Aydan Kansu

Monogenic mutations differentially affect the quantity and quality of T follicular helper cells in patients with human primary immunodeficiencies

BACKGROUND Follicular helper T (TFH) cells underpin T cell-dependent humoral immunity and the success of most vaccines. TFH cells also contribute to human immune disorders, such as autoimmunity, immunodeficiency, and malignancy. Understanding the molecular requirements for the generation and function of TFH cells will provide strategies for targeting these cells to modulate their behavior in the setting of these immunologic abnormalities. OBJECTIVE We sought to determine the signaling pathways and cellular interactions required for the development and function of TFH cells in human subjects. METHODS Human primary immunodeficiencies (PIDs) resulting from monogenic mutations provide a unique opportunity to assess the requirement for particular molecules in regulating human lymphocyte function. Circulating follicular helper T (cTFH) cell subsets, memory B cells, and serum immunoglobulin levels were quantified and functionally assessed in healthy control subjects, as well as in patients with PIDs resulting from mutations in STAT3, STAT1, TYK2, IL21, IL21R, IL10R, IFNGR1/2, IL12RB1, CD40LG, NEMO, ICOS, or BTK. RESULTS Loss-of-function (LOF) mutations in STAT3, IL10R, CD40LG, NEMO, ICOS, or BTK reduced cTFH cell frequencies. STAT3 and IL21/R LOF and STAT1 gain-of-function mutations skewed cTFH cell differentiation toward a phenotype characterized by overexpression of IFN-γ and programmed death 1. IFN-γ inhibited cTFH cell function in vitro and in vivo, as corroborated by hypergammaglobulinemia in patients with IFNGR1/2, STAT1, and IL12RB1 LOF mutations. CONCLUSION Specific mutations affect the quantity and quality of cTFH cells, highlighting the need to assess TFH cells in patients by using multiple criteria, including phenotype and function. Furthermore, IFN-γ functions in vivo to restrain TFH cell-induced B-cell differentiation. These findings shed new light on TFH cell biology and the integrated signaling pathways required for their generation, maintenance, and effector function and explain the compromised humoral immunity seen in patients with some PIDs.

Early-onset inflammatory bowel disease and common variable immunodeficiency–like disease caused by IL-21 deficiency

BACKGROUND Alterations of immune homeostasis in the gut can result in development of inflammatory bowel disease (IBD). Recently, Mendelian forms of IBD have been discovered, as exemplified by deficiency of IL-10 or its receptor subunits. In addition, other types of primary immunodeficiency disorders might be associated with intestinal inflammation as one of their leading clinical presentations. OBJECTIVE We investigated a large consanguineous family with 3 children who presented with early-onset IBD within the first year of life, leading to death in infancy in 2 of them. METHODS Homozygosity mapping combined with exome sequencing was performed to identify the molecular cause of the disorder. Functional experiments were performed to assess the effect of IL-21 on the immune system. RESULTS A homozygous mutation in IL21 was discovered that showed perfect segregation with the disease. Deficiency of IL-21 resulted in reduced numbers of circulating CD19(+) B cells, including IgM(+) naive and class-switched IgG memory B cells, with a concomitant increase in transitional B-cell numbers. In vitro assays demonstrated that mutant IL-21(Leu49Pro) did not induce signal transducer and activator of transcription 3 phosphorylation and immunoglobulin class-switch recombination. CONCLUSION Our study uncovers IL-21 deficiency as a novel cause of early-onset IBD in human subjects accompanied by defects in B-cell development similar to those found in patients with common variable immunodeficiency. IBD might mask an underlying primary immunodeficiency, as illustrated here with IL-21 deficiency.

Current therapeutic approaches in childhood chronic hepatitis B infection: A multicenter study

Background and Aim:  The aim of the present study was to compare the therapeutic efficacy of three different regimens in childhood chronic hepatitis B (CHB) infection.

Atypical manifestation of LRBA deficiency with predominant IBD-like phenotype.

Background:Inflammatory bowel diseases (IBDs) denote a heterogeneous group of disorders associated with an imbalance of gut microbiome and the immune system. Importance of the immune system in the gut is endorsed by the presence of IBD-like symptoms in several primary immunodeficiencies. A fraction of early-onset IBDs presenting with more severe disease course and incomplete response to conventional treatment is assumed to be inherited in a Mendelian fashion, as exemplified by the recent discovery of interleukin (IL)-10 (receptor) deficiency. Methods:We analyzed a patient born to consanguineous parents suffering from severe intestinal manifestations since 6 months of age and later diagnosed as IBD. Eventually, she developed autoimmune manifestations including thyroiditis and type I diabetes at the age of 6 and 9 years, respectively. Combined single-nucleotide polymorphism array-based homozygosity mapping and exome sequencing was performed to identify the underlying genetic defect. Protein structural predictions were calculated using I-TASSER. Immunoblot was performed to assess protein expression. Flow cytometric analysis was applied to investigate B-cell subpopulations. Results:We identified a homozygous missense mutation (p.Ile2824Pro) in lipopolysaccharide-responsive and beige-like anchor (LRBA) affecting the C-terminal WD40 domain of the protein. In contrast to previously published LRBA-deficient patients, the mutant protein was expressed at similar levels to healthy controls. Immunophenotyping of the index patient revealed normal B-cell subpopulations except increased CD21low B cells. Conclusions:We describe a patient with a novel missense mutation in LRBA who presented with IBD-like symptoms at early age, illustrating that LRBA deficiency should be considered in the differential diagnosis for IBD(-like) disease even in the absence of overt immunodeficiency.

The value of the levels of acute phase reactants for the prediction of familial Mediterranean fever associated amyloidosis: a case control study

In order to determine the role of levels of acute phase proteins (APPs) for the development of amyloidosis in familial Mediterranean fever (FMF) patients, the levels of serum amyloid A (SAA), C reactive protein (CRP), fibrinogen and erythrocyte sedimentation rate were measured in paired sera of 36 FMF patients during and in between acute attacks, 39 of their healthy parents (obligate heterozgotes), and 15 patients with FMF associated amyloidosis. To compare the levels of APPs, 39 patients with chronic infections or inflammatory diseases who may develop secondary amyloidosis, 20 patients with acute infections who are known to have elevated acute phase response but will never develop amyloidosis and 19 healthy controls were included. The median levels of all APPs are increased in the patients with FMF during attacks and a significant decrease was observed after the attack was over. The level of SAA was above reference range in all FMF patients during the attack free period and the level of at least one other APP was also above normal in 64% of the patients. Both CRP and SAA levels were found to be higher in obligate heterozygotes compared to controls. The levels of SAA in patients with FMF during the attack-free period, obligate heterozygotes and patients with FMF-amyloidosis were found to be similar. The levels in each group were found to be higher than SAA levels found in healthy controls yet lower than the levels measured in the patients with acute infections and patients with chronic inflammation or chronic infections. In conclusion, our results show that SAA level reflects subclinical inflammation with high sensitivity but its value for the prediction of amyloid formation process seems to be low.

Celiac disease: presentation of 109 children.

Purpose The clinical features of patients with celiac disease (CD) are variable. In the present study, clinical and laboratory features of 109 patients with CD were retrospectively evaluated. Materials and Methods In all cases, diagnosis of CD was made by European Society for Paediatric Gastroenterology, Hepatology and Nutrition (ESPGHAN) criteria and clinical and laboratory findings, including hematological and biochemical analyses, immunoglobulin levels, autoantibodies [antinucler antibody (ANA), antidouble stranded DNA (dsDNA), antimitochondrial antibody (AMA), anti-smooth muscle antibody (ASMA), liver kidney antibody (LKM-1), anti thyroid peroxidase (TPO), anti thyroglobulin (Tg)], bone mineral density (BMD), and electroencephalogram were evaluated. The type of CD was recorded. Results Of 109 patients with CD, 66 (60.6%) were classical type, 41 (37.6%) were atypical type and 2 (1.8%) were silent type. The mean age was 8.81 ± 4.63 years and the most common symptom was diarrhea (53.2%) followed by failure to thrive, short stature, and abdominal pain. Paleness (40.4%), underweight (34.8%), and short stature (31.2%) were the most common findings. Iron deficinecy anemia (81.6%), zinc deficiency (64.1%), prolonged prothrombin time (35.8%), and elevated transaminase levels (24.7%) were the most common laboratory findings. Eight percent of patients had at least 1 autoantibody, and 28 of 52 patients had low BMD. Four of 38 patients had abnormalty in electroencephalograms. The prevalance of selective immunoglobulin (Ig) A deficiency was 9.1%. Histocompatibility antigen HLA-DQ and/or DQ8 genotypes were found in 91% of patients. Abdominal distention, iron deficiency, prolonged prothrombine time, hypoalbuminemia, and elevated transaminase levels were more significantly frequent in the classical type than atypical type (p < 0.005). Conclusion Although classical CD was seen in most patients in the present study, clinical variability of the condition should be kept in mind.

Burden of celiac disease in the Mediterranean area

AIM To estimate the burden of undiagnosed celiac disease (CD) in the Mediterranean area in terms of morbidity, mortality and health cost. METHODS For statistics regarding the population of each country in the Mediterranean area, we accessed authoritative international sources (World Bank, World Health Organization and United Nations). The prevalence of CD was obtained for most countries from published reports. An overall prevalence rate of 1% cases/total population was finally estimated to represent the frequency of the disease in the area, since none of the available confidence intervals of the reported rates significantly excluded this rate. The distribution of symptoms and complications was obtained from reliable reports in the same cohort. A standardized mortality rate of 1.8 was obtained from recent reports. Crude health cost was estimated for the years between symptoms and diagnosis for adults and children, and was standardized for purchasing power parity to account for the different economic profiles amongst Mediterranean countries. RESULTS In the next 10 years, the Mediterranean area will have about half a billion inhabitants, of which 120 million will be children. The projected number of CD diagnoses in 2020 is 5 million cases (1 million celiac children), with a relative increase of 11% compared to 2010. Based on the 2010 rate, there will be about 550,000 symptomatic adults and about 240,000 sick children: 85% of the symptomatic patients will suffer from gastrointestinal complaints, 40% are likely to have anemia, 30% will likely have osteopenia, 20% of children will have short stature, and 10% will have abnormal liver enzymes. The estimated standardized medical costs for symptomatic celiac patients during the delay between symptom onset and diagnosis (mean 6 years for adults, 2 years for children) will be about €4 billion (€387 million for children) over the next 10 years. A delay in diagnosis is expected to increase mortality: about 600,000 celiac patients will die in the next 10 years, with an excess of 44.4% vs age- and sex-matched controls. CONCLUSION In the near future, the burden of CD will increase tremendously. Few Mediterranean countries are able to face this expanding epidemic alone.

Celiac disease in Turkish short‐statured children and the value of antigliadin antibody in diagnosis

Abstract Background. It is generally accepted that celiac disease (CD) must always be taken into consideration when dealing with children manifesting growth failure. It is, therefore, important to have laboratory tests capable of detecting patients who should undergo intestinal biopsy. In this study, we have prospectively evaluated clinical characteristics, gliadin antibody measurements and duodenal biopsies in 47 children with short stature and without gastrointestinal symptoms, in order to determine the incidence of CD and the diagnostic value of immunoglobulin (Ig)A and IgG antigliadin antibodies (AGA) for CD.

Celiac disease and autoimmune thyroid disease in children with type 1 diabetes mellitus: clinical and HLA-genotyping results.

Objective: Increased prevalence of celiac disease (CD) and autoimmune thyroid disorders (ATD) in patients with Type 1 diabetes mellitus (T1D) has been widely reported. Such an association may lead to adverse effects on the growth, bone metabolism and fertility, and response to therapy may become difficult. The aim of this study was to evaluate the clinical findings and HLA typing results in patients with T1D associated with CD or ATD. Methods: The association of CD and ATD was evaluated in 38 children with T1D aged 1.5−16.8 years who had been followed for 48.3±28 months. Diagnosis of CD was based on positivity for serum endomysial IgA antibody and histopathological findings of intestinal biopsy specimens. Thyroid autoimmunity was assessed by antithyroglobulin and antithyroid peroxidase antibodies and with diagnostic ultrasonographic findings. Results: ATD was detected in 31.5%, and CD−in 7.8% of T1D patients. Subjects with CD showed either no symptoms or suggestive problems such as short stature, hepatosteatosis, pubertal delay and difficulties in the control of diabetes. Patients with ATD had no clinical symptoms. DQ8 was the most prominent finding in CD. Conclusions: It is essential that patients with T1D, regardless of presence or absence of symptoms, should be investigated for CD and ATD. Conflict of interest:None declared.

A Successful HSCT in a Girl with Novel LRBA Mutation with Refractory Celiac Disease

To the Editor The gastrointestinal tract is the largest lymphoid organ in the body. One of the major functions of the gastrointestinal tract is maintaining of the balance between active immunity, tolerance and immunosuppression. Dysregulation of this physiologic process can lead to diseases such as food allergy, celiac disease (CD) or inflammatory bowel disease [1]. Therefore, gastrointestinal symptoms such as chronic diarrhea and malabsorption might be indicative of primary immunodeficiency diseases [1]. A 10-year-old girl referred to our clinic with a six-year history of chronic watery diarrhea and unresponsiveness to a gluten free diet. She had been evaluated and treated previously for chronic diarrhea, intermittent fever, recurrent pneumonia, candida esophagitis, pancytopenia, hypoalbuminemia, hypolipidemia, vitamin B12 and folic acid deficiencies. She was diagnosed with CD, based on serologic and histopathological findings. She was placed on a strict gluten free diet for a year, but diarrhea did not improve. She has two healthy brothers. Her parents were consanguineous. On physical examination, she was cachectic; with height for age below 3 % (height SDS −5.18) and weight for age below 3 % (weight SDS −5.27). Bone age and height age of the patient were 6 years, 10 months and 5 years, 3 months, respectively. She had protuberant abdomen and clubbing. Liver and spleenwere palpable at 1 cm and 4 cm below the costal margins. Laboratory tests revealed mildly increased liver transaminases. Hemoglobin was 8.32 g/dl; MCV, 85 fL; RDW, 23.4 %; white blood cell, 5570/mm; platelet, 230,000/mm; reticulocyte count, 1 % and ferritin, 2.8 ng/ml. Coombs test was negative. Sedimentation rate was 18 mm/h, C-reactive protein, 1.78 mg/dl. Stool examinations were normal. 25-hydroxi vitamin D level was 25.7 ng/ml. Insulin like growth factor 1 (IGF-1) was 3.5 ng/mL (Normal, 108–648 ng/mL) and insulin like growth factor binding protein (IGFBP-3), 580 ng/mL (Normal, 2690–7200 ng/mL). Stimulated IGF-1 and IGFBP-3 were 2.85 ng/mL and 720 ng/mL, respectively, both markedly reduced. Basal and stimulated growth hormone levels were compatible with growth hormone insensitivity (12.9 ng/mL and 9.79 ng/mL, respectively). Anti-tissue transglutaminase IgA was positive with a titer of 200 IU/ml. Thyroid auto-antibodies, anti-saccharomyces cerevicea antibody and pANCA were negative. Bone mineral density showed severe osteoporosis (Z score, −5). Chest X-ray showed reticular density in the parenchyma of the lung. High-resolution chest tomography showed bilateral tubular bronchiectasis. Smear staining for acid resistant bacteria and tuberculosis PCR, and culture were negative. Upper gastrointestinal endoscopic examination revealed scalloping in the duodenal mucosa. Colonoscopy showed nonspecific Buket Dalgic and Aydan Ikinciogullari contributed equally to this work.