Loss of B Cells in Patients with Heterozygous Mutations in IKAROS.

BACKGROUND: Common variable immunodeficiency (CVID) is characterized by late-onset hypogammaglobulinemia in the absence of predisposing factors. The genetic cause is unknown in the majority of cases, and less than 10% of patients have a family history of the disease. Most patients have normal numbers of B cells but lack plasma cells. METHODS: We used whole-exome sequencing and array-based comparative genomic hybridization to evaluate a subset of patients with CVID and low B-cell numbers. Mutant proteins were analyzed for DNA binding with the use of an electrophoretic mobility-shift assay (EMSA) and confocal microscopy. Flow cytometry was used to analyze peripheral-blood lymphocytes and bone marrow aspirates. RESULTS: Six different heterozygous mutations in IKZF1, the gene encoding the transcription factor IKAROS, were identified in 29 persons from six families. In two families, the mutation was a de novo event in the proband. All the mutations, four amino acid substitutions, an intragenic deletion, and a 4.7-Mb multigene deletion involved the DNA-binding domain of IKAROS. The proteins bearing missense mutations failed to bind target DNA sequences on EMSA and confocal microscopy; however, they did not inhibit the binding of wild-type IKAROS. Studies in family members showed progressive loss of B cells and serum immunoglobulins. Bone marrow aspirates in two patients had markedly decreased early B-cell precursors, but plasma cells were present. Acute lymphoblastic leukemia developed in 2 of the 29 patients. CONCLUSIONS: Heterozygous mutations in the transcription factor IKAROS caused an autosomal dominant form of CVID that is associated with a striking decrease in B-cell numbers. (Funded by the National Institutes of Health and others.).

Activated STING in a vascular and pulmonary syndrome.

BACKGROUND: The study of autoinflammatory diseases has uncovered mechanisms underlying cytokine dysregulation and inflammation. METHODS: We analyzed the DNA of an index patient with early-onset systemic inflammation, cutaneous vasculopathy, and pulmonary inflammation. We sequenced a candidate gene, TMEM173, encoding the stimulator of interferon genes (STING), in this patient and in five unrelated children with similar clinical phenotypes. Four children were evaluated clinically and immunologically. With the STING ligand cyclic guanosine monophosphate-adenosine monophosphate (cGAMP), we stimulated peripheral-blood mononuclear cells and fibroblasts from patients and controls, as well as commercially obtained endothelial cells, and then assayed transcription of IFNB1, the gene encoding interferon-ß, in the stimulated cells. We analyzed IFNB1 reporter levels in HEK293T cells cotransfected with mutant or nonmutant STING constructs. Mutant STING leads to increased phosphorylation of signal transducer and activator of transcription 1 (STAT1), so we tested the effect of Janus kinase (JAK) inhibitors on STAT1 phosphorylation in lymphocytes from the affected children and controls. RESULTS: We identified three mutations in exon 5 of TMEM173 in the six patients. Elevated transcription of IFNB1 and other gene targets of STING in peripheral-blood mononuclear cells from the patients indicated constitutive activation of the pathway that cannot be further up-regulated with stimulation. On stimulation with cGAMP, fibroblasts from the patients showed increased transcription of IFNB1 but not of the genes encoding interleukin-1 (IL1), interleukin-6 (IL6), or tumor necrosis factor (TNF). HEK293T cells transfected with mutant constructs show elevated IFNB1 reporter levels. STING is expressed in endothelial cells, and exposure of these cells to cGAMP resulted in endothelial activation and apoptosis. Constitutive up-regulation of phosphorylated STAT1 in patients' lymphocytes was reduced by JAK inhibitors. CONCLUSIONS: STING-associated vasculopathy with onset in infancy (SAVI) is an autoinflammatory disease caused by gain-of-function mutations in TMEM173. (Funded by the Intramural Research Program of the National Institute of Arthritis and Musculoskeletal and Skin Diseases; ClinicalTrials.gov number, NCT00059748.).

[Patient Satisfaction after Pitch Elevation and Development of a Therapy Algorithm]. / Zufriedenheit nach Stimmerhöhung bei Transsexualität ­ Entwicklung eines Therapiealgorithmus.

Objective: Voice feminization is an important step in the therapy of male-to-female transsexualism. Approaches are conservative voice therapy and surgical interventions. The most powerful parameter of gender perception is the fundamental frequency. Besides the vocal pitch, there are other parameters influencing gender perception of a voice, e. g. intonation, prosody or formant frequencies. Material and methods: In 21 male to female transgender persons after surgical elevation of the vocal pitch the Voice Handicap Index (VHI), the Life Satisfaction Questionnaire (FLZ) and a new addendum were used. A new algorithm for voice feminization in male-to-female transsexualism was deduced. Results: After elevation of the vocal pitch, the self-confidence of the male-to-female transgender persons has increased. Despite of an elevated pitch some persons were not satisfied with their voice. Conclusion: Surgical intervention changes only the pitch of a voice. To change other parameters, conservative voice therapy is necessary. If the transgender persons are able to reach a satisfying female voice with conservative voice therapy alone, surgical intervention is not indicated.

Mutations in PIK3CD can cause hyper IgM syndrome (HIGM) associated with increased cancer susceptibility.

Autosomal dominant gain of function mutations in the gene encoding PI3K p110δ were recently associated with a novel combined immune deficiency characterized by recurrent sinopulmonary infections, CD4 lymphopenia, reduced class-switched memory B cells, lymphadenopathy, CMV and/or EBV viremia and EBV-related lymphoma. A subset of affected patients also had elevated serum IgM. Here we describe three patients in two families who were diagnosed with HIGM at a young age and were recently found to carry heterozygous mutations in PIK3CD. These patients had an abnormal circulating B cell distribution featuring a preponderance of early transitional (T1) B cells and plasmablasts. When stimulated in vitro, PIK3CD mutated B cells were able to secrete class-switched immunoglobulins. This finding implies that the patients' elevated serum IgM levels were unlikely a product of an intrinsic B cell functional inability to class switch. All three patients developed malignant lymphoproliferative syndromes that were not associated with EBV. Thus, we identified a novel subset of patients with PIK3CD mutations associated with HIGM, despite indications of preserved in vitro B cell class switch recombination, as well as susceptibility to non-EBV-associated malignancies.

Reproducibility of airway responsiveness in horses using flowmetric plethysmography and histamine bronchoprovocation.

BACKGROUND: Inflammatory airway disease has a high prevalence in horses, but is often a diagnostic challenge. Flowmetric plethysmography and histamine bronchoprovocation (FP/HBP) is a simple and effective tool for diagnosis, but reproducibility of these measurements made over time has not been established. HYPOTHESIS: We hypothesize that the measurement of airway responsiveness in horses using FP/HBP is consistent over both short and long periods of time. ANIMALS: Twenty-nine healthy adult horses from 2 university herds. METHODS: In this prospective experimental study, airway responsiveness was determined in each horse at day 0 (baseline [BL]) with FP/ HBP, using PC35 (provocative concentration of histamine needed to increase Delta(flow) by 35%) as a measure of airway responsiveness. Each horse was re-tested 1-4 weeks after BL (short-term [ST]) and again at 3-12 months after BL (long-term [LT]). RESULTS: In the ST period, 23/27 (85%) of the horses had a PC35 that was within 1 doubling concentration of histamine of their BL value, with a mean change of 0.52 doubling concentrations (95% CI 0.26-0.79, range 0-2.06). For the LT data, 19/26 (73%) of horses were within 1 doubling concentration of their BL value, with a mean change of 0.81 doubling concentrations (95% CI 0.45-1.17, range 0.14-3.10). There was no significant difference in reproducibility between the 2 groups of subjects. CONCLUSIONS AND CLINICAL IMPORTANCE: Repeated measurements of airway responsiveness obtained with FP/HBP show acceptable reproducibility over time periods up to a year. However, caution must be used when testing horses when ambient air temperature is low.

Flowmetric comparison of respiratory inductance plethysmography and pneumotachography in horses.

Respiratory inductance plethysmographic (RIP) and pneumotachographic (Pn) flows were compared dynamically in horses with bronchoconstriction. On a breath-by-breath basis, RIP was normalized to inspiratory volume from Pn, and peak [peak of subtracted final exhalation waveform (SFE(max))] and selected area [integral of subtracted final waveform during first 25% of exhaled volume (SFE(int))] differences between RIP and Pn flows during early expiration were measured in three settings: 1) healthy horses (n = 8) undergoing histamine bronchoprovocation; 2) horses with naturally occurring lower airway obstruction (AO) (n = 7); and 3) healthy horses (n = 6) given lobeline. HCl to induce hyperpnea. In setting 1, histamine challenge induced a dose-dependent increase in SFE(max) and SFE(int) differences. A test index of airway reactivity (interpolated histamine dose that increased SFE(max) by 35%) closely correlated (r(s) = 0.93, P = 0.001) with a conventional index (histamine dose that induced a 35% decrease in dynamic compliance). In setting 2, in horses with AO, SFE(max) and SFE(int) were markedly elevated, and their absolute values correlated significantly (P < 0.005) with pulmonary resistance and the maximum change in transpulmonary pressure. The effects of bronchodilator treatment on the SFE(max) and SFE(int) were also highly significant (P < 0.0001). In setting 3, hyperpnea, but not tachypnea, caused significant (P < 0.01) increases in SFE(max) but not in SFE(int). In conclusion, dynamic comparisons between RIP and Pn provide a defensible method for quantifying AO during tidal breathing, without the need for invasive instrumentation.

Supersensitivity to isoprenaline induced in cultured neonatal rat heart cells by certain eicosatetraenoic acids.

Among a number of racemic eicosatetraenoic acids (HETEs) investigated, 15-R/S HETE and 11-R/S-HETE were the only ones that enormously potentiated the chronotropic action of isoprenaline on neonatal rat heart myocytes in rocked culture. The effect of the 15-R/S-HETE was exclusively due to the S isomer.

Modulation of the beta-adrenergic response in cultured rat heart cells. I. Beta-adrenergic supersensitivity is induced by lactate via a phospholipase A2 and 15-lipoxygenase involving pathway.

Incubation of rocker-cultured neonatal rat heart cells with 3 mM L(+)-lactate led to a sharp increase in the sensitivity of cardiomyocytes to the beta-adrenergic agonist isoprenaline, as measured by their chronotropic response. This effect was accompanied by a reduction in the arachidonic acid content of the total phospholipids. The phospholipase A2-activator melittin as well as free arachidonic acid induced this supersensitivity to the same degree. On the other hand, the L(+)-lactate-evoked supersensitivity could be blocked by the phospholipase A2 inhibitors mepacrine and n-bromophenacyl-bromide, suggesting an involvement of phospholipase A2 in the process of beta-adrenergic sensitization. The sensitizing action of arachidonic acid was blocked by the lipoxygenase inhibitors esculetin and nordihydroguaiaretic acid, but not by the cyclo-oxygenase inhibitor indomethacin. Supersensitivity was likewise evoked by 15-S-hydroxyeicosatetraenoic acid (15-S-HETE), but not by 5-S-HPETE or 5-S-HETE. These findings suggest that the phospholipase A2-15-lipoxygenase pathway plays a role in the induction of beta-adrenergic supersensitivity in the cultured cardiomyocytes and point to a new physiological role of the lipoxygenase product 15-S-HETE.

Modulation of the beta-adrenergic-response in cultured rat heart cells. II. Mammary-derived growth inhibitor (MDGI) blocks induction of beta-adrenergic supersensitivity. Dissociation from lipid-binding activity of MDGI.

'Mammary-derived growth inhibitor (MDGI)' is a 14.5 kDa polypeptide with growth-inhibitory activity for various mammary epithelial cells in vitro which is highly homologous to cardiac fatty acid-binding protein (H-FABP). Here we describe a new biological activity of MDGI: Inhibition of L(+)-lactate-, arachidonic acid- and 15-S-hydroxyeicosatetraenoic acid-induced supersensitivity of neonatal rat heart cells for beta-adrenergic stimulation, concerning particularly a small population of beta 2-receptors. Synthetic peptides corresponding to the MDGI-sequence, residue 121-131 mimic the effect of MDGI. Measurements of lipid-binding to MDGI and synthetic peptides excluded the binding of arachidonic acid, 15-S-hydroxyeicosatetraenoic acid or beta-adrenergic agonists to MDGI or the peptides as the mechanism for this effect. Also, no direct interference of MDGI and the synthetic peptides with the binding of the beta-adrenergic agent CGP 12177 to its receptor on A431 cells could be detected. We suggest that MDGI and the peptides act by interference with the function of the beta 2-adrenergic receptor and that this mechanism might also be relevant for the growth-inhibitory activity of MDGI. Furthermore, the data point to a possible function of H-FABP for the modulation of beta-adrenergic sensitivity of cardiac myocytes.

Clinical studies of families with hearing loss attributable to mutations in the connexin 26 gene (GJB2/DFNB1)

OBJECTIVE: This retrospective study describes the phenotype associated with the single most common cause of genetic hearing loss. The frequency of childhood deafness is estimated at 1/500. Half of this hearing loss is genetic and approximately 80% of genetic hearing loss is nonsyndromic and inherited in an autosomal recessive manner. Approximately 50% of childhood nonsyndromic recessive hearing loss is caused by mutations in the connexin 26 (Cx26) gene (GJB2/DFNB1), making it the most common form of autosomal recessive nonsyndromic hearing loss with a carrier rate estimated to be as high as 2.8%. One mutation, 35delG, accounts for approximately 75% to 80% of mutations at this gene. METHODS: Hearing loss was examined in 46 individuals from 24 families who were either homozygous or compound heterozygous for Cx26 mutations. A subset of these individuals were examined for vestibular function, otoacoustic emissions, auditory brainstem response, temporal bone computed tomography, electrocardiography, urinalyses, dysmorphology, and thyroid function. RESULTS: Although all persons had hearing impairment, no consistent audiologic phenotype was observed. Hearing loss varied from mild-moderate to profound, even within the group of families homozygous for the common mutation 35delG, suggesting that other factors modify the phenotypic effects of mutations in Cx26. Furthermore, the hearing loss was observed to be progressive in a number of cases. No associations with inner ear abnormality, thyroid dysfunction, heart conduction defect, urinalyses, dysmorphic features, or retinal abnormality were noted. CONCLUSION: Newborns with confirmed hearing loss should have Cx26 testing. Cx26 testing will help define a group in which approximately 60% will have profound or severe-profound hearing loss and require aggressive language intervention (many of these patients will be candidates for cochlear implants).