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Apoptosis, inflammation, and wound healing are critical pathophysiological events associated with various liver diseases. Currently, there is a lack of in vivo approaches to study hepatocyte apoptosis-induced liver injury and repair. To address this critical knowledge gap, we developed a unique genetically modified mouse model, namely, 3-Transgene (Tg) with inducible Hepatocyte-Specific Apoptosis Phenotype (3xTg-iHAP) in this study. The 3xTg-iHAP mice possess three transgenes including Alb-Cre, Rosa26-rtTA, and tetO-Fasl on a B6 background. These mice are phenotypically normal, viable, and fertile. After subcutaneous administration of a single dose of doxycycline (5 mg/kg, Dox) to 3xTg-iHAP mice, we observed a complete histological spectrum of sterile liver wound-healing responses: asymptomatic hepatocyte apoptosis at 8 h, necrotic liver injury and sterile inflammation at 48 h, followed by hepatocyte mitosis and regeneration within 7 days. During the injury phase, the mice exhibited an increase in the biomarkers of alanine aminotransferase (ALT), chemokine (C-X-C motif) ligand 1 (CXCL1), and IL-6 in peripheral blood, as well as α-smooth muscle actin (α-SMA) protein in liver tissues. Conversely, the mice displayed a decrease in these markers in the recovery phase. Remarkably, this model shows that the sterile liver injury following elevated hepatocyte apoptosis is associated with an increase in myeloid cells in the liver. Within 7 days post-Dox administration, the liver of Dox-treated 3xTg-iHAP mice displays a normal histological structure, indicating the completion of wound healing. Together, we established a novel mouse model of injury and regeneration induced by hepatocyte apoptosis. This tool provides a robust in vivo platform for studying the pathophysiology of sterile liver inflammation, regeneration, and new therapeutic interventions for liver diseases. NEW & NOTEWORTHY: Bu et al. present a triple-transgenic mouse model, namely, 3xTg-iHAP mice that are engineered to explore hepatocyte apoptosis-triggered sterile liver injury and regeneration. This model demonstrates a full spectrum of liver wound-healing responses from asymptomatic apoptosis to injury, myeloid cell-dominant sterile inflammation, and repair after induction of hepatocyte-specific apoptosis. The robust nature of this model makes it an invaluable in vivo tool for studying sterile liver inflammation, regeneration, and new therapeutic strategies. [ABSTRACT FROM AUTHOR]

Probiotic nutrients have shown promise in therapy for the treatment of gastrointestinal inflammation, infection, and atopic disease. Intestinal dendritic cells (DC) play a critical role in shaping the intestinal immune response. In this study, we tested the effect of a probiotic preparation (VSL#3) on DC distribution and phenotypes within the intestinal mucosa using a lineage depletion-based flow cytometric analysis. In naive C57BL/10J mice, intestinal mucosal DC were composed of plasmacytoid DC (pDC) and myeloid DC (mDC). The pDC were the dominant form in lamina propria and Peyer's patches, whereas mDC were the prevailing type in the mesenteric lymph nodes. Additional characterization of pDC and mDC with flow cytometry revealed that they expressed heterogeneous phenotypes in the intestinal mucosa. In mice gavaged with the probiotic VSL#3 for 7 d, the proportion of pDC within the lamina propria was >60% lower, whereas the pDC subset in the mesenteric lymph nodes was more than 200% greater than in sham-treated controls (P < 0.01). Within pDC, the proportion of functionally unique [CX3CR1.sup.+] DC was greater than in controls in both the lamina propria and the Peyer's patches (P < 0.01). In contrast to pDC, the mDC number was greater than in controls in all intestinal lymphoid tissue compartments in VSL#3-treated mice (P < 0.01). In conclusion, this study suggests that phenotypically and functionally distinct DC subsets are localized to specific lymphoid tissues within the intestinal mucosa and that the VSL#3 probiotic nutritional supplement alters the distribution of the DC subsets within the intestinal mucosa. These changes may be important in the alteration of mucosal immunity following probiotic VSL#3 therapy. J. Nutr. 139:1595-1602, 2009.

Milk fat globule-EGF factor 8 (MFG-E8)/lactadherin participates in several cell surface-mediated regulatory events. Although its mRNA is present in the gut, the physiological roles of MFG-E8 in the intestinal mucosa have not been explored. Here we show that MFG-E8 was expressed in intestinal lamina propria macrophages from mice. Using a wound-healing assay, MFG-E8 was shown to promote the migration of intestinal epithelial cells through a PKC[epsilon]-dependent mechanism. MFG-E8 bound to phosphatidylserine and triggered reorientation of the actin cytoskeleton in intestinal epithelial cells at the wound edge. Depleting MFG-E8 in mice by administration of anti-MFG-E8 antibody or targeted deletion of the MFG-E8 gene resulted in a slowing of enterocyte migration along the crypt-villus axis and focal mucosal injury. Moreover, in septic mice, intestinal MFG-E8 expression was downregulated, which correlated with intestinal injury, interrupted enterocyte migration, and impaired restitution. Treatment with recombinant MFG-E8 restored enterocyte migration, whereas deletion of MFG-E8 impeded mucosal healing in mice with sepsis. These results suggest that a decrease in intestinal MFG-E8 impairs intestinal mucosal repair in sepsis. Together, our data indicate that MFG-E8 plays an important role in the maintenance of intestinal epithelial homeostasis and the promotion of mucosal healing and suggest that recombinant MFG-E8 may be beneficial for the treatment of bowel injuries., Introduction Intestinal mucosa is covered with an epithelial lining that turns over rapidly and continuously throughout life. Cell proliferation, differentiation, and migration are crucial events required for the maintenance of [...]

Trefoil factor 3 (intestinal trefoil factor) is a cytoprotective factor in the gut. Herein we compared the effect of trefoil factor 3 with tumor necrosis factor-[alpha] on 1) activation of NF-[kappa]B in intestinal epithelial cells; 2) expression of Twist protein (a molecule essential for downregulation of nuclear factor-[kappa]B activity in vivo); and 3) production of interleukin-8. We showed that Twist protein is constitutively expressed in intestinal epithelial cells. Tumor necrosis factor-[alpha] induced persistent degradation of Twist protein in intestinal epithelial cells via a signaling pathway linked to proteasome, which was associated with prolonged activation of NF-[kappa]B. In contrast to tumor necrosis factor, trefoil factor 3 triggered transient activation of NF-[kappa]B and prolonged upregulation of Twist protein in intestinal epithelial cells via an ERK kinase-mediated pathway. Unlike tumor necrosis factor-[alpha], transient activation of NF-[kappa]B by trefoil factor 3 is not associated with induction of IL-8 in cells. To examine the role of Twist protein in intestinal epithelial cells, we silenced the Twist expression by siRNA. Our data showed that trefoil factor 3 induced interleukin-8 production after silencing Twist in intestinal epithelial cells. Together, these observations indicated that 1) trefoil factor 3 triggers a diverse signal from tumor necrosis factor-[alpha] on the activation of NF-[kappa]B and its associated molecules in intestinal epithelial cells; and 2) trefoil factor 3-induced Twist protein plays an important role in the modulation of inflammatory cytokine production in intestinal epithelial cells. trefoil factor 3; signal transduction

Zhu, Ya-Qin, Yu Lu, and Xiao-Di Tan. Monochloramine induces reorganization of nuclear speckles and phosphorylation of SRp30 in human colonic epithelial cells: role of protein kinase C. Am J Physiol Cell Physiol 285: C1294-C1303, 2003. First published June 25, 2003; 10.1152/ajpcell.00090.2003.--Intestinal epithelial cells are constantly stimulated by reactive oxidant metabolites (ROMs) in inflamed mucosa. Monochloramine (N[H.sub.2]Cl), a cell-permeant ROM, is particularly relevant to the pathogenesis of inflammation in the gastrointestinal tract. Nuclear speckles, a unique nuclear subcompartment, accumulate a family of proteins, namely, serine- and arginine-rich (SR) proteins. They play important roles in regulation of pre-mRNA splicing. Currently, little is known about the link between inflammatory stimulation and the pre-mRNA splicing process, although gene expression is changed in inflamed tissues. The present study was designed to investigate whether stimulation of human colonic epithelial cells (HT-29 and Caco-2 cell lines) with (N[H.sub.2]Cl) affects nuclear speckles and their components. By indirect immunofluorescence, nuclear speckles have been shown to undergo rapid aggregation after (N[H.sub.2]Cl) stimulation. By utilizing Western blotting, SRp30 (a subset of SR proteins) in intestinal epithelial cells was found to be phosphorylated after (N[H.sub.2]Cl) treatment, whereas other SR proteins were not responsive to (N[H.sub.2]Cl) stimulation. The cytotoxic effect of (N[H.sub.2]Cl) was excluded by both negative lactate dehydrogenase assay and propidium iodide staining. Therefore, (N[H.sub.2]Cl)-induced morphological changes on nuclear speckles and phosphorylated SRp30 do not result from intestinal epithelial injury. Furthermore, the effect of (N[H.sub.2]Cl) on nuclear speckles and SRp30 was blocked by bisindolylmaleimide I, a selective PKC inhibitor. Together, the available data suggest that stimulation of intestinal epithelial cells with (N[H.sub.2]Cl) results in a consequent change on pre-mRNA splicing machinery via a distinctive signal pathway involving activation of PKC. This effect may contribute to oxidant-induced pathophysiological changes in the gastrointestinal tract. intestinal epithelial cell; reactive oxygen metabolites; pre-mRNA splicing machinery; SR proteins; signal transduction