Type 1 interferon suppresses expression and glucocorticoid induction of glucocorticoid-induced leucine zipper (GILZ)

SLE is a systemic multi-organ autoimmune condition associated with reduced life expectancy and quality of life. Glucocorticoids (GC) are heavily relied on for SLE treatment but are associated with detrimental metabolic effects. Type 1 interferons (IFN) are central to SLE pathogenesis and may confer GC insensitivity. Glucocorticoid-induced leucine zipper (GILZ) mediates many effects of GC relevant to SLE pathogenesis, but the effect of IFN on GC regulation of GILZ is unknown. We performed in vitro experiments using human PBMC to examine the effect of IFN on GILZ expression. JAK inhibitors tofacitinib and tosylate salt were used in vivo and in vitro respectively to investigate JAK-STAT pathway dependence of our observations. ChiP was performed to examine glucocorticoid receptor (GR) binding at the GILZ locus. Several public data sets were mined for correlating clinical data. High IFN was associated with suppressed GILZ and reduced GILZ relevant to GC exposure in a large SLE population. IFN directly reduced GILZ expression and suppressed the induction of GILZ by GC in vitro in human leukocytes. IFN actions on GILZ expression were dependent on the JAK1/Tyk2 pathway, as evidenced by loss of the inhibitory effect of IFN on GILZ in the presence of JAK inhibitors. Activation of this pathway led to reduced GR binding in key regulatory regions of the GILZ locus. IFN directly suppresses GILZ expression and GILZ upregulation by GC, indicating a potential mechanism for IFN-induced GC resistance. This work has important implications for the ongoing development of targeted GC-sparing therapeutics in SLE.

GILZ regulates type I interferon release and sequesters STAT1

Glucocorticoids remain a mainstay of modern medicine due to their ability to broadly suppress immune activation. However, they cause severe adverse effects that warrant urgent development of a safer alternative. The glucocorticoid-induced leucine zipper (GILZ) gene, TSC22D3, is one of the most highly upregulated genes in response to glucocorticoid treatment, and reduced GILZ mRNA and protein levels are associated with increased severity of inflammation in systemic lupus erythematosus (SLE), Ulcerative Colitis, Psoriasis, and other autoimmune/autoinflammatory diseases. Here, we demonstrate that low GILZ permits expression of a type I interferon (IFN) signature, which is exacerbated in response to TLR7 and TLR9 stimulation. Conversely, overexpression of GILZ prevents IFN-stimulated gene (ISG) up-regulation in response to IFNα. Moreover, GILZ directly binds STAT1 and prevents its nuclear translocation, thereby negatively regulating IFN-induced gene expression and the auto-amplification loop of the IFN response. Thus, GILZ powerfully regulates both the expression and action of type I IFN, suggesting restoration of GILZ as an attractive therapeutic strategy for reducing reliance on glucocorticoids.

The ghrelin gene products and exendin-4 promote survival of human pancreatic islet endothelial cells in hyperglycaemic conditions, through phosphoinositide 3-kinase/Akt, extracellular signal-related kinase (ERK)1/2 and cAMP/protein kinase A (PKA) signalling pathways

AIMS/HYPOTHESIS

Pancreatic islet microendothelium exhibits unique features in interdependent relationship with beta cells. Gastrointestinal products of the ghrelin gene, acylated ghrelin (AG), unacylated ghrelin (UAG) and obestatin (Ob), and the incretin, glucagon-like peptide-1 (GLP-1), prevent apoptosis of pancreatic beta cells. We investigated whether the ghrelin gene products and the GLP-1 receptor agonist exendin-4 (Ex-4) display survival effects in human pancreatic islet microendothelial cells (MECs) exposed to chronic hyperglycaemia.

METHODS

Islet MECs were cultured in high glucose concentration and treated with AG, UAG, Ob or Ex-4. Apoptosis was assessed by DNA fragmentation, Hoechst staining of the nuclei and caspase-3 activity. Western blot analyses and pharmacological inhibition of protein kinase B (Akt) and extracellular signal-related kinase (ERK)1/2 pathways, detection of intracellular cAMP levels and blockade of adenylyl cyclase (AC)/cAMP/protein kinase A (PKA) signalling were performed. Levels of NO, IL-1β and vascular endothelial growth factor (VEGF)-A in cell culture supernatant fractions were measured.

RESULTS

Islet MECs express the ghrelin receptor GHS-R1A as well as GLP-1R. Treatment with AG, UAG, Ob and Ex-4 promoted cell survival and significantly inhibited glucose-induced apoptosis, through activation of PI3K/Akt, ERK1/2 phosphorylation and intracellular cAMP increase. Moreover, peptides upregulated B cell lymphoma 2 (BCL-2) and downregulated BCL-2-associated X protein (BAX) and CD40 ligand (CD40L) production, and significantly reduced the secretion of NO, IL-1β and VEGF-A.

CONCLUSIONS/INTERPRETATION

The ghrelin gene-derived peptides and Ex-4 exert cytoprotective effects in islet MECs. The anti-apoptotic effects involve phosphoinositide 3-kinase (PI3K)/Akt, ERK1/2 and cAMP/PKA pathways. These peptides could therefore represent a potential tool to improve islet vascularisation and, indirectly, islet cell function.

Surveillance for rotavirus in Argentina

Group A rotaviruses are the major cause of severe gastroenteritis in young children worldwide. Because rotavirus vaccination appeared imminent, a nationwide surveillance program was organized between October 1996 and October 1998 in the largest Argentine cities. Surveillance for disease burden, rotavirus detection, and rotavirus typing was undertaken at nine locations. Results showed rotavirus to be associated with 42% of diarrhea admissions. Although the prevalent G types changed from year to year, common G types were found in 96% of the cases and were usually associated with common P types. Uncommon G types, G9 and G5, were found at low prevalence and uncommon G/P combinations occurred at almost every study site. These data suggest that a rotavirus vaccine could substantially decrease the rotavirus disease burden in Argentina, but that introduction of a vaccine should be accompanied by a concurrent surveillance system.

Multicentered study of viral acute lower respiratory infections in children from four cities of Argentina, 1993-1994

This study describes the first multicentered study of acute lower respiratory infection viral etiology in young children from four different geographical areas of Argentina. A total of 1,278 children under 5 years of age, hospitalized in primary care centers from Buenos Aires, Córdoba, Santa Fé and Mar del Plata cities during a 2-year period were studied (1993-1994). Nasopharyngeal aspirates were investigated for respiratory syncytial virus (RSV), adenovirus, parainfluenza, and influenza A and B viruses by indirect immunofluorescence. Out of the patients studied, 946 (74%) were under 1 year of age. Viruses were detected in 399 patients (32%). RSV was observed in 25.3% of the samples, representing 78.2% of all viral positive cases. Adenoviruses were detected in 2.5% of the cases, parainfluenza in 2.2%, influenza A in 2.1%, and influenza B in 0.2%. Compared with other viruses, the higher RSV frequency was statistically significant (P < 0.000). Most RSV cases were detected between May and September with a significant peak in July (P < 0.000). Pneumonia was observed in 46% of the patients, bronchiolitis in 41% and other entities in 13%. The case fatality rate observed during the 2 year study was 0.73%. Most of the above respiratory viruses were detected in the four cities, however, the frequency of RSV and influenza were different in the southern city.

Factors that make difficult the implementation of an integrated leprosy control programme in health zone II, Santa Fe Province, Argentina

With the help of a pre-tested, structured questionnaire and participatory observation, effects of several variables that have a bearing on the process of integration were studied in Zone II of the Santa Fe Province of Argentina. Patient's knowledge and the presence of an NGO were identified as factors facilitating integration. The presence of a vertical programme staff and insufficient commitment towards integration were identified as factors hindering integration.

[Rotavirus laboratory network: results after one year of observation]

Rotavirus is the most common cause of severe diarrhea in children and it has been estimated that in Argentina Rotavirus is responsible for 21,000 hospitalizations, 85,000 medical attentions and an annual medical cost of US$ 27 millions. Given that a Rotavirus vaccine is about to be approved, a laboratory network based surveillance system was organized. Herein, we present the results after one year of study. Severe diarrhea was responsible for 9% of pediatric hospitalizations and rotavirus was detected in 42.1% of the diarrhea cases. We estimated that Rotavirus causes 3.8% of pediatric hospitalizations. The number of diarrhea and Rotavirus diarrhea hospitalizations was greater during the first year of life (62% and 71.3%, respectively). The number of diarrhea hospitalizations during the December-May semester was significantly higher than the rest of the year. A Rotavirus diarrhea peak was detected between April and June. These results indicate that Rotavirus is the most important etiological agent of severe diarrhea in Argentine children and show the importance of performing Rotavirus diagnosis in every pediatric hospital. The additional costs will be compensated by many benefits such as better use of antibiotics, improved nosocomial spread control, better handling of hospital beds and of laboratory resources and of the hospitalized patient.

[Usefulness of the enzyme immunoassay in the diagnosis of tuberculosis]

To assess the usefulness of enzyme immunoassay as a rapid method of diagnosing tuberculosis, a study was conducted of 687 serum samples from 271 children and 416 adults. With 55 sera from nontuberculous children as controls, the specificity was 0.98, and with 137 controls from the adult population, 0.93. Prior vaccination with BCG did not influence the level of detectable anti-PPD antibody. The results were similar in healthy PPD-positive and negative adults. The test differentiated mycoses and nontuberculous mycobacterioses from tuberculosis. The sensitivity rates in 49 children and 200 adults diagnosed with bacteriologically confirmed pulmonary and extrapulmonary tuberculosis were calculated at 0.51 and 0.69, respectively. In those tuberculosis cases not bacteriologically confirmed or at other sites, the test was positive in 28.1% of 114 children and in 48.6% of 35 adults. The cost, speed, and availability of reagents for this test were comparable to those for direct microscopic examination. Both methods were positive for 49% of the tuberculosis cases confirmed by culture, and a total of 84% of those cases were found positive using one method or the other. It is concluded that enzyme immunoassay can be especially useful in the rapid diagnosis of nonbacilliferous pulmonary, extrapulmonary, and childhood tuberculosis.

Detection of circulating antibodies to purified protein derivative by enzyme-linked immunosorbent assay: its potential for the rapid diagnosis of tuberculosis

An enzyme-linked immunosorbent assay for detecting antibodies to purified protein derivative was evaluated as a rapid method for serodiagnosis of childhood tuberculosis. Its specificity for IgG antibodies was 0.98 as determined in 55 sera from nontuberculous children who showed no significant effect of previous Bacillus Calmette-Guérin vaccination on the production of specific antibodies. Results were negative in 29 of 33 (87.9%) tuberculin-positive children and in 18 of 20 (90.0%) contacts, none of whom had evidence of tuberculosis. The sensitivity of this test was 0.51 as determined in 49 sera from bacteriologically confirmed cases; 17 of 27 smear positive cases and 8 of 22 children with positive cultures were detected. Results were positive in 32 of 114 (28.1%) patients with a diagnosis of tuberculosis not confirmed by microbiology. Consequently whereas a negative result does not rule out tuberculosis, a positive result is a strong indication of the disease. The IgM antibody determination yielded much less discriminative results.

Evaluation of the effectiveness of BCG vaccination using the case-control method in Buenos Aires, Argentina

A retrospective case-control study was conducted in Argentina to determine the protection conferred by BCG vaccination against tuberculosis in children under six years of age, in an area where coverage is about 55%. A total of 175 tuberculosis patients were included. Five controls selected from patients treated at the same hospital as those under study for reasons other than tuberculosis were matched to each case on the basis of age, socioeconomic origin, nutritional status and place of residence. Information on BCG vaccination status was collected by an independent examiner. Tuberculosis localizations were as follows: 152 pulmonary, pleural and/or miliary; 18 meningitis; 2 lymphadenitis; 2 osteoarticular; and 1 otic. The diagnosis was based on bacteriological and histopathological tests, computerized tomography, radiology, clinical examination, endoscopy, and proved source of infection. The protective effect of BCG among those who were vaccinated was 73.0% with 95% confidence limits of 82% and 62%. According to these results BCG vaccination given early in life is very effective in preventing tuberculosis.