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LIGHT/TNFSF14 is increased in patients with type 2 diabetes mellitus and promotes islet cell dysfunction and endothelial cell inflammation in vitro

View Article: PubMed Central - PubMed

ABSTRACT

Aims/hypothesis: Activation of inflammatory pathways is involved in the pathogenesis of type 2 diabetes mellitus. On the basis of its role in vascular inflammation and in metabolic disorders, we hypothesised that the TNF superfamily (TNFSF) member 14 (LIGHT/TNFSF14) could be involved in the pathogenesis of type 2 diabetes mellitus.

Methods: Plasma levels of LIGHT were measured in two cohorts of type 2 diabetes mellitus patients (191 Italian and 40 Norwegian). Human pancreatic islet cells and arterial endothelial cells were used to explore regulation and relevant effects of LIGHT in vitro.

Results: Our major findings were: (1) in both diabetic cohorts, plasma levels of LIGHT were significantly raised compared with sex- and age-matched healthy controls (n = 32); (2) enhanced release from activated platelets seems to be an important contributor to the raised LIGHT levels in type 2 diabetes mellitus; (3) in human pancreatic islet cells, inflammatory cytokines increased the release of LIGHT and upregulated mRNA and protein levels of the LIGHT receptors lymphotoxin β receptor (LTβR) and TNF receptor superfamily member 14 (HVEM/TNFRSF14); (4) in these cells, LIGHT attenuated the insulin release in response to high glucose at least partly via pro-apoptotic effects; and (5) in human arterial endothelial cells, glucose boosted inflammatory response to LIGHT, accompanied by an upregulation of mRNA levels of HVEM (also known as TNFRSF14) and LTβR (also known as LTBR).

Conclusions/interpretation: Our findings show that patients with type 2 diabetes mellitus are characterised by increased plasma LIGHT levels. Our in vitro findings suggest that LIGHT may contribute to the progression of type 2 diabetes mellitus by attenuating insulin secretion in pancreatic islet cells and by contributing to vascular inflammation.

Electronic supplementary material: The online version of this article (doi:10.1007/s00125-016-4036-y) contains peer-reviewed but unedited supplementary material, which is available to authorised users.

No MeSH data available.


Related in: MedlinePlus

LIGHT increases the inflammatory potential of glucose-stimulated HAEC cells. HAECs were stimulated for 3 h (a, b) or 6 h (c, d) with either LIGHT (200 ng/ml), d-glucose (10 mmol/l) or a combination thereof. Gene expression of the LTβR (a) and HVEM (b) were examined by qPCR and data are given in relation to the control gene β-actin. The levels of IL-8 (c) and MCP-1 (d) were assessed in cell supernatant fractions by ELISA. (c, d) The cells were pretreated for 6 h as described above, followed by incubation with LIGHT (200 ng/ml) for 24 h. The medium was changed before the last incubation with LIGHT for 24 h. In all experiments, unstimulated cells received vehicle. Data are presented as mean ± SEM (n = 4–6). *p < 0.05, **p < 0.01 and ***p < 0.001 vs unstimulated cells (Student’s t test). †p < 0.05, ††p < 0.01 and †††p < 0.001 vs glucose or LIGHT alone. Gluc, glucose; Unstim, unstimulated
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Fig5: LIGHT increases the inflammatory potential of glucose-stimulated HAEC cells. HAECs were stimulated for 3 h (a, b) or 6 h (c, d) with either LIGHT (200 ng/ml), d-glucose (10 mmol/l) or a combination thereof. Gene expression of the LTβR (a) and HVEM (b) were examined by qPCR and data are given in relation to the control gene β-actin. The levels of IL-8 (c) and MCP-1 (d) were assessed in cell supernatant fractions by ELISA. (c, d) The cells were pretreated for 6 h as described above, followed by incubation with LIGHT (200 ng/ml) for 24 h. The medium was changed before the last incubation with LIGHT for 24 h. In all experiments, unstimulated cells received vehicle. Data are presented as mean ± SEM (n = 4–6). *p < 0.05, **p < 0.01 and ***p < 0.001 vs unstimulated cells (Student’s t test). †p < 0.05, ††p < 0.01 and †††p < 0.001 vs glucose or LIGHT alone. Gluc, glucose; Unstim, unstimulated

Mentions: Vascular inflammation is an important complication of type 2 diabetes mellitus [2], and we and others have shown that LIGHT activates inflammatory responses in endothelial cells [5, 9, 20]. We therefore next examined the regulation of the two LIGHT receptors and the effect of LIGHT on inflammatory responses in HAECs with and without glucose exposure. First, LIGHT, especially when combined with glucose (10 mmol/l), markedly enhanced the expression of LTβR mRNA (Fig. 5a). Second, while glucose (10 mmol/l) and LIGHT (200 ng/ml) had no effect on HVEM expression, the combination of these stimuli induced a modest but significant effect on HVEM mRNA levels after culturing for 3 h (Fig. 5b). Third, pre-incubation of HAECs with glucose (10 mmol/l) and LIGHT (200 ng/ml) for 6 h resulted in the release of significantly higher levels of IL-8 and MCP-1, two prototypical endothelial-derived inflammatory chemokines, when the cells were further stimulated with LIGHT for an additional 24 h compared with cells pre-incubated with glucose or LIGHT alone (Fig. 5c, d). This finding suggests that glucose could enhance the LIGHT-mediated inflammatory response in arterial endothelial cells, potentially via a mechanism involving upregulation of its receptors in these cells.Fig. 5


LIGHT/TNFSF14 is increased in patients with type 2 diabetes mellitus and promotes islet cell dysfunction and endothelial cell inflammation in vitro
LIGHT increases the inflammatory potential of glucose-stimulated HAEC cells. HAECs were stimulated for 3 h (a, b) or 6 h (c, d) with either LIGHT (200 ng/ml), d-glucose (10 mmol/l) or a combination thereof. Gene expression of the LTβR (a) and HVEM (b) were examined by qPCR and data are given in relation to the control gene β-actin. The levels of IL-8 (c) and MCP-1 (d) were assessed in cell supernatant fractions by ELISA. (c, d) The cells were pretreated for 6 h as described above, followed by incubation with LIGHT (200 ng/ml) for 24 h. The medium was changed before the last incubation with LIGHT for 24 h. In all experiments, unstimulated cells received vehicle. Data are presented as mean ± SEM (n = 4–6). *p < 0.05, **p < 0.01 and ***p < 0.001 vs unstimulated cells (Student’s t test). †p < 0.05, ††p < 0.01 and †††p < 0.001 vs glucose or LIGHT alone. Gluc, glucose; Unstim, unstimulated
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Related In: Results  -  Collection

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Fig5: LIGHT increases the inflammatory potential of glucose-stimulated HAEC cells. HAECs were stimulated for 3 h (a, b) or 6 h (c, d) with either LIGHT (200 ng/ml), d-glucose (10 mmol/l) or a combination thereof. Gene expression of the LTβR (a) and HVEM (b) were examined by qPCR and data are given in relation to the control gene β-actin. The levels of IL-8 (c) and MCP-1 (d) were assessed in cell supernatant fractions by ELISA. (c, d) The cells were pretreated for 6 h as described above, followed by incubation with LIGHT (200 ng/ml) for 24 h. The medium was changed before the last incubation with LIGHT for 24 h. In all experiments, unstimulated cells received vehicle. Data are presented as mean ± SEM (n = 4–6). *p < 0.05, **p < 0.01 and ***p < 0.001 vs unstimulated cells (Student’s t test). †p < 0.05, ††p < 0.01 and †††p < 0.001 vs glucose or LIGHT alone. Gluc, glucose; Unstim, unstimulated
Mentions: Vascular inflammation is an important complication of type 2 diabetes mellitus [2], and we and others have shown that LIGHT activates inflammatory responses in endothelial cells [5, 9, 20]. We therefore next examined the regulation of the two LIGHT receptors and the effect of LIGHT on inflammatory responses in HAECs with and without glucose exposure. First, LIGHT, especially when combined with glucose (10 mmol/l), markedly enhanced the expression of LTβR mRNA (Fig. 5a). Second, while glucose (10 mmol/l) and LIGHT (200 ng/ml) had no effect on HVEM expression, the combination of these stimuli induced a modest but significant effect on HVEM mRNA levels after culturing for 3 h (Fig. 5b). Third, pre-incubation of HAECs with glucose (10 mmol/l) and LIGHT (200 ng/ml) for 6 h resulted in the release of significantly higher levels of IL-8 and MCP-1, two prototypical endothelial-derived inflammatory chemokines, when the cells were further stimulated with LIGHT for an additional 24 h compared with cells pre-incubated with glucose or LIGHT alone (Fig. 5c, d). This finding suggests that glucose could enhance the LIGHT-mediated inflammatory response in arterial endothelial cells, potentially via a mechanism involving upregulation of its receptors in these cells.Fig. 5

View Article: PubMed Central - PubMed

ABSTRACT

Aims/hypothesis: Activation of inflammatory pathways is involved in the pathogenesis of type 2 diabetes mellitus. On the basis of its role in vascular inflammation and in metabolic disorders, we hypothesised that the TNF superfamily (TNFSF) member 14 (LIGHT/TNFSF14) could be involved in the pathogenesis of type 2 diabetes mellitus.

Methods: Plasma levels of LIGHT were measured in two cohorts of type 2 diabetes mellitus patients (191 Italian and 40 Norwegian). Human pancreatic islet cells and arterial endothelial cells were used to explore regulation and relevant effects of LIGHT in vitro.

Results: Our major findings were: (1) in both diabetic cohorts, plasma levels of LIGHT were significantly raised compared with sex- and age-matched healthy controls (n&thinsp;=&thinsp;32); (2) enhanced release from activated platelets seems to be an important contributor to the raised LIGHT levels in type 2 diabetes mellitus; (3) in human pancreatic islet cells, inflammatory cytokines increased the release of LIGHT and upregulated mRNA and protein levels of the LIGHT receptors lymphotoxin &beta; receptor (LT&beta;R) and TNF receptor superfamily member 14 (HVEM/TNFRSF14); (4) in these cells, LIGHT attenuated the insulin release in response to high glucose at least partly via pro-apoptotic effects; and (5) in human arterial endothelial cells, glucose boosted inflammatory response to LIGHT, accompanied by an upregulation of mRNA levels of HVEM (also known as TNFRSF14) and LT&beta;R (also known as LTBR).

Conclusions/interpretation: Our findings show that patients with type 2 diabetes mellitus are characterised by increased plasma LIGHT levels. Our in vitro findings suggest that LIGHT may contribute to the progression of type 2 diabetes mellitus by attenuating insulin secretion in pancreatic islet cells and by contributing to vascular inflammation.

Electronic supplementary material: The online version of this article (doi:10.1007/s00125-016-4036-y) contains peer-reviewed but unedited supplementary material, which is available to authorised users.

No MeSH data available.


Related in: MedlinePlus