SIP24/24p3 is a secreted murine acute phase protein which has been speculated to play an anti-inflammatory role in vivo. Recently SIP24/24p3 has been found to be able to specifically induce apoptosis in leukocytes. By using (35)S metabolic labeling method, we studied the regulation of SIP24/24p3 by glucocorticoid and pro-inflammatory cytokines IL-6 and TNF-alpha in cultured Balb/c 3T3 and BNL cells. The following results were observed: (1) dexamethasone induced the expression of SIP24/24p3 in both Balb/c 3T3 and BNL cells, the induction was more significant in BNL cells; (2) dexamethasone and IL-6 synergistically induced the expression of SIP24/24p3 in both Balb/c 3T3 and BNL cells; (3) in Balb/c 3T3 cells dexamethasone and TNF-alpha acted synergistically to induce the expression of SIP24/24p3, whereas in BNL cells dexamethasone and TNF-alpha induced the expression of SIP24/24p3 in an additive manner; (4) dexamethasone and IL-6/TNF-alpha acted synergistically in Balb/c 3T3 cells and additively in BNL cells to induce the expression of SIP24/24p3. The inducibility of SIP24/24p3 by multiple factors will help to explain its highly specific expression in vivo. The difference in the expression patterns of SIP24/24p3 in different cell types is also suggestive to its expression and regulation in hepatic and extrahepatic tissues. Finally, the fact that SIP24/24p3 protein can be induced by both pro-inflammatory as well as anti-inflammatory factors is indicative of the important role of SIP24/24p3 in the entire acute phase response process.
Acute-Phase Proteins ; biosynthesis ; genetics ; Animals ; BALB 3T3 Cells ; Carrier Proteins ; biosynthesis ; genetics ; Cytokines ; pharmacology ; Dexamethasone ; pharmacology ; Drug Synergism ; Gene Expression Regulation ; Interleukin-6 ; pharmacology ; Lipocalin-2 ; Lipocalins ; Mice ; Mice, Inbred BALB C ; Oncogene Proteins ; biosynthesis ; genetics ; RNA, Messenger ; biosynthesis ; genetics ; Tumor Necrosis Factor-alpha ; pharmacology

We investigated acute effects of intermittent large dose bisphophonate therapy in osteoporotic patients. Peripheral blood mononuclear cells were incubated with alendronate (100 micrometer) for 18 hr, in vitro and cytokine expressions were measured by real-time RT-PCR. Pamidronate 30 mg was administered on 26 osteoporotic patients; and acute phase reactants, inflammatory cytokines and bone biomarkers were measured. The in vitro study showed significant increase in mRNA expression of IL-6, TNF-alpha and IFN-gamma. A notable rise in serum C-reactive protein (CRP) was observed over 3 days after pamidronate infusion (P=0.026). Serum levels of TNF-alpha, IL-6 and IFN-gamma were also significantly increased (P=0.009, 0.014, 0.035, respectively) and the increase in IL-6 levels were strongly correlated with CRP levels (P=0.04). Serum calcium and c-telopeptide levels rapidly decreased after the treatment (P=0.02, <0.001, respectively). This study showed that mRNA expression of inflammatory cytokines at peripheral blood mononuclear cells (PBMC) level were observed within 18 hr and marked elevation of inflammatory cytokines and acute phase reactants were demonstrated after pamidronate infusion at the dose for osteoporosis. Our studies confirmed that intermittent large dose aminobisphosphonate causes acute inflammation.
Acute-Phase Proteins/biosynthesis/genetics ; Adult ; Aged ; Aged, 80 and over ; Alendronate/pharmacology ; Biological Markers/blood ; Blood Cells/drug effects ; Bone Density Conservation Agents/*administration & dosage ; C-Reactive Protein/genetics/metabolism ; Calcium/blood ; Collagen Type I/blood ; Diphosphonates/*administration & dosage ; Female ; Humans ; Injections, Intravenous ; Interferon-gamma/blood/genetics ; Interleukin-6/blood/genetics ; Male ; Middle Aged ; Osteoporosis/*drug therapy ; Peptides/blood ; RNA, Messenger/metabolism ; Tumor Necrosis Factor-alpha/genetics/metabolism