As a Chinese traditional patent medicine, Tripterygium wilfordii glycosides (TWG) have been approved by the China State Food and Drug Administration (Z32021007) for autoimmune and inflammatory diseases. Application of TWG leads to significant decrease of the inflammatory cytokines, such as IL-6, IL-1β, and TNF-α. However, little is known whether TWG could regulate the anti-inflammatory cytokines and what the mechanism is. Here, we found that TWG could induce the upregulation of IL-37 which is a new anti-inflammatory cytokine. Furthermore, the inhibitors of ERK1/2 and/or p38 MAPK pathways suppressed IL-37 expression induced by TWG, indicating that the two pathways took part in this process. In conclusion, TWG could upregulate the anti-inflammatory cytokine IL-37 and ERK1/2 and p38 MAPK signal pathways were involved in the upregulation of IL-37 induced by TWG. The results showed that TWG had a potent activity on promoting the expression of IL-37, a new anti-inflammatory cytokine, which help further understanding the anti-inflammatory mechanism for the clinical application of TWG in therapy of diseases.

Interleukin 4 (IL-4) diminishes cytokine activation of human macrophage. IL-4 binding to monocyte IL-4R is associated with protein kinase C (PKC) translocation to a nuclear fraction. The cleavage of diacyglycerol (DAG), an activator of PKC, from membrane phospholipids was investigated to define the proximal events of IL-4R signaling. IL-4 induced a statistically significant time-and dose-dependent generation of DAG. The IL-4-triggered production of DAG was not derived from phosphatidylinositol 4,5-bisphosphate (PIP2) hydrolysis, since neither cytosolic calcium flux nor liberation of inositol phosphates was detected in response to IL-4. Experiments were performed using [14C- methyl]choline-labeled U937 cells and monocytes to determine whether IL- 4R activated phospholipase C (PLC), PLD, or PLA2 to use membrane phosphatidylcholine (PC) to form DAG. IL-4 induced a time- and dose- dependent increase of phosphocholine (pchol) with concomitant degradation of membrane PC (p < 0.05 compared with control). The finding that the peak reduction of PC was equivalent to peak production of pchol suggested that IL-4R signaling involved the activation of a PC- specific PLC. Changes in choline (chol) or lyso-PC and glycerolphosphocholine, the respective products of PC cleavage by PLD or PLA2, were not detected in IL-4-treated cells. In contrast, exogenous PLD induced an increase in chol and concomitant loss of membrane PC. Additional investigation suggested that IL-4R signaling does not involve PLD. In cells labeled with L-lyso-3-PC 1-[1- 14C]palmitoyl, PLD but not IL-4, increased the production of phosphatidic acid (PA) and phosphatidyl-ethanol when pretreated with ethanol. Propranolol, an inhibitor of phosphatidate phosphohydrolase, and calyculin A, a phosphatase 1 and 2A inhibitor, blocked DAG production in response to FMLP but not to IL-4. In propranolol pretreated cells, PMA but not IL-4 triggered the production of PA and lowered the amount of DAG. Evidence that PLA2 is not coupled to IL-4R is the detection of arachidonate production in response to FMLP but not to IL-4. Furthermore, IL-4R is not coupled to sphingomyelinase (SMase) since IL-4, unlike exogenous SMase, did not generate ceramide but induced the hydrolysis of PC to pchol that was comparable to exogenous PLC. In summary, IL-4R signaling in monocytes and U937 cells involves PLC and not PLD, PLA2, or SMase, and it uses PC and not PIP2 to form DAG.

as a novel anti-inflammatory cytokine of the interleukin (il)-1 family, il-37 protects the human body from diseases characterized by excessive inflammation. The pathologic process of hyperhomocysteinemia (hHcy) is accompanied by persistent inflammation. However, little is known regarding the role of IL-37 in hHcy. In the present study, the levels of cytokines including il-37, il-1β, il-6 and tumor necrosis factor-α in the supernatant were detected by ELISA. mRNA and protein expression were detected by Reverse transcription-quantitative PCR and western blotting, respectively. LDH level was determined by ELISA and the cell viability was detected through CCK-8 kit. In the present study, mean serum IL-37 levels of patients with hHcy were 32.3% lower than those of controls (P<0.01). In peripheral blood mononuclear cells (PBMCs) from patients with hHcy, mean IL-37 mRNA expression was 73.5% lower (P<0.01) and IL-37 protein expression was 77.7% lower compared with that of healthy controls (P<0.01). Furthermore, the results demonstrated that exogenous homocysteine (Hcy) stimulation markedly downregulated the mRNA and protein expression levels of il-37 in PBMcs in vitro. in 293T cells, overexpression of il-37 restored the cell viability impaired by Hcy, and reduced the release of lactate dehydrogenase and the proinflammatory cytokines IL-1β, il-6 and tumor necrosis factor-α. In conclusion, IL-37 was downregulated by Hcy in vivo and in vitro, and il-37 exhibited a protective role against cell injury induced by Hcy.

IL-6 is a cytokine synthesized by T cells and macrophages (M phi). It has pleiotropic effects on diverse cell types and is recognized for its "pro-inflammatory" properties. In mice, IL-4, IL-5, IL-6, and IL-10 are produced by Th-2 cells. Because IL-10 suppresses Th-1 clones, and IL-4 broadly deactivates M phi, experiments were carried out to investigate the in vitro effects of recombinant human IL-6 on cytokine activation of human M phi. Pretreatment with IL-6 induced a dose- and time-dependent suppression of IFN-gamma (1000 U/mL) and TNF-alpha (25 ng/mL) activation of M phi for the killing of L. amazonensis. At doses greater than 0.1 to 100 ng/mL, IL-6 inhibited IFN-gamma and TNF-alpha activation by 21 to 93% and 36 to 82%, respectively. IL-6 alone had no effect on M phi viability and intracellular L. amazonensis growth. Blockade of M phi activation was greatest when IL-6 was added 24 or 48 h before infection and treatment with IFN-gamma or TNF-alpha. Furthermore, mAb against IL-6 abrogated the inhibitory activity of IL-6. Similarly IL-6 pretreatment suppressed M phi activation for antileishmanial capacity by IL-3, granulocyte-monocyte-CSF (GM-CSF) and IL-1 beta. Because cytokine induction of antileishmanial activity is associated with enhancement of oxidative capacity, the effect of IL-6 on this mechanism was evaluated. Pretreatment with IL-6 down-modulated TNF-alpha (25 ng/mL) enhancement of M phi oxidative capacity in a dose- and time-dependent manner. A similar depression of oxidative capacity was observed for GM-CSF and IL-3 but not for IFN-gamma. Furthermore, NG-monomethyl-L-arginine (a nitric oxide synthase inhibitor) had no effect on IFN-gamma and TNF-alpha activation of antileishmanial activity and nitrites/nitrates were not reliably assayed from M phi culture supernatants. These findings suggest that IL-6 down-modulates cytokine activation of M phi antileishmanial capacity by inhibiting oxygen-dependent and undefined oxygen-independent mechanisms.

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