The endocycle restores tissue tension in the Drosophila abdomen post wound repair.

Polyploidy frequently arises in response to injury, aging, and disease. Despite its prevalence, major gaps exist in our understanding of how polyploid cells alter tissue function. In the adult Drosophila epithelium, wound healing is dependent on the generation of multinucleated polyploid cells resulting in a permanent change in the epithelial architecture. Here, we study how the wound-induced polyploid cells affect tissue function by altering epithelial mechanics. The mechanosensor nonmuscle myosin II is activated and upregulated in wound-induced polyploid cells and persists after healing completes. Polyploidy enhances relative epithelial tension, which is dependent on the endocycle and not cell fusion post injury. Remarkably, the enhanced epithelial tension mimics the relative tension of the lateral muscle fibers, which are permanently severed by the injury. As a result, we found that the wound-induced polyploid cells remodel the epithelium to maintain fly abdominal movements, which may help compensate for lost tissue tension.

Teprenone ameliorates diclofenac-induced small intestinal injury via inhibiting protease activated receptors 1 and 2 activity.

OBJECTIVE: This study aimed to investigate specific protein expression of injured intestinal mucosa induced by diclofenac, and explore the protective effects of teprenone on it. METHODS: Intestinal damage of Sprague Dawley male rats was gradually induced by the intragastric administration of diclofenac. After the last drug administration, the intestinal mucosa was taken off with an interval of 24 h, subsequently, its general histological injury and ultrastructure were observed and analysed by a transmission electron microscope. The expression levels of PAR1 and PAR2 protein were detected by immunohistochemistry and real-time polymerase chain reaction (PCR). RESULTS: The Reuter and Chiu scores of small intestinal damage were 5.63 ± 1.30 and 4.25 ± 0.70 respectively in the model group, which could be protected by teprenone (100 mg/kg⋅day) with the degree of 55.7% and 44%. Optical microscopy and transmission electron microscope showed that intestinal mucosa and ultrastructure were severely damaged. Distributed in the cytoplasm or aligned with the nucleus, the expression of PAR1 and PAR2 was significantly upregulated after the administration of diclofenac, while it was relieved after the treatment of teprenone. CONCLUSION: Our study presents a new view that teprenone might protect NSAIDs-induced (diclofenac) intestinal injury via suppressing the expression of PAR1 and PAR2.

Detection of Reg3γ by Immunohistochemistry in Cerulein-Induced Model of Acute Pancreatic Injury in Mice and Rats.

OBJECTIVE: In a continuation of previous work, Reg3γ protein was further evaluated as a biomarker of pancreatic injury using immunohistochemistry in an additional species. METHODS: Mice and rats were treated with intraperitoneal cerulein injections, creating acute pancreatic injury. Mice received 2, 4, or 6 doses, and rats received 1, 2, or 3 doses of cerulein creating low, medium, and high treatment groups. Control animals were dosed with phosphate-buffered saline at corresponding volumes and intervals. Groups of 6 animals were killed 1, 3, 6, 24, and 48 hours after final treatments. Reg3γ immunohistochemical staining and image analysis were performed on pancreatic tissue obtained 6, 24, or 48 hours after control or cerulein treatment. Staining was quantified using image analysis software to calculate area of positivity as a percentage of total tissue area. RESULTS: Percent positivity of Reg3γ in both species rose by 6 hours, peaked by 24 hours across all 3 cerulein doses, and dropped significantly by 48 hours. In high-dose rats with accompanying gene expression data, Reg3γ gene expression corresponded temporally with quantitative staining data. CONCLUSIONS: Reg3γ staining quantified through image analysis showed a time- and dose-response in cerulein-treated mice and rats.

Peritoneal cavity lavage reduces the presence of mitochondrial damage associated molecular patterns in open abdomen patients.

BACKGROUND: Mitochondrial damage-associated molecular patterns (mtDAMPs), such as mitochondrial DNA and N-formylated peptides, are endogenous molecules released from tissue after traumatic injury. mtDAMPs are potent activators of the innate immune system. They have similarities with bacteria, which allow mtDAMPs to interact with the same pattern recognition receptors and mediate the development of systemic inflammatory response syndrome (SIRS). Current recommendations for management of an open abdomen include returning to the operating room every 48 hours for peritoneal cavity lavage until definitive procedure. These patients are often critically ill and develop SIRS. We hypothesized that mitochondrial DAMPs are present in the peritoneal cavity fluid in this setting, and that they accumulate in the interval between washouts. METHODS: We conducted a prospective pilot study of critically ill adult patients undergoing open abdomen management in the surgical and trauma intensive care units. Peritoneal fluid was collected daily from 10 open abdomen patients. Specimens were analyzed via quantitative polymerase chain reaction (qPCR) for mitochondrial DNA (mtDNA), via enzyme immunoassay for DNAse activity and via Western blot analysis for the ND6 subunit of the NADH: ubiquinone oxidoreductase, an N-formylated peptide. RESULTS: We observed a reduction in the expression of ND6 the day after lavage of the peritoneal cavity, that was statistically different from the days with no lavage (% change in ND6 expression, postoperative from washout: -50 ± 11 vs. no washout day, 42 ± 9; p < 0.05). Contrary to expectation, the mtDNA levels remained relatively constant from sample to sample. We then hypothesized that DNAse present in the effluent may be degrading mtDNA. CONCLUSION: These results indicate that the peritoneal cavity irrigation reduces the presence of mitochondrial DAMPs in the open abdomen. It is possible that increased frequency of peritoneal cavity lavage may lead to decreased systemic absorption of mtDAMPs, thereby reducing the risk of SIRS. LEVEL OF EVIDENCE: Prospective study, Case Series, Level V.

Induction of MIC-1/growth differentiation factor-15 following bile duct injury.

Macrophage inflammatory peptide-1 (MIC-1)/growth/differentiation factor-15 (GDF-15) is a divergent member of the transforming growth factor-beta superfamily cloned by others and us. MIC-1/GDF-15 is expressed in the liver, breast, and colon. Studies have demonstrated a growth-inhibiting effect of MIC-1/GDF-15 on colon and breast cancer cell lines in vitro and on tumor growth in vivo. We previously reported that MIC-1 expression is rapidly induced after a wide variety of murine acute and chronic liver injuries including aniline dye administration. I hypothesized, therefore, that MIC-1/GDF-15 may be a mediator of biliary tract injury and could play a role in regulation of bile duct proliferation. C57BL/6 mice underwent surgical ligation of the common bile duct. Northern blot analysis revealed a time-dependent induction of MIC-1/GDF-15 mRNA in the liver. In situ hybridization of liver sections for MIC-1/GDF-15 expression after bile duct ligation demonstrated a zone 1 or periportal expression pattern, consistent with expression of MIC-1 in periductular hepatocytes. Northern blot analysis of liver mRNA from patients with sclerosing cholangitis or cirrhosis also demonstrated enhanced expression of MIC-1/GDF-15. MIC-1/GDF-15 is expressed after bile duct injury in mice and humans. Taken together with the previously demonstrated growth inhibitory effects of MIC-1/GDF-15 on normal and transformed cells, MIC-1/GDF-15 may play a role in regulation of bile duct proliferation and biliary tumor formation.