The cholesterol biosynthesis pathway regulates IL-10 expression in human Th1 cells.

The mechanisms controlling CD4+ T cell switching from an effector to an anti-inflammatory (IL-10+) phenotype play an important role in the persistence of chronic inflammatory diseases. Here, we identify the cholesterol biosynthesis pathway as a key regulator of this process. Pathway analysis of cultured cytokine-producing human T cells reveals a significant association between IL-10 and cholesterol metabolism gene expression. Inhibition of the cholesterol biosynthesis pathway with atorvastatin or 25-hydroxycholesterol during switching from IFNγ+ to IL-10+ shows a specific block in immune resolution, defined as a significant decrease in IL-10 expression. Mechanistically, the master transcriptional regulator of IL10 in T cells, c-Maf, is significantly decreased by physiological levels of 25-hydroxycholesterol. Strikingly, progression to rheumatoid arthritis is associated with altered expression of cholesterol biosynthesis genes in synovial biopsies of predisposed individuals. Our data reveal a link between sterol metabolism and the regulation of the anti-inflammatory response in human CD4+ T cells.

The protease inhibitor cystatin C down-regulates the release of IL-ß and TNF-α in lipopolysaccharide activated monocytes.

Human cystatin C, a member of the cysteine proteinase-inhibitory family, is produced by all nucleated cells and has important roles in regulating natural immunity. Nematode homologs to human cystatin C have been shown to have anti-inflammatory effects on monocytes and to reduce colitis in mice. In Crohn's disease, pathogenic activated monocytes help drive inflammatory processes via the release of proinflammatory cytokines and chemokines. In particular, tumor necrosis factor-α-producing inflammatory monocytes have a central role in the intestinal inflammation in patients with Crohn's disease. We investigated the potential of human cystatin C to regulate pathogenic activated monocytes and its potential as an Immunomodulator in Crohn's disease. We found that cystatin C significantly decreased the lipopolysaccharide-stimulated release and expression of interleukin-1ß and tumor necrosis factor-α in monocyte and peripheral blood mononuclear cell cultures from healthy donors, whereas interleukin-6 and interleukin-8 levels were unchanged. A similar reduction of interleukin-1ß and tumor necrosis factor-α was also seen in peripheral blood mononuclear cell cultures from patients with Crohn's disease, and in particular, tumor necrosis factor-α was reduced in supernatants from lamina propria cell cultures from patients with Crohn's disease. Further investigation revealed that cystatin C was internalized by monocytes via an active endocytic process, decreased phosphorylation of the mitogen-activated protein kinase pathway extracellular signal-regulated kinase-1/2, and altered surface marker expression. The ability of cystatin C to modulate the cytokine expression of monocytes, together with its protease-inhibitory function, indicates that modulation of the local cystatin C expression could be an option in future Crohn's disease therapy.

The nonerythropoietic asialoerythropoietin protects against neonatal hypoxia-ischemia as potently as erythropoietin.

Recently, erythropoietin (EPO) and the nonerythropoietic derivative asialoEPO have been linked to tissue protection in the nervous system. In this study, we tested their effects in a model of neonatal hypoxia-ischemia (HI) in 7-day-old rats (unilateral carotid ligation and exposure to 7.7% O(2) for 50 min). EPO (10 U/g body weight = 80 ng/g; n = 24), asialoEPO (80 ng/g; n = 23) or vehicle (phosphate-buffered saline with 0.1% human serum albumin; n = 24) was injected intraperitoneally 4 h before HI. Both drugs were protective, as judged by measuring the infarct volumes, neuropathological score and gross morphological score. The infarct volumes were significantly reduced by both EPO (52%) and asialoEPO (55%) treatment, even though the plasma levels of asialoEPO had dropped below the detection limit (1 pm) at the onset of HI, while those of EPO were in the nanomolar range. Thus, a brief trigger by asialoEPO before the insult appears to be sufficient for protection. Proteomics analysis after asialoEPO treatment alone (no HI) revealed at least one differentially up-regulated protein, synaptosome-associated protein of 25 kDa (SNAP-25). Activation (phosphorylation) of ERK was significantly reduced in asialoEPO-treated animals after HI. EPO and the nonerythropoietic asialoEPO both provided significant and equal neuroprotection when administered 4 h prior to HI in 7-day-old rats. The protection might be related to reduced ERK activation and up-regulation of SNAP-25.