Electroacupuncture Pretreatment Attenuates Intestinal Injury after Autogenous Orthotopic Liver Transplantation in Rats via the JAK/STAT Pathway

Critical Signaling Transduction Pathways and Intestinal Barrier: Implications for Pathophysiology and Therapeutics

The intestinal barrier is a sum of the functions and structures consisting of the intestinal mucosal epithelium, mucus, intestinal flora, secretory immunoglobulins, and digestive juices. It is the first-line defense mechanism that resists nonspecific infections with powerful functions that include physical, endocrine, and immune defenses. Health and physiological homeostasis are greatly dependent on the sturdiness of the intestinal barrier shield, whose dysfunction can contribute to the progression of numerous types of intestinal diseases. Disorders of internal homeostasis may also induce barrier impairment and form vicious cycles during the response to diseases. Therefore, the identification of the underlying mechanisms involved in intestinal barrier function and the development of effective drugs targeting its damage have become popular research topics. Evidence has shown that multiple signaling pathways and corresponding critical molecules are extensively involved in the regulation of the barrier pathophysiological state. Ectopic expression or activation of signaling pathways plays an essential role in the process of shield destruction. Although some drugs, such as molecular or signaling inhibitors, are currently used for the treatment of intestinal diseases, their efficacy cannot meet current medical requirements. In this review, we summarize the current achievements in research on the relationships between the intestinal barrier and signaling pathways. The limitations and future perspectives are also discussed to provide new horizons for targeted therapies for restoring intestinal barrier function that have translational potential.

The bi-directional role of the gut-brain axis in inflammatory and other gastrointestinal diseases

PURPOSE OF REVIEW

There is a growing body of evidence implicating the role of the gut-brain axis in a multitude of inflammatory and non-inflammatory gastrointestinal disorders. The interaction between the gut and the brain is bidirectional and its therapeutic manipulation is gaining traction as the new frontier in the management of gastrointestinal disorders. This review summarizes the recent literature on this subject and serves as a reference for future research directions.

RECENT FINDINGS

Recent studies have shown that the gut-brain axis, through its main communicator - the vagal nerve - plays a multimodal role in manipulating gastrointestinal physiology. This is evident systemically via the cholinergic anti-inflammatory pathway, through its effect on intestinal barrier function and also locally on intestinal epithelial and immune cells. Vagal nerve stimulation and faecal microbiota transplantation are two ways by which therapeutic manipulation has been attempted with success.

SUMMARY

There has been exceptional progress in our understanding of the gut-brain axis in recent literature. Its role in the modulation of a multitude of gastrointestinal disorders is becoming clear. Preclinical findings are sufficient for this research to proceed to clinical trials in order to harness its clinical therapeutic potential for the care of patients.

Neuropathic Pain Creates Systemic Ultrastructural Changes in the Nervous System Corrected by Electroacupuncture but Not by Pregabalin

Purpose

It is unclear whether neuropathological structural changes in the peripheral nervous system and central nervous system can occur in the spared nerve injury model. In this study, we investigated the pathological changes in the nervous system in a model of neuropathic pain as well as the effects of electroacupuncture (EA) and pregabalin (PGB) administration as regards pain relief and tissue repair.

Patients and Methods

Forty adult male SD rats were equally and randomly divided into 4 groups: spared nerve injury group (SNI, n = 10), SNI with electroacupuncture group (EA, n = 10), SNI with pregabalin group (PGB, n =10) and sham-operated group (Sham, n=10). EA and PGB were given from postoperative day (POD) 14 to 36. EA (2 Hz and 100 Hz alternating frequencies, intensities ranging from 1–1.5–2 mA) was applied to the left “zusanli” (ST36) and “Yanglingquan” (GB34) acupoints for 30 minutes. The mechanical withdrawal thresholds (MWTs) were tested with von Frey filaments. Moreover, the organizational and structural alterations of the bilateral prefrontal cortex, hippocampus, sciatic nerves and the thoracic, lumbar spinal cords and dorsal root ganglions (DRGs) were examined via light and electron microscopy.

Results

MWTs of left hind paw demonstrated a remarkable decrease in the SNI model (P < 0.05). In the SNI model, ultrastructural changes including demyelination and damaged neurons were observed at all levels of the peripheral nervous system (PNS) and central nervous system (CNS). In addition, EA improved MWTs and restored the normal structure of neurons. However, the effect was not found in the PGB treatment group.

Conclusion

Chronic pain can induce extensive damage to the central and peripheral nervous systems. Meanwhile, EA and PGB can both alleviate chronic pain syndromes in rats, but EA also restores the normal cellular structures, while PGB is associated with no improvement.

Electroacupuncture Attenuates Cancer-Induced Bone Pain via NF-κB/CXCL12 Signaling in Midbrain Periaqueductal Gray

Electroacupuncture (EA) is effective in various chronic pains. NF-κB and CXCL12 modulate the formation of chronic pain. Herein, we hypothesized that EA alleviates cancer-induced bone pain (CIBP) through NF-κB/CXCL12 axis in midbrain periaqueductal gray (PAG), which participates in "top-down" pain modulatory circuits. In order to filter the optimum EA frequency for CIBP treatment, 2, 100, or 2/100 Hz EA was set up. In addition, ipsilateral, contralateral, and bilateral EA groups were established to affirm the optimal EA scheme. Bilateral 2/100 Hz EA was considered as the optimal therapeutic scheme and was applied in a subsequent experiment. Western blotting along with immunofluorescence illustrated that CIBP induces a rapid and substantial increase in CXCL12 protein level and NF-κB phosphorylation in vlPAG from day 6 to day 12. Anti-CXCL12 neutralizing antibody and pAAV-U6-shRNA(CXCL12)-CMV-EGFP-WPRE in vlPAG remarkably improved the mechanical pain threshold of the hind paw in CIBP model relative to the control. EA inhibited the upregulation of pNF-κB and CXCL12 in vlPAG of CIBP. The recombinant CXCL12 and pAAV-CMV-CXCL12-EF1a-EGFP-3Xflag-WPRE reversed the abirritation of EA in the CIBP rat model. NF-κB phosphorylation mediated-CXCL12 expression contributed to CIBP allodynia, whereas EA suppressed NF-κB phosphorylation in CIBP. According to the above evidence, we conclude that bilateral 2/100 Hz EA is an optimal therapeutic scheme for CIBP. The abirritation mechanism of EA might reduce the expression of CXCL12 by inhibiting the activation of NF-κB, which might lead to the restraint of descending facilitation of CIBP.

Exercise-induced peptide EIP-22 protect myocardial from ischaemia/reperfusion injury via activating JAK2/STAT3 signalling pathway

Recent studies have revealed that exercise has myocardial protective effects, but the exact mechanism remains unclear. Studies have increasingly found that peptides play a protective role in myocardial ischaemia‐reperfusion (I/R) injury. However, little is known about the role of exercise‐induced peptides in myocardial I/R injury. To elucidate the effect of exercise‐induced peptide EIP‐22 in myocardial I/R injury, we first determined the effect of EIP‐22 on hypoxia/reperfusion (H/R)‐ or H₂O₂‐induced injury via assessing cell viability and lactate dehydrogenase (LDH) level. In addition, reactive oxygen species (ROS) accumulation and mitochondrial membrane potential (MMP) was assessed by fluorescence microscope. Meanwhile, Western blot and TUNEL methods were used to detect apoptosis level. Then, we conducted mice I/R injury model and verified the effect of EIP‐22 by measuring cardiac function, evaluating heart pathology and detecting serum LDH, CK‐MB and cTnI level. Finally, the main signalling pathway was analysed by RNA‐seq. In vitro, EIP‐22 treatment significantly improved cells viabilities and MMP and attenuated the LDH, ROS and apoptosis level. In vivo, EIP‐22 distinctly improved cardiac function, ameliorated myocardial infarction area and fibrosis and decreased serum LDH, CK‐MB and cTnI level. Mechanistically, JAK/STAT signalling pathway was focussed by RNA‐seq and we confirmed that EIP‐22 up‐regulated the expression of p‐JAK2 and p‐STAT3. Moreover, AG490, a selective inhibitor of JAK2/STAT3, eliminated the protective roles of EIP‐22. The results uncovered that exercise‐induced peptide EIP‐22 protected cardiomyocytes from myocardial I/R injury via activating JAK2/STAT3 signalling pathway and might be a new candidate molecule for the treatment of myocardial I/R injury.