IFN-γ promotes transendothelial migration of CD4+ T cells across the blood-brain barrier.

Transendothelial migration (TEM) of Th1 and Th17 cells across the blood-brain barrier (BBB) has a critical role in the development of experimental autoimmune encephalomyelitis (EAE). How cytokines produced by inflammatory Th1 and Th17 cells damage the endothelial BBB and promote transendothelial migration of immune cells into the central nervous system (CNS) during autoimmunity is not understood. We therefore investigated the effect of various cytokines on brain endothelial cells. Among the various cytokines tested, such as Th1 (IFN-γ, IL-1α, IL-1ß, TNF-α, IL-12), Th2 (IL-3, IL-4, IL-6 and IL-13), Th17 (IL-17A, IL-17F, IL-21, IL-22, IL-23, GM-CSF) and Treg-specific cytokines (IL-10 and TGF-ß), IFN-γ predominantly showed increased expression of ICAM-1, VCAM-1, MAdCAM-1, H2-Kb and I-Ab molecules on brain endothelial cells. Furthermore, IFN-γ induced transendothelial migration of CD4+ T cells from the apical (luminal side) to the basal side (abluminal side) of the endothelial monolayer to chemokine CCL21 in a STAT-1-dependent manner. IFN-γ also favored the transcellular route of TEM of CD4+ T cells. Multicolor immunofluorescence and confocal microscopic analysis showed that IFN-γ induced relocalization of ICAM-1, PECAM-1, ZO-1 and VE-cadherin in the endothelial cells, which affected the migration of CD4+ T cells. These findings reveal that the IFN-γ produced during inflammation could contribute towards disrupting the BBB and promoting TEM of CD4+ T cells. Our findings also indicate that strategies that interfere with the activation of CNS endothelial cells may help in controlling neuroinflammation and autoimmunity.

Simultaneous imaging of microRNA or mRNA territories with protein territory in mammalian cells at single cell resolution.

Cellular mechanisms that inhibit mRNA translation by regulatory molecules involving microRNAs (miRNAs), a class of noncoding RNAs (ncRNAs), are well recognized in recent days. However, methodologies that measure these changes in cell populations lack the capabilities to observe such effects at single cell resolution. This is mostly due to the low level of transcript abundance and the heterogeneity of cell populations, together with the inability to measure transcripts and proteins at the same time. Here, we combine an in situ TaqMan PCR method with immunostaining so as to amplify low abundance transcripts in cellular compartments and image these efficiently at single cell resolution. The method offers flexibility to end-users for further fine-tuning of this optimized protocol based on the number of PCR cycles for individual genes in any cell type. After immunostaining, confocal microscopy is performed to detect the fluorescence of TaqMan probes (representing amplified transcripts/miRNA) and fluorophores tagged to antibodies (representing proteins) simultaneously. The presented technique offers an important tool to understand functional genomics as well as molecular mechanism of transcriptional and translational regulation so as to map these at single cell resolution.

Cellular detection of multiple antigens at single cell resolution using antibodies generated from the same species.

Biology at a cellular level comes with a great amount of heterogeneity. It is now evident that even clonally propagated cells in an in vitro population do not express the same set of cellular epitopes. The vascular endothelial as well as blood cells show a very high degree of heterogeneity in expression of specific proteins. Although several methods exist for identification of genome or transcriptome from a single cell, there is still limited advancement in detection of multiple cellular antigens in a single cell. This has been mainly due to the limited availability of different antibodies. Single-cell detection methods involving the use of multiple monoclonal antibodies generated in the same species would therefore provide with an important tool for cellular detection of antigens. Here, we describe a method to assess multiple proteins in a cell using different antibodies generated in the same species.

Lactobacillus plantarum (VR1) isolated from an ayurvedic medicine (Kutajarista) ameliorates in vitro cellular damage caused by Aeromonas veronii.

BACKGROUND: Lactobacillus plantarum is considered as a safe and effective probiotic microorganism. Among various sources of isolation, traditionally fermented foods are considered to be rich in Lactobacillus spp., which can be exploited for their probiotic attribute. Antibacterial property of L. plantarum has been demonstrated against various enteric pathogens in both in vitro and in vivo systems. This study was aimed at characterizing L. plantarum isolated from Kutajarista, an ayurvedic fermented biomedicine, and assessing its antagonistic property against a common enteropathogen Aeromonas veronii. RESULTS: We report the isolation of L. plantarum (VR1) from Kutajarista, and efficacy of its cell free supernatant (CFS) in amelioration of cytotoxicity caused by Aeromonas veronii. On the part of probiotic attributes, VR1 was tolerant to pH 2, 0.3% bile salts and simulated gastric juice. Additionally, VR1 also exhibited adhesive property to human intestinal HT-29 cell line. Furthermore, CFS of VR1 was antibacterial to enteric pathogens like Pseudomonas aeruginosa, Staphylococcus aureus, Escherichia coli, Aeromonas veronii and clinical isolates of P. aeruginosa and E. coli. Detailed study regarding the effect of VR1 CFS on A. veronii cytotoxicity showed a significant decrease in vacuole formation and detrimental cellular changes in Vero cells. On the other hand, A. veronii CFS caused disruption of tight junction proteins ZO-1 and actin in MDCK cell line, which was prevented by pre-incubation with CFS of VR1. CONCLUSIONS: This is the first study to report isolation of L. plantarum (VR1) from Kutajarista and characterisation for its probiotic attributes. Our study demonstrates the antagonistic property of VR1 to A. veronii and effect of VR1 CFS in reduction of cellular damage caused by A. veronii in both Vero and MDCK cell lines.

Association of small Rho GTPases and actin ring formation in epithelial cells during the invasion by Candida albicans.

Invasion of epithelial cells is a major virulence determinant of Candida albicans; however, the molecular events that occur during invasion are not discerned. This study is aimed to elucidate the role of the host's actin remodeling and involvement of small GTPases during invasion. Actin filaments formed a rigid ring-like structure in the rabbit corneal epithelial cell line SIRC after C. albicans invasion. During invasion, an increase in the mRNA content of Cdc42, Rac1 and RhoA GTPase was observed in SIRC cells. Immunochemical staining and expression of chimeric green fluorescent protein (GFP)-GTPases showed that all three GTPases colocalize at invasion and actin polymerization sites. This colocalization was not seen in SIRC cells expressing a GFP-tagged dominant-negative mutant of GTPases. Inhibition of invasion was observed in SIRC cells expressing dominant-negative mutants of Rac1 and RhoA GTPases. Involvement of zonula occludens-1 (ZO-1) was observed in the process of actin-mediated endocytosis of C. albicans. Actin, GTPases and ZO-1 were colocalized in epithelial cells during uptake of polymethylmethacrylate beads coated with spent medium from a C. albicans culture. The results indicate that host actin remodeling and recruitment of small GTPases occur during invasion and molecules that are shed or secreted by C. albicans are probably responsible for cytoskeletal reorganization.