokinesis 8 (DOCK8) gene. The disease has a wide clinical spectrum encompassing recurrent infections (candidiasis, viral and bacterial infections), virally driven malignancies and immune dysregulatory features, including autoimmune (cytopenia and vasculitis) as well as allergic disorders (eczema, asthma, and food allergy). Hypomorphic function and somatic reversion of DOCK8 has been reported to result in incomplete phenotype without IgE overproduction. Here we describe a case of DOCK8 deficiency in a 8-year-old Caucasian girl. The patient's disease was initially classified as autoimmune thrombocytopenia, which then evolved toward a combined immunodeficiency phenotype with recurrent infections, persistent EBV infection and lymphoproliferation. Two novel variants (one deletion and one premature stop codon) were characterized, resulting in markedly reduced, but not absent, DOCK8 expression. Somatic reversion of the DOCK8 deletion was identified in T cells. Hypomorphic function and somatic reversion were associated with restricted T cell repertoire, decreased STAT5 phosphorylation and impaired immune synapse functioning in T cells. Although the patient presented with incomplete phenotype (absence of markedly increase IgE and eosinophil count), sclerosing cholangitis was incidentally detected, thus indicating that hypomorphic function and somatic reversion of DOCK8 may delay disease progression but do not necessarily prevent from severe complications.