Mian Zhou

Mechanism of the Anti-inflammatory Effect of Curcumin: PPAR-γ Activation

Curcumin, the phytochemical component in turmeric, is used as a dietary spice and a topical ointment for the treatment of inflammation in India for centuries. Curcumin (diferuloylmethane) is relatively insoluble in water, but dissolves in acetone, dimethylsulphoxide, and ethanol. Commercial grade curcumin contains 10–20% curcuminoids, desmethoxycurcumin, and bisdesmethoxycurcumin and they are as effective as pure curcumin. Based on a number of clinical studies in carcinogenesis, a daily oral dose of 3.6u2009g curcumin has been efficacious for colorectal cancer and advocates its advancement into Phase II clinical studies. In addition to the anticancer effects, curcumin has been effective against a variety of disease conditions in both in vitro and in vivo preclinical studies. The present review highlights the importance of curcumin as an anti-inflammatory agent and suggests that the beneficial effect of curcumin is mediated by the upregulation of peroxisome proliferator-activated receptor-γ (PPAR-γ) activation.

Cold-inducible RNA-binding protein (CIRP) triggers inflammatory responses in hemorrhagic shock and sepsis

A systemic inflammatory response is observed in patients undergoing hemorrhagic shock and sepsis. Here we report increased levels of cold-inducible RNA-binding protein (CIRP) in the blood of individuals admitted to the surgical intensive care unit with hemorrhagic shock. In animal models of hemorrhage and sepsis, CIRP is upregulated in the heart and liver and released into the circulation. In macrophages under hypoxic stress, CIRP translocates from the nucleus to the cytosol and is released. Recombinant CIRP stimulates the release of tumor necrosis factor-α (TNF-α) and HMGB1 from macrophages and induces inflammatory responses and causes tissue injury when injected in vivo. Hemorrhage-induced TNF-α and HMGB1 release and lethality were reduced in CIRP-deficient mice. Blockade of CIRP using antisera to CIRP attenuated inflammatory cytokine release and mortality after hemorrhage and sepsis. The activity of extracellular CIRP is mediated through the Toll-like receptor 4 (TLR4)–myeloid differentiation factor 2 (MD2) complex. Surface plasmon resonance analysis indicated that CIRP binds to the TLR4-MD2 complex, as well as to TLR4 and MD2 individually. In particular, human CIRP amino acid residues 106–125 bind to MD2 with high affinity. Thus, CIRP is a damage-associated molecular pattern molecule that promotes inflammatory responses in shock and sepsis.

Milk Fat Globule Epidermal Growth Factor 8 Attenuates Acute Lung Injury in Mice after Intestinal Ischemia and Reperfusion

RATIONALEnMilk fat globule epidermal growth factor 8 (MFG-E8) is a potent opsonin for the clearance of apoptotic cells and is produced by mononuclear cells of immune competent organs including the spleen and lungs. It attenuates chronic and acute inflammation such as autoimmune glomerulonephritis and bacterial sepsis by enhancing apoptotic cell clearance. Ischemia-reperfusion (I/R) injury of the gut results in severe inflammation, apoptosis, and remote organ damage, including acute lung injury (ALI).nnnOBJECTIVESnTo determine whether MFG-E8 attenuates intestinal and pulmonary inflammation after gut I/R.nnnMETHODSnWild-type (WT) and MFG-E8(-/-) mice underwent superior mesenteric artery occlusion for 90 minutes, followed by reperfusion for 4 hours. A group of WT mice was treated with 0.4 microg/20 g recombinant murine MFG-E8 (rmMFG-E8) at the beginning of reperfusion. Four hours after reperfusion, MFG-E8, cytokines, myeloperoxidase activity, apoptosis, and histopathology were assessed. A 24-hour survival study was conducted in rmMFG-E8- and vehicle-treated WT mice.nnnMEASUREMENTS AND MAIN RESULTSnMesenteric I/R caused severe widespread injury and inflammation of the small intestines and remote organs, including the lungs. MFG-E8 levels decreased in the spleen and lungs by 50 to 60%, suggesting impaired apoptotic cell clearance. Treatment with rmMFG-E8 significantly suppressed inflammation (TNF-alpha, IL-6, IL-1beta, and myeloperoxidase) and injury of the lungs, liver, and kidneys. MFG-E8-deficient mice suffered from greatly increased inflammation and potentiated ALI, whereas treatment with rmMFG-E8 significantly improved the survival in WT mice.nnnCONCLUSIONSnMFG-E8 attenuates inflammation and ALI after gut I/R and may represent a novel therapeutic agent.

Sympathetic excitotoxicity in sepsis: pro-inflammatory priming of macrophages by norepinephrine.

In the history of medicine, the interaction between mind and body has been repeatedly proposed. However, the influence of the nervous system on the immune regulation has, until now, drawn little attention. In this regard, the adrenergic system has been explored, and mainly catecholamine-mediated anti-inflammatory effects have been described. These inhibitory effects of epinephrine and norepinephrine were found to be mediated by beta2-adrenoceptors expressed on mononuclear cells. Recently, the role of the parasympathetic nervous system in the local anti-inflammatory reflex has been investigated. Stimulation of the vagus nerve decreases the pro-inflammatory response of macrophages via alpha7-cholinergic receptors. Thus, both the sympathetic and parasympathetic nervous systems are thought to work hand in hand in their anti-inflammatory responses. Here we discuss the deteriorating effects of the release of norepinephrine in sepsis. We have discovered that organ dysfunction in severe sepsis is mediated at least in part by an increase in pro-inflammatory cytokine release from Kupffer cells, which is caused by a priming via gut-derived norepinephrine. The sympathetic nervous system and gut-derived norepinephrine mediate the pro-inflammatory effects by activating alpha2A-adrenoceptor on Kupffer cells. In this review, we will focus on the differential function of the noradrenergic system on local and systemic inflammatory responses and the possibilities of the modulation of sympathetic outflow by centrally active inhibitors such as the novel peptide ghrelin or NMDA-receptor blockers. Furthermore, we will introduce the new concept of sympathetic excitotoxicity in sepsis characterized by the neurogenic priming of the systemic pro-inflammatory response.

Ghrelin hyporesponsiveness contributes to age-related hyperinflammation in septic shock.

Objective:To test the hypothesis that hyporesponsiveness to ghrelin due to reduced growth hormone (GH) contributes to the aging-related hyperinflammatory state in sepsis. Summary Background Data:Sepsis and septic shock are a serious problem, particularly in the geriatric population. Ghrelin is an endogenous ligand for the GH secretagogue receptor 1a (GHSR1a, ie, ghrelin receptor). The decline in GH with age is directly associated with many adverse changes that occur with aging. However, the role of GH, ghrelin, and GHSR1a in the age-associated vulnerability to sepsis remains unknown. Methods:Male Fischer 344 rats (young: 3 months; aged: 24 months) were used. Plasma GH levels, ghrelin receptor expression, and neuronal activity in the parasympathostimulatory nuclei of the brain stem in normal young and aged animals were measured. Endotoxemia was induced by intravenous injection of lipopolysaccharide (LPS, 15 mg/kg BW). Results:While LPS-induced release of proinflammatory cytokines from macrophages isolated from aged rats decreased, LPS injection resulted in an in vivo hyperinflammatory state. GH levels were lower in aged rats, which was associated with lower expression of GHSR1a in the dorsal vagal complex and a decrease in parasympathostimulatory neuronal activity. GHSR1a antagonist elevated LPS-induced cytokine release in young rats. GH increased GHSR-1a expression in the dorsal vagal complex in aged rats. Coadministration of ghrelin and GH, but not ghrelin alone or GH alone, markedly reduced cytokine levels and organ injury after endotoxemia in aged rats, which was associated with significantly elevated parasympathostimulatory neuronal activity. Conclusions:These findings suggest that the reduced central (brain) responsiveness to ghrelin due to the decreased GH, plays a major role in producing the hyperinflammatory state, resulting in severe organ injuries and high mortality after endotoxemia in aged animals. Ghrelin and GH can be developed as a novel therapy for sepsis in the geriatric population.

Differential expression of cytochrome P450 isoforms in the lungs of septic animals

Objective:Sepsis is characterized by an early, hyperdynamic phase and a late, hypodynamic phase. Although studies have shown that cytochrome P450 (CYP) plays an important role in the regulation of vascular reactivity, alterations of vascular CYP isoforms in sepsis remain unknown. Since CYP2C11 and CYP2J4 convert arachidonic acid to vasodilative epoxyeicosatrienoic acids, and CYP4A3 metabolizes arachidonic acid to both epoxyeicosatrienoic acids and vasoconstrictive 19,20-hydroxyeicosatetraenoic acid, the aim of this study was to examine the expression of these isoforms in sepsis and their association with hemodynamic changes. Design:Prospective, controlled, and randomized animal study. Setting:An institute research laboratory. Subjects:Male adult Sprague-Dawley rats were subjected either to polymicrobial sepsis by cecal ligation and puncture or to sham operation followed by the administration of normal saline solution (i.e., fluid resuscitation). Interventions:At 5 hrs (early sepsis) or 20 hrs (late sepsis) after cecal ligation and puncture, blood vessel-rich tissues (i.e., lungs) were harvested. The expression of CYP isoforms at both messenger RNA and protein levels was determined by reverse transcription polymerase chain reaction and Western blot analysis (CYP2C11), respectively. Hemodynamic variables were measured by radioactive microspheres. Main Results:The results indicate that the gene expression of CYP2C11 and CYP2J4 was significantly down-regulated at 20 hrs after cecal ligation and puncture, whereas the expression of CYP4A3 was markedly up-regulated at 5 hrs. The protein concentrations of CYP2C11 also decreased significantly at 20 hrs after cecal ligation and puncture. Although total peripheral resistance markedly increased, mean arterial pressure did not change significantly at 20 hrs after the onset of sepsis. In contrast, cardiac output and pulmonary perfusion markedly decreased in late sepsis. Conclusions:Since the up-regulated CYP4A3 is associated with the early, hyperdynamic phase of sepsis and the down-regulated CYP2C11 and CYP2J4 are associated with the late, hypodynamic phase, vascular CYP isoforms that metabolize arachidonic acid may be involved in regulating the cardiovascular response during the progression of sepsis.