CD24(hi)CD27(+) B cells from patients with allergic asthma have impaired regulatory activity in response to lipopolysaccharide

BACKGROUND

Regulatory B cells have been identified that strongly reduce allergic and auto-immune inflammation in experimental models by producing IL-10. Recently, several human regulatory B-cell subsets with an impaired function in auto-immunity have been described, but there is no information on regulatory B cells in allergic asthma.

OBJECTIVE

In this study, the frequency and function of IL-10 producing B-cell subsets in allergic asthma were investigated.

METHODS

Isolated peripheral blood B cells from 13 patients with allergic asthma and matched healthy controls were analyzed for the expression of different regulatory B-cell markers. Next, the B cells were activated by lipopolysaccharide (LPS), CpG or through the B-cell receptor, followed by co-culture with endogenous memory CD4(+) T cells and house dust mite allergen DerP1.

RESULTS

Lower number of IL-10 producing B cells were found in patients in response to LPS, however, this was not the case when B cells were activated through the B-cell receptor or by CpG. Further dissection showed that only the CD24(hi)CD27(+) B-cell subset was reduced in number and IL-10 production to LPS. In response to DerP1, CD4(+) T cells from patients co-cultured with LPS-primed total B cells produced less IL-10 compared to similar cultures from controls. These results are in line with the finding that sorted CD24(hi)CD27(+) B cells are responsible for the induction of IL-10(+) CD4(+) T cells.

CONCLUSIONS

Taken together, these data indicate that CD24(hi)CD27(+) B cells from allergic asthma patients produce less IL-10 in response to LPS leading to a weaker IL-10 induction in T cells in response to DerP1, which may play a role in allergic asthma.

Distinctive Phenotypic Abnormalities Associated with Submicroscopic 21q22 Deletion Including DYRK1A

Partial monosomy 21 has been reported, but the phenotypes described are variable with location and size of the deletion. We present 2 patients with a partially overlapping microdeletion of 21q22 and a striking phenotypic resemblance. They both presented with severe psychomotor delay, behavioral problems, no speech, microcephaly, feeding problems with frequent regurgitation, idiopathic thrombocytopenia, obesity, deep set eyes, down turned corners of the mouth, dysplastic ears, and small chin. Brain MRI showed cerebral atrophy mostly evident in frontal and temporal lobes, widened ventricles and thin corpus callosum in both cases, and in one patient evidence of a migration disorder. The first patient also presented with epilepsy and a ventricular septum defect. The second patient had a unilateral Peters anomaly. Microarray analysis showed a partially overlapping microdeletion spanning about 2.5 Mb in the 21q22.1-q22.2 region including the DYRK1A gene and excluding RUNX1. These patients present with a recognizable phenotype specific for this 21q22.1-q22.2 locus. We searched the literature for patients with overlapping deletions including the DYRK1A gene, in order to define other genes responsible for this presentation.

Megalencephaly and perisylvian polymicrogyria with postaxial polydactyly and hydrocephalus (MPPH): report of a new case

Megalencephaly (MEG), or enlargement of the brain, can either represent a familial variant with normal cerebral structure, or a rare brain malformation associated with developmental delay and neurological problems. MEG has been split into two subtypes: anatomical and metabolic. The latter features a build-up inside the cells owing to metabolic causes. Anatomical MEG has been detected in many different conditions, including many overgrowth syndromes. In 2004 Mirzaa et al. reported five non-consanguineous patients with a new MCA/MR syndrome characterized by severe congenital MEG with polymicrogyria (PMG), postaxial polydactyly (POLY) and hydrocephalus (HYD). The authors argued that these findings identified a new and distinct malformation syndrome, which they named MPPH. We report on a new case of MPPH, the first to be described after the original series (Mirzaa et al., 2004).

Brain abnormalities in a case of malonyl-CoA decarboxylase deficiency

Malonyl-CoA decarboxylase (MCD) deficiency is an extremely rare inborn error of metabolism that presents with metabolic acidosis, hypoglycemia, and/or cardiomyopathy. Patients also show neurological signs and symptoms that have been infrequently reported. We describe a girl with MCD deficiency, whose brain MRI shows white matter abnormalities and additionally diffuse pachygyria and periventricular heterotopia, consistent with a malformation of cortical development. MLYCD-gene sequence analysis shows normal genomic sequence but no messenger product, suggesting an abnormality of transcription regulation. Our patient has strikingly low appetite, which is interesting in the light of the proposed role of malonyl-CoA in the regulation of feeding control, but this remains to be confirmed in other patients. Considering the incomplete understanding of the role of metabolic pathways in brain development, patients with MCD deficiency should be evaluated with brain MRI and unexplained malformations of cortical development should be reason for metabolic screening.

Alveolar nitric oxide versus measures of peripheral airway dysfunction in severe asthma

Alveolar nitric oxide (NO) is a measure of peripheral airway inflammation in asthma, potentially associated with disease severity. The relationship between alveolar NO and physiological tests of peripheral airway (dys)function has not been investigated. The present authors hypothesised that peripheral airway inflammation and dysfunction are inter-related and associated with asthma severity. Alveolar NO was compared between 17 patients with mild-to-moderate asthma and 14 patients with severe asthma and related to total lung capacity (TLC), residual volume (RV)/TLC, thoracic gas volume (FRC), slope of the single breath nitrogen washout curve (dN2), closing capacity (CC)/TLC and fall in forced vital capacity at the provocative concentration of methacholine causing a 20% fall in forced expiratory volume in one second. In patients with severe asthma, strong correlations were found between alveolar NO and RV/TLC % pred, FRC % pred, dN2, and CC/TLC. Patients with oral steroid-dependent asthma had higher alveolar NO levels (2.7 ppb) compared with the other patients with severe (0.6 ppb) and mild-to-moderate asthma (0.3 ppb). The present authors conclude that alveolar nitric oxide is closely related to parameters of peripheral airway dysfunction in patients with severe asthma, and that oral steroid-dependent asthmatics have more peripheral airway disease than nonsteroid-dependent asthmatics. This suggests that patients on chronic oral steroid treatment have more extensive disease and require additional anti-inflammatory treatment to better target the peripheral airways.

Homozygosity for the p.K136E mutation in the SLC17A5 gene as cause of an Italian severe Salla disease

Lysosomal free sialic acid storage diseases are recessively inherited allelic neurodegenerative disorders that include Salla disease (SD) and infantile sialic acid storage disease (ISSD) caused by mutations in the SLC17A5 gene encoding for a lysosomal membrane protein, sialin, transporting sialic acid from lysosomes. The classical form of SD, enriched in the Finnish population, is related to the p.R39C designed Salla(FIN) founder mutation. A more severe phenotype is due both to compound heterozygosity for the p.R39C mutation and to different mutations. The p.R39C has not been reported in ISSD. We identified the first case of SD caused by the homozygosity for p.K136E (c.406A>G) mutation, showing a severe clinical picture, as demonstrated by the early age at onset, the degree of motor retardation, the occurrence of peripheral nerve involvement, as well as cerebral hypomyelination. Recently, in vitro functional studies have shown that the p.K136E mutant produces a mislocalization and a reduced activity of the intracellular sialin. We discuss the in vivo phenotypic consequence of the p.K136E in relation to the results obtained by the in vitro functional characterization of the p.K136E mutant. The severity of the clinical picture, in comparison with the classical SD, may be explained by the fact that the p.K136E mutation mislocalizes the protein to a greater degree than p.R39C. On the other hand, the presence of a residual transport activity may account for the absence of hepatosplenomegaly, dysostosis multiplex, and early lethality typical of ISSD and related to the abolished transport activity found in this latter form.

Relationship between exhaled nitric oxide and airway hyperresponsiveness following experimental rhinovirus infection in asthmatic subjects

Exhaled nitric oxide (NO) is elevated in asthmatics, and varies with disease severity. We postulated that a respiratory virus infection increases exhaled NO levels in asthma, and examined the relationship between the virus-induced changes in exhaled NO and in airway hyperresponsiveness to histamine. In a parallel study, seven patients underwent experimental rhinovirus 16 (RV16) inoculation at days 0 and 1, whilst seven patients received placebo. Exhaled NO was measured at baseline (day 0) and at days 1, 2 and 3 after inoculation. Histamine challenges were performed prior to (day -7) and after inoculation (day 3), and were expressed as provocative concentration causing a 20% fall in forced expiratory volume in one second (FEV1) (PC20). Following RV16 infection there was a significant increase in NO at days 2 and 3 as compared to baseline (median change (range): 4.2 (7.5) parts per billion (ppb), p=0.03, and 3.0 (10.1) ppb, p=0.02, respectively). Furthermore, PC20 decreased significantly following RV16 infection (mean+/-SD change in doubling dose: -0.65+/-0.54, p=0.02), whereas PC20 did not change in the placebo group (p=0.1). There was a significant correlation between the RV16-induced changes in exhaled NO levels at day 2 and the accompanying changes in PC20 at day 3 (rank correlation coefficient (rs): 0.86, p=0.01). Hence, the greater the increase in exhaled NO, the smaller the decrease in PC20. We conclude that rhinovirus infection increases exhaled nitric oxide levels in asthmatics, and that this increase is inversely associated with worsening of airway hyperresponsiveness to histamine. These results suggest that viral induction of nitric oxide synthase within the airways may play a protective role in exacerbations of asthma.

Relationship between loss in parenchymal elastic recoil pressure and maximal airway narrowing in subjects with alpha1-antitrypsin deficiency

Airway hyperresponsiveness is characterized by an increase in sensitivity and excessive airway narrowing to inhaled bronchoconstrictor stimuli. There is experimental evidence that maximal airway narrowing is related to lung elasticity in normal and asthmatic subjects. We hypothesized that reduced lung elasticity by parenchymal destruction increases the level of maximal airway narrowing in subjects with alpha1-antitrypsin deficiency. To that end, we measured complete dose-response curves to methacholine, quasistatic pressure-volume (P-V) curves, diffusion capacity for carbon monoxide per unit lung volume (DLCO/VA), and mean lung density by spirometrically controlled computed tomography (CT) scan in eight non- or ex-smoking subjects with alpha1-antitrypsin deficiency. Methacholine dose-response curves were expressed as the provocative concentration causing 20% fall in FEV1 (PC20). A maximal response plateau was considered if > or = 3 highest doses fell within a 5% response range, the maximal response (MFEV1) being the average value on the plateau. The P-V curves were characterized by an index of compliance (exponent K), and elastic recoil pressures at 90, and 100% of TLC (PL90 and PLmax). In all subjects a complete dose-response curve to methacholine could be recorded. MFEV1 was significantly correlated with logPC20 (r = -0.94, p < 0.001), but not with baseline FEV1 (r = -0.53, p > 0.15). There was a significant relationship between MFEV1 and PL90 (r = -0.79, p < 0.02), PLmax (r = -0.87, p < 0.005), and K (r = 0.79, p < 0.02). Furthermore MFEV1 was significantly correlated with DLCO/VA (r = -0.76, p < 0.03) and with lung density (r = 0.78, p < 0.04). We conclude that in subjects with alpha1-antitrypsin deficiency the level of maximal airway narrowing increases with loss in lung elasticity, with reduction in diffusing capacity, and with lowered mean lung density. This suggests that loss in elastic recoil pressure secondary to parenchymal destruction contributes to excessive airway narrowing in humans in vivo.

Effects of 24R,25-dihydroxyvitamin D3 in combination with 1 alpha-hydroxyvitamin D3 in predialysis renal insufficiency: biochemistry and histomorphometry of cancellous bone

The effect of combined administration of 24R,25-dihydroxyvitamin D3 (24,25-(OH)2D3) and 1 alpha-hydroxyvitamin D3 (1 alpha-(OH)D3) was studied in 24 non-dialyzed patients with chronic renal insufficiency (CRI), matched pairwise as to age, sex, and creatinine clearance (Cr.cl). Low Ca intake had been supplemented beforehand. Then, 1 alpha-(OH)D3 (mean dose 0.55 micrograms daily) was given orally to all patients for 3 months (T0 to T3). Subsequently, patients were assigned randomly to 6 months further treatment either with 1 alpha-(OH)D3 alone (Group A) or with 1 alpha-(OH)D3 plus a high dosage of 24,25-(OH)2D3 (50 micrograms orally, twice weekly) (Group B). Histomorphometry was performed at T0, T3, and T9. In both groups iPTH was equally suppressed, into the lower normal range. Whereas in Group A, serum Ca rose steadily and Cr.cl declined, in Group B both parameters levelled off between T6 and T9. At T9, in Group A the elevated resorption and osteoid indices had normalized markedly, but osteoblasts (Ob.Pm) and mineralizing boundaries (M.Bd) were depressed considerably between T3 and T9. In contrast, in Group B, preservation of Ob.Pm and improved mineralizing activity were observed (M.Bd at T9 > T3 > T0). Resorption indices hardly changed. In the patients with high Ob.Pm at T0, cancellous bone area increased significantly. This was not observed in Group A. Thus, in Group B, osteoblast recruitment appeared maintained and M.Bd appeared normalized. Decline of remodeling toward an adynamic state with an increased risk of hypercalcemia appeared prevented.

A method for isolating smooth muscle cells from pig urinary bladder with low concentrations of collagenase and papain: the relation between calcium concentration and isolated cell length

The present study describes a method for isolating single smooth muscle cells from pig urinary bladder using a continuous resuspension device. Low concentrations of collagenase and papain were sufficient to obtain a high yield of viable smooth muscle cells, which remained viable for about 3-4 h as tested with fluorescein diacetate. Addition of fetal calf serum increased the lifespan of the isolated cells and the percentage of contractile smooth muscle cells, but caused spontaneous shortening of the cells. The length and volume of the isolated smooth muscle cells depended on the calcium concentration used in the isolation buffer solution. The isolated muscle cells were apparently relaxed if a calcium concentration less than 1.0 mmol/l was used in the isolation medium. In higher calcium concentrations the isolated cells were significantly shorter, probably as a result of a contraction caused by mechanical stimulation of the cells during the isolation procedure.

Cell length measurements in longitudinal smooth muscle strips of the pig urinary bladder

In this study the length of smooth muscle cells in muscle bundles of pig urinary bladder wall was determined after dissection in Tyrode buffers with different calcium concentrations ([Ca2+]). Previous studies have shown that the length of isolated smooth muscle cells decreases with an increase in [Ca2+] in the buffer. Unlike the results in isolated cells, no significant differences in length were found between cells in strips subjected to different [Ca2+]. Cells in bundles dissected from filled bladders were significantly larger than those dissected from emptied bladders. Cells in strips from emptied bladders dissected in 1.8 mM Ca(2+)-Tyrode buffer were shorter than those obtained in Ca(2+)-free buffer. From the measurements it was concluded that: (1) Cell length in intact tissue is directly related to tissue length; series elastic structures external to the cells do not allow significant shortening of the cells. (2) Passive parallel elasticity outside the cells accounts for passive shortening when bladders are emptied manually. (3) Cell length is not related to empty bladder weight. (4) A positive relation exists between empty bladder weight and bladder capacity.