Exosomes in Intestinal Inflammation.

Exosomes are 30-150 nm sized vesicles released by a variety of cells, and are found in most physiological compartments (feces, blood, urine, saliva, breast milk). They can contain different cargo, including nucleic acids, proteins and lipids. In Inflammatory Bowel Disease (IBD), a distinct exosome profile can be detected in blood and fecal samples. In addition, circulating exosomes can carry targets on their surface for monoclonal antibodies used as IBD therapy. This review aims to understand the exosome profile in humans and other mammals, the cargo contained in them, the effect of exosomes on the gut, and the application of exosomes in IBD therapy.

MAPK and NF-κB signalling pathways regulate the expression of miRNA, let-7f in human endocervical epithelial cells.

MicroRNAs (miRNAs) mediate post-transcriptional gene suppression and are a critical component of the complex regulatory networks in epithelial immune responses. Transcription of miRNA genes in epithelial cells can be elaborately controlled through Toll-like receptors (TLRs), and associated nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB) and mitogen-activated protein kinase (MAPK) pathways, leading to nuclear transcription factor associated-transactivation and transrepression of miRNAs. MiRNA, let-7f is involved in the regulation of innate immune responses post TLR3 stimulation in human endocervical cells (End1/E6E7) and decreased let-7f is associated with poor immune activation. Thus, expression of let-7f is under strict control. However, the mechanism by which let-7f is regulated in these cells is not known. Therefore, in the present study, we have investigated the role of MAPK and NF-κB in the transcription of let-7f. We report that signalling of TLR3, results in activation of multiple signalling pathways including MAPK/ERK, JNK, p38, and NF-κB. Of these MAPK/ p38 and JNK directly influence the expression of let-7f in End1/E6E7 cells. Inhibition of ERK and NF-κB up regulates the expression of let-7f and its transcription factor, C/EBPß. In conclusion, we have identified a system through which TLR3 mediated immune response is regulated by C/EBPß and let-7f through the temporal activation of MAPK and NF-κB in human endocervical cells.

Transcription factor CCAAT/enhancer-binding protein-ß upregulates microRNA, let-7f-1 in human endocervical cells.

PROBLEM: In endocervical epithelial cells (End1/E6E7), miRNA let-7f plays an important role in the control of innate immunity. The underlying molecular mechanism for let-7f regulation in these cells remains largely unclear. METHODS OF STUDY: let-7f was knocked down in End1/E6E7 cells using siRNA, and differential gene expression was analyzed by microarray. Differentially expressed genes were validated by qPCR and Western blot. Expression of let-7f was studied by qPCR after inhibition of C/EBPß with betulinic acid (BA) and pCMVß plasmid and after overexpression of C/EBPß with pCMVß+ plasmid. ChIP assay was performed to confirm binding of C/EBPß to let-7f promoter. Levels of Lin28A/B were checked by qPCR after similar treatment. RESULTS: let-7f knockdown (KD) affects the expression of many transcription factors (eg, C/EBPß) which are important regulators of immune responses. We observed let-7f-1 promoter to contain 6 C/EBPß binding sites. KD of C/EBPß led to decreased let-7f expression while overexpression of C/EBPß increased its expression. Treatment of End1/E6E7 cells with TLR-3 ligand, poly(I:C) increased binding of C/EBPß at binding sites 3, 5, and 6. Expression of Lin28A/B also changed upon inhibition and overexpression of C/EBPß. Its expression is opposite to that of let-7f in End1/E6E7 cells. CONCLUSION: let-7f-1 is a direct target of transcription factor, C/EBPß in End1/E6E7 cells.

Hemoglobin expression in nonerythroid cells: novel or ubiquitous?

Hemoglobin (Hb) is a major protein involved in transport of oxygen (O2). Red blood cells (RBCs) contain maximum amount of Hb and because of their unique structure and plasticity they transport O2 to various tissues of the body at an optimal concentration. Recently, it has been reported that, apart from RBCs, Hb is also expressed by nonerythroid cells such as epithelial cells of different origin. The cells expressing Hb are from the tissues where maintenance of O2 homeostasis is of paramount importance. Hb expression has been observed in the epithelial cells from human tissues including lungs, neurons, retina, and endometrium. Our group has recently demonstrated that Hb is expressed by the cervicovaginal epithelial cells. We further showed that, apart from maintaining O2 homeostasis, Hb and the peptides derived from it play an indispensable role in the protection of vaginal epithelium by exhibiting antimicrobial activity. In this review, we discuss the significance of Hb expression in vaginal epithelial cells and its role in the recognition of pathogens thereby reducing the risk and/or severity of inflammation and/or infections and the possible mechanism by which Hb exhibits antimicrobial and antioxidative functions.