M2 polarization of murine peritoneal macrophages induces regulatory cytokine production and suppresses T-cell proliferation.

Bone-marrow-derived macrophages are divided into two phenotypically and functionally distinct subsets, M1 and M2 macrophages. Recently, it was shown that adoptive transfer of M2-polarized peritoneal macrophages reduced the severity of experimental colitis in mice. However, it is still unclear whether peritoneal macrophages possess the same ability to be polarized to cells with functionally different phenotypes and cytokine production patterns as bone-marrow-derived macrophages. To address this question, we examined the ability of peritoneal macrophages to be polarized to the M1 and M2 phenotypes and determined the specific cytokine profiles of cells with each phenotype. We showed that peritoneal macrophages, as well as bone-marrow-derived macrophages, were differentiated into M1 and M2 phenotypes following stimulation with interferon-γ (IFN-γ) and interleukin-4 (IL-4)/IL-13, respectively. Following in vitro stimulation with lipopolysaccharide, M2-polarized peritoneal macrophages predominantly expressed T helper type 2 (Th2) cytokines and regulatory cytokines, including IL-4, IL-13, transforming growth factor-ß and IL-10, whereas M1-polarized peritoneal macrophages expressed negligible amounts of Th1 and pro-inflammatory cytokines. ELISA showed that M2-polarized peritoneal macrophages produced significantly more IL-10 than M1-polarized peritoneal macrophages. Notably, M2-polarized peritoneal macrophages contributed more to the suppression of T-cell proliferation than did M1-polarized peritoneal macrophages. The mRNA expression of Th2 cytokines, including IL-4 and IL-13, increased in T-cells co-cultured with M2-polarized macrophages. Hence, our findings showed that M2 polarization of peritoneal macrophages induced regulatory cytokine production and suppressed T-cell proliferation in vitro, and that resident peritoneal macrophages could be used as a new adoptive transfer therapy for autoimmune/inflammatory diseases after polarization to the regulatory phenotype ex vivo.

An Increased Serum N-Terminal Telopeptide of Type I Collagen, a Biochemical Marker of Increased Bone Resorption, Is Associated with Infliximab Therapy in Patients with Crohn's Disease.

BACKGROUND: Osteopenia and osteoporosis are considered to be extra-intestinal manifestations of inflammatory bowel disease (IBD). Anti-tumor necrosis factor (TNF)-α biologics have been introduced as novel medications for an active IBD. However, it is still not well documented whether anti-TNF-α affects the frequency of bone loss or abnormality of bone mineral markers among patients with IBD. AIMS: This study was to investigate the biochemical basis of low bone mineral density (BMD) and increased turnover in IBD during infliximab (IFX) therapy. METHODS: Forty patients with Crohn's disease (CD), 80 patients with ulcerative colitis (UC), and 65 age- and gender-matched controls were included. BMD was measured with dual-energy X-ray absorptiometry, and vitamins K and D were measured as serum undercarboxylated osteocalcin (ucOC) and 1,25-(OH)2D, respectively. Bone formation and resorption were based on measuring bone-specific alkaline phosphatase (BAP) and serum N-terminal telopeptide of type I collagen (NTx), respectively. RESULTS: Significantly lower BMD was found in patients with UC and CD as compared to controls (P < 0.05). BAP, 1,25-(OH)2D, ucOC, and NTx were significantly higher in CD patients, but not in UC patients as compared to controls (P < 0.05). Further, serum NTx level was significantly higher in CD patients who were receiving IFX as compared to CD patients who were not receiving IFX (P < 0.01). CONCLUSIONS: A lower BMD and higher bone metabolism markers were found in CD patients as compared to controls or UC patients. A significant increased serum level of NTx, a biochemical marker of increased bone resorption, was observed in CD patients during IFX therapy.

Induction of murine TNBS colitis is strictly controlled by a modified method using continuous inhalation anesthesia with sevoflurane.

BACKGROUND: Trinitrobenzenesulfonic acid (TNBS)-induced colitis is one of the most widely used experimental colitis models. However, there is no standard procedure for inducing colitis by TNBS because it is difficult to achieve a uniform distribution of colitis. We have developed a modified method of murine TNBS-induced colitis that involves inhalation anesthesia with sevoflurane combined with both single and repeated TNBS administrations. AIMS: To compare the usefulness of our newly developed method for inducing murine TNBS-induced colitis with that of conventional intraperitoneal anesthesia. METHODS: TNBS in ethanol was administered to C57BL/6J mice held in an inverted vertical position either under continuous inhalation anesthesia with sevoflurane, in accordance with our newly developed method, or by intraperitoneal injection with 2.5 % avertin, in accordance with the conventional procedure. Body weight change, cytokine profile, and histological findings were examined during the course of colitis. RESULTS: The dispersion of anesthesia time, TNBS retention time, and nadir weight during the course of colitis was decreased using the newly developed method compared with the conventional procedure. Optimization of the modified TNBS-induced colitis, as evidenced by the predominant expression of Th1 and Th17 cytokines on day 7, was attained by the injection of 2.25 mg TNBS in 55 % ethanol. Regulation of the TNBS retention time using inhalation anesthesia with sevoflurane allowed strict control of the disease severity of TNBS-induced colitis. Using the modified method we were also able to develop a chronic TNBS-induced colitis model by repeated TNBS administration without excessive mortality of the mice. CONCLUSIONS: Our modified method for murine TNBS-induced colitis using continuous inhalation anesthesia with sevoflurane provides a better experimental colitis model following both single and repeated TNBS administrations.

Digoxin Attenuates Murine Experimental Colitis by Downregulating Th17-related Cytokines.

BACKGROUND: Digoxin, a cardiac glycoside used for the treatment of heart failure, was reported to inhibit the retinoid-related orphan receptor gamma t (RORγt) and attenuate the severity of experimental autoimmune encephalomyelitis and arthritis in mice. However, the effects of digoxin in a mice model of inflammatory bowel disease have not been elucidated. METHODS: Colitis was induced in severe combined immunodeficiency mice by adoptive transfer of CD45RB CD4 T cells. Digoxin or a vehicle was injected into mice with colitis intraperitoneally every other day and changes in body weight were evaluated. After 6 to 8 weeks, the treated mice were killed and evaluated for histological score, T-cell subset, and cytokine messenger RNA (mRNA) expression in the colonic tissue. RESULTS: Wasting disease and histological damage were significantly attenuated in digoxin-treated mice with colitis compared with those in the vehicle-treated mice. In addition, the mRNAs of Th17-related cytokines were downregulated, whereas those of interleukin-10 were upregulated in the colonic mucosa of digoxin-treated mice. However, unexpectedly, the mRNA expression level of tumor necrosis factor alpha did not decrease in the colonic mucosa of digoxin-treated mice with colitis. This observation suggests that digoxin may ameliorate colitis by a tumor necrosis factor alpha-independent pathway. CONCLUSIONS: This study has shown for the first time that treatment with digoxin can ameliorate murine experimental colitis. This finding suggests that the suppression of Th17 using reagents such as digoxin could be effective in treating Crohn's disease refractory to anti-tumor necrosis factor alpha therapy.