Butanol production from corncob residue using Clostridium beijerinckii NCIMB 8052

Aims: Not all lactic acid bacteria possess the ability to confer health benefits for the host. Thus, it becomes necessary to screen and characterize numerous strains to obtain ideal probiotics. Here, two Lactobacillus plantarum strains (CECT 7315 and CECT 7316) were isolated and characterized. Methods and Results: In vitro and in vivo tests were carried out for demonstrating the abilities as probiotics of CECT 7315/CECT 7316 Lact. plantarum strains. Both strains showed high ability to survive at gastro‐intestinal tract conditions and to adhere to intestinal epithelial cells, as well as great inhibitory activity against a wide range of enteropathogens and ability to induce the production of anti‐inflammatory cytokine IL‐10. Conclusions: Lactobacillus plantarum CECT 7315/CECT 7316 because of their potential probiotic properties could be excellent candidates for being tested in clinical trials aimed to demonstrate beneficial effects on human health. Significance and Impact of the Study: Probiotics are live micro‐organisms that confer a health benefit for the host. However, not all the lactic acid bacteria possess the ability to confer health benefits for the host. In this study, two Lact. plantarum strains (CECT 7315 and CECT 7316) were isolated and characterized to demonstrate their excellent qualities as potential probiotic strains.     

Role of nucleotide‐binding oligomerization domain 1 (NOD1) in pericyte‐mediated vascular inflammation

We have recently described the response of human brain pericytes to lipopolysaccharide (LPS) through toll‐like receptor 4 (TLR4). However, Gram‐negative pathogen‐associated molecular patterns include not only LPS but also peptidoglycan (PGN). Given that the presence of co‐purified PGN in the LPS preparation previously used could not be ruled out, we decided to analyse the expression of the intracellular PGN receptors NOD1 and NOD2 in HBP and compare the responses to their cognate agonists and ultrapure LPS. Our findings show for the first time that NOD1 is expressed in pericytes, whereas NOD2 expression is barely detectable. The NOD1 agonist C12‐iE‐DAP induced IL6 and IL8 gene expression by pericytes as well as release of cytokines into culture supernatant. Moreover, we demonstrated the synergistic effects of NOD1 and TLR4 agonists on the induction of IL8. Using NOD1 silencing in HBP, we showed a requirement for C12‐iE‐DAP‐dependent signalling. Finally, we could discriminate NOD1 and TLR4 pathways in pericytes by pharmacological targeting of RIPK2, a kinase involved in NOD1 but not in TLR4 signalling cascade. p38 MAPK and NF‐κB appear to be downstream mediators in the NOD1 pathway. In summary, these results indicate that pericytes can sense Gram‐negative bacterial products by both NOD1 and TLR4 receptors, acting through distinct pathways. This provides new insight about how brain pericytes participate in the inflammatory response and may have implications for disease management.     

Corilagin suppresses RANKL‐induced osteoclastogenesis and inhibits oestrogen deficiency‐induced bone loss via the NF‐κB and PI3K/AKT signalling pathways

Over‐activated osteoclastogenesis, which is initiated by inflammation, has been implicated in osteoporosis. Corilagin, a natural compound extracted from various medicinal herbaceous plants, such as Cinnamomum cassia, has antioxidant and anti‐inflammatory activities. We found that Corilagin suppressed osteoclast differentiation in a dose‐dependent manner, significantly decreased osteoclast‐related gene expression and impaired bone resorption by osteoclasts. Moreover, phosphorylation of members of the nuclear factor‐kappaB (NF‐κB) and PI3K/AKT signalling pathways was reduced by Corilagin. In a murine model of osteoporosis, Corilagin inhibited osteoclast functions in vivo and restored oestrogen deficiency‐induced bone loss. In conclusion, our findings suggested that Corilagin inhibited osteoclastogenesis by down‐regulating the NF‐κB and PI3K/AKT signalling pathways, thus showing its potential possibility for the treatment of osteoporosis.     

Role of aldo‐keto reductase family 1 member B1 (AKR1B1) in the cancer process and its therapeutic potential

The role of aldo‐keto reductase family 1 member B1 (AKR1B1) in cancer is not totally clear but growing evidence is suggesting to have a great impact on cancer progression. AKR1B1 could participate in a complicated network of signalling pathways, proteins and miRNAs such as mir‐21 mediating mechanisms like inflammatory responses, cell cycle, epithelial to mesenchymal transition, cell survival and apoptosis. AKR1B1 has been shown to be mostly overexpressed in cancer. This overexpression has been associated with inflammatory mediators including nuclear factor kappa‐light‐chain‐enhancer of activated B cells (NFκB), cell cycle mediators such as cyclins and cyclin‐dependent kinases (CDKs), survival proteins and pathways like mammalian target of rapamycin (mTOR) and protein kinase B (PKB) or AKT, and other regulatory factors in response to reactive oxygen species (ROS) and prostaglandin synthesis. In addition, inhibition of AKR1B1 has been shown to mostly have anti‐cancer effects. Several studies have also suggested that AKR1B1 inhibition as an adjuvant therapy could render tumour cells more sensitive to anti‐cancer therapy or alleviate the adverse effects of therapy. AKR1B1 could also be considered as a potential cancer diagnostic biomarker since its promoter has shown high levels of methylation. Although pre‐clinical investigations on the role of AKR1B1 in cancer and the application of its inhibitors have shown promising results, the lack of clinical studies on AKR1B1 inhibitors has hampered the use of these drugs to treat cancer. Thus, there is a need to conduct more clinical studies on the application of AKR1B1 inhibitors as adjuvant therapy on different cancers.     

Immunostimulatory activity of potential probiotic yeast strains in the dorsal air pouch system and the gut mucosa

Aims: To determine the immunostimulatory activity of 15 presumptive probiotic yeast strains in the dorsal air pouch system in comparison with their activity in the gut mucosa. Methods and Results: Presumptive probiotic yeast strains previously isolated from human gastrointestinal tract and Feta cheese were further characterized genotypically and biochemically. The Saccharomyces cerevisiae 982, Saccharomyces boulardii KK1 and Kluyveromyces lactis 630 strains exhibited in the air pouch increased polymorphonuclear cell influx and phagocytic activity as well as cytokine production with similar potency as the probiotics Ultra levure S. boulardii and Lactobacillus acidophilus NCFB 1748. Oral administration of these strains in mice results in differential activation of small intestine immune responses concerning IgA and cytokine production as well as Toll‐like receptor expression. Conclusion: Besides the Saccharomyces strains 982 and KK1, the K. lactis 630 strain could also be considered as a candidate probiotic. Significance and Impact of the Study: The air pouch model may be used as an alternative and rapid method for the discrimination and selection of potential probiotic yeast strains.     

Negative regulation of toll-like receptor-mediated immune responses

Toll-like receptors (TLRs) are involved in host defence against invading pathogens, functioning as primary sensors of microbial products and activating signalling pathways that induce the expression of immune and pro-inflammatory genes. However, TLRs have also been implicated in several immune-mediated and inflammatory diseases. As the immune system needs to constantly strike a balance between activation and inhibition to avoid detrimental and inappropriate inflammatory responses, TLR signalling must be tightly regulated. Here, we discuss the various negative regulatory mechanisms that have evolved to attenuate TLR signalling to maintain this immunological balance.     

TLR2 and TLR4 activation induces p38 MAPK‐dependent phosphorylation of S6 kinase 1 in C2C12 myotubes

Toll‐like receptors 2 (TLR2) and 4 (TLR4) are present in the plasma membrane of skeletal muscle cells where their functions remain incompletely resolved. They can bind various extracellular ligands, such as FSL‐1, lipopolysaccharide (LPS) and/or palmitic acid (PA). We have investigated the link between PA, TLR2/4 and ribosomal S6 kinase 1 (S6K1) in C2C12 myotubes. Incubation with agonists of either TLR2 or TLR4, and with a high concentration of PA, increased S6K1 phosphorylation. Canonical upstream kinases of S6K1, protein kinase B (PKB) and mammalian target of rapamycin complex 1 (mTORC1), were regulated in the opposite way by PA, indicating that these kinases were probably not involved. By using the SB202190 inhibitor, p38 MAPK (mitogen‐activated protein kinase) was found to be a key mediator of PA‐induced phosphorylation of S6K1. Downregulation of either tlr2 or tlr4 gene expression by small interfering RNAs prevented the activation of both p38 MAPK and S6K1 by FSL‐1, LPS or PA. Thus TLR2 and TLR4 agonists can increase the level of S6K1 phosphorylation in a p38 MAPK‐dependent way in C2C12 myotubes. As PA induced the same intracellular signalling, a novel atypical pathway for PA is induced at the cellular membrane level and results in a higher phosphorylation state of S6K1.     

Attenuation of diabetic cardiomyopathy by relying on kirenol to suppress inflammation in a diabetic rat model

Diabetic cardiomyopathy is characterized by diabetes‐induced myocardial abnormalities, accompanied by inflammatory response and alterations in inflammation‐related signalling pathways. Kirenol, isolated from Herba Siegesbeckiae, has potent anti‐inflammatory properties. In this study, we aimed to investigate the cardioprotective effect of kirenol against DCM and underlying the potential mechanisms in a type 2 diabetes mellitus model. Kirenol treatment significantly decreased high glucose‐induced cardiofibroblasts proliferation and increased the cardiomyocytes viability, prevented the loss of mitochondrial membrane potential and further attenuated cardiomyocytes apoptosis, accompanied by a reduction in apoptosis‐related protein expression. Kirenol gavage could affect the expression of pro‐inflammatory cytokines in a dose‐dependent manner but not lower lipid profiles, and only decrease fasting plasma glucose, fasting plasma insulin and mean HbA1c levels in high‐dose kirenol‐treated group at some time‐points. Left ventricular dysfunction, hypertrophy, fibrosis and cell apoptosis, as structural and functional abnormalities, were ameliorated by kirenol administration. Moreover, in diabetic hearts, oral kirenol significantly attenuated activation of mitogen‐activated protein kinase subfamily and nuclear translocation of NF‐κB and Smad2/3 and decreased phosphorylation of IκBα and both fibrosis‐related and apoptosis‐related proteins. In an Electrophoretic mobility shift assay, the binding activities of NF‐κB, Smad3/4, SP1 and AP‐1 in the nucleus of diabetic myocardium were significantly down‐regulated by kirenol treatment. Additionally, high dose significantly enhanced myocardial Akt phosphorylation without intraperitoneal injection of insulin. Kirenol may have potent cardioprotective effects on treating for the established diabetic cardiomyopathy, which involves the inhibition of inflammation and fibrosis‐related signalling pathways and is independent of lowering hyperglycaemia, hyperinsulinemia and lipid profiles.     

Action mechanisms of probiotics on Candida spp. and candidiasis prevention: an update

Due to the high incidence of fungal infections caused by Candida species and their increasing resistance to antimicrobial treatments, alternative therapies such as probiotics have been studied. It has been show that several species of the genus Lactobacillus have anti-Candida activity, probably by direct inhibition, through competition for adhesion sites or production of secondary metabolites, and by indirect inhibition, through stimulation of the immune system of their host. However, the mechanisms of inhibition of these probiotics on Candida species have not yet been fully elucidated since this effect is related to more than one inhibition pathway. In the literature, several in vitro and in vivo studies have been developed seeking to elucidate the probiotics mechanisms of action. These studies have been focused on C. albicans inhibition assays, including analysis of antimicrobial activity, adherence capacity, biofilms formation, filamentation and interference on virulence genes, as well as assays of experimental candidiasis in invertebrate and vertebrate models. In this context, the purpose of this review was to gather different studies focused on the action mechanism of probiotic strains on Candida sp. and to discuss their impact on the candidiasis prevention.     

An LXR–NCOA5 gene regulatory complex directs inflammatory crosstalk‐dependent repression of macrophage cholesterol efflux

LXR–cofactor complexes activate the gene expression program responsible for cholesterol efflux in macrophages. Inflammation antagonizes this program, resulting in foam cell formation and atherosclerosis; however, the molecular mechanisms underlying this antagonism remain to be fully elucidated. We use promoter enrichment‐quantitative mass spectrometry (PE‐QMS) to characterize the composition of gene regulatory complexes assembled at the promoter of the lipid transporter Abca1 following downregulation of its expression. We identify a subset of proteins that show LXR ligand‐ and binding‐dependent association with the Abca1 promoter and demonstrate they differentially control Abca1 expression. We determine that NCOA5 is linked to inflammatory Toll‐like receptor (TLR) signaling and establish that NCOA5 functions as an LXR corepressor to attenuate Abca1 expression. Importantly, TLR3–LXR signal crosstalk promotes recruitment of NCOA5 to the Abca1 promoter together with loss of RNA polymerase II and reduced cholesterol efflux. Together, these data significantly expand our knowledge of regulatory inputs impinging on the Abca1 promoter and indicate a central role for NCOA5 in mediating crosstalk between pro‐inflammatory and anti‐inflammatory pathways that results in repression of macrophage cholesterol efflux.     

Anti-Adhesion Effects of Lactobacillus Strains on Caco-2 Cells Against Escherichia Coli and Their Application in Ameliorating the Symptoms of Dextran Sulfate Sodium-Induced Colitis in Mice

The beneficial effects of probiotics on ameliorating ulcerative colitis (UC) have attracted much attention in recent years. Nevertheless, the number of these identified probiotics is still limited. In addition, the adhesion abilities of probiotics are considered to be a key determinant for probiotic efficacy. However, the relationship between the adhesion abilities of probiotics and their role in ameliorating UC has been poorly studied to date. This study measured the adhesion abilities of four Lactobacillus strains to Caco-2 cells and their anti-adhesion effects on Caco-2 cells against pathogenic bacteria, as well as their application in ameliorating the symptoms of dextran sulfate sodium-induced UC, and further illustrated the relationship between these two potential probiotic properties of probiotics and their beneficial effects on UC. Results suggested that the adhesion abilities of the four tested Lactobacillus strains exists highly strain-specific and the mechanisms of their anti-adhesion effect on Caco-2 cells against Escherichia coli may be different. Moreover, all these strains had promising effects on ameliorating UC by reducing inflammatory response and improving the intestinal mucosal barrier function, as well as promoting the production of SCFAs. In conclusion, the four tested Lactobacillus strains can be considered as alternative dietary supplements in alleviating UC. In addition, it could be concluded that there is no significant correlation between the adhesion abilities of probiotics and their role in ameliorating UC, which further illustrated that the adhesion properties of probiotics in vitro may not be suitable as the key criterion for screening potential strains with UC-alleviating effects.

     

Mycobacterial lipoprotein activates autophagy via TLR2/1/CD14 and a functional vitamin D receptor signalling

In human monocytes, Toll‐like receptor (TLR) 2/1 activation leads to vitamin D3‐dependent antimycobacterial activities, but the molecular mechanisms by which TLR2/1 stimulation induces antimicrobial activities against mycobacteria remain unclear. Here we show that TLR2/1/CD14 stimulation by mycobacterial lipoprotein LpqH can robustly activate antibacterial autophagy through vitamin D receptor signalling activation and cathelicidin induction. We found that CCAAT/enhancer‐binding protein (C/EBP)‐β‐dependent induction of 25‐hydroxycholecalciferol‐1α‐hydroxylase (Cyp27b1) hydroxylase was critical for LpqH‐induced cathelicidin expression and autophagy. In addition, increases in intracellular calcium following AMP‐activated protein kinase (AMPK) activation played a crucial role in LpqH‐induced autophagy. Moreover, AMPK‐dependent p38 mitogen‐activated protein kinase (MAPK) activation was required for LpqH‐induced Cyp27b1 expression and autophagy activation. Collectively, these data suggest that TLR2/1/CD14‐Ca²⁺‐AMPK‐p38 MAPK pathways contribute to C/EBP‐β‐dependent expression of Cyp27b1 and cathelicidin, which played an essential role in LpqH‐induced autophagy. Furthermore, these results establish a previously uncharacterized signalling pathway of antimycobacterial host defence through a functional link of TLR2/1/CD14‐dependent sensing to the induction of autophagy.     

Mechanisms of prostate cancer cell survival after inhibition of AR expression

Recent reports have shown that the AR is the key determinant of the molecular changes required for driving prostate cancer cells from an androgen‐dependent to an androgen‐independent or androgen depletion‐independent (ADI) state. Several recent publications suggest that down‐regulation of AR expression should therefore be considered the principal strategy for the treatment of ADI prostate cancer. However, no valid data is available about how androgen‐dependent prostate cancer cells respond to apoptosis‐inducing drugs after knocking down AR expression and whether prostate cancer cells escape apoptosis after inhibition of AR expression. This review will focus on mechanisms of prostate cancer cell survival after inhibition of AR activity mediated either by androgen depletion or by targeting the expression of AR by siRNA. We have shown that knocking down AR expression by siRNA induced PI3K‐independent activation of Akt, which was mediated by calcium/calmodulin‐dependent kinase II (CaMKII). We also showed that the expression of CaMKII genes is under AR control: active AR in the presence of androgens inhibits CaMKII gene expression whereas inhibition of AR activity results in an elevated level of kinase activity and in enhanced expression of CaMKII genes. This in turn activates the anti‐apoptotic PI3K/Akt pathways. CaMKII also express anti‐apoptotic activity that is independent from the Akt pathway. This may therefore be an important mechanism by which prostate cancer cells escape apoptosis after androgen depletion or knocking down AR expression. In addition, we have found that there is another way to escape cell death after AR inhibition: DNA damaging agents cannot fully activate p53 in the absence of AR and as a result p53 down stream targets, for example, microRNA‐34, cannot be activated and induce apoptosis. This implies that there may be a need for re‐evaluation of the therapeutic approaches to human prostate cancer. J. Cell. Biochem. 106: 363–371, 2009. © 2008 Wiley‐Liss, Inc.     

Identification of key genes and pathways associated with different immune statuses of hepatitis B virus infection

We aimed to identify key genes and pathways associated with different immune statuses of hepatitis B virus (HBV) infection. The gene expression and DNA methylation profiles were analysed in different immune statuses of HBV infection. Differentially expressed genes (DEGs) and differentially methylated genes (DMGs) were identified, followed by their functional and integrative analyses. The differential expression of IgG Fc receptors (FcγRs) in chronic HBV‐infected patients and immune cells during different stages of HBV infection was investigated. Toll‐like receptor (TLR) signalling pathway (including TLR6) and leucocyte transendothelial migration pathway (including integrin subunit beta 1) were enriched during acute infection. Key DEGs, such as FcγR Ib and FcγR Ia, and interferon‐alpha inducible protein 27 showed correlation with alanine aminotransferase levels, and they were differentially expressed between acute and immune‐tolerant phases and between immune‐tolerant and immune‐clearance phases. The integrative analysis of DNA methylation profile showed that lowly methylated and highly expressed genes, including cytotoxic T lymphocyte‐associated protein 4 and mitogen‐activated protein kinase 3 were enriched in T cell receptor signalling pathway during acute infection. Highly methylated and lowly expressed genes, such as Ras association domain family member 1 and cyclin‐dependent kinase inhibitor 2A were identified in chronic infection. Furthermore, differentially expressed FcγR Ia, FcγR IIa and FcγR IIb, CD3^?CD56⁺CD16⁺ natural killer cells and CD14^highCD16⁺ monocytes were identified between immune‐tolerant and immune‐clearance phases by experimental validation. The above genes and pathways may be used to distinguish different immune statuses of HBV infection.