The role of Smad1/5 in mantle immunity of the pearl oyster Pinctada fucata martensii

The Smad protein family is an important medium for transducing BMP-Smads signals, and which have been proved that their important role in regulating shell biomineralization in Pinctada fucata martensii in our previous study. The members of TGF-β superfamily were involved in innate immunity in vertebrates and invertebrates, and Smad regulatory networks construct a balanced immune system. However, little is known about the role of Smad1/5 in immunity in P. f. martensii. The present study shows that the tissue distribution and the expression profiles of Smad1/5 at developmental stages suggested its wide distribution and crucial role in development at embryonic stages other than larval stage; the increased expression of bone morphogenetic proteins 2 (BMP2), Smad4, Smad1/5 and MSX mRNAs at mantle tissue after LPS and Poly (I:C) challenged implied the potential immune role of Smad1/5 and BMP2-Smad signals to defense against bacterial and virus infections; the reduced expression of immune gene nuclear factor kappa-B (NF-κB), matrix metalloproteinase (MMP), interleukin 17 (IL-17), CuZn-superoxide dismutase (CuZn-SOD), tissue inhibitors of metalloproteinase (TIMP) and lipopolysaccharide-induced TNF-α factor (LITAF) mRNA following knockdown of Smad1/5 indicated that Smad1/5 can regulate their expression via BMP2-Smads pathway in the immunity process; the up-regulated expression of Smad1/5 and BMP2-Smad signals genes, and immune genes during wound healing indicated that Smad1/5 and BMP2-Smad signals genes may be involved in wound healing collaborated with immune genes via a different and complex Smads signaling pathway. These results indicated Smad1/5 could regulate innate immunity via BMP2-Smads signal pathway, and which provided new insights into the relationship between BMP2-Smads signal pathway and mantle immunity.

Betalain Alleviates Airway Inflammation in an Ovalbumin-Induced-Asthma Mouse Model via the TGF-β1/Smad Signaling Pathway

Global industrialization not only improved the quality life of millions but also paved the way to solving many health problems. One among them is allergic asthma, which affects approximately 20% of the global population. Poor air quality is the major culprit in allergic asthma, which not only affects the individual's health, but also impairs his or her life quality and that of family members. Asthma is a chronic pulmonary inflammatory disease characterized by excess mucus production, airway hyperresponsiveness, and bronchoconstriction. Inhalation of corticosteroids, leukotriene modifiers, and β-adrenergic agonists is one treatment prescribed to control the symptoms of asthma, but there is still no effective cure. Phytochemicals such as carotenoids, phenolics, alkaloids, and nitrogen and organosulfur compounds are proven to possess immense pharmacological properties. Betalain is one such phytochemical present in plants of the order Caryophyllales. It is a water-soluble nitrogen-based pigment proven to possess antimicrobial, antioxidant, anti-inflammatory, hepatoprotective, antilipidemic, antidiabetic, and anticancer properties. We examined the curative potential of betalain against allergic asthma in a mouse model. Betalain treatment effectively decreased lung weight and infiltration of inflammatory cells in BAL fluid, and lowered IgE, eotaxin, and cytokine levels in asthma-induced mice. It also improved pulmonary mechanics and decreased oxidative stress and nitric oxide levels. Betalain significantly decreased gene expression of TGF-β and its downstream signaling Smad proteins. Lung histology confirmed that betalain protected the lung tissue of mice from ovalbumin-induced allergic asthma. Overall, our results show that betalain is a potent antiallergic drug that effectively protects mice from ovalbumin-induced allergic asthma. With further research, it can be prescribed as a treatment for asthma in humans.

Theacrine alleviates chronic inflammation by enhancing TGF-β-mediated shifts via TGF-β/SMAD pathway in Freund's incomplete adjuvant-induced rats

Rheumatoid arthritis is a chronic and systemic autoimmune disease, which affects approximately 1% of the adult population worldwide. The present study investigated the therapeutic effect of theacrine (TC) on arthritis and its mechanisms in Freund's incomplete adjuvant (FIA)-induced SD rats. Rats were randomly divided into 5 groups: i) healthy control; ii) model; iii) positive control with methotrexate (MTX); iv) treatment with 12.5 mg/kg TC; and v) treatment with 25.0 mg/kg TC. The apparent scores, including changes in body weights, degree of paw swelling and arthritis indicators, were analyzed to evaluate the anti-chronic inflammatory effect of TC. The levels of interleukin (IL)-6 and transforming growth factor-β (TGF-β) in serum were measured by enzyme-linked immunosorbent assay. The protein and RNA expression levels of the critical factors in rats were measured to elucidate the mechanisms responsible for chronic inflammation and to verify molecular indexes of chronic inflammatory conditions. TC notably suppressed the severity of FIA-induced rat by attenuating the apparent scores, animal weight and inflammatory indexes in the 25 mg/kg TC group compared with the FIA rat model. Furthermore, TC significantly decreased the levels of IL-6 and increased the levels of TGF-β. Histopathological examinations indicated that TC rescued the synovial hyperplasia and inflammatory cell infiltration in joint tissues. In addition, TC enhanced TGF-β-mediated shifts in inflammatory marker expression in joint tissue. Overall, the present study demonstrated that TC exerted a superior anti-arthritic effect via the suppression of IL-6 and the activation of TGF-β by the TGF-β/SMAD pathway.

Coreopsis tinctoria Nutt ameliorates high glucose-induced renal fibrosis and inflammation via the TGF-β1/SMADS/AMPK/NF-κB pathways

BACKGROUND

Coreopsis tinctoria Nutt is an ethnomedicine widely used in Xinjiang, China. It is consumed as a herbal tea by local Uyghur people to treat high blood pressure and diarrhea. Our previous study confirmed that the ethyl acetate extract of Coreopsis tinctoria (AC) had a protective effect on diabetic nephropathy (DN) in an in vivo experiment. Here we aim to elucidate the protective mechanism of AC and marein, the main ingredient in Coreopsis tinctoria on renal fibrosis and inflammation in vitro under high glucose (HG) conditions.

METHODS

A HG-induced barrier dysfunction model in rat mesangial cells (HBZY-1) was established. The cells were exposed to AC and marein and/or HG for 24 h. Then, the renal protective effects of AC and marein via transforming growth factor-β1 (TGF-β1)/Smads, AMP-activated kinase protein (AMPK), and nuclear factor kappa beta (NF-κB) signaling were assessed.

RESULTS

Both AC and marein suppressed rat mesangial cell hyperplasia and significantly attenuated the expression of HG-disrupted fibrotic and inflammatory proteins in HBZY-1 cells. It was also confirmed that AC and marein remarkably attenuated HG-induced renal inflammation and fibrosis by regulating the AMPK, TGF-β1/Smads, and NF-κB signaling pathways.

CONCLUSION

These results indicated that AC and marein may delay the progression of DN, at least in part, by suppressing HG-induced renal inflammation and fibrosis. Marein may be one of the bioactive compounds in AC.

Molecular characterization of two distinct Smads gene and their roles in the response to bacteria change and wound healing from Hyriopsis cumingii

The proteins of Smad family are critical components of the TGF-β superfamily signal pathway. In this paper, we cloned two intracellular mediators of TGF-β signaling, Smad3 and Smad5, from the pearl mussel Hyriopsis cumingii. The full length cDNA of HcSmad3 and HcSmad5 were 2052 bp and 1908 bp and encoded two polypeptides of 418 and 461amino acid residues, respectively. The deduced amino acid of HcSmad3 and HcSmad5 possessed two putative conserved domains, MH1 and MH2, a conserved phosphorylation motif SSXS at the carboxyl-terminal. The two Smad genes were detected muscle, mantle, hepatopancreas and gill, but with a very low level in heamocytes. The transcripts of Smad3 and Smad5 were up-regulated in hemocytes and hepatopancreas after A. hydrophila and PGN stimulation. However, the expression of Smad3 and Smad5 were only up-regulated in hepatopancreas after A. hydrophila stimulation. The transcripts of Smad3 and Smad5 had a slight change in hepatopancreas after PGN stimulation. The transcripts of HcSmad3 showed very little increase and HcSmad5 mRNA significantly up-regulated after wounding.

SMAD regulatory networks construct a balanced immune system

A balanced immune response requires combating infectious assaults while striving to maintain quiescence towards the self. One of the central players in this process is the pleiotropic cytokine transforming growth factor-β (TGF-β), whose deficiency results in spontaneous systemic autoimmunity in mice. The dominant function of TGF-β is to regulate the peripheral immune homeostasis, particularly in the microbe-rich and antigen-rich environment of the gut. To maintain intestinal integrity, the epithelial cells, myeloid cells and lymphocytes that inhabit the gut secrete TGF-β, which acts in both paracrine and autocrine fashions to activate its signal transducers, the SMAD transcription factors. The SMAD pathway regulates the production of IgA by B cells, maintains the protective mucosal barrier and promotes the balanced differentiation of CD4(+) T cells into inflammatory T helper type 17 cells and suppressive FOXP3(+) T regulatory cells. While encounters with pathogenic microbes activate SMAD proteins to evoke a protective inflammatory immune response, SMAD activation and synergism with immunoregulatory factors such as the vitamin A metabolite retinoic acid enforce immunosuppression toward commensal microbes and innocuous food antigens. Such complementary context-dependent functions of TGF-β are achieved by the co-operation of SMAD proteins with distinct dominant transcription activators and accessory chromatin modifiers. This review highlights recent advances in unravelling the molecular basis for the multi-faceted functions of TGF-β in the gut that are dictacted by fluid orchestrations of SMADs and their myriad partners.

The functional interactions of commensal bacteria with intestinal secretory IgA

PURPOSE OF REVIEW

The aim of this article is to describe the immune geography of IgA induction by commensal intestinal bacteria and the underlying mechanisms of cytokine and costimulatory signalling between dendritic cells, B cells and T cells.

RECENT FINDINGS

Intestinal dendritic cells sample commensal intestinal bacteria that penetrate the epithelial layer and induce IgA+ B cells to seed the mucosa with IgA plasma cells. Constitutive secretion of retinoic acid by intestinal dendritic cells directs the specificity of the IgA class switch and homing receptor expression in Peyer's patch B cells. In-vivo experiments have shown that TGF-beta is a vital cytokine for IgA induction in vivo, and the tumour necrosis factor family members BAFF and APRIL provide key costimulatory signals. After transport through the epithelial layer secretory IgA limits penetration of commensal bacteria back through the epithelium and shapes the density of different bacterial species in the intestinal lumen.

SUMMARY

Production of IgA is an important adaptation to the presence of commensal intestinal bacteria and induction of the response is compartmentalized within the intestinal mucosal immune system. This compartmentalization allows a vigorous mucosal immune response to commensals without needing the systemic immune system to be tolerant of these organisms.

TGFbeta signalling in control of T-cell-mediated self-reactivity

In the immune system, transforming growth factor-beta (TGFbeta) affects multiple cell lineages by either promoting or opposing their differentiation, survival and proliferation. Understanding the cellular mechanisms of TGFbeta-mediated regulation is complicated due to a broad distribution of TGFbeta receptors on the surface of different immune-cell types. Recent studies using in vivo genetic approaches revealed a critical role for TGFbeta signalling in T cells in restraining fatal autoimmune lesions. Here, we review recent advances in our understanding of a role for TGFbeta signalling in the regulation of T-cell differentiation in the thymus and in the periphery, with a particular emphasis on TGFbeta-mediated control of self-reactive T cells.

Transforming growth factor β1 up-regulates interferon regulatory factor 8 during dendritic cell development

Langerhans cells (LC) represent the cutaneous contingent of dendritic cells (DC). Their development critically depends on transforming growth factor beta1 (TGF-beta1) as demonstrated by analysis of TGF-beta1(-/-) mice, which lack LC. Here we used a two-step culture system and transcriptional profiling by DNA microarrays to search for TGF-beta1 target genes in DC. The study identified interferon regulatory factor 8 (IRF-8) as a novel target gene of TGF-beta1 signaling in DC. TGF-beta1 effectively induced Smad2/3 phosphorylation and IRF-8 RNA and protein expression. Blocking the TGF-beta1/Smad pathway by ectopic expression of inhibitory Smad7 and by SB431542 inhibitor abolished TGF-beta1 induced up-regulation of IRF-8. Furthermore, TGF-beta1-dependent induction of IRF-8 occurred in the absence of protein biosynthesis, suggesting a direct action of TGF-beta1/Smad signaling on IRF-8 gene activity. TGF-beta1 also induced expression of the chemokine receptor CCR7 and enhanced DC migration towards CCR7 ligand ELC. DC of IRF-8(-/-) mice show reduced CCR7 expression and migratory activity, thereby implicating the TGF-beta1/Smad/IRF-8 signaling pathway in CCR7 regulation. Thus, this study identified a novel TGF-beta1/Smad/IRF-8 signaling pathway with an impact on DC phenotype and function.

Regulation of galectin-1 expression by transforming growth factor beta1 in metastatic mammary adenocarcinoma cells: implications for tumor-immune escape

Tumors escape from immune surveillance by producing immunosuppressive cytokines and proapototic factors, including TGF-beta and galectin-1 (Gal-1). Since immunosuppressive mechanisms might act in concert to confer tumor-immune privilege, we investigated the potential cross talk between TGF-beta and Gal-1 in highly metastatic mammary adenocarcinoma (LM3) cells. While Gal-1 treatment was not capable of regulating TGF-beta synthesis, a pronounced and dose-dependent increase in Gal-1 expression was observed when tumor cells were treated with TGF-beta(1. )This effect was also observed in the murine lung adenocarcinoma LP07 and in the human breast adenocarcinoma MCF-7 cell lines. TGF-beta1-mediated upregulation of Gal-1 expression was specifically mediated by TbetaRI and TbetaRII, since it was abrogated when LM3 cells were infected with retroviral vectors expressing the dominant negative forms of these receptors. In addition, gal-1 gene sequence analysis revealed the presence of three putative binding sites for Smad4 and Smad3 transcription factors, consistent with the ability of TGF-beta(1) to trigger a Smad-dependent signaling pathway in these cells. Thus, TGF-beta(1) may trigger a Smad-dependent pathway to control Gal-1 expression, suggesting that distinct mechanisms might cooperate in tilting the balance toward an immunosuppressive environment at the tumor site.