Glucocorticoid (GC) effects on skeletal development have not been established. The objective of this pQCT study was to assess volumetric BMD (vBMD) and cortical dimensions in childhood steroid-sensitive nephrotic syndrome (SSNS), a disorder with minimal independent deleterious skeletal effects. Tibia pQCT was used to assess trabecular and cortical vBMD, cortical dimensions, and muscle area in 55 SSNS (age, 5−19 yr) and >650 control participants. Race-, sex-, and age-, or tibia length–specific Z-scores were generated for pQCT outcomes. Bone biomarkers included bone-specific alkaline phosphatase and urinary deoxypyridinoline. SSNS participants had lower height Z-scores (p < 0.0001) compared with controls. In SSNS, Z-scores for cortical area were greater (+0.37; 95% CI = 0.09, 0.66; p = 0.01), for cortical vBMD were greater (+1.17; 95% CI = 0.89, 1.45; p < 0.0001), and for trabecular vBMD were lower (−0.60; 95% CI, = −0.89, −0.31; p < 0.0001) compared with controls. Muscle area (+0.34; 95% CI = 0.08, 0.61; p = 0.01) and fat area (+0.56; 95% CI = 0.27, 0.84; p < 0.001) Z-scores were greater in SSNS, and adjustment for muscle area eliminated the greater cortical area in SSNS. Bone formation and resorption biomarkers were significantly and inversely associated with cortical vBMD in SSNS and controls and were significantly lower in the 34 SSNS participants taking GCs at the time of the study compared with controls. In conclusion, GCs in SSNS were associated with significantly greater cortical vBMD and cortical area and lower trabecular vBMD, with evidence of low bone turnover. Lower bone biomarkers were associated with greater cortical vBMD. Studies are needed to determine the fracture implications of these varied effects.

The impact of glucocorticoids (GC) on skeletal development has not been established. The objective of this study was to examine changes in volumetric BMD (vBMD) and cortical structure over one year in childhood nephrotic syndrome (NS) and to identify associations with concurrent GC exposure and growth. Fifty-six NS participants, ages 5–21 years, were enrolled a median of 4.3 (0.5, 8.1) years after diagnosis. Tibia peripheral quantitative CT (pQCT) scans were obtained at enrollment and 6 and 12 months later. Sex, race and age-specific Z-scores were generated for trabecular vBMD (TrabBMD-Z), cortical vBMD (CortBMD-Z), and cortical area (CortArea-Z) based on > 650 reference participants. CortArea-Z was further adjusted for tibia length-for-age Z-score. Quasi-least squares regression was used to identify determinants of changes in pQCT Z-scores. At enrollment, mean TrabBMD-Z (−0.54 ±1.32) was significantly lower (p=0.0001) and CortBMD-Z (0.73 ± 1.16, p<0.0001) and CortArea-Z (0.27 ± 0.91, p=0.03) significantly greater in NS, vs. reference participants, as previously described. Forty-eight (86%) participants were treated with GC over the study interval (median dose 0.29 mg/kg/day). On average, TrabBMD-Z and CortBMD-Z did not change significantly over the study interval; however, CortArea-Z decreased (p=0.003). Greater GC dose (p<0.001), lesser increases in tibia length (p<0.001) and lesser increases in CortArea-Z (p=0.003) were independently associated with greater increases in CortBMD-Z. Greater increases in tibia length were associated with greater declines in CortArea-Z (p < 0.01); this association was absent in reference participants (interaction p<0.02). In conclusion, GC therapy was associated with increases in CortBMD-Z, potentially related to suppressed bone formation and greater secondary mineralization. Conversely, greater growth and expansion of CortArea-Z (i.e. new bone formation) were associated with declines in CortBMD-Z. Greater linear growth was associated with impaired expansion of cortical area in NS. Studies are needed to determine the fracture implications of these findings.

Highlights d Post-translational SUMOylation critically protects sensory neuron function d SUMOylation regulates bioenergetic enzymes and controls toxic metabolites d SUMOylation functionally regulates the nociceptive ion channel TRPV1 d De-SUMOylation accelerates progression of diabetic neuropathy

BackgroundCancer-associated pain is a major cause of poor quality of life in cancer patients and is frequently resistant to conventional therapy. Recent studies indicate that some hematopoietic growth factors, namely granulocyte macrophage colony stimulating factor (GMCSF) and granulocyte colony stimulating factor (GCSF), are abundantly released in the tumor microenvironment and play a key role in regulating tumor-nerve interactions and tumor-associated pain by activating receptors on dorsal root ganglion (DRG) neurons. Moreover, these hematopoietic factors have been highly implicated in postsurgical pain, inflammatory pain and osteoarthritic pain. However, the molecular mechanisms via which G-/GMCSF bring about nociceptive sensitization and elicit pain are not known.ResultsIn order to elucidate G-/GMCSF mediated transcriptional changes in the sensory neurons, we performed a comprehensive, genome-wide analysis of changes in the transcriptome of DRG neurons brought about by exposure to GMCSF or GCSF. We present complete information on regulated genes and validated profiling analyses and report novel regulatory networks and interaction maps revealed by detailed bioinformatics analyses. Amongst these, we validate calpain 2, matrix metalloproteinase 9 (MMP9) and a RhoGTPase Rac1 as well as Tumor necrosis factor alpha (TNFα) as transcriptional targets of G-/GMCSF and demonstrate the importance of MMP9 and Rac1 in GMCSF-induced nociceptor sensitization.ConclusionWith integrative approach of bioinformatics, in vivo pharmacology and behavioral analyses, our results not only indicate that transcriptional control by G-/GMCSF signaling regulates a variety of established pain modulators, but also uncover a large number of novel targets, paving the way for translational analyses in the context of pain disorders.