Cyclosporin A and FK506 reduce interleukin-5 mRNA abundance by inhibiting gene transcription

Treatment of lymphocyte-variant hypereosinophilic syndrome (L-HES): what to consider after confirming the elusive diagnosis

Lymphocyte-variant hypereosinophilic syndrome (L-HES) is a rare disease driven by immunophenotypically aberrant T cells producing eosinophilopoetic cytokines such as interleukin-5 (IL-5). Treatment is challenging because L-HES is relatively steroid resistant and not amenable to tyrosine kinase inhibitors. We searched the literature for clinical trials and observational studies, including case reports, of patients treated for L-HES. In all, 25 studies were selected; two were randomised controlled trials of IL-5 blockade, which included some patients with L-HES, and the rest were observational studies. Corticosteroids are often used as first-line therapy, but patients with L-HES have lower response rates than other types of HES. Treatments that reduce symptoms and steroid dependence in some patients include interferon-alpha (IFN-α), anti-IL-5 monoclonal antibodies, cyclosporine and mycophenolate. These drugs target T-cell activation and proliferation, or IL-5 directly. Although effective, IFN-α and cyclosporine were commonly reported to cause side-effects resulting in discontinuation. Alemtuzumab can induce remissions, but these are generally short lived. The anti-IL-5 monoclonal antibodies mepolizumab and benralizumab are effective and well tolerated, but with a high rate of relapse once withdrawn. Hydroxyurea, methotrexate, imatinib were unsuccessful in most patients studied. More prospective clinical trials are needed for patients with L-HES.

Azithromycin in viral infections

Azithromycin (AZM) is a synthetic macrolide antibiotic effective against a broad range of bacterial and mycobacterial infections. Due to an additional range of anti-viral and anti-inflammatory properties, it has been given to patients with the coronaviruses SARS-CoV or MERS-CoV. It is now being investigated as a potential candidate treatment for SARS-CoV-2 having been identified as a candidate therapeutic for this virus by both in vitro and in silico drug screens. To date there are no randomised trial data on its use in any novel coronavirus infection, although a large number of trials are currently in progress. In this review, we summarise data from in vitro, murine and human clinical studies on the anti-viral and anti-inflammatory properties of macrolides, particularly AZM. AZM reduces in vitro replication of several classes of viruses including rhinovirus, influenza A, Zika virus, Ebola, enteroviruses and coronaviruses, via several mechanisms. AZM enhances expression of anti-viral pattern recognition receptors and induction of anti-viral type I and III interferon responses. Of relevance to severe coronavirus-19 disease (COVID-19), which is characterised by an over-exuberant innate inflammatory response, AZM also has anti-inflammatory properties including suppression of IL-1beta, IL-2, TNF and GM-CSF. AZM inhibits T cells by inhibiting calcineurin signalling, mammalian target of rapamycin activity and NFκB activation. AZM particularly targets granulocytes where it concentrates markedly in lysosomes, particularly affecting accumulation, adhesion, degranulation and apoptosis of neutrophils. Given its proven safety, affordability and global availability, tempered by significant concerns about antimicrobial stewardship, there is an urgent mandate to perform well-designed and conducted randomised clinical trials.

Effect of azithromycin on asthma exacerbations and quality of life in adults with persistent uncontrolled asthma (AMAZES): a randomised, double-blind, placebo-controlled trial

BACKGROUND

Exacerbations of asthma cause a substantial global illness burden. Adults with uncontrolled persistent asthma despite maintenance treatment require additional therapy. Since macrolide antibiotics can be used to treat persistent asthma, we aimed to assess the efficacy and safety of oral azithromycin as add-on therapy in patients with uncontrolled persistent asthma on medium-to-high dose inhaled corticosteroids plus a long-acting bronchodilator.

METHODS

We did a randomised, double-blind, placebo controlled parallel group trial to determine whether oral azithromycin decreases the frequency of asthma exacerbations in adults (≥18 years) with symptomatic asthma despite current use of inhaled corticosteroid and long-acting bronchodilator, and who had no hearing impairment or abnormal prolongation of the corrected QT interval. Patients were randomly assigned (1:1) to receive azithromycin 500 mg or placebo three times per week for 48 weeks. Patients were centrally allocated using concealed random allocation from a computer-generated random numbers table with permuted blocks of 4 or 6 and stratification for centre and past smoking. Primary efficacy endpoints were the rate of total (severe and moderate) asthma exacerbations over 48 weeks and asthma quality of life. Data were analysed on an intention-to-treat basis. The trial is registered at the Australian and New Zealand Clinical Trials Registry (ANZCTR), number 12609000197235.

FINDINGS

Between June 12, 2009, and Jan 31, 2015, 420 patients were randomly assigned (213 in the azithromycin group and 207 in the placebo group). Azithromycin reduced asthma exacerbations (1·07 per patient-year [95% CI 0·85-1·29]) compared with placebo (1·86 per patient-year [1·54-2·18]; incidence rate ratio [IRR] 0·59 [95% CI 0·47-0·74]; p<0·0001). The proportion of patients experiencing at least one asthma exacerbation was reduced by azithromycin treatment (127 [61%] patients in the placebo group vs 94 [44%] patients in the azithromycin group, p<0·0001). Azithromycin significantly improved asthma-related quality of life (adjusted mean difference, 0·36 [95% CI 0·21-0·52]; p=0·001). Diarrhoea was more common in azithromycin-treated patients (72 [34%] vs 39 [19%]; p=0·001).

INTERPRETATION

Adults with persistent symptomatic asthma experience fewer asthma exacerbations and improved quality of life when treated with oral azithromycin for 48 weeks. Azithromycin might be a useful add-on therapy in persistent asthma.

FUNDING

National Health and Medical Research Council of Australia, John Hunter Hospital Charitable Trust.

Bilirubin prevents acute DSS-induced colitis by inhibiting leukocyte infiltration and suppressing upregulation of inducible nitric oxide synthase

Bilirubin is thought to exert anti-inflammatory effects by inhibiting vascular cell adhesion molecule-1 (VCAM-1)-dependent leukocyte migration and by suppressing the expression of inducible nitric oxide synthase (iNOS). As VCAM-1 and iNOS are important mediators of tissue injury in the dextran sodium sulfate (DSS) murine model of inflammatory colitis, we examined whether bilirubin prevents colonic injury in DSS-treated mice. Male C57BL/6 mice were administered 2.5% DSS in the drinking water for 7 days, while simultaneously receiving intraperitoneal injections of bilirubin (30 mg/kg) or potassium phosphate vehicle. Disease activity was monitored, peripheral blood counts and serum nitrate levels were determined, and intestinal specimens were analyzed for histological injury, leukocyte infiltration, and iNOS expression. The effect of bilirubin on IL-5 production by HSB-2 cells and on Jurkat cell transendothelial migration also was determined. DSS-treated mice that simultaneously received bilirubin lost less body weight, had lower serum nitrate levels, and exhibited reduced disease severity than vehicle-treated animals. Concordantly, histopathological analyses revealed that bilirubin-treated mice manifested significantly less colonic injury, including reduced infiltration of eosinophils, lymphocytes, and monocytes, and diminished iNOS expression. Bilirubin administration also was associated with decreased eosinophil and monocyte infiltration into the small intestine, with a corresponding increase in peripheral blood eosinophilia. Bilirubin prevented Jurkat migration but did not alter IL-5 production. In conclusion, bilirubin prevents DSS-induced colitis by inhibiting the migration of leukocytes across the vascular endothelium and by suppressing iNOS expression.

The effect of topical FK506 (tacrolimus) in a mouse model of allergic rhinitis

BACKGROUND

The management of allergic rhinitis (AR) encompasses education, pharmacotherapy, immunotherapy, and surgery. FK506 (tacrolimus) is an immunosuppressant that inhibits allergic reactions. The purpose of this study was to reveal whether FK506 treatment reduces allergic inflammation in an AR mouse model and to elucidate the mechanisms.

METHODS

Forty mice were divided into four groups: control, AR, FK (FK506), and dexamethasone (DEX). All mice except for the control group were sensitized by an i.p. injection of ovalbumin (OVA). After sensitization, the FK and DEX groups were treated with FK506 and DEX intranasally. All sensitized mice were challenged intranasally with OVA. Allergic symptoms and tissue eosinophil counts were recorded. Interleukin (IL)-5, interferon gamma, and IL-10 levels in nasal lavage fluid (NALF) and serum OVA-specific IgE levels were measured. T-bet, GATA-3, and Foxp3 mRNA expression in splenic mononuclear cells were determined by real-time polymerase chain reaction.

RESULTS

In the FK group and DEX group, allergic symptoms, serum OVA-specific IgE, tissue eosinophil counts, IL-5 in NALF, and GATA-3 mRNAs expression decreased (p < 0.05), and IL-10 in NALF and Foxp3 mRNAs expression increased compared with the AR group (p < 0.05). No significant difference was observed between the FK group and the DEX group.

CONCLUSION

These results suggest that topical FK506 may reduce allergic inflammation and have potency equal to DEX in the AR model. This mechanism may involve not only Th2 cells but also regulatory T cells. Additional studies are needed on FK506, but in the future, we can consider FK506 as an alternative to topical steroids in the treatment of AR.

The cytokine network in asthma and chronic obstructive pulmonary disease

Asthma and chronic obstructive pulmonary disease (COPD) are very common inflammatory diseases of the airways. They both cause airway narrowing and are increasing in incidence throughout the world, imposing enormous burdens on health care. Cytokines play a key role in orchestrating the chronic inflammation and structural changes of the respiratory tract in both asthma and COPD and have become important targets for the development of new therapeutic strategies in these diseases.

Biology of the eosinophil

In this review, we aim to put in perspective the biology of a multifunctional leukocyte, the eosinophil, by placing it in the context of innate and adaptive immune responses. Eosinophils have a unique contribution in initiating inflammatory and adaptive responses, due to their bidirectional interactions with dendritic cells and T cells, as well as their large panel of secreted cytokines and soluble mediators. The mechanisms and consequences of eosinophil responses in experimental inflammatory models and human diseases are discussed.

High-mobility group box proteins modulate tumor necrosis factor-alpha expression in osteoclastogenesis via a novel deoxyribonucleic acid sequence

We have previously shown that mice lacking the TSH receptor (TSHR) exhibit osteoporosis due to enhanced osteoclast formation. The fact that this enhancement is not observed in double-null mice of TSHR and TNFalpha suggests that TNFalpha overexpression in osteoclast progenitors (macrophages) may be involved. It is unknown how TNFalpha expression is regulated in osteoclastogenesis. Here, we describe a receptor activator for nuclear factor-kappaB ligand (RANKL)-responsive sequence (CCG AGA CAG AGG TGT AGG GCC), spanning from -157 to -137 bp of the 5'-flanking region of the TNFalpha gene, which functions as a cis-acting regulatory element. We further show how RANKL treatment stimulates the high-mobility group box proteins (HMGB) HMGB1 and HMGB2 to bind the RANKL-responsive sequence and up-regulates TNFalpha transcription. Exogenous HMGB elicits the expression of cytokines, including TNFalpha, as well as osteoclast formation. Conversely, TSH inhibits the expression of HMGB and TNFalpha and the formation of osteoclasts. These results suggest that HMGB play a pivotal role in osteoclastogenesis. We also show a direct correlation between the expression of HMGB and TNFalpha and osteoclast formation in TSHR-null mice and TNFalpha-null mice. Taken together, we conclude that HMGB and TNFalpha play critical roles in the regulation of osteoclastogenesis and the remodeling of bone.

Eosinophilic inflammation: mechanisms regulating IL-5 transcription in human T lymphocytes

BACKGROUND

Interleukin (IL)-5 is a key regulator of eosinophilia in allergic inflammation and parasite infections but the mechanisms regulating IL-5 expression in activated human T lymphocytes are poorly understood. From studies on mouse cells, the activation protein (AP)-1 and GATA-3 sites in the proximal promoter region appear to be important in IL-5 regulation but the significance of an adjacent Ets/nuclear factor of activated T cell (NFAT) site has been less clear.

METHODS

Interleukin-5 transcriptional activity was measured by transfection of reporter genes into the human HSB-2 cells and normal T lymphocytes. Expression vectors encoding transcription factors were used for transactivation studies and IL-5 expression measured using reporter genes and mRNA levels. Transcription factor binding was shown with chromatin immunoprecipitation (ChIP).

RESULTS

HSB-2 cells showed high inducible expression of IL-5 mRNA. Mutation of reporter gene plasmids showed the Ets/NFAT site was of equal importance to the AP-1 and GATA-3 sites in regulating IL-5 transcription. Transactivation by Ets1 increased luciferase expression 15-fold, in the absence of stimulation, and AP-1 (c-Fos/c-Jun) and GATA-3 gave transactivations of 85-fold, and 100-fold, respectively. Synergistic interactions were demonstrated between Ets1, GATA-3 and AP-1. Dominant-negative AP-1 inhibited IL-5 transcription. Transactivation by GATA-3 and synergy between GATA-3, Ets1 and AP-1 were verified measuring IL-5 mRNA levels. Chromatin immunoprecipitation showed increased binding of Ets1 and GATA-3 to the IL-5 promoter after stimulation. The importance of the Ets1 site and of synergistic interactions between the three transcription factors were verified with primary human T cells.

CONCLUSION

Ets1, GATA-3 and AP-1 synergize to regulate IL-5 transcription in human T cells.

Heat shock transcription factor 1 down-regulates spermatocyte-specific 70 kDa heat shock protein expression prior to the induction of apoptosis in mouse testes

Expression of constitutively active heat shock transcription factor 1 (HSF1) in mouse spermatocytes induces apoptosis and leads to male infertility. We report here that prior to the onset of massive apoptosis caused by expression of active HSF1 in spermatocytes a marked reduction in spermatocyte-specific Hsp70.2 mRNA and protein levels occurs. In addition, HSP70.2 protein relocalizes from a predominant cytoplasmic to a nuclear position in developing spermatocytes that express active HSF1. Later in the developmental stages, cells undergoing HSF1-induced apoptosis essentially lack the HSP70.2 protein. The down-regulation of Hsp70.2 gene expression by HSF1 is paradoxical because HSF1 is the prototypical activator of HSP genes. Furthermore, HSF1-mediated repression neither involved a heat shock element (HSE)-like sequence adjacent to the Hsp70.2 gene nor were Hsp70.2 promoter sequences associated directly with HSF1. Interestingly, other spermatocyte- and spermatid-specific transcripts are also down-regulated in testes of transgenic mice expressing active HSF1, suggesting involvement of a putative HSF1-dependent block of development of spermatogenic cells. Importantly however, transcription of the Hsp70.2 gene is down-regulated in testes of wild-type mice subjected to a hyperthermia that induces transient activation of HSF1, indicating that the spermatocyte-specific activity of HSF1 might misdirect a network of transcription factors required for proper regulation of Hsp70.2.

Eosinophilic folliculitis in a Caucasian patient: association with toxocariasis?

Sterile eosinophilic folliculitis, a clinical entity first described by Ofuji in 1970, is a rather rare skin disorder, in particular in the non-Asian population. We report the first case of eosinophilic folliculitis associated with toxocariasis in a Caucasian patient. Topical and systemic anti-inflammatory and antiphlogistic therapy along with systemic antihelminthic treatment resulted in complete remission of the skin lesions. In addition, there was a marked decrease of antibodies to Toxocara antigens in the patient's serum following antihelminthic therapy. Given that (I) some cases of eosinophilic folliculitis have been reported which were associated with infestation with metazoan parasites; (2) infestations with the roundworm Toxocara canis are known to induce eosinophilic reactions in some tissues; and (3) therapy-induced remission of eosinophilic folliculitis was accompanied by a decrease of Toxocara-directed antibodies in the patient's serum, we propose that there is an aetiopathogenic link between toxocariasis and eosinophilic folliculitis in this patient.

IL-9 modulated MUC4 gene and glycoprotein expression in airway epithelial cells

Compromised epithelial cell integrity is a common feature associated with chronic lung inflammatory states such as asthma. While epithelial cell damage is largely due to sustained effects of inflammatory mediators localized to airways, the subsequent process of epithelial cell differentiation is attributed to members of the transmembrane receptor tyrosine kinase family called the ErbB's. MUC4, a large molecular weight membrane-bound glycoprotein, has recently been identified as a potential ligand for the ErbB-2 receptor. In this study, we investigated the possible role of interleukin-9 (IL-9), a Th2 cytokine, on MUC4 expression using a lung cancer cell line, NCI-H650. We determined that IL-9 up-regulates MUC4 expression in a time and concentration-dependent fashion. Nuclear run-on assays indicated transcriptional regulation of MUC4 while no post-transcriptional mRNA stabilization was observed by actinomycin D chase experiments. IL-9 also increased MUC4 glycoprotein expression as determined by Western blots using a monoclonal antibody specific for a non-tandem repeat region on ASGP-2 region of MUC4. Furthermore, a JAK3-selective inhibitor 4-(4'-hydroxyphenyl) amino-6, 7-dimethoxyquinazoline (WHI-P131), substantially reduced IL-9-induced MUC4 mRNA expression in a dose-dependent fashion. These results implicate a potential role for IL-9 upon MUC4 expression in human airway epithelial cells.

IL-4 induced MUC4 enhancement in respiratory epithelial cells in vitro is mediated through JAK-3 selective signaling

BACKGROUND

Recent studies have identified MUC4 mucin as a ligand for activation of ErbB2, a receptor tyrosine kinase that modulates epithelial cell proliferation following epithelial damage in airways of asthmatics. In this study, we investigated the potential role of IL-4, one of the Th2 inflammatory cytokines persistent in asthmatic airways, in regulating MUC4 expression using a cell line NCI-H650.

METHODS

Real time PCR analysis was performed to determine concentration and time dependent effects of IL-4 upon MUC4 expression. Nuclear run on experiments were carried out to explore potential transcriptional modulation. Western blotting experiments using a monoclonal antibody specific to ASGP-2 domain of MUC4 were performed to analyze MUC4 glycoprotein levels in plasma membrane fractions. To analyze potential signal transduction cascades, IL-4 treated confluent cultures were co-incubated, separately with a pan-JAK inhibitor, a JAK-3 selective inhibitor or a MEK-1, 2 (MAPK) inhibitor at various concentrations before MUC4 transcript analysis. Corresponding transcription factor activation was tested by western blotting using a monoclonal p-STAT-6 antibody.

RESULTS

MUC4 levels increased in a concentration and time specific fashion reaching peak expression at 2.5 ng/ml and 8 h. Nuclear run on experiments revealed transcriptional enhancement. Corresponding increases in MUC4 glycoprotein levels were observed in plasma membrane fractions. Pan-JAK inhibitor revealed marked reduction in IL-4 stimulated MUC4 levels and JAK3 selective inhibitor down-regulated MUC4 mRNA expression in a concentration-dependent fashion. In accordance with the above observations, STAT-6 activation was detected within 5 minutes of IL-4 stimulus. No effect in MUC4 levels was observed on using a MAPK inhibitor.

CONCLUSION

These observations signify a potential role for IL-4 in MUC4 up-regulation in airway epithelia.

Aging increases stromal/osteoblastic cell-induced osteoclastogenesis and alters the osteoclast precursor pool in the mouse

Stromal/osteoblastic cell expression of RANKL and M-CSF regulates osteoclastogenesis. We show that aging is accompanied by increased RANKL and M-CSF expression, increased stromal/osteoblastic cell-induced osteoclastogenesis, and expansion of the osteoclast precursor pool. These changes correlate with age-related alterations in the relationship between osteoblasts and osteoclasts in cancellous bone.

INTRODUCTION

Bone mass is maintained through a balance between osteoblast and osteoclast activity. Osteoblasts regulate the number and activity of osteoclasts through expression of RANKL, osteoprotegerin (OPG), and macrophage-colony stimulation factor (M-CSF). To determine whether age-related changes in stromal/osteoblastic cell expression of RANKL, OPG, and M-CSF are associated with stimulation of osteoclastogenesis and whether the osteoclast precursor pool changes with age, we studied cultures of stromal/osteoblastic cells and osteoclast precursor cells from animals of different ages and examined how aging influences bone cell populations in vivo.

MATERIALS AND METHODS

Osteoclast precursors from male C57BL/6 mice of 6 weeks (young), 6 months (adult), and 24 months (old) of age were either co-cultured with stromal/osteoblastic cells from young, adult, or old mice or treated with M-CSF, RANKL, and/or OPG. Osteoclast precursor pool size was determined by fluorescence-activated cell sorting (FACS), and osteoclast formation was assessed by measuring the number of multinucleated TRACP(+) cells and pit formation. The levels of mRNA for RANKL, M-CSF, and OPG were determined by quantitative RT-PCR, and transcription was measured by PCR-based run-on assays. Osteoblast and osteoclast numbers in bone were measured by histomorphometry.

RESULTS

Osteoclast formation increased dramatically when stromal/osteoblastic cells from old compared with young donors were used to induce osteoclastogenesis. Regardless of the origin of the stromal/osteoblastic cells, the number of osteoclasts formed from the nonadherent population of cells increased with increasing age. Stromal/osteoblastic cell expression of RANKL and M-CSF increased, whereas OPG decreased with aging. Exogenously administered RANKL and M-CSF increased, dose-dependently, osteoclast formation from all donors, but the response was greater in cells from old donors. Osteoclast formation in vitro positively, and the ratio of osteoblasts to osteoclasts in vivo negatively, correlated with the ratio of RANKL to OPG expression in stromal/osteoblastic cells for all ages. The effects of RANKL-induced osteoclastogenesis in vitro were blocked by OPG, suggesting a causal relationship between RANKL expression and osteoclast-inducing potential. The osteoclast precursor pool and expression of RANK and c-fms increased with age.

CONCLUSIONS

Our results show that aging significantly increases stromal/osteoblastic cell-induced osteoclastogenesis, promotes expansion of the osteoclast precursor pool and alters the relationship between osteoblasts and osteoclasts in cancellous bone.

Interleukin-10 Induces Uteroglobin-related Protein (UGRP) 1 Gene Expression in Lung Epithelial Cells through Homeodomain Transcription Factor T/EBP/NKX2.1

UGRP1 is a downstream target gene for homeodomain transcription factor T/EBP/NKX2.1, which is predominantly expressed in lung epithelial cells, and may play an anti-inflammatory role in lung inflammation. To understand the role of UGRP1 in inflammation, its expression was investigated in relation to cytokine signaling. In vivo experiments using mouse embryonic lung organ culture and intranasal administration of interleukin (IL) 10 revealed that constitutive expression of Ugrp1 mRNA is enhanced by IL-10. Increase of protein levels was also demonstrated by immunohistochemistry using embryonic lungs. This IL-10 induction of Ugrp1 gene expression occurs at the transcriptional level when examined using mouse embryonic lung primary cultures. In human lung NCI-H441 cells that in contrast to mouse lung cells, do not exhibit constitutive expression of the gene, expression of the UGRP1 gene was induced in a rapid and stable fashion. Two T/EBP, but not STAT3, binding sites located in the human UGRP1 gene promoter are responsible for IL-10 induction of the UGRP1 gene as judged by transfection, gel shift, and chromatin immunoprecipitation analyses. The IL-10 receptor chains, IL-10R1 and IL-10R2, are expressed in H441 cells, however, STAT3 was only weakly activated upon IL-10 treatment. In contrast, STAT3 was strongly activated when the cells were treated with other cytokines such as IL-22 and interferon-beta but UGRP1 expression was not increased. Together these results demonstrate that IL-10 induces UGRP1 gene expression in lung epithelial cells through a T/EBP/NKX2.1-dependent pathway. The results further suggest that UGRP1 might be a target for IL-10 anti-inflammatory activities in the lung.

Post-transcriptional Control of Human maxiK Potassium Channel Activity and Acute Oxygen Sensitivity by Chronic Hypoxia

Various cardiorespiratory diseases (e.g. congestive heart failure, emphysema) result in systemic hypoxia and patients consequently demonstrate adaptive cellular responses which predispose them to conditions such as pulmonary hypertension and stroke. Central to many affected excitable tissues is activity of large conductance, Ca2+-activated K+ (maxiK) channels. We have studied maxiK channel activity in HEK293 cells stably co-expressing the most widely distributed of the human alpha- and beta-subunits that constitute these channel following maneuvers which mimic severe hypoxia. At all [Ca2+]i, chronic hypoxia (approximately 18 mm Hg, 72 h) increased K+ current density, most markedly at physiological [Ca2+]i K+ currents in cells cultured in normoxia showed a [Ca2+]i-dependent sensitivity to acute hypoxic inhibition ( approximately 25 mm Hg, 3 min). However, chronic hypoxia dramatically changed the Ca2+ sensitivity of this acute hypoxic inhibitory profile such that low [Ca2+]i could sustain an acute hypoxic inhibitory response. Chronic hypoxia caused no change in alpha-subunit immunoreactivity with Western blotting but evoked a 3-fold increase in beta-subunit expression. These observations were fully supported by immunocytochemistry, which also suggested that chronic hypoxia augmented alpha/beta-subunit co-localization at the plasma membrane. Using a novel nuclear run-on assay and RNase protection we found that chronic hypoxia did not alter mRNA production rates or steady-state levels, which suggests that this important environmental cue modulates maxiK channel function via post-transcriptional mechanisms.

Evidence for post-transcriptional regulation of interleukin-5 by dexamethasone

Interleukin-5 (IL-5) is a T helper type 2 cytokine, which is implicated in the pathogenesis of eosinophilic diseases such as asthma. Both peripheral blood mononuclear cells (PBMC) and primary human T cells display similar patterns of IL-5 expression when stimulated with both phorbol-12-myristate 13-acetate and phytohaemagglutinin. The expression of IL-5 stimulated by these agents was shown to require de novo transcription and translation. However, although dexamethasone was a potent inhibitor of both IL-5 release and messenger RNA accumulation from PBMC and T cells, dexamethasone had no effect on the luciferase activity of a reporter construct under the control of an IL-5 promoter region transiently transfected into primary human T cells. Furthermore, dexamethasone appeared to decrease the stability of IL-5 messenger RNA and this effect was dependent upon de novo transcription. Taken together, the results presented here suggest that, whilst transcriptional processes predominantly regulate IL-5 release, the mechanism by which dexamethasone inhibits IL-5 is post-transcriptional.

Ocular allergy guidelines: a practical treatment algorithm

The treatment of ocular allergy requires a better understanding of the spectrum of clinical disorders involving various components of the immune system, and of interactions at the conjunctival surface. The immune response focuses primarily on the different levels of activity of Th2 lymphocytes and various other immune cells associated with allergic disorders, including mast cells, eosinophils, fibroblasts, and epithelial and endothelial cells. Ocular allergic disorders include seasonal allergic conjunctivitis (SAC), perennial allergic conjunctivitis (PAC), vernal keratoconjunctivitis (VKC), giant papillary conjunctivitis (GPC) and atopic keratoconjunctivitis (AKC), which, through immunopathological and molecular immunological techniques, can all be better appreciated as being part of a larger spectrum of an atopic disease state. In SAC, pathological changes, such as increased mast-cell activation, the presence of migratory inflammatory cells, and early signs of cellular activation at the molecular level, are minimal. In PAC, these changes are more pronounced in line with the increased duration of allergenic stimulation. In more chronic forms of allergic conjunctivitis, such as VKC in children and AKC in adults, the following changes are evident: a persistent state of mast cell, eosinophil and lymphocyte activation; noted switching from connective-tissue to mucosal-type mast cells; increased involvement of corneal pathology; and follicular development and fibrosis. The treatment of acute and more chronic forms of allergic conjunctivitis has focused in the past on symptomatic relief of symptoms, but with a better understanding of the mechanisms involved we can now provide interventional therapeutic strategies and symptomatic relief. Our advances in the basic understanding of these conditions are providing the foundation for guidelines that improve the ocular health of patients with ocular allergies.

The human IL-3 locus is regulated cooperatively by two NFAT-dependent enhancers that have distinct tissue-specific activities

The human IL-3 gene is expressed by activated T cells, mast cells, and eosinophils. We previously identified an enhancer 14 kb upstream of the IL-3 gene, but this element only functioned in a subset of T cells and not in mast cells. To identify additional mechanisms governing IL-3 gene expression, we mapped DNase I hypersensitive (DH) sites and evolutionarily conserved DNA sequences in the IL-3 locus. The most conserved sequence lies 4.5 kb upstream of the IL-3 gene and it encompassed an inducible cyclosporin A-sensitive DH site. A 245-bp fragment spanning this DH site functioned as a cyclosporin A-sensitive enhancer, and was induced by calcium and kinase signaling pathways in both T cells and mast cells via an array of three NFAT sites. The enhancer also encompassed AML1, AP-1, and Sp1 binding sites that potentially mediate function in both T and myeloid lineage cells, but these sites were not required for in vitro enhancer function in T cells. In stably transfected T cells, the -4.5-kb enhancer cooperated with the -14-kb enhancer to activate the IL-3 promoter. Hence, the IL-3 gene is regulated by two enhancers that have distinct but overlapping tissue specificities. We also identified a prominent constitutive DH site at -4.1 kb in T cells, mast cells, and CD34(+) myeloid cells. This element lacked in vitro enhancer function, but may have a developmental role because it appears to be the first DH site to exist upstream of the IL-3 gene during hemopoietic development before IL-3 expression.

Roles of CCAAT/enhancer-binding protein in transcriptional regulation of the human IL-5 gene

Interleukin-5 (IL-5) plays a critical role in the pathogenesis of eosinophil-associated allergic disorders, such as asthma. IL-5 may also play a major role in the development of eosinophilia-associated lymphoproliferative disorders caused by human T lymphotropic virus type I (HTLV-I). In this study, we have investigated the control mechanisms for IL-5 production and found that ectopic expression of NF-IL6 (C/EBPbeta) increases endogenous IL-5 mRNA expression. The IL-5 promoter contains four C/EBP consensus sequences. We show here that one of the C/EBP site at - 235 promoter region binds to NF-IL6 protein with high affinity and interacts with NF-IL6 and NF-IL6beta (C/EBPdelta) in Jurkat T cells. Mutations within the C/EBP sequence reduced the promoter activity in response to T cell activation by more than 50 %. In addition, we show that in vivo inducible expression of Tax protein in Jurkat T cells stably transfected with Tax further increased ionomycin plus phorbol ester stimulated IL-5 promoter activity. The effect of Tax on IL-5 promoter activity was abolished when the C/EBP site was mutated. Thus, the C/EBP site may be also involved in HTLV-I Tax-mediated up-regulation of IL-5 gene expression. Our data suggest that C/EBP proteins may regulate IL-5 gene expression in response to different stimulation signals.

Effects of cyclosporin A administered into the airways against antigen-induced airway inflammation and hyperreactivity in the rat

The immunosuppressant cyclosporin A given orally has anti-asthma properties but carries an undesirable risk of systemic effects. We administered cyclosporin A to Brown Norway rats either orally (p.o.) or topically by intratracheal (i.t.) instillation into the airways before inhaled antigen. Cyclosporin A suppressed the antigen-induced accumulation of activated (CD25+) CD4+ T lymphocytes and eosinophils in the lung, interleukin-5 mRNA expression in lung tissue and airway hyperreactivity. Intratracheal cyclosporin A suppressed cell accumulation at a 10-fold lower dose than that required orally. Minimum effective doses were 3 mg x kg(-1) i.t. and 30 mg x kg(-1) p.o. Intratracheal administration reduced the plasma concentration and systemic exposure compared with an equieffective oral dose, but the reduction (4-5-fold) was not as large as anticipated. Our data suggests that although topical administration to asthmatics would provide some potential for an improved safety margin, it may not offer any major advantage over existing oral therapy. However, the data clearly demonstrate that a novel immunosuppressant with similar anti-inflammatory properties but reduced potential for systemic effects would offer an attractive therapy for severe asthma.

Expression of DNA topoisomerases in chronic proliferative kidney disease

BACKGROUND

Circulating autoantibodies to human topoisomerases have been reported in glomerular kidney disease associated with scleroderma and systemic lupus erythematosus. However, limited information is available about the expression of topoisomerases in the kidney under normal and pathological conditions.

METHODS

The expression of DNA topoisomerases I and IIalpha was studied by immunohistochemistry on archival biopsies from 70 patients with chronic renal diseases. Normal kidney tissue was examined for comparison. Topoisomerase I was detected by means of monoclonal antibody (mAb) C21, and topoisomerase IIalpha was detected by means of mAb Ki-S4. In addition, mAb Ki-M1p was used to assess the density of monocytic infiltrates. All parameters were assessed in a semiquantitative manner.

RESULTS

Glomerular topoisomerase IIalpha levels were increased in mesangial proliferative glomerulonephritis (MPGN), rapidly progressive glomerulonephritis (RPGN), and lupus nephritis (LN) and were reduced in membranous glomerulonephritis (MGN), chronic transplant nephropathy (CTN), and tubulointerstitial nephritis (TIN). Tubular epithelia displayed high topoisomerase IIalpha levels in mesangiocapillary glomerulonephritis (MCGN), RPGN, TIN, miscellaneous entities (MISC) and LN, and displayed low levels in MPGN and CTN. Topoisomerase I expression was high in the glomeruli of focal segmental glomerulosclerosis (FSGS), MCGN, and RPGN and was extreme in LN, whereas it was strikingly diminished in the glomeruli of MGN, CTN, and TIN. Almost all conditions displayed lower tubular topoisomerase I levels than normal kidney, except for LN, in which the enzyme content was markedly increased. Increased glomerular monocytic infiltrates were found in FSGS, MCGN, RPGN, TIN, and LN, and tubulointerstitial Ki-M1p+ cells were seen at high numbers in MCGN, RPGN, TIN, MISC, and LN. The expression of the topoisomerases I and IIalpha was significantly correlated; also, topoisomerases showed a positive association with the density of monocytic infiltrates. The parameter profiles exhibited significant differences between distinct types of chronic renal disease.

CONCLUSION

Topoisomerase IIalpha expression is tightly linked to cell cycling, and topoisomerase I is likely a reflection of gene transcription. Rapidly progressing glomerular disease therefore appears to be accompanied by active mesangial cell proliferation and increased metabolic activity in glomerular cells. The correlation with inflammatory infiltrates is likely to reflect a positive feedback mechanism involving cytokines, growth factors, and adhesion molecules. Assessment of topoisomerases may therefore be of diagnostic help and might allow prognostic predictions. Provided that our observations are supported by clinicopathological follow-up studies, one might envisage the use of topoisomerase inhibitors in the therapy of chronic proliferative renal disease refractory to current treatment protocols.

DNase I footprinting of the human interleukin-5 gene promoter

A characteristic feature of allergic asthma is the overexpression of the T helper type 2 (Th2) cytokines interleukin-4 (IL-4), IL-5 and IL-13 by T lymphocytes. Of these cytokines, IL-5 is critical for the growth, survival and recruitment of eosinophils which are thought to be responsible for the tissue damage observed in asthmatic airways. The expression of human IL-5 is primarily regulated at the transcriptional level; however, little is known about the mechanisms that control its transcription. Using nuclear extracts from allergen-specific human T-cell clones we have performed DNase I footprinting of the human IL-5 promoter in order to establish sites occupied by transcription factors. We show footprints covering the conserved lymphokine element 0 ¿(CLE0) -60 to -44 base pairs (bp) and GATA (-73 to -62 bp) elements, which have previously been identified to be important in the regulation of the murine IL-5 promoter. We also describe a footprint covering a considerably extended Octamer binding site (-249 to -217 bp), which encompasses two hitherto unidentified CCAAT/enhancer binding protein consensus binding sites. We have also identified a previously unknown Ets binding site (-274 to -264 bp). These novel data on the regions of the human IL-5 promoter that are bound by transcription factors should allow dissection of the regulatory mechanisms involved in the transcription of IL-5 in the T-helper lymphocytes of asthmatics.

Regulation of antigen-induced human T-lymphocyte responses by calcineurin antagonists

BACKGROUND

Cyclosporin A (CS) and tacrolimus (FK506, FK) are calcineurin antagonists used widely as T-cell immunosuppressants; however, their relative efficacy on antigen-stimulated T-cell subsets remains undefined.

OBJECTIVE

We have examined the effects of CS and FK on antigen-driven proliferation and cytokine generation from human PBMCs and T-cell clones.

METHODS

Proliferation was assessed by tritiated thymidine incorporation. Cytokine generation was assessed by reverse transcription-PCR and ELISA.

RESULTS

Ragweed- and tetanus toxoid-driven proliferation of PBMCs was down-regulated equally by CS or FK. Gene expression for proinflammatory cytokines (IL-4, IL-5, IL-13, and IFN-gamma) assessed by reverse transcription-PCR was down-regulated in a concentration-dependent manner by either drug. Antigen-induced proliferation of ragweed-specific Th0, Th1, or Th2 clones was inhibited by either CS or FK. Cytokine gene expression and protein secretion into culture supernatants (IL-4, IL-5, IL-13, and IFN-gamma) were down-regulated in a concentration-dependent manner by either CS or FK in all relevant T-cell subsets. Interestingly, down-regulation of IL-5 protein generation from Th0 and Th2 clones was consistently less sensitive to either drug than was the effect on either IL-4 or IL-13 protein generation.

CONCLUSION

CS and FK promote equivalent down-regulation of Th0, Th1, and Th2 responses; however, IL-5 generation is relatively insensitive to the immunomodulatory effects of calcineurin antagonists.

Differential regulation of cytokine expression after allergen exposure of sensitized rats by cyclosporin A and corticosteroids: relationship to bronchial hyperresponsiveness

BACKGROUND

Cyclosporin A and dexamethasone exhibit different effects on allergic airway eosinophilia and bronchial hyperresponsiveness (BHR).

OBJECTIVE

We determined whether these were related to alteration of cytokine expression, particularly with regard to the profile of Th1- versus Th2-derived cytokines.

METHODS

Brown-Norway rats sensitized with ovalbumin were administered cyclosporine or dexamethasone before ovalbumin aerosol challenge. Bronchial responsiveness was measured 18 to 24 hours after aerosol exposure. Airway cellular influx was determined by bronchoalveolar lavage and tissue immunohistochemistry. The expression of Th1 and Th2 cytokine messenger RNA (mRNA) was analyzed by reverse transcriptase-PCR.

RESULTS

Ovalbumin exposure induced significant BHR, with increases in eosinophils, lymphocytes, and neutrophils in bronchoalveolar lavage fluid and an increase in eosinophils, CD2(+) and CD8(+), but not CD4(+) T cells, in the airway submucosa. IL-2, IFN-gamma, IL-4, and IL-5 mRNA expression in the lungs of sensitized ovalbumin-exposed rats was increased (P <.05) compared with controls. Cyclosporin A had no significant effect on BHR and neutrophil accumulation but reduced the number of bronchoalveolar lavage eosinophils (P <.002), airway submucosal eosinophils, and CD4(+) and CD8(+) T cells (P <.02). It also suppressed the induced mRNA expression of IL-2, IL-4, IL-5, and IFN-gamma. By contrast, the inflammatory cell influx and mRNA expression for IL-2, IL-4, and IL-5, as well as BHR, were suppressed by dexamethasone. However, an increase in IL-10 and IFN-gamma mRNA expression was found.

CONCLUSION

The differential activities of cyclosporin A and dexamethasone on inflammatory cell influx, particularly neutrophils, or cytokine expression such as IL-10 and IFN-gamma may underlie their contrasting effects on BHR.

Biology of IL-5 in health and disease

LEARNING OBJECTIVES

Reading this article will increase the readers' knowledge of the biology of interleukin-5 (IL-5), an important cytokine. The immune and inflammatory responses of any organism are the basis of the defense mechanism ensuring its survival. The role of IL-5 in these processes, as well as in the pathogenesis of various diseases has been discussed along with the effects of various pharmacologic agents on the production and function of IL-5.

DATA SOURCES

A detailed literature search was performed. Studies considered relevant and important, in all languages, which involved humans and animals were used.

STUDY SELECTION

Information was obtained only from peer reviewed journals.

RESULTS

Interleukin-5 is normally produced by T-cells, mast cells, and eosinophils while Reed Sternberg and Epstein Barr virus (EBV) transformed cells also produce IL-5. Monoclonal antibodies (mAb) to IL-5 are potent inhibitors of IL-5 mediated tissue damage, secondary to eosinophil infiltration. The majority of the studies on IL-5 are preliminary, often the information is obtained from animal studies or in vitro systems and occasionally from pathologic tissue analysis. This along with the absence of confirmatory studies is a limiting factor. Nonetheless, the role of IL-5 in allergic and immunologic disease and asthma may be central to their pathogenesis.

CONCLUSIONS

Interleukin-5 is an important molecule that is participant to many processes that maintain health and are involved directly or indirectly in the pathogenesis of disease. Some pharmacologic agents can modify IL-5 production in vivo. Development of selective inhibitors of IL-5 may have a potential use for specific therapy of certain autoimmune, inflammatory, and neoplastic diseases.

Effects of cyclosporin A and dinactin on T-cell proliferation, interleukin-5 production, and murine pulmonary inflammation

We compared the effects of cyclosporin A (CSA) and a macrotetrolide antibiotic, dinactin, on human T-cell proliferation and cytokine production induced by stimulation of the T-cell receptor alone (monoclonal antibody [mAb] directed against CD3) or in combination with costimulatory signals (mAbs directed against CD3 and CD28). These agents were also examined in a murine model of interleukin (IL)-5-mediated pulmonary inflammation. Dinactin inhibited T-cell proliferation induced by IL-2, by mAb to CD3, and by mAbs to CD3 plus alpha-CD28 with identical dose-response curves (IC50 = 10-20 ng/ml). Dinactin inhibited cytokine production with IC50 values of 10 ng/ml for IL-4 and IL-5 and 30 or 60 ng/ml for interferon-gamma or IL-2, respectively. Unlike CSA, exogenous IL-2 did not alter the dinactin-mediated effects on T cells, and nuclear run-on and steady-state messenger RNA (mRNA) analysis showed that dinactin inhibited cytokine production through a post-transcriptional mechanism. CSA selectively blocked T-cell receptor-induced T-cell proliferation and cytokine production (IC50 = 10 ng/ml). Under costimulatory conditions, IL-5 synthesis was only minimally inhibited by high concentrations of CSA, and at CSA concentrations of less than 125 ng/ml, IL-5 was significantly increased above control values. Dinactin and CSA reduced pulmonary eosinophilia when administered within 1 d of airway antigen challenge. Of the cytokine mRNAs examined in the lungs of CSA-pretreated, antigen-challenged mice, IL-5 mRNA levels were the least reduced, paralleling the resistance of IL-5 to CSA observed in vitro and suggesting a role for CD28 in the in vivo induction of IL-5.

Characterisation of inducible DNase I hypersensitive sites flanking the human interleukin-5 gene

Interleukin-5 (IL-5) production is necessary for eosinophilia associated with allergic conditions and parasitic infection. IL-5 mRNA is transiently expressed by activated T-lymphocytes. In this report, we have analysed DNA regulatory regions associated with inducible IL-5 expression in the human HSB-2 T-cell line. Only low levels of transcriptional activity were induced in cells transfected with up to 1.2 kb of DNA upstream of the IL-5 gene. DNase I hypersensitivity analysis was employed to identify additional regulatory sequences located outside this region. Two hypersensitivity sites (HS) were identified, one 2.5 kb 5' and the other 1.6 kb 3' from the gene, that were induced on activation of HSB-2 cells by stimuli that induced IL-5 expression. The 5' site, but not the 3' site, was found in primary human T-cells. The presence of the 5' HS did not always coincide with IL-5 expression. Inclusion of the region encompassing the 5' HS in promoter studies mediated a moderate increase in transcriptional activity, suggesting that enhancer elements essential for induction of maximal IL-5 transcription reside at a greater distance from the IL-5 gene.

Interleukin-5 mRNA stability in human T cells is regulated differently than interleukin-2, interleukin-3, interleukin-4, granulocyte/macrophage colony-stimulating factor, and interferon-gamma

Interleukin-5 (IL-5) transcriptional activation and mRNA stability were investigated in a human TH0 T-cell clone (SP-B21) and in nonclonal CD4 TH2 cells, differentiated in vitro from peripheral blood T cells. Cells were stimulated with alpha-CD3 monoclonal antibody (mAb) with and without alpha-CD28 mAb. Comparison to other cytokine genes revealed aspects of mRNA regulation unique to IL-5. The half-life (t1/2) of IL-5 mRNA, determined by addition of actinomycin D (ActinoD) or cyclosporin A (CSA) was longer (by >= 2 h) than that of IL-2, IL-3, IL-4, interferon-gamma, or granulocyte/macrophage colony-stimulating factor. With the exception of IL-5, t1/2 values were significantly shorter with CSA as the transcriptional inhibitor than with ActinoD. The t1/2 value of IL-5 mRNA, but not the other cytokine transcripts, determined with either ActinoD or CSA, was longer than predicted from the kinetics of steady-state mRNA decline. Co-stimulation of both cell types with alpha-CD28 mAb increased the stability of cytokine transcripts weakly, and IL-5 remained the most stable transcript. Thus, the degradation pathway that targets IL-5 is distinct from the other cytokine transcripts measured and involves proteins whose transcription is blocked by ActinoD and CSA. From examination of the levels of transcription initiation (nuclear run-on assay) and steady-state mRNA attained in cultures stimulated in the presence of the protein synthesis inhibitor, cycloheximide, only IL-5 transcription initiation had an absolute dependency on new protein synthesis.