Erythropoietin and stem cell factor are the key cytokines that regulate early stages of erythroid differentiation. However, it remains undetermined whether additional cytokines also play a role in the differentiation program. Here, we report that osteopontin (OPN) is highly expressed and secreted by erythroblasts during differentiation. We also demonstrate that OPNdeficient human and mouse erythroblasts exhibit defects in F-actin filaments, and addition of exogenous OPN to OPN-deficient erythroblasts restored the F-actin filaments in these cells. Furthermore, our studies demonstrate that OPN contributes to erythroblast proliferation. OPN knock-out male mice exhibit lower hematocrit and hemoglobin levels compared with their wild-type counterparts. We also show that OPN mediates phosphorylation or activation of multiple proteins including Rac-1 GTPase and the actin-binding protein, adducin, in human erythroblasts. In addition, we show that the OPN effects include regulation of intracellular calcium in human erythroblasts. Finally, we demonstrate that human erythroblasts express CD44 and integrins ␤ 1 and ␣ 4 , three known receptors for OPN, and that the integrin ␤ 1 receptor is involved in transmitting the proliferative signal. Together these results provide evidence for signal transduction by OPN and contribution to multiple functions during the erythroid differentiation program in human and mouse.Early stages of erythroid cell differentiation are regulated by multiple growth factors including interleukin-3, erythropoietin (EPO), 4 and stem cell factor (SCF) (1, 2). EPO and SCF have distinct functions. The predominant role of EPO is to deliver survival signals and maintain cell viability (3, 4), whereas SCF provides signals for cell proliferation (4 -6). Together these two growth factors guide the erythroid differentiation program from the early basophilic stage through the late polychromatic stage of maturation. However, the effects of these cytokines explain only the early stages of erythropoiesis. We were interested in identifying additional cytokines and/or factors involved in the erythroid differentiation program, especially factors that regulate the remodeling of the cytoskeleton. To achieve these objectives we developed methods to obtain extremely pure primary erythroblasts that synchronously differentiate into reticulocytes. Utilizing these cells, we screened a cDNA microarray and identified OPN as one of the cytokines that is highly expressed by erythroblasts during differentiation.OPN is a multifunctional cytokine that is highly expressed during bone remodeling and has pro-inflammatory effects (7-12). OPN has anti-apoptotic, chemotactic, and proliferative properties, depending on the cell type and context. It also plays a vital role in the delayed-type immune response and is known to be secreted by activated T cells and macrophages (13). OPN knock-out mice are viable and live a normal life span but suffer from bone defects and problems with wound and fracture healing (14). To date, OPN has not been show...

Intracerebral infection of susceptible mice with Theiler’s murine encephalomyelitis virus results in immune-mediated inflammatory demyelination in the white matter and consequent clinical symptoms. This system has been utilized as an important virus model for human multiple sclerosis. Although the potential involvement of virus-specific Th cells has been studied extensively, very little is known about the nature of T cells infiltrating the CNS during viral infection and their role in the development of demyelinating disease. In this study, the clonal nature of T cells in the spinal cord during the disease course was analyzed using size spectratyping and sequencing of the TCR β-chain CDR3 region. These studies clearly indicate that T cells are clonally expanded in the CNS after viral infection, although the overall TCR repertoire appears to be diverse. The clonal expansion appears to be Ag-driven in that it includes Th cells specific for known viral epitopes. Interestingly, such restricted accumulation of T cells was not detectable in the infiltrates of mice with proteolipid protein peptide-induced experimental autoimmune encephalomyelitis. The initial T cell repertoire (7–9 days postinfection) seems to be more diverse than that observed in the later stage (65 days) of virally induced demyelination, despite the more restricted utilization of Vβ subfamilies. These results strongly suggest continuous stimulation and clonal expansion of virus-specific T cells in the CNS of Theiler’s murine encephalomyelitis virus-infected mice during the entire course of demyelinating disease.

Theiler's virus infection induces an immune-mediated demyelinating disease, providing a relevant animal model of human multiple sclerosis. VP2(121-130)-specific CD8+ T cells in resistant H-2b mice account for the majority of CNS-infiltrating CD8+ T cells. To further study the role of the CD8(+) T cells, we generated a panel of mutant viruses substituted with L, G, or T at the anchor residue (M130) of the VP2(121-130) epitope. M130L virus (M130L-V) with a substitution of M with L displayed similar properties as wild-type virus (WT-V). However, M130G-V and M130T-V could not establish a persistent infection in the CNS. The level of both virus-specific CD8+ and CD4+ T cell responses is significantly reduced in mice infected with these variant viruses. While all mutant and wild-type viruses replicate comparably in BHK cells, replication of M130G-V and M130T-V in macrophages was significantly lower compared to those infected with WT-V and M130L-V. Interestingly, these mutant viruses deficient in replication in primary mouse cells showed drastically reduced binding ability to the cells. These results suggest that the anchor residue of the predominant CD8+ T cell epitope of TMEV in resistant mice is critical for the virus to infect target cells and this deficiency may result in poor viral persistence leading to correspondingly low T cell responses in the periphery and CNS. Thus, selection of the cellular binding region of the virus as the predominant epitope for CD8+ T cells in resistant mice may provide a distinct advantage in controlling viral persistence by preventing escape mutations.

Rhinovirus (RV), a member of the Picornaviridae family, accounts for many virus-induced asthma exacerbations. RV induces airway cell chemokine expression both in vivo and in vitro. Because of the known interactions of proteases with cellular functions, we hypothesized that RV 3C protease is sufficient for cytokine up-regulation. A cDNA encoding RV16 3C protease was constructed by PCR amplification and transfected into 16HBE14oϪ human bronchial epithelial cells. 3C protease induced expression of both IL-8 and GM-CSF, as well as transcription from both the IL-8 and GM-CSF promoters. 3C expression also induced activator protein 1 and NF-B transcriptional activation. Finally, mutation of IL-8 promoter AP-1 and NF-B promoter sequences significantly reduced 3C-induced responses. Together, these data suggest expression of RV16 3C protease is RVs are the most common upper respiratory pathogens, inducing the majority of common colds worldwide. Viral infections trigger asthma in 80 to 85% of asthma exacerbations in children and 44% in adults (1, 2) RV, a member of the Picornaviridae family of small, positive-stranded RNA viruses, accounts for much of virus-induced asthma exacerbations (1, 2). Cytokines are elaborated in vivo in the nasal mucosa, and most likely also from bronchial epithelium, after RV infection. Neutrophils, eosinophils, and lymphocytes increase in the nasal secretions of RV-infected patients compared with uninfected controls (3, 4).The cytokines IL-8 and GM-CSF have been implicated in the pathogenesis of asthma. IL-8 is a potent activator and chemoattractant of neutrophils (5) and eosinophils (6), and GM-CSF promotes the differentiation and survival of recruited eosinophils (7). Increased levels of IL-8, GM-CSF (8), and ICAM-1 (9), the receptor of 90% of RV serotypes, as well as IL-1 and IL-6, have been found in the nasal secretions of individuals infected with RVs (10 -12). In bronchial mucosal biopsies obtained after experimental infection with RV, Bardin and colleagues (13) noted a significant increase in submucosal lymphocytes and epithelial eosinophils, which, in asthmatics, persisted into convalescence. Although increases in cytokine secretion in the nasal mucosa does not prove increased expression in the epithelium in the lower airways, taken together the above data strongly suggest that cytokine elaboration is increased in the RV-infected lower airway epithelium.RV infection also induces cytokine production and adhesion molecule expression in cell culture. Divergent findings regard-

Celastrus orbiculatus Thunb has been known as an ethnopharmacological medicinal plant for antitumor, anti-inflammatory, and analgesic effects. Although various pharmacological studies of C. orbiculatus extract has been reported, an anti-inflammatory mechanism study of their phytochemical constituents has not been fully elucidated. In this study, compounds 1–17, including undescribed podocarpane-type trinorditerpenoid (3), were purified from C. orbiculatus and their chemical structure were determined by high-resolution electrospray ionization mass (HRESIMS) and nuclear magnetic resonance (NMR) spectroscopic data. To investigate the anti-inflammatory activity of compounds 1–17, nitric oxide (NO) secretion was evaluated in LPS-treated murine macrophages, RAW264.7 cells. Among compounds 1–17, deoxynimbidiol (1) and new trinorditerpenoid (3) showed the most potent inhibitory effects (IC50: 4.9 and 12.6 μM, respectively) on lipopolysaccharide- (LPS-) stimulated NO releases as well as proinflammatory mediators, such as inducible nitric oxide (iNOS), cyclooxygenase- (COX-) 2, interleukin- (IL-) 1β, IL-6, and tumor necrosis factor- (TNF-) α. Its inhibitory activity of proinflammatory mediators is contributed by suppressing the activation of nuclear transcription factor- (NF-) κB and mitogen-activated protein kinase (MAPK) signaling cascades including p65, inhibition of NF-κB (IκB), extracellular signal-regulated kinase (ERK), c-Jun NH2-terminal kinase (JNK), and p38. Therefore, these results demonstrated that diterpenoids 1 and 3 obtained from C. orbiculatus may be considered a potential candidate for the treatment of inflammatory diseases.