Involvement of CCN1 Protein and TLR2/4 Signaling Pathways in Intestinal Epithelial Cells Response to Listeria monocytogenes

CCN1 is well studied in terms of its functions in injury repair, cell adhesion survival and apoptosis, bacterial clearance and mediation of inflammation-related pathways, such as the TLR2/4 pathways. However, the role of CCN1 protein and its interaction with TLR2/4 pathways in intestinal epithelial cells was not elucidated after Listeria monocytogenes infection. The results of this study confirm that L. monocytogenes infection induced intestinal inflammation and increased the protein expression of CCN1, TLR2, TLR4 and p38, which followed a similar tendency in the expression of genes related to the TLR2/4 pathways. In addition, organoids infected by L. monocytogenes showed a significant increase in the expression of CCN1 and the activation of TLR2/4 pathways. Furthermore, pre-treatment with CCN1 protein to organoids infected by L. monocytogenes could increase the related genes of TLR2/4 pathways and up-regulate the expression of TNF, and increase the count of pathogens in organoids, which indicates that the interaction between the CCN1 protein and TLR2/4 signaling pathways in intestinal epithelial cells occurred after L. monocytogenes infection. This study will provide a novel insight of the role of CCN1 protein after L. monocytogenes infection in the intestine.

Cellular communication network factor 1 (CCN1) knockdown exerts a protective effect for hepatic ischemia/reperfusion injury by deactivating the MEK/ERK pathway

OBJECTIVE

Hepatic ischemia/reperfusion injury (IRI) is an unsettled and intractable conundrum in clinical treatment after liver transplantation and resection. Cellular communication network factor 1 (CCN1) is upregulated in liver IRI and may play a key role in this process. The objective of this study is to investigate the regulatory mechanism of CCN1 in liver IRI, which may provide new insight into liver IRI clinical treatment.

METHODS

The hepatic ischemia/reperfusion model was established in male C57BL/6 mice by occlusion of vessels in the liver followed by reperfusion. The mice were transfected with two small interfering RNAs (siRNAs) against CCN1 for CCN1 knockdown. The hypoxia/reoxygenation (HR) model was established in vitro using mouse hepatic cells followed by transfection with a siRNA and treatment with an ERK activator TPA to confirm the effects of CCN1 on the MEK/ERK pathway in liver IRI.

RESULTS

In hepatic IRI, CCN1 was upregulated and its knockdown reduced alanine aminotransferase and aspartate transaminase levels, myeloperoxidase activity, and the levels of IL-6 and TNF-α. CCN1 downregulation alleviated inflammatory cell infiltration and apoptosis in the liver. The expressions of cleaved caspase-9, cleaved caspase-3, Bax, and CHOP were decreased with an increased Bcl-2 level after CCN1 knockdown. The phosphorylation and activation of proteins in ER stress and MEK/ERK pathway were inhibited by CCN1 knockdown. In vitro, the levels of proinflammatory cytokines, apoptosis-inducing proteins, and proteins in ER stress and MEK/ERK pathway, which were decreased by CCN1 knockdown in HR, were restored by TPA, confirming that the activation of ERK aggravated cell apoptosis after reoxygenation.

CONCLUSION

Overall, CCN1 knockdown may suppress the inflammation, apoptosis during hepatic IRI by reducing the MEK/ERK pathway activation, which may be a breakthrough point in clinical alleviation of hepatic IRI caused by liver transplantation and resection.

Exosome-Derived MicroRNAs of Human Milk and Their Effects on Infant Health and Development

Multiple biologically active components of human milk support infant growth, health and development. Milk provides a wide spectrum of mammary epithelial cell-derived extracellular vesicles (MEVs) for the infant. Although the whole spectrum of MEVs appears to be of functional importance for the growing infant, the majority of recent studies report on the MEV subfraction of milk exosomes (MEX) and their miRNA cargo, which are in the focus of this review. MEX and the dominant miRNA-148a play a key role in intestinal maturation, barrier function and suppression of nuclear factor-κB (NF-κB) signaling and may thus be helpful for the prevention and treatment of necrotizing enterocolitis. MEX and their miRNAs reach the systemic circulation and may impact epigenetic programming of various organs including the liver, thymus, brain, pancreatic islets, beige, brown and white adipose tissue as well as bones. Translational evidence indicates that MEX and their miRNAs control the expression of global cellular regulators such as DNA methyltransferase 1-which is important for the up-regulation of developmental genes including insulin, insulin-like growth factor-1, α-synuclein and forkhead box P3-and receptor-interacting protein 140, which is important for the regulation of multiple nuclear receptors. MEX-derived miRNA-148a and miRNA-30b may stimulate the expression of uncoupling protein 1, the key inducer of thermogenesis converting white into beige/brown adipose tissue. MEX have to be considered as signalosomes derived from the maternal lactation genome emitted to promote growth, maturation, immunological and metabolic programming of the offspring. Deeper insights into milk's molecular biology allow the conclusion that infants are both "breast-fed" and "breast-programmed". In this regard, MEX miRNA-deficient artificial formula is not an adequate substitute for breastfeeding, the birthright of all mammals.

NR4A1 knockdown confers hepatoprotection against ischaemia-reperfusion injury by suppressing TGFβ1 via inhibition of CYR61/NF-κB in mouse hepatocytes

Nuclear receptor subfamily 4, group A, member 1 (NR4A1) can aggravate ischaemia‐reperfusion (I/R) injury in the heart, kidney and brain. Thus, the present study aimed to unravel the role of NR4A1 on hepatic I/R injury. For this purpose, the mouse hepatic I/R model and H/R‐exposed mouse hepatocytes model were established to stimulate the hepatic and hepatocellular damage. Then, the levels of ALT and AST as well as TNF‐α and IL‐1β expression were measured in the mouse serum and supernatant of hepatocyte s, respectively. Thereafter, we quantified the levels of NR4A1, CYR61, NF‐kB p65 and TGFβ1 under pathological conditions, and their interactions were analysed using ChIP and dual‐luciferase reporter gene assays. The in vivo and in vitro effects of NR4A1, CYR61, NF‐kB p65 and TGFβ1 on I/R‐induced hepatic and H/R‐induced hepatocellular damage were evaluated using gain‐ and loss‐of‐function approaches. NR4A1 was up‐regulated in the hepatic tissues of I/R‐operated mice and in H/R‐treated hepatocytes. Silencing NR4A1 relieved the I/R‐induced hepatic injury, as supported by suppression of ALT and AST as well as TNF‐α and IL‐1β. Meanwhile, NR4A1 knockdown attenuated the H/R‐induced hepatocellular damage by inhibiting the apoptosis of hepatocyte s. Moreover, we also found that NR4A1 up‐regulated the expression of CYR61 which resulted in the activation of the NF‐κB signalling pathway, thereby enhancing the transcription of TGFβ1, which was validated to be the mechanism underlying the contributory role of NR4A1 in hepatic I/R injury. Taken together, NR4A1 silencing reduced the expression of CYR61/NF‐κB/TGFβ1, thereby relieving the hepatic I/R injury.

Exosomal MicroRNAs in Milk from Mothers Delivering Preterm Infants Survive in Vitro Digestion and Are Taken Up by Human Intestinal Cells

SCOPE

This study investigates the ability of preterm milk exosomes to survive gastric/pancreatic digestion, internalization by intestinal epithelia, and the microRNAs (miRNAs) contents.

METHODS AND RESULTS

At average infant age 1 week and 6 days, milk is collected from mothers who delivered preterm and term infants (n = 10). Milk is exposed to conditions simulating infant gut digestion. Exosomes are isolated and lysed, and the exposed miRNAs are sequenced. Preterm milk exosomes survive in vitro digestion, and can be taken up by intestinal epithelia. Three hundred and thirty miRNAs are identified as preterm milk exosome miRNAs, and in vitro digestion does not have a pronounced effect on their expression. The abundant miRNAs in preterm milk exosomes are similar to those from term milk. Twenty-one low abundance miRNAs are specifically expressed in preterm milk exosomes compared to early term milk in the current study and what previously is found in mature term milk.

CONCLUSION

These results for the first time reveal the survivability of preterm milk exosomes following simulated gastric/pancreatic digestion. The authors demonstrate the richness of the miRNAs content in these exosomes. The results improve the knowledge of preterm milk biology and the molecular basis by which exosome miRNAs may uniquely affect preterm infants during early development.

Intestinal Stem Cell Isolation and Culture in a Porcine Model of Segmental Small Intestinal Ischemia

Intestinal ischemia remains a major cause of morbidity and mortality in human and veterinary patients. Many disease processes result in intestinal ischemia, when the blood supply and therefore oxygen is decreased to the intestine. This leads to intestinal barrier loss and damage to the underlying tissue. Intestinal stem cells reside at the base of the crypts of Lieberkühn and are responsible for intestinal renewal during homeostasis and following injury. Ex vivo cell culture techniques have allowed for the successful study of epithelial stem cell interactions by establishing culture conditions that support the growth of three-dimensional epithelial organ-like systems (termed "enteroids" and "colonoids" from the small and large intestine, respectively). These enteroids are composed of crypt and villus-like domains and mature to contain all of the cell types found within the epithelium. Historically, murine models have been utilized to study intestinal injury. However, a porcine model offers several advantages including similarity of size as well as gastrointestinal anatomy and physiology to that of humans. By utilizing a porcine model, we establish a protocol in which segmental loops of intestinal ischemia can be created within a single animal, enabling the study of differing time points of ischemic injury and repair in vivo. Additionally, we describe a method to isolate and culture the intestinal stem cells from the ischemic loops of intestine, allowing for the continued study of epithelial repair, modulated by stem cells, ex vivo.