Solar ultraviolet B radiation promotes α-MSH secretion to attenuate the function of ILC2s via the pituitary-lung axis.

The immunomodulatory effects of ultraviolet B (UVB) radiation in human diseases have been described. Whether type 2 lung inflammation is directly affected by solar ultraviolet (UV) radiation is not fully understood. Here, we show a possible negative correlation between solar UVB radiation and asthmatic inflammation in humans and mice. UVB exposure to the eyes induces hypothalamus-pituitary activation and α-melanocyte-stimulating hormone (α-MSH) accumulation in the serum to suppress allergic airway inflammation by targeting group 2 innate lymphoid cells (ILC2) through the MC5R receptor in mice. The α-MSH/MC5R interaction limits ILC2 function through attenuation of JAK/STAT and NF-κB signaling. Consistently, we observe that the plasma α-MSH concentration is negatively correlated with the number and function of ILC2s in the peripheral blood mononuclear cells (PBMC) of patients with asthma. We provide insights into how solar UVB radiation-driven neuroendocrine α-MSH restricts ILC2-mediated lung inflammation and offer a possible strategy for controlling allergic diseases.

Autocrine TGF-alpha is associated with Benzo(a)pyrene-induced mucus production and MUC5AC expression during allergic asthma.

OBJECTS: Benzo(a)pyrene (BaP), an environmental pollutant, is present in high concentrations in urban smog and cigarette smoke and has been reported to promote high mucin 5AC (MUC5AC) expression. Epithelium-derived inflammatory cytokines are considered an important modulator of mucus oversecretion and MUC5AC overexpression. Here, we investigated whether the effect of BaP on MUC5AC overexpression was associated with cytokine autocrine activity in vivo and in vitro. METHODS: In vivo, BALB/c mice were treated with ovalbumin (OVA) in the presence or absence of BaP. Allergy-induced mucus production was assessed by Alcian Blue Periodic acid Schiff (AB-PAS) staining. The human airway epithelial cell line NCI-H292 was used in vitro. MUC5AC and transforming growth factor (TGF)-α mRNA levels were assessed with real-time quantitative PCR. The concentration of cytokines was measured by ELISA. The MUC5AC, p-ERK, ERK, p-EGFR and EGFR proteins were detected by Western blotting in cells or by immunohistochemistry in mouse lungs. Small-interfering RNAs were used for gene silencing. RESULTS: TGF-α was overproduced in the supernatant of NCI-H292 cells treated with BaP. Knockdown of TGF-α expression inhibited the BaP-induced increase in MUC5AC expression and subsequent activation of the EGFR-ERK signalling pathway. Knocking down aryl hydrocarbon receptor (AhR) expression or treatment with an ROS inhibitor (N-acetyl-L-cysteine) could relieve the TGF-α secretion induced by BaP in epithelial cells. In an animal study, coexposure to BaP with OVA increased mucus production, MUC5AC expression and ROS-EGFR-ERK activation in the lung as well as TGF-α levels in bronchoalveolar lavage fluid (BALF). Furthermore, the concentration of TGF-α in BALF was correlated with MUC5AC mRNA levels. Additionally, TGF-α expression was found to be positively correlated with MUC5AC expression in the airway epithelial cells of smokers. Compared with non-smoker asthma patients, TGF-α serum levels were also elevated in smoker asthma patients. CONCLUSION: Autocrine TGF-α was associated with BaP-induced MUC5AC expression in vitro and in vivo. BaP induced TGF-α secretion by activating AhR and producing ROS, which led to activation of the EGFR-ERK pathway.

Serum magnesium in patients with severe acute respiratory syndrome coronavirus 2 from Wuhan, China.

The aim of the study was to evaluate the significance of hypomagnesemia in patients with coronavirus disease 2019 (COVID-19) and clarify its possible pathogenesis. A retrospective cohort study was conducted by reviewing 83 patients hospitalized in Guanggu district, Wuhan Third Hospital, China. Clinical histories, laboratory findings and outcome data were collected. Eighteen patients had hypomagnesemia during hospitalization. Fourteen patients were in the critical group and six died. In the critical group, serum magnesium (0.72 ± 0.15 mmol/L) was much lower than that in the moderate and severe groups. At the same time, we also found that several indicators are correlated with the level of magnesium. The level of magnesium was positively associated with the lymphocyte count (r = 0.203, P = 0.004) and platelet count (r = 0.217, P = 0.002) but negatively related to the levels of CRP (r = -0.277, P = 0.000), LDH (r = -0.185, P = 0.011) and α-hydroxybutyrate dehydrogenase (r = -0.198, P = 0.008) in the critical group. Hypomagnesemia might increase symptoms and may be associated with mortality in COVID-19 by affecting enzyme activity and activating the inflammatory response. Thus, magnesium might play a key role in the pathogenesis of COVID-19.

Resveratrol inhibits MUC5AC expression by regulating SPDEF in lung cancer cells.

BACKGROUND: MUC5AC was recently identified to play important roles in the proliferation and metastasis of malignant mucinous lung tumor cells. Resveratrol (Res), a natural compound with anticancer effects in lung cancer cells, has been reported to inhibit mucin production in airway epithelial cells. This study aimed to investigate the inhibitory effect of Res on MUC5AC expression in lung mucinous adenocarcinoma cells and the potential mechanisms. METHODS: Mucus-producing A549 human lung carcinoma cells were used to test the effects of Res on SPDEF and MUC5AC expression. Gene and protein expression was assessed by real-time quantitative PCR (qPCR), immunofluorescence and western blotting assays. SPDEF lentivirus was used to upregulate SPDEF expression levels in mucus-producing A549 human lung carcinoma cells. Cell proliferation was assessed by Cell Counting Kit-8 (CCK-8) assay. RESULTS: Res decreased MUC5AC expression in an SPDEF-dependent manner in mucus-producing A549 human lung carcinoma cells, and this change was accompanied by decreased ERK expression and AKT pathway activation. Moreover, SPDEF was found to be overexpressed in lung adenocarcinoma (LUAD), especially in mucinous adenocarcinoma. In-vitro functional assays showed that overexpression of SPDEF reduced the chemosensitivity of A549 cells to cisplatin (DDP). In addition, Res treatment increased A549 cell chemosensitivity to DDP by inhibiting the SPDEF-MUC5AC axis. CONCLUSION: Our results indicate that the SPDEF-MUC5AC axis is associated with DDP sensitivity, and that Res decreases SPDEF and MUC5AC expression by inhibiting ERK and AKT signaling in A549 cells, which provides a potential pharmacotherapy for the prevention and therapeutic management of mucinous adenocarcinoma.

Investigation of the Active Ingredients and Mechanism of Polygonum cuspidatum in Asthma Based on Network Pharmacology and Experimental Verification.

BACKGROUND: Polygonum cuspidatum is a Chinese medicine commonly used to treat phlegm-heat asthma. However, its anti-asthmatic active ingredients and mechanism are still unknown. The aim of this study was to predict the active ingredients and pathways of Polygonum cuspidatum and to further explore the potential molecular mechanism in asthma by using network pharmacology. METHODS: The active ingredients and their targets related to Polygonum cuspidatum were seeked out with the TCM systematic pharmacology analysis platform (TCMSP), and the ingredient-target network was constructed. The GeneCards, DrugBank and OMIM databases were used to collect and screen asthma targets, and then the drug-target-disease interaction network was constructed with Cytoscape software. A target protein-protein interaction (PPI) network was constructed using the STRING database to screen key targets. Finally, GO and KEGG analyses were used to identify biological processes and signaling pathways. The anti-asthmatic effects of Polygonum cuspidatum and its active ingredients were tested in vitro for regulating airway smooth muscle (ASM) cells proliferation and MUC5AC expression, two main symptoms of asthma, by using Real-time PCR, Western blotting, CCK-8 assays and annexin V-FITC staining. RESULTS: Twelve active ingredients in Polygonum cuspidatum and 479 related target proteins were screened in the relevant databases. Among these target proteins, 191 genes had been found to be differentially expressed in asthma. PPI network analysis and KEGG pathway enrichment analysis predicted that the Polygonum cuspidatum could regulate the AKT, MAPK and apoptosis signaling pathways. Consistently, further in vitro experiments demonstrated that Polygonum cuspidatum and resveratrol (one active ingredient of Polygonum cuspidatum) were shown to inhibit ASM cells proliferation and promoted apoptosis of ASM cells. Furthermore, Polygonum cuspidatum and resveratrol inhibited PDGF-induced AKT/mTOR activation in ASM cells. In addition, Polygonum cuspidatum decreased H2O2 induced MUC5AC overexpression in airway epithelial NCI-H292 cells. CONCLUSION: Polygonum cuspidatum could alleviate the symptoms of asthma including ASM cells proliferation and MUC5AC expression through the mechanisms predicted by network pharmacology, which provides a basis for further understanding of Polygonum cuspidatum in the treatment of asthma.

Benzo(a)pyrene induces MUC5AC expression through the AhR/mitochondrial ROS/ERK pathway in airway epithelial cells.

OBJECTIVES: Benzo(a)pyrene (BaP) is a ubiquitous air pollutants, and BaP exposure leads to a risk of respiratory diseases. The oversecretion of airway mucus and high expression of mucin 5AC (MUC5AC) are associated with common respiratory disorders caused by air pollution. We aimed to investigate the effect of BaP on MUC5AC expression, especially the mechanisms by which BaP induces MUC5AC gene expression. METHODS: The human airway epithelial cell NCI-H292 was used to test the effects of BaP on the expression of MUC5AC in vitro. MUC5AC mRNA and protein expression were assessed with real-time quantitative PCR, immunochemistry, and western blotting. A luciferase assay was conducted to detect the activity of the promoter. The total cellular ROS and mitochondrial ROS were measured by corresponding probes. Small-interfering RNAs were used for gene silencing. AhR-overexpressing cell lines were constructed by transfection with AhR overexpression lentivirus. RESULTS: We found that BaP stimulation upregulated the MUC5AC mRNA and protein levels and activated the ERK pathway. Suppressing ERK with U0126 (an ERK inhibitor) or knocking down ERK with siRNA decreased BaP-induced MUC5AC expression. The luciferase activity transfected with the MUC5AC promoter and cAMP-response element (CRE) was increased after BaP treatment, whereas CREB siRNA suppressed the BaP-induced overexpression of MUC5AC. In addition, BaP increased mitochondrial ROS production, and Mito-TEMP, a mitochondrial ROS inhibitor, inhibited BaP-induced MUC5AC expression and ERK activation. BaP increased the mRNA levels of CYP1A1 and CYP1B1, while Alizarin, a CYP1s inhibitor, suppressed the effects of BaP, including the MUC5AC overexpression, ERK activation and mitochondrial ROS generation. BaP induced the translocation of aryl hydrocarbon receptor (AhR) from the cytoplasm to the nucleus. SiRNA-mediated knockdown or chemical inhibition of AhR decreased the BaP-induced expression of MUC5AC, while the overexpression of AhR significantly enhanced the BaP-induced expression of MUC5AC. ITE, an endogenous AhR ligand, also upregulated the mRNA and protein expression of MUC5AC. Furthermore, resveratrol treatment inhibited the BaP-induced MUC5AC overexpression, AhR translocation, mitochondrial ROS production and ERK pathway activation. CONCLUSION: Here, we highlighted the crucial role of AhR/mitochondrial ROS/ERK pathway activation in BaP-induced MUC5AC overexpression and identified resveratrol as a promising drug to reduce BaP-induced MUC5AC overexpression.

Qi-Xian Decoction Upregulated E-cadherin Expression in Human Lung Epithelial Cells and Ovalbumin-Challenged Mice by Inhibiting Reactive Oxygen Species-Mediated Extracellular-Signal-Regulated Kinase (ERK) Activation.

BACKGROUND Loss of the epithelial barrier is characterized by a reduction in E-cadherin expression and is a hallmark of asthma. Qi-xian decoction (QXT) is a Chinese medicinal formula that has been used to effectively treat asthma. This study aimed to investigate the effect of QXT on E-cadherin expression in human lung epithelial 16HBE cells and ovalbumin-challenged mice and to explore the underlying molecular mechanism. MATERIAL AND METHODS Ovalbumin (OVA)-induced mice were used as a model of asthma. Real-time PCR and Western blotting were utilized to examine mRNA and protein levels. Lung tissue reactive oxygen species (ROS) levels were evaluated using dichloro-dihydro-fluorescein diacetate (DCFH-DA). Serum superoxide dismutase (SOD) and the total antioxidant capacity (TAOC) were measured via enzyme-linked immunosorbent assay (ELISA)-based analyses. 16HBE cells were utilized to explore the effect of QXT or hydrogen peroxide (H2O2) on the expression of E-cadherin in vitro. RESULTS We found that QXT treatment increased E-cadherin expression and decreased extracellular-signal-regulated kinase (ERK) phosphorylation levels in the lung tissues of OVA-challenged mice. QXT also downregulated ROS levels and increased serum SOD and TAOC levels in OVA-challenged mice. In vitro studies demonstrated that increased ROS generation induced by H2O2 resulted in decreased E-cadherin expression levels in 16HBE cells, which was attenuated by inhibition of ERK signaling. Moreover, the H2O2-induced downregulation of E-cadherin expression, increased ROS generation, and ERK activation in 16HBE cells were restored by treatment with QXT water or ethanol extract. CONCLUSIONS These data demonstrate that one mechanism by which QXT protects against asthma is to restore E-cadherin expression in vivo and in vitro by inhibiting ROS-mediated ERK activation.

Decreasing Arl4c expression by inhibition of AKT signal in human lung adenocarcinoma cells.

PURPOSE: Arl4c is overexpressed in several cancer tissues and is involved in cancer development. Nevertheless, the exact mechanism that regulates Arl4c expression in lung cancer has not been fully elucidated. The aim of this study was to investigate the regulatory mechanism of Arl4c and to explore potential chemotherapeutic drugs targeting Arl4c. METHODS: Immunohistochemistry was used to examine Arl4c expression levels in human lung adenocarcinoma cancer specimens. Protein expression was detected by western blot. Overexpression of Arl4c-Flag protein was used to detect the ubiquitination of Arl4c. A short interfering RNA against Arl4c was used for gene silencing. RESULTS: Arl4c was overexpressed in lung cancer tissues, and knockdown of Arl4c expression by siRNA decreased lung cancer A549 and 95-D cell proliferation. In addition, Arl4c expression was downregulated via inhibition of the AKT pathway in A549 and 95-D cells, whereas exposure to benzo (a) pyrene (a carcinogen in smoke) increased Arl4c expression in 16HBE cells via AKT activation. Finally, we found that chemotherapy drug hydroxycamptothecin (HCPT) could decrease Arl4c expression levels by inhibiting the activation of the AKT pathway in A549 and 95-D cells. Moreover, accumulation of ubiquitinated Arl4c protein was increased by HCPT and LY294002 (an AKT inhibitor) treatment whereas the proteasome inhibitor MG-132 attenuated the inhibitory effect of HCPT and LY294002 on Arl4c expression. CONCLUSION: Here, we highlighted the AKT pathway as an important regulatory pathway for Arl4c expression in lung cancer cells and identified HCPT as a promising drug for lung adenocarcinoma treatment that functioned by targeting Arl4c expression.

Curcumin suppresses MUC5AC production via interfering with the EGFR signaling pathway.

Excessive mucin production in the airway may contribute to airway inflammatory diseases. Curcumin has been reported to prevent mucin 5AC (MUC5AC) production in human airway epithelial cells; however, the molecular targets of curcumin involved in regulating MUC5AC expression have remained elusive. The present study aimed to elucidate the molecular mechanisms by which curcumin regulates MUC5AC production, utilizing the NCI­H292 human airway epithelial cell line featuring MUC5AC hypersecretion. Curcumin was able to counteract the endothelial growth factor (EGF)­stimulated mRNA and protein expression of MUC5AC. In addition, curcumin treatment prevented EGF­induced phosphorylation of EGF receptor (EGFR) as well as the downstream AKT and signal transducer and activator of transcription 3 (STAT3), while inhibition of PI3K and STAT3 signaling significantly attenuated the expression of MUC5AC that was induced by EGF. Furthermore, EGF­induced increases in the levels of phosphorylated STAT3 in the nuclear fraction were inhibited by curcumin and PI3K inhibitors. In addition, treatment with curcumin significantly decreased MUC5AC and EGFR expression in a time­dependent manner under basal conditions. These results demonstrated that curcumin inhibited MUC5AC protein expression in NCI­H292 cells under basal conditions as well under EGF stimulation. This inhibition was accompanied by decreased activation of the EGFR/AKT/STAT3 pathway and reduced EGFR expression, which indicated that curcumin may have a dual role in interfering with the EGFR signaling pathway and inhibiting mucin expression in human airway epithelial cells.

The outcome and the influencing factors of the age of onset in post-mortem of chronic bronchitis patients: a retrospective study.

Purpose: Chronic bronchitis is thought to occur in elderly patients, and smoking seems to be an important risk factor. The outcomes related to the age of onset in patients with chronic bronchitis are still unclear. Patients and methods: A retrospective study was conducted on deceased patients whose diagnosis included bronchitis from 2010 to 2016. Patients were separated into two groups according to the age of onset (Group I, age ≤50 years old; Group II, age >50 years old). Information regarding disease course, smoking history, death age, number of admissions per year, Hugh Jones Index, and self-reported comorbidities of the patients was recorded. Results: The courses of chronic cough and sputum were 33.38±7.73 years and 14.44±8.60 years in Group I and Group II, respectively (p<0.05). The death ages of Group I and Group II were 77.65±7.87 years and 84.69±6.67 years, respectively (p<0.05). There was a significant negative correlation between the number of hospital admissions per year and the age of onset. The age of onset was negatively associated with daily smoking count (r=-0.210) and total smoking count (r=-0.146). In Group I, there were fewer cases of coronary heart disease (OR =0.41 [0.24-0.71]), neurological diseases (OR =0.48 [0.24-0.97]), and total comorbidities (OR =0.67 [0.54-0.85]) than in Group II. Conclusion: Patients with early onset chronic bronchitis had a longer history, younger death age, poorer health status, and lower incidence of comorbidities.

Curcumin Inhibits Growth of Human NCI-H292 Lung Squamous Cell Carcinoma Cells by Increasing FOXA2 Expression.

Lung squamous cell carcinoma (LSCC) is a common histological lung cancer subtype, but unlike lung adenocarcinoma, limited therapeutic options are available for treatment. Curcumin, a natural compound, may have anticancer effects in various cancer cells, but how it may be used to treat LSCC has not been well studied. Here, we applied curcumin to a human NCI-H292 LSCC cell line to test anticancer effects and explored underlying potential mechanisms of action. Curcumin treatment inhibited NCI-H292 cell growth and increased FOXA2 expression in a time-dependent manner. FOXA2 expression was decreased in LSCC tissues compared with adjacent normal tissues and knockdown of FOXA2 increased NCI-H292 cells proliferation. Inhibition of cell proliferation by curcumin was attenuated by FOXA2 knockdown. Moreover inhibition of STAT3 pathways by curcumin increased FOXA2 expression in NCI-H292 cells whereas a STAT3 activator (IL-6) significantly inhibited curcumin-induced FOXA2 expression. Also, SOCS1 and SOCS3, negative regulators of STAT3 activity, were upregulated by curcumin treatment. Thus, curcumin inhibited human NCI-H292 cells growth by increasing FOXA2 expression via regulation of STAT3 signaling pathways.

Suppression of Sirtuin-1 Increases IL-6 Expression by Activation of the Akt Pathway During Allergic Asthma.

BACKGROUND/AIMS: A growing number of studies have demonstrated that the activity and expression level of sirtuin-1 (SIRT1) are decreased in asthma patients; however, the mechanisms underlying decreased SIRT1 expression and function are still not completely understood. Interleukin (IL)-6 plays important roles in inflammation during allergic asthma. In this study, we examined whether loss of SIRT1 activity regulated the expression of IL-6 and further verified the underlying mechanisms. METHODS: The human airway epithelial cell line 16HBE was used to test the effects of the SIRT1 inhibitor (salermide) on expression of IL-6. IL-6 mRNA and protein expression were assessed with real-time polymerase chain reaction (PCR), immunochemistry, and ELISA. OVA-challenged mice were used as an asthma model to investigate the effect of SIRT1 activation on IL-6 and relative Akt phosphorylation level. RESULTS: We found that inhibition of SIRT1 increased IL-6 mRNA and protein levels in a time-dependent manner, which was accompanied by increased Akt pathway activation in 16HBE cells. Furthermore activation of Akt showed upregulated expression of the IL-6 protein whereas Akt inhibitor, LY294002 or Akt siRNA significantly inhibited SIRT1-regulated IL-6 expression. Conversely, activation of SIRT1 inhibited Akt activation and IL-6 expression in an asthmatic mice model and 16HBE cells. CONCLUSION: Our results indicate the potential role of SIRT1 in regulating inflammation by modulation of IL-6 expression in an Akt-dependent manner during allergic asthma.

High-throughput screening of antagonists for the orphan G-protein coupled receptor GPR139.

AIM: To discover antagonists of the orphan G-protein coupled receptor GPR139 through high-throughput screening of a collection of diverse small molecules. METHODS: Calcium mobilization assays were used to identify initial hits and for subsequent confirmation studies. RESULTS: Five small molecule antagonists, representing 4 different scaffolds, were identified following high-throughput screening of 16 000 synthetic compounds. CONCLUSION: The findings provide important tools for further study of this orphan G-protein coupled receptor.

High-throughput screening and sensitized bacteria identify an M. tuberculosis dihydrofolate reductase inhibitor with whole cell activity.

Mycobacterium tuberculosis (Mtb), the causative agent of tuberculosis, is a bacterial pathogen that claims roughly 1.4 million lives every year. Current drug regimens are inefficient at clearing infection, requiring at least 6 months of chemotherapy, and resistance to existing agents is rising. There is an urgent need for new drugs that are more effective and faster acting. The folate pathway has been successfully targeted in other pathogens and diseases, but has not yielded a lead drug against tuberculosis. We developed a high-throughput screening assay against Mtb dihydrofolate reductase (DHFR), a critical enzyme in the folate pathway, and screened a library consisting of 32,000 synthetic and natural product-derived compounds. One potent inhibitor containing a quinazoline ring was identified. This compound was active against the wild-type laboratory strain H37Rv (MIC(99) = 207 µM). In addition, an Mtb strain with artificially lowered DHFR levels showed increased sensitivity to this compound (MIC(99) = 70.7 µM), supporting that the inhibition was target-specific. Our results demonstrate the potential to identify Mtb DHFR inhibitors with activity against whole cells, and indicate the power of using a recombinant strain of Mtb expressing lower levels of DHFR to facilitate the discovery of antimycobacterial agents. With these new tools, we highlight the folate pathway as a potential target for new drugs to combat the tuberculosis epidemic.

Plasma orexin-a levels in COPD patients with hypercapnic respiratory failure.

Orexins have previously been shown to promote wakefulness, regulate lipid metabolism and participate in energy homeostasis. The aim of the study was to determine the relationship between plasma orexin-A and body composition in COPD in-patients with hypercapnic respiratory failure. 40 patients with hypercapnic respiratory failure and 22 healthy individuals were enrolled prospectively in this study. Plasma orexin-A levels, BMI, SaO(2), PaCO(2) and PaO(2) were noted for all the patients. Plasma orexin-A levels were higher in the underweight (UW) group, normal weight (NW) group and overweight (OW) group of COPD patients as compared with UW, NW and OW group of the control group (P < .05). Plasma orexin-A in COPD patients were higher in the OW group than in the NW group and the UW group. Plasma orexin-A levels showed significant correlation with body mass index (BMI), independent of PaO(2) (r = 0.576; P < .05) and %fat (r = 0.367; P < .05); a negative correlation was noted between plasma orexin-A levels and PaO(2) (r = -0.738; P < .05) and SaO(2) (r = -0.616; P < .05). Our results suggest that orexin-A levels are high in COPD patients with hypercapnic respiratory failure, and vary according to BMI and body composition. Orexin-A may be associated with the severity of hypoxemia in COPD patients with hypercapnic respiratory failure.

Nicotinic acid inhibits glucose-stimulated insulin secretion via the G protein-coupled receptor PUMA-G in murine islet ß cells.

OBJECTIVES: Chronic administration of nicotinic acid (NA), a potent antilipidemic compound, aggravates glycemic control in diabetic patients. It is not known if NA has direct effects on islet ß cells. METHODS: Real-time reverse transcriptase-polymerase chain reaction, in situ hybridization, and immunofluorescence techniques were used to examine the expression of NA receptor PUMA-G, a member of the G protein-coupled receptor (G-PCR) family, in murine islet ß cells. Calcium transient was measured using confocal microscopy, whereas the intracellular cyclic adenosine monophosphate and glucose-stimulated insulin secretion (GSIS) from isolated islets were determined by the enzyme-linked immunosorbent assay. RESULTS: High levels of PUMA-G transcripts and protein were detected in all ß cells, and about 40% of α cells. PUMA-G transcripts increased more than 3-fold in islets incubated with interferon γ. Cyclic adenosine monophosphate accumulation, induced by IBMX/forskolin, was inhibited by NA; however, the inhibition was completely abolished by pretreatment of the culture with pertussis toxin. No calcium transient was detected in islet cells in the presence of NA. Static incubation of islets with NA led to an approximately 30% reduction of GSIS. CONCLUSIONS: The results indicated that PUMA-G stimulation by NA in islet ß cells inhibited GSIS likely via activation of the Gi signaling pathway.

Enhanced insulin production from murine islet beta cells incubated on poly(3-hydroxybutyrate-co-3-hydroxyhexanoate).

Islet transplantation represents an important alternative for the treatment of diabetes. However, the selection of suitable materials is critical for the success of such an implantation application. In this study, cellular migration, aggregation, and insulin production of a murine islet beta-cell line, NIT-1 cells on microbially produced polyesters poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) (PHBHHx), poly(3-hydroxybutyrate-co-4-hydroxybutyrate) (P3HB4HB) or polylactic acid (PLA) films were investigated. Spherical islet-like structures were only detected on PHBHHx films after 48 h cultivation. To understand the mechanism underlying the formation of cell aggregates, NIT-1-GFP, a stable transfectant of the green fluorescent protein was used in a time-lapse imaging study. Cell aggregation began on PHBHHx at 2 h, and became obvious at 4 h. Furthermore, cells on PHBHHx displayed higher metabolic activities measured by MTT assay than that on tissue culture plate. More importantly, insulin gene expression as well as extracellular secretion was upregulated after growth on PHBHHx for 72 h. Thus, PHBHHx can be a strong candidate for islet transplantation.

Heterogeneity in mitotic activity and telomere length implies an important role of young islets in the maintenance of islet mass in the adult pancreas.

Understanding the mechanisms of beta-cell dynamics in postnatal animals is central to cure diabetes. A major obstacle in evaluating the status of pancreatic cells is the lack of surface markers. Here we performed quantitative measurements of two internal markers to follow the developmental history of islets. One marker, cell-cycle activity, was established by measuring expression of Ki67 and the incorporation of 5-bromodeoxyuridine. The other marker, the aging process, was delineated by the determination of telomere length. Moreover, islet neogenesis, possibly from ductal precursors, was monitored by pancreatic duct labeling with an enhanced green fluorescence protein (EGFP) transgene. We found that islets from younger animals, on average, expressed higher Ki67 transcripts, displayed elevated 5-bromodeoxyuridine incorporation, and had longer telomeres. However, significant heterogeneity of these parameters was observed among islets from the same mouse. In contrast, the levels of proinsulin-1 transcripts in islets of different ages did not change significantly. Moreover, mitotic activities correlated significantly with telomere lengths of individual islets. Lastly, after 5.5 d pancreatic duct labeling, a few EGFP-positive islets could be identified in neonatal but not from adult pancreases. Compared with unlabeled control islets, EGFP-positive islets had higher mitotic activities and longer telomeres. The results suggest that islets are born at different time points during the embryonic and neonatal stages and imply that young islets might play an important role in the maintenance of islet mass in the adult pancreas.