Background Lifestyle therapy with resistance training is a potent measure to counteract age‐related loss in muscle strength and mass. Unfortunately, many individuals fail to respond in the expected manner. This phenomenon is particularly common among older adults and those with chronic diseases (e.g. chronic obstructive pulmonary disease, COPD) and may involve endocrine variables such as vitamin D. At present, the effects of vitamin D supplementation on responses to resistance training remain largely unexplored. Methods Ninety‐five male and female participants (healthy, n = 71; COPD, n = 24; age 68 ± 5 years) were randomly assigned to receive either vitamin D3 or placebo supplementation for 28 weeks in a double‐blinded manner (latitude 61°N, September–May). Seventy‐eight participants completed the RCT, which was initiated by 12 weeks of supplementation‐only (two weeks with 10 000 IU/day, followed by 2000 IU/day), followed by 13 weeks of combined supplementation (2000 IU/day) and supervised whole‐body resistance training (twice weekly), interspersed with testing and measurements. Outcome measures included multiple assessments of muscle strength (nvariables = 7), endurance performance (n = 6), and muscle mass (n = 3, legs, primary), as well as muscle quality (legs), muscle biology (m. vastus lateralis; muscle fibre characteristics, transcriptome), and health‐related variables (e.g. visceral fat mass and blood lipid profile). For main outcome domains such as muscle strength and muscle mass, weighted combined factors were calculated from the range of singular assessments. Results Overall, 13 weeks of resistance training increased muscle strength (13% ± 8%), muscle mass (9% ± 8%), and endurance performance (one‐legged, 23% ± 15%; whole‐body, 8% ± 7%), assessed as weighted combined factors, and were associated with changes in health variables (e.g. visceral fat, −6% ± 21%; [LDL]serum, −4% ± 14%) and muscle tissue characteristics such as fibre type proportions (e.g. IIX, −3% points), myonuclei per fibre (30% ± 65%), total RNA/rRNA abundances (15%/6–19%), and transcriptome profiles (e.g. 312 differentially expressed genes). Vitamin D3 supplementation did not affect training‐associated changes for any of the main outcome domains, despite robust increases in [25(OH)D]serum (∆49% vs. placebo). No conditional effects were observed for COPD vs. healthy or pre‐RCT [25(OH)D]serum. In secondary analyses, vitamin D3 affected expression of gene sets involved in vascular functions in muscle tissue and strength gains in participants with high fat mass, which advocates further study. Conclusions Vitamin D3 supplementation did not affect muscular responses to resistance training in older adults with or without COPD.

Emerging evidence indicates that neuroinflammatory responses in astroglia, including chemokine expression, are altered by opioids. Astroglial chemokines, such as CXCL10, are instrumental in response to many neuropathological insults. Opioid mediated disruption of astroglial CXCL10 expression may be detrimental in opioid abusers or patients receiving acute opioid therapy. We have characterized the in vitro effects of opioids on CXCL10 protein expression in human astroglial (A172) cells. The proinflammatory cytokine, tumor necrosis factor (TNF)α induced CXCL10 expression in A172 cells. Using MG-132, helenalin and SN50 [inhibitors of the transcription factor, nuclear factor (NF)-κB], we determined that NF-κB activation is instrumental in TNFα induced CXCL10 expression in A172 astroglia. Morphine exposure during the 24 h TNFα stimulation period did not alter CXCL10 expression. However, fentanyl, a more potent mu opioid receptor (MOR) agonist, inhibited TNFα induced CXCL10 expression. Interestingly, neither the nonselective opioid receptor antagonist, naltrexone nor β-funaltrexamine (β-FNA), a highly selective MOR antagonist, blocked fentanyl mediated inhibition of TNFα induced CXCL10 expression. Rather, β-FNA dose dependently inhibited TNFα induced CXCL10 expression with a greater potency than that observed for fentanyl. Immunoblot analysis indicated that morphine, fentanyl and β-FNA each reduced TNFα induced nuclear translocation of NF-κB p65. These data show that β-FNA and fentanyl inhibit TNFα induced CXCL10 expression via a MOR independent mechanism. Data also suggest that inhibition of TNFα induced CXCL10 expression by fentanyl and β-FNA is not directly related to a reduction in NF-κB p65 nuclear translocation. Further investigation is necessary in order to fully elucidate the mechanism through which these two opioid compounds inhibit CXCL10 expression. Understanding the mechanism by which chemokine expression is suppressed, particularly by the opioid antagonist, β-FNA, may provide insights into the development of safe and effective treatments for neuroinflammation.

The inducible isoform of nitric-oxide synthase (iNOS) is involved in neuropathogenesis associated with infection and disease in the brain. Hence, there is considerable interest in the identification of therapeutic interventions to prevent iNOS-mediated pathology. Astroglia are a major site of iNOS expression during neuropathogenesis. To mimic a key component of neuroinflammation, human A172 astroglial cells were exposed in vitro to a cytokine mixture containing interferon γ, tumor necrosis factor α, and interleukin-1β, resulting in significant iNOS expression. Next, we assessed the effects of the mu opioid receptor antagonist, β-funaltrexamine (β-FNA), on cytokine induced iNOS expression in human astroglia. β-FNA dose-dependently inhibited iNOS expression. β-FNA transcriptionally (or pre-transcriptionally) inhibited cytokine-induced iNOS activation as indicated by a significant decrease in NOS2 messenger RNA expression. Further characterization of the novel, anti-inflammatory actions of β-FNA may provide insights for pharmacologic strategies to treat or prevent brain pathologies associated with neuroinflammation.

Increased inflammatory signaling in microglia is implicated in the pathogenesis of neurodegenerative diseases, trauma, psychiatric disorders, and anxiety/depression. Understanding inflammatory signaling in microglia is critical for advancing treatment options. Studying rodent-derived microglia has yielded substantial information, yet, much remains to better understand inflammatory signaling in human microglia. Hence, there is great interest in developing immortalized human microglial cell lines. The C20 human microglial cell line was recently developed and our primary objective was to advance our knowledge of inflammatory signaling in these cells. Methods: Expression of the microglia specific marker transmembrane protein 119 (TMEM119) was assessed by western blot analysis. Lipopolysaccharide (LPS)-and interleukin-1β (IL-1β)-induced cytokine/chemokine expression was determined by ELISA. Phosphorylation of inhibitory kappa B alpha (IκBα), nuclear factor (NF)-κB p65, and p38 mitogen-activated protein kinase (p38 MAPK) was measured by western blot analysis. Results: TMEM119 was expressed in unstimulated C20 cells, and to a greater extent in IL-1β-stimulated cells. IL-1β significantly induced IL-6, monocyte chemoattractant protein-1/CCL2, and interferon-γ inducible protein 10/CXCL10 expression. LPS induced CCL2 expression, but not IL-6 or CXCL10 expression. IL-1β induced inflammatory signaling as indicated by increased phosphorylation of IκBα, NF-κB p65 and p38 MAPK. Conclusion: We provide the first evidence that C20 microglia express TMEM119. This is the initial report of IL-1βinduced activation of IκBα, NF-κB p65, and p38 MAPK and subsequent CXCL10, CCL2 and IL-6 secretion in C20 cells. These findings advance our understanding of inflammatory signaling in C20 cells and support the value of this cell line as a research tool.

Neuroinflammation is an integral component of neurodegenerative disorders, CNS infection and trauma. Astroglial chemokines, such as CXCL10, are instrumental in neuroinflammatory signaling as well as neurotoxicity. We have utilized proinflammatory-induced CXCL10 expression in normal human astrocytes (NHA) as a model in which to assess the anti-inflammatory actions of the selective, mu-opioid receptor (MOR) antagonist, β-funaltrexamine (β-FNA). Interferon (IFN)γ + HIV-1 Tat-induced CXCL10 expression (secreted protein and mRNA) was inhibited by co-treatment with β-FNA. Neither the MOR-selective antagonist, D-Phe-Cys-Tyr-D-Trp-Arg-Pen-Thr-NH2 (CTAP) nor the nonselective opioid receptor antagonist, naltrexone inhibited IFNγ + HIV-1 Tat-induced CXCL10 expression. Furthermore, co-treatment with excess CTAP or naltrexone did not prevent β-FNA mediated inhibition of IFNγ + HIV-1 Tat-induced CXCL10 expression. Additionally, we utilized an inhibitor of NF-κB activation (SN50) to demonstrate that IFNγ + HIV-1 Tat-induced CXCL10 expression is NF-κB-dependent in NHA. Subsequent experiments revealed that β-FNA did not significantly affect NF-κB activation. Interestingly, we discovered that β-FNA inhibited p38 activation as indicated by decreased expression of phospho-p38. Together, these findings suggest that the inhibitory actions of β-FNA are MOR-independent and mediated, in part, via a transcriptional mechanism. These findings add to our understanding of the mechanism by which chemokine expression is inhibited by β-FNA. In conjunction with future investigations, these novel findings are expected to provide insights into the development of safe and effective treatments for neuroinflammation.