NFAM1 Promotes Pro-Inflammatory Cytokine Production in Mouse and Human Monocytes.

NFAT activating protein with ITAM motif 1 (NFAM1) is an ITAM bearing-transmembrane receptor that has been reported to play a role in B cell signaling and development. We performed expression analysis of NFAM1 using publicly available gene expression data sets and found that NFAM1 expression is significantly induced in intestinal biopsies from Crohn's disease (CD) and ulcerative colitis (UC) patients. At the cellular level, we further observed high expression of NFAM1 in monocytes and neutrophils, and low expression in B and T cells. To explore the role of NFAM1 in multiple immune cells and its potential role in IBD, we generated NFAM1-/- mice. In contrast with previous reports using NFAM1-transgenic mice, NFAM1-/- mice have no obvious defects in immune cell development, or B cell responses. Interestingly, NFAM1-/- monocytes produce reduced levels of TNF-α in response to activation by multiple IBD-relevant stimuli, including CD40L, TLR ligands and MDP. Additional cytokines and chemokines such as IL-6, IL-12, CCL3 and CCL4 are also reduced in CD40L stimulated NFAM1-/- monocytes. Collectively, these findings indicate that NFAM1 promotes monocyte activation, thereby amplifying the response to diverse stimuli. Similarly, we observed that deletion of NFAM1 in human monocytes reduces expression of CD40L-induced CCL4. Lastly, to assess the role of NFAM1 in IBD, we compared development of anti-CD40 induced colitis in NFAM1+/+ and NFAM1-/- mice. We found that although NFAM1 deletion had no impact on development of gut pathology, we did observe a decrease in serum TNF-α, confirming that NFAM1 promotes pro-inflammatory cytokine production in vivo. Taken together, we conclude that NFAM1 functions to amplify cytokine production and should be further evaluated as a therapeutic target for treatment of autoimmune disease.

Culture conditions for equine bone marrow mesenchymal stem cells and expression of key transcription factors during their differentiation into osteoblasts.

BACKGROUND: The use of equine bone marrow mesenchymal stem cells (BMSC) is a novel method to improve fracture healing in horses. However, additional research is needed to identify optimal culture conditions and to determine the mechanisms involved in regulating BMSC differentiation into osteoblasts. The objectives of the experiments were to determine: 1) if autologous or commercial serum is better for proliferation and differentiation of equine BMSC into osteoblasts, and 2) the expression of key transcription factors during the differentiation of equine BMSC into osteoblasts. Equine BMSC were isolated from the sterna of 3 horses, treated with purchased fetal bovine serum (FBS) or autologous horse serum (HS), and cell proliferation determined. To induce osteoblast differentiation, cells were incubated with L-ascorbic acid-2-phosphate and glycerol-2-phosphate in the presence or absence of human bone morphogenetic protein2 (BMP2), dexamethasone (DEX), or combination of the two. Alkaline phosphatase (ALP) activity, a marker of osteoblast differentiation, was determined by ELISA. Total RNA was isolated from differentiating BMSC between d 0 to 18 to determine expression of runt-related transcription factor2 (Runx2), osterix (Osx), and T-box3 (Tbx3). Data were analyzed by ANOVA. RESULTS: Relative to control, FBS and HS increased cell number (133 ± 5 and 116 ± 5%, respectively; P < 0.001) and 5-bromo-2'-deoxyuridine (BrdU) incorporation (167 ± 6 and 120 ± 6%, respectively; P < 0.001). Treatment with DEX increased ALP activity compared with control (1,638 ± 38%; P < 0.001). In the absence and presence of Dex, BMP-2 did not alter ALP activity (P > 0.8). Runt-related transcription factor2 expression increased 3-fold (P < 0.001) by d 6 of culture. Osterix expression increased 9-fold (P < 0.05) by d 18 of culture. Expression of Tbx3 increased 1.8-fold at d 3 (P < 0.01); however expression was reduced 4-fold at d 18 (P < 0.01). CONCLUSIONS: Dexamethasone, but not BMP-2, is required for differentiation of equine BMSC into osteoblasts. In addition, expression of Runx2 and osterix increased and expression of Tbx3 is reduced during differentiation.