Airway smooth muscle cell proliferation is increased in asthma

Increased airway smooth muscle (ASM) within the bronchial wall of asthmatic patients has been well documented and is likely to be the result of increased muscle proliferation. We have for the first time been able to culture ASM cells from asthmatic patients and to compare their proliferation rate with that of nonasthmatic patients. Asthmatic ASM cell cultures (n = 12) were established from explanted lungs and endobronchial biopsies. Nonasthmatic ASM cells (n = 10) were obtained from explanted tissue from patients with no airway disease, emphysema, carcinoma, and fibrosing alveolitis. Cell counts, tritiated thymidine incorporation, and cell cycle analysis were conducted over 7 d. Asthmatic ASM cell numbers at Days 3, 5, and 7 were significantly higher than corresponding values for nonasthmatic cells (p < 0.05). Tritiated thymidine incorporation was increased 3.2-fold in asthmatic cells compared with nonasthmatic cells within the first 24 h (p = 0.026). Flow cytometric analysis of DNA content on Days 1 and 2 revealed that a significantly greater percentage of asthmatic ASM cells were in the G2 + M phase (p < 0.05). This study shows for the first time that proliferation of ASM cells is increased in patients with asthma and provides evidence for an intrinsic abnormality in the ASM cell in this disease.

KEYWORDS

asthma; human airway smooth muscle; cell culture; cell proliferation; hyperplasia

Ordering of ruthenium cluster carbonyls in mesoporous silica

The anionic ruthenium cluster carbonylates [Ru6C(CO)16]2- or [H2Ru10(CO)25]2- interspersed with bis(triphenylphosphino)iminium counterions (PPN+) are incorporated from solution into the pores of MCM-41 mesoporous silica (3 nanometers in diameter), where they form tightly packed arrays. These arrays were shown by high-resolution transmission electron microscopy, Fourier transform optical diffraction, and computer simulations to be well ordered both along and perpendicular to the axis of the cylindrical pores. In their denuded state produced by gentle thermolysis, the cluster carbonylates yield nanoparticles of ruthenium that are less well ordered than their assimilated precursors but show good activity as hydrogenation catalysts for hexene and cyclooctene. In both their as-prepared and denuded states, these encapsulated clusters are likely to exhibit interesting electronic and other properties.

Partial and generalized epilepsy with febrile seizures plus and a novel SCN1A mutation

BACKGROUND

Generalized epilepsy with febrile seizures plus (GEFS+) is an autosomal dominant syndrome characterized by febrile seizures (FS) and a variety of afebrile generalized seizure types. GEFS+ has previously been linked to mutations in two genes encoding the voltage-gated sodium channel alpha-subunit (SCN1A) and beta1-subunit (SCN1B). We studied a large family with FS and partial as well as generalized seizure types.

METHODS

All but two living affected family members were interviewed and examined. Information on deceased affected family members was sought. EEG for 11 affected family members and one unaffected family member were obtained. Genetic linkage analysis and mutation screening of SCN1A were performed on blood samples from 16 affected individuals and their first-degree relatives.

RESULTS

There were 27 affected family members; 18 were alive at the time of the study. All affected family members had FS; seven had FS only, and 19 also had afebrile seizures. Eleven individuals continued to have FS beyond 6 years of age. FS were complex in 12 family members, usually with prolonged duration. The index patient had right temporal lobe epilepsy and hippocampal sclerosis. Four other patients had strong historical evidence of temporal lobe epilepsy, and three others had nonlocalizing evidence of partial epilepsy. Pedigree analysis indicated autosomal dominant transmission. All affected individuals who were tested and one asymptomatic individual had a sodium channel mutation of SCN1A, an A-->C transversion at nucleotide 3809 resulting in the substitution of lysine 1270 by threonine in the D3/S2 segment (designated as K1270T).

CONCLUSIONS

Our findings indicate that partial epilepsy preceded by FS can be associated with sodium channel mutations and may represent a variant of GEFS+.

The production of extracellular matrix proteins by human passively sensitized airway smooth-muscle cells in culture: the effect of beclomethasone

Airway remodeling is a key feature of persistent asthma. Part of the remodeling process involves the laying down of extracellular matrix (ECM) proteins within the airways. In this study we compared the production of ECM proteins by human airway smooth-muscle (ASM) cells in culture after exposure to 10% serum from an asthmatic individual or 10% serum from a nonasthmatic individual with or without beclomethasone (0.01 to 100 nM). Enzyme-linked immunosorbent assays were done with antibodies to human fibronectin; perlecan; elastin; the laminin beta(1), gamma(1), beta(2), alpha(1) chains; thrombospondin; chondroitin sulfate; collagen types I, III, IV, and V; versican; and decorin. Serum from the asthmatic individual, when compared with that from the nonasthmatic individual, caused a significant increase in the production of fibronectin, perlecan, laminin gamma(1), and chondroitin sulfate. Beclomethasone caused a significant reduction in the number of cells exposed to serum from either the asthmatic or nonasthmatic individual, but did not reverse the increase in ECM protein induced by the former. These results suggest an interaction between the ASM and the allergic process that may alter components of the airway wall in asthma, and that corticosteroids may not prevent the fibrosis induced by resident cells within the airways.

Dependence of lymphopenia-induced T cell proliferation on the abundance of peptide/ MHC epitopes and strength of their interaction with T cell receptors

Factors that affect naive T cell proliferation in syngeneic lymphopenic hosts were investigated. 2C T cell receptor (TCR) transgenic T cells lacking both CD8 and CD4 survived but hardly proliferated. Proliferation of CD8(+) 2C cells was proportional to the abundance of cognate peptide/MHC complexes and was severely inhibited by injection of anti-CD8 antibody. Weakly reactive self-peptides slightly enhanced CD8(+) 2C cell proliferation whereas a potent agonist peptide promoted much more rapid proliferation, but inflammation-stimulating adjuvant had only a small effect on the rate of cell proliferation. The findings suggest that under uniform lymphopenic conditions, the widely different rates of proliferation of T cells expressing various TCR, or the same TCR in the presence or absence of CD8, reflect the strength of interaction between TCR and MHC associated with particular self-peptides.

Structure Dependence of NO Adsorption and Dissociation on Platinum Surfaces

The influence of surface structure on NO chemisorption and dissociation on Pt[100]-(1x1), Pt[211], and Pt[410] has been studied using density functional theory slab calculations with the generalized gradient corrections. The presence of steps on Pt[211] strengthens the NO-surface chemisorption bond, but the barrier for NO dissociation remains high. On the other hand, the steps on Pt[410] help to stabilize the N and O adatoms that form upon dissociation and the transition state. The calculated barrier of 80.2 kJ/mol on Pt[410] is in good agreement with experiment. These results show that both the presence of steps and the nature of the steps are important to activate NO. An ensemble of square-arranged Pt atoms has been identified as an important feature in activating the N-O bond.

Molecular analysis of a major antigenic region of the 240-kD protein of Mi-2 autoantigen

Anti-Mi-2 autoantibody is strongly associated with dermatomyositis and found in sera of 20% of patients. Mi-2 antigen contains at least eight components and previous evidence suggested that the 240-kD protein was the antigenic component for at least some sera. In this study, anti-M-2 patient sera were used to screen human thymocyte and HeLa cell lambda gt11 expression libraries, and two clones from each had plaques specifically reactive with anti-Mi-2 sera. Studies with affinity-purified antibody supported the identification of the clones. All of 44 anti-Mi-2 sera reacted with the plaques, but none of 44 control sera reacted significantly. The cDNAs were identical, and full sequencing of one revealed an open reading frame spanning a 1,054-bp insert. Rescreening the library with the cDNA yielded a 1,589-bp cDNA that continued the open reading frame. The Mi-2 cDNA hybridized to a single 7.5-8.0 kb mRNA of HeLa cells, by Northern blot. Rabbit antiserum directed at a portion of the cDNA product reacted with HeLa 240-kD Mi-2 protein. The sequence was notable for four potential zinc-fingers and several charged regions. The protein encoded by the cDNA produced in vitro reacted with only one of five of the Mi-2 sera. These findings indicate that the Mi-2 240 kD is a novel protein that is antigenic for all Mi-2 sera, and strongly suggests that a major common epitope is conformational in nature.

Cloning of a complementary DNA coding for the 100-kD antigenic protein of the PM-Scl autoantigen

Anti-PM-Scl antibodies are associated with polymyositis-scleroderma overlap or either disease alone. Among sera from 39 patients with anti-PM-Scl, 23 recognized the 100-kD band in immunoblot against HeLa cell extract, 16 of which also stained the 70-kD band. A human thymocyte lambda gt11 cDNA expression library was screened with anti-PM-Scl serum, and two clones were identified whose products reacted with 33 and 37 of 39 anti-PM-Scl sera, respectively, but none of 26 negative control sera. Affinity-purified antibody reacting specifically with plaques of the clone stained the 100-kD band on immunoblot, reacted with nucleoli of HEp-2 cells, and immunoprecipitated the PM-Scl protein complex. Partial sequences of both inserts were identical. One insert was fully sequenced, and additional 5' and 3' sequence was obtained using a gene-specific primer to form a cDNA with HeLa cell RNA as template followed by PCR. The complete nucleotide sequence included 2,739-bp coding for a predicted full-length protein of 98,088 D. There was no homology with the PM-Scl 75-kD protein and no significant homology with other proteins. A mixed-charge cluster was identified, with 22 charged amino acids of 37. In conclusion, the full-length cDNA sequence was determined coding for the PM-Scl 100-kD protein, the most commonly antigenic protein of the PM-Scl complex.

Thyroid hormone concentrations in severely or critically ill patients with COVID-19

OBJECTIVE

COVID-19 is a new coronavirus infectious disease. We aimed to study the characteristics of thyroid hormone levels in patients with COVID-19 and to explore whether thyroid hormone predicts all-cause mortality of severely or critically ill patients.

METHODS

The clinical data of 100 patients with COVID-19, who were admitted to Wuhan Tongji Hospital from February 8 to March 8, 2020, were analyzed in this retrospective study. The patients were followed up for 6-41 days. Patients were grouped into non-severe illness and severe or critical illness, which included survivors and non-survivors. Multivariate Cox proportional hazards analysis was used to estimate hazard ratios (HRs) and 95% confidence intervals (CIs) for all-cause mortality in association with continuous and the lower two quartiles of thyroid hormone concentrations in severely or critically ill patients.

RESULTS

The means of free T3 (FT3) were 4.40, 3.73 and 2.76 pmol/L in non-severely ill patients, survivors and non-survivors, respectively. The lower (versus upper) two quartiles of FT3 was associated with all-cause mortality HR (95% CI) of 9.23 (2.01, 42.28). The HR (95% CI) for all-cause mortality in association with continuous FT3 concentration was 0.41 (0.21, 0.81). In the multivariate-adjusted models, free T4 (FT4), TSH and FT3/FT4 were not significantly related to all-cause mortality. Patients with FT3 less than 3.10 pmol/L had increased all-cause mortality.

CONCLUSION

FT3 concentration was significantly lower in patients with severe COVID-19 than in non-severely ill patients. Reduced FT3 independently predicted all-cause mortality of patients with severe COVID-19.

AMPA receptor activation and phosphatase inhibition affect neonatal rat respiratory rhythm generation

1. We investigated the role of alpha-amino-3-hydroxy-5-methylisoxazole-4-propionate (AMPA) receptors and their regulation in affecting respiratory-related neurones in a neonatal rat medullary slice that spontaneously generates respiratory-related rhythm and motor output in the hypoglossal (XII) nerve. 2. Bath application of the AMPA receptor antagonist 1-(4-aminophenyl)-4-methyl-7,8-methylenedioxy-5H-2, 3-benzodiazepine (GYKI) completely blocked XII nerve activity, as well as respiratory-related synaptic drives in neurones within the preBötzinger Complex (preBotC), site of rhythm generation in the slice. 3. Local application of GYKI to the preBötC blocked respiratory rhythm. Local application of AMPA to the preBötC increased rhythm frequency and depolarized respiratory-related neurones. 4. In the presence of tetrodotoxin (TTX), GYKI completely blocked the inward current induced by local application of AMPA, but not that induced by kainate. 5. Local application of okadaic acid, a membrane-permeable inhibitor of phosphatase 1 and 2A, to the preBotC increased the frequency of respiratory motor discharge. 6. Intracellular application of microcystin, a membrane-impermeable inhibitor of phosphatase 1 and 2A, enhanced endogenous inspiratory drive and exogenous AMPA-induced current (in the presence of TTX) in preBotC inspiratory neurones. Both the enhanced inspiratory drive and the increased AMPA-induced current were completely blocked by GYKI. 7. We suggest that AMPA receptor activation and AMPA receptor modulation by phosphorylation are crucial for the rhythm generation within the preBötC.

Dislocation-controlled perforated layer phase in a PEO- b-PS diblock copolymer

Small angle x-ray analyses show that the shear-induced hexagonal perforated layer phase in a poly(ethylene oxide)- b-polystyrene diblock copolymer consists of trigonal (R3;m) twins and a hexagonal (P6(3)/mmc) structure, with trigonal twins being majority components. Transmission electron microscopy reveals that the hexagonal structure is generated through sequential intrinsic stacking faults on the second layer from a previous edge dislocation line, while the trigonal twins are formed by successive intrinsic stacking faults on neighboring layers due to the plastic deformation under mechanical shear.

Corticosteroids and β₂-agonists upregulate mitogen-activated protein kinase phosphatase 1: in vitro mechanisms

BACKGROUND AND PURPOSE

Airway remodelling is a consequence of long-term inflammation and MAPKs are key signalling molecules that drive pro-inflammatory pathways. The endogenous MAPK deactivator--MAPK phosphatase 1 (MKP-1)--is a critical negative regulator of the myriad pro-inflammatory pathways activated by MAPKs in the airway.

EXPERIMENTAL APPROACH

Herein we investigated the molecular mechanisms responsible for the upregulation of MKP-1 in airway smooth muscle (ASM) by the corticosteroid dexamethasone and the β₂-agonist formoterol, added alone and in combination.

KEY RESULTS

MKP-1 is a corticosteroid-inducible gene whose expression is enhanced by long-acting β₂-agonists in an additive manner. Formoterol induced MKP-1 expression via the β₂-adrenoceptor and we provide the first direct evidence (utilizing overexpression of PKIα, a highly selective PKA inhibitor) to show that PKA mediates β₂-agonist-induced MKP-1 upregulation. Dexamethasone activated MKP-1 transcription in ASM cells via a cis-acting corticosteroid-responsive region located between -1380 and -1266 bp of the MKP-1 promoter. While the 3'-untranslated region of MKP-1 contains adenylate + uridylate elements responsible for regulation at the post-transcriptional level, actinomycin D chase experiments revealed that there was no increase in MKP-1 mRNA stability in the presence of dexamethasone, formoterol, alone or in combination. Rather, there was an additive effect of the asthma therapeutics on MKP-1 transcription.

CONCLUSIONS AND IMPLICATIONS

Taken together, these studies allow us a greater understanding of the molecular basis of MKP-1 regulation by corticosteroids and β₂-agonists and this new knowledge may lead to elucidation of optimized corticosteroid-sparing therapies in the future.

IκBα glutathionylation and reduced histone H3 phosphorylation inhibit eotaxin and RANTES

Airway smooth muscle cells (ASMCs) secrete eotaxin and RANTES (regulated on activation, normal T-cell expressed and secreted) in response to tumour necrosis factor (TNF)-α, which is inhibited by the nuclear factor (NF)-κB inhibitor dimethylfumarate (DMF). NF-κB/IκB (inhibitor of NF-κB) glutathionylation and changes in chromatin remodelling can inhibit NF-κB activity. In this study, we determined whether NF-κB/IκB glutathionylation and reduced histone H3 phosphorylation might underlie the inhibitory effect of DMF on NF-κB activity, and eotaxin and RANTES secretion. Primary human ASMCs were treated with DMF, diamide and/or glutathione (GSH) ethylester (OEt) prior to TNF-α stimulation and were subsequently analysed by ELISA, electrophoretic mobility shift assay, immunofluorescence, co-immunoprecipitation or immunoblotting. DMF reduced intracellular GSH and induced IκBα glutathionylation (IκBα-SSG), which inhibited IκBα degradation, NF-κB p65 nuclear entry and NF-κB/DNA binding. In addition, DMF inhibited the phosphorylation of histone H3, which was possibly mediated by the inhibitory effect of DMF on mitogen- and stress-activated protein kinase (MSK)-1. However, p38 mitogen-activated protein kinase (MAPK), extracellular signal-regulated kinase MAPK and MAPK phosphatase-1, upstream of MSK-1, were not inhibited by DMF. Importantly, DMF-mediated effects on NF-κB, histone H3, eotaxin and RANTES were reversed by addition of GSH-OEt. Our data suggest that DMF inhibits NF-κB-dependent eotaxin and RANTES secretion by reduction of GSH with subsequent induction of IκBα-SSG and inhibition of histone H3 phosphorylation. Our findings offer new potential drug targets to reduce airway inflammation in asthma.