In this large, well-characterized cohort assessed at multiple timepoints, we observed an inflammatory signature of delirium involving elevated interleukin-6 at POD2, which may be an important disease marker for delirium. We also observed preliminary evidence for involvement of other cytokines.

We examined the direct effects of IL-7 on osteoclastogenesis in murine bone marrow cultures, using cells from wild-type and IL-7- and IL-7 receptor (IL-7R)-deficient mice. IL-7 inhibited osteoclast-like cells (OCL) formation in macrophage colony-stimulating factor (M-CSF) and receptor activator of nuclear factor kappaB ligand (RANKL)-stimulated (both at 30 ng/ml) murine bone marrow cultures. Significant inhibitory effects were seen at 1 ng/ml (57%) and 10 ng/ml (86%). IL-7 also inhibited (P < 0.05) OCL formation in bone marrow cultures that were stimulated with vitamin D(3) (10(-8) M, 60%), bovine PTH (bPTH) (100 ng/ml, 54%), or RANKL alone (30 ng/ml, 50%). IL-7 (10 ng/ml) increased expression of the B lymphocyte marker B220 from 40-86% of total nonadherent cells in cultures treated with M-CSF and RANKL. Bone marrow cells from IL-7-deficient [IL-7 knockout (KO)] mice showed a significant (P < 0.05) increase in tartrate-resistant acid phosphatase(+) OCL numbers in cultures that were stimulated with vitamin D(3) (136 +/- 13.3%), bPTH (196 +/- 18.8%), or M-CSF and RANKL (160 +/- 7.2%). In contrast, in vitro osteoclast formation in bone marrow from IL-7R-deficient (IL-7R KO) mice showed a significant decrease in tartrate-resistant acid phosphatase(+) OCL numbers in cultures that were stimulated with vitamin D(3), PTH, RANKL, or M-CSF and RANKL. These results demonstrate that there are differences in the mechanisms regulating OCL formation between IL-7 KO and IL-7R KO cells. It seems that IL-7 is a direct inhibitor of OCL formation in vitro, based on results of adding IL-7 to wild-type cultures and the responses of IL-7 KO cells. It is unknown why IL-7R KO cells behave differently from IL-7 KO cells in vitro. However, it is possible that additional cytokines interact with IL-7R and that loss of these signals contributes to the responses of IL-7R KO cells. Alternatively, IL-7 may interact with multiple receptors.

We examined the ability of 1,25 (OH)2 vitamin D3 (Vit D) to stimulate osteoclast-like cell (OCL) formation in cocultures of spleen cells and primary calvarial osteoblasts from wild-type (WT) and IL-1R type 1-deficient (knockout; KO) mice. Vit D dose dependently increased OCL in cocultures containing WT osteoblasts. In contrast, there was a 90% reduction in OCL numbers in cocultures containing KO osteoblasts. In cocultures with either WT or KO osteoblasts, treatment with Vit D increased receptor activator of NF-κB ligand mRNA by 17-, 19-, or 3.5-fold, respectively. Vit D decreased osteoprotegerin mRNA to undetectable in all groups. Intracellular IL-1α protein increased after Vit D treatment in cocultures containing WT, but not KO osteoblasts. We also examined direct effects of Vit D, IL-1α, and their combination on gene expression in primary osteoblasts. In WT cells, Vit D and IL-1 stimulated receptor activator of NF-κB ligand mRNA expression by 3- and 4-fold, respectively, and their combination produced a 7-fold increase. Inhibition of osteoprotegerin mRNA in WT cells was partial with either agent alone and greatest with their combination. In KO cells, only Vit D stimulated a response. IL-1 alone increased IL-1α protein expression in WT osteoblasts. However, in combination with Vit D, there was a synergistic response (100-fold increase). In KO cultures, there were no effects of IL-1, Vit D, or their combination on IL-1α protein. These results demonstrate interactions between IL-1 and Vit D in primary osteoblasts that appear important in both regulation of IL-1α production and the ability of Vit D to support osteoclastogenesis.

No abstract

We examined the effects that ovariectomy had on sclerostin mRNA and protein levels in the bones of 8-week-old mice that were either sham-operated (SHAM) or ovariectomized (OVX) and then sacrificed 3 or 6 wks. later. In this model bone loss occurred between 3 and 5 wks. Post-surgery. In calvaria OVX significantly decrease sclerostin mRNA levels at 6 wks. post-surgery (by 52%) but had no significant effect at 3 wks. In contrast, sclerostin mRNA levels were significantly lower in OVX femurs at 3 wks. post-surgery (by 53%) but equal to that of SHAM at 6 wks. The effects of OVX on sclerostin were not a global response of osteocytes since they were not mimicked by changes in the mRNA levels for 2 other relatively osteocyte-specific genes: DMP-1 and FGF-23. Sclerostin protein decreased by 83% and 60%, respectively at 3 and 6 wks. post-surgery in calvaria and by 38% in lumbar vertebrae at 6 wks. We also detected decreases in sclerostin by immunohistochemistry in cortical osteocytes of the humerus at 3 wks. post-surgery. However, there were no significant effects of OVX on sclerostin protein in femurs or on serum sclerostin at 3 and 6 wks. post-surgery. These results demonstrate that OVX has variable effects on sclerostin mRNA and protein in mice, which are dependent on the bones examined and the time after surgery. Given the discrepancy between the effects of OVX on serum sclerostin levels and sclerostin mRNA and protein levels in various bones, these results argue that, at least in mice, serum sclerostin levels may not accurately reflect changes in the local production of sclerostin in bones. Additional studies are needed to evaluate whether this is also the case in humans.