Discussion

Effect of intermediate dose dexamethasone on post-operative pain in lumbar spine surgery: A randomized, triple-blind, placebo-controlled trial

OBJECTIVES

Dexamethasone has demonstrated analgesic properties and is used as an adjunctive pain agent for many procedures. We evaluated the efficacy of a single, intermediate dose of dexamethasone on post-operative analgesic consumption, and pain scores for lumbar spine surgery.

METHODS

Eighty patients aged between 18 and 70 scheduled for lumbar decompressive laminectomy were randomly allocated into two groups to receive either intravenous 0.2 mg/kg dexamethasone (group D = 40) or normal saline (group P = 40) before anesthetic induction. Post-operative total morphine consumption and the respective pain score at the PACU, 4, 6, 12, 24 and 48 h were evaluated. In addition, any adverse events were recorded.

RESULTS

Total post-operative morphine consumption within 48 h was significantly lower in group D (34.5 vs. 42.5 mg, p = 0.031); however, the respective morphine consumption at each assessment was similar between groups. The respective NRS pain score at rest and upon movement in both groups was not significantly different for any time comparison. The average NRS pain score at rest and upon movement within 48 h was similar in both groups (i.e., NRS at rest Group D 3.6 vs. Group P 3.8, p = 0.936, and NRS for movement Group D 6.2 vs. Group P 6.3, p = 0.791). The adverse events within 48 h were also similar and serious complications (i.e., respiratory depression or surgical infection) were not found in either group.

CONCLUSION

A single, intermediate dose of dexamethasone before anesthetic induction could minimally decrease post-operative morphine consumption within 48 h after lumbar decompressive laminectomy without any effect on the pain score.

Immature dendritic cells reduce proinflammatory cytokine production by a coculture of macrophages and apoptotic cells in a cell-to-cell contact-dependent manner

We have demonstrated that phagocytosis of late apoptotic cells by mouse macrophages leads to the production of proinflammatory cytokines, notably macrophage-inflammatory protein (MIP-2), and therefore, a yet-unknown mechanism(s) should keep our body free of inflammation. In this study, we examined the effect of the addition of immature dendritic cells (iDCs) to a coculture of macrophages and apoptotic cells on MIP-2 production and phagocytosis by macrophages. The addition of iDCs to the coculture reduced MIP-2 production significantly but unexpectedly enhanced the phagocytosis by macrophages. Further study revealed that the reduction of MIP-2 production was dependent on cell-to-cell contact partly involving the beta(2) integrin family Mac-1. In addition, anti-inflammatory cytokines, interleukin-10 and transforming growth factor-beta, were involved in the reduction of MIP-2 production, as antibodies against these cytokines recovered MIP-2 production. Both cytokines were expressed by iDCs more significantly than macrophages at the mRNA levels, although they were hardly detected in the supernatant at the protein levels, suggesting that minute amounts of these anti-inflammatory cytokines were produced mainly by iDCs to block MIP-2 production in a cell-to-cell contact-dependent manner. Thus, this study reveals a new mechanism by which MIP-2 production by macrophages phagocytosing apoptotic cells is prevented.

Glucocorticoid augmentation of macrophage capacity for phagocytosis of apoptotic cells is associated with reduced p130Cas expression, loss of paxillin/pyk2 phosphorylation, and high levels of active Rac

Phagocytic clearance of apoptotic granulocytes has a pivotal role in determining an inflammatory outcome, resolution or progression to a chronic state associated with development of fibrotic repair mechanisms, and/or autoimmune responses. In this study, we describe reprogramming of monocyte to macrophage differentiation by glucocorticoids, resulting in a marked augmentation of their capacity for phagocytosis of apoptotic neutrophils. This monocyte/macrophage phenotype was characterized by decreased phosphorylation, and therefore recruitment of paxillin and pyk2 to focal contacts and a down-regulation of p130Cas, a key adaptor molecule in integrin adhesion signaling. Glucocorticoid-treated cells also displayed higher levels of active Rac and cytoskeletal activity, which were mirrored by increases in phagocytic capability for apoptotic neutrophils. We propose that changes in the capacity for reorganization of cytoskeletal elements induced by glucocorticoids are essential for efficient phagocytic uptake of apoptotic cells.

Effects of glucocorticoids on endogenous and transcellular metabolism of eicosanoids in asthma

BACKGROUND

Human blood polymorphonuclear cells, which biosynthesize eicosanoids from the 5-lipoxygenase (5-LO) pathway, are likely to be involved in asthma, in which glucocorticoids represent the first line of therapy. Their effects on leukotriene release after a short course of treatment, which have been reported in several studies, are controversial.

OBJECTIVE

We sought to investigate whether long-term oral glucocorticoids inhibit lipid mediators from the 5-LO pathway.

METHODS

Twelve normal control subjects, 29 asthmatic subjects, and 50 glucocorticoid-dependent asthmatic subjects were included in the study. Polymorphonuclear cells were studied for endogenous and transcellular metabolism of eicosanoids.

RESULTS

Total leukotriene B(4) production was significantly lower in cells from glucocorticoid-dependent asthmatic subjects (mean +/- SD, 177 +/- 26 ng/10(7) cells) than in control subjects (406 +/- 27), untreated asthmatic subjects (421 +/- 34), and asthmatic subjects treated with inhaled glucocorticoids (290 +/- 56). When incubated with arachidonic acid, these polymorphonuclear cells released very low amounts of 5(S)- and 12(S)-hydroxy-eicosatetraenoic acid (HETE), whereas endogenous 15(S)-HETE was found in substantial amounts. The transformation of exogenous 15(S)-HETE into 5(S),15(S)-diHETE and lipoxins was significantly more important in untreated asthmatic subjects than in control subjects and glucocorticoid-dependent asthmatic subjects.

CONCLUSION

This study showed that long-term oral corticotherapy affects the 5-LO activity and leads to a decrease production of all metabolites in contrast to short-term or inhaled glucocorticoids. This study also questions the site of action of glucocorticoids in regulating the availability of arachidonic acid and potential eicosanoid regulation, as previously held in phospholipase A2 studies.

Analysis of adrenocortical secretory responses during acute an prolonged immune stimulation in inflammation-susceptible and -resistant rat strains

Endogenous corticosterone secreted during immune challenge restricts the inflammatory process and genetic variations in this neuroendocrine-immune dialogue have been suggested to influence an individuals sensitivity to develop chronic inflammatory disorders. We have tested inflammation-susceptible Dark Agouti (DA) rats and resistant, MHC-identical, PVG.1AV1 rats for their abilities to secrete corticosterone in response to acute challenge with bacterial lipopolysaccharide (LPS) or a prolonged activation of the nonspecific immune system with arthritogenic yeast beta-glucan. Intravenous injection of LPS triggered equipotent secretion of corticosterone in both rat strains. Interestingly, peak concentrations of corticosterone did not differ significantly between the strains. Intradermal injection of beta-glucan caused severe, monophasic, polyarthritis in DA rats while PVG.1AV1 responded with significantly milder joint inflammation. Importantly, serial sampling of plasma from glucan-injected DA and PVG.1AV1 rats did not reveal elevated concentrations of plasma corticosterone at any time from days 1-30 postinjection compared to preinjection values, in spite of the ongoing inflammatory process. Interestingly, adrenalectomized, beta-glucan-challenged DA rats responded with an aggravated arthritic process, indicating an anti-inflammatory role for the basal levels of corticosterone that were detected in intact DA rats challenged with beta-glucan. Moreover, substitution with subcutaneous corticosterone-secreting pellets, yielding moderate stress-levels, significantly attenuated the arthritic response. In contrast, adrenalectomized and glucan-challenged PVG.1AV1 rats did not respond with an elevated arthritic response, suggesting that these rats contain the arthritic process via corticosterone-independent mechanisms. In conclusion, the hypothalamic-pituitary-adrenal axis in both rat strains exhibited strong activation after challenge with LPS. This contrasted to the basal corticosterone levels observed strains during a prolonged arthritic process. No correlation between ability to secrete corticosterone and susceptibility to inflammation could be demonstrated. Basal levels of endogenous corticosterone appeared to restrain inflammation in beta-glucan-challenged DA rats whereas resistance to inflammation in PVG.1AV1 rats may be mediated via corticosterone-independent mechanisms.

Fetuin (alpha2-HS-glycoprotein) opsonizes cationic macrophagedeactivating molecules

Macrophages become activated by bacterial endotoxin (lipopolysaccharide) and other stimuli to release proinflammatory cytokines and NO. To prevent release of toxic or potentially lethal quantities of these factors, the state of macrophage activation is counter-regulated by anti-inflammatory mediators (e.g., glucocorticoid hormones, interleukin 10, and transforming growth factor type beta). Fetuin, a negative acute-phase protein, recently was implicated as an anti-inflammatory mediator, because it is required for macrophage deactivation by spermine. In the present studies, we found that fetuin is necessary for macrophages to respond to CNI-1493, a tetravalent guanylhydrazone inhibitor of p38 mitogen-activated protein kinase phosphorylation. Fetuin dose-dependently increases macrophage uptake of CNI-1493, which can be specifically inhibited by anti-human fetuin antibodies. Anti-human fetuin antibodies render primary human peripheral blood mononuclear cells insensitive to deactivation by CNI-1493. Thus, macrophages use fetuin as an opsonin for cationic-deactivating molecules, both endogenous (e.g., spermine) and pharmacologic (e.g., CNI-1493). This role of fetuin as an opsonic participant in macrophage-deactivating mechanisms has implications for understanding and manipulating the innate immune response.