Botulinum Toxin A, a Better Choice for Skeletal Muscle Block in a Comparative Study With Lidocaine in Rats.

A positive response to scalene muscle block (SMB) is an important indication for the diagnosis of thoracic outlet syndrome. Lidocaine injection is commonly used in clinical practice in SMB, although there have been some cases of misdiagnosis. Botulinum toxin A (BTX-A) is one of the therapeutic agents in SMB, but whether it is also indicated for SMB diagnosis is controversial. To evaluate the muscle block efficiency of these two drugs, the contraction strength was repeatedly recorded on tibialis anterior muscle in rats. It was found that at a safe dosage, 2% lidocaine performed best at 40 µL, but it still exhibits an unsatisfactory partial blocking efficiency. Moreover, neither lidocaine injection in combination with epinephrine or dexamethasone nor multiple locations injection could improve the blocking efficiency. On the other hand, injections of 3, 6, and 12 U/kg BTX-A all showed almost complete muscle block. Gait analysis showed that antagonistic gastrocnemius muscle, responsible for heel rising, was paralyzed for nonspecific blockage in the 12 U/kg BTX-A group, but not in the 3 U/kg or 6 U/kg BTX-A group. Cleaved synaptosomal associated protein 25 (c-SNAP 25) was stained to test the transportation of BTX-A, and was additionally observed in the peripheral muscles in 6 and 12 U/kg groups. c-SNAP 25, however, was barely detectable in the spinal cord after BTX-A administration. Therefore, our results suggest that low dosage of BTX-A may be a promising option for the diagnostic SMB of thoracic outlet syndrome. SIGNIFICANCE STATEMENT: Muscle block is important for the diagnosis and treatment of thoracic outlet syndrome and commonly performed with lidocaine. However, misdiagnosis was observed sometimes. Here, we found that intramuscular injection of optimal dosage lidocaine only partially blocked the muscle contraction in rats, whereas low-dosage botulinum toxin, barely used in diagnostic block, showed almost complete block without affecting the central nervous system. This study suggests that botulinum toxin might be more suitable for muscle block than lidocaine in clinical practice.

Protein Tyrosine Phosphatase Receptor Type D Regulates Neuropathic Pain After Nerve Injury via the STING-IFN-I Pathway.

Neuropathic pain is usually caused by injury or dysfunction of the somatosensory system, and medicine is a common way of treatment. Currently, there are still no satisfactory drugs, like opioids and lidocaine, which carry a high risk of addiction. Protein tyrosine phosphatase receptor type D (PTPRD) is a known therapeutic target in addiction pathways and small molecule inhibitors targeting it, such as 7-butoxy illudalic acid analog (7-BIA), have recently been developed to tackle addition. PTPRD is also upregulated in the dorsal root ganglion (DRG) in a rat model of neuropathic pain, but is not yet clear whether PTPRD contributes to the development of neuropathic pain. Here, we established a chronic constriction injury (CCI) and evaluated PTPRD expression and its association with neuropathic pain. PTPRD expression was found to gradually increase after CCI in DRGs, and its expression was concomitant with the progressive development of hypersensitivity as assessed by both mechanical and thermal stimuli. Both PTPRD knockdown and administration of PTPRD inhibitor 7-BIA alleviated CCI-induced neuropathic pain while upregulating STING and IFN-α in the DRG. Treatment with H-151, a STING inhibitor, abolished the analgesic effects of PTPRD knockdown. Taken together, our study suggests that increased levels of PTPRD in the DRG following CCI are involved in the development of neuropathic pain via the STING-IFN-I pathway. 7-BIA, a small molecule inhibitor of PTPRD with anti-addiction effects, may represent a novel and safe therapeutic strategy for the clinical management of neuropathic pain without the risk of addiction.

lncRNA TINCR attenuates the proliferation and invasion, and enhances the apoptosis of cutaneous malignant melanoma cells by regulating the miR­424­5p/LATS1 axis.

Cutaneous malignant melanoma (CMM) is responsible for ≥1/2 of skin cancer­related mortalities. The aberrant expression of long non­coding RNAs (lncRNAs) has been associated with the development of CMM. However, to the best of our knowledge, the role of the lncRNA TINCR ubiquitin domain containing (TINCR) in CMM has not been previously investigated, and thus, the current study aimed to evaluate this in vitro and in vivo. Reverse transcription­quantitative PCR (RT­qPCR) was used to analyze microRNA (miR)­424­5p expression, and RT­qPCR and western blotting were used to measure TINCR, large tumor suppressor kinase 1 (LATS1), cellular communication network factor 2 (CTGF), cellular communication network factor 1 (CCN1) and AXL receptor tyrosine kinase (AXL) mRNA and protein expression levels, respectively. Cell Counting Kit­8, flow cytometry and Transwell assays were used to detect the proliferation, apoptosis and invasion of CMM cell lines, respectively. The binding sites between TINCR and miR­424­5p were predicted using the miRDB database. A dual luciferase reporter assay and RT­qPCR were used to identify the relationship between TINCR and miR­424­5p in CMM cell lines. The bioinformatics analysis revealed that TINCR was one of the most significantly downregulated lncRNAs in CMM, and advanced stage CMM tissues showed the greatest decrease in TINCR expression. Moreover, in the collected CMM tissues and tested cell lines of the current study, TINCR expression was found to be downregulated compared with the respective controls. Notably, TINCR overexpression inhibited the expression levels of CTGF, CCN1 and AXL, decreased the proliferation and invasion, and induced the apoptosis of CMM cell lines. In addition, a mutual binding association was identified between miR­424­5p and TINCR in CMM cells. LATS1, a target of miR­424­5p, was found to be positively regulated by TINCR. TINCR activated Hippo signaling and repressed the activity of Yes 1 associated transcriptional regulator by regulating LATS1 expression, while LATS1 knockdown reversed the effect of TINCR overexpression on CMM cells. Collectively, the findings of the present study suggested that TINCR may attenuate the progression of CMM by regulating the miR­424­5p/LATS1 signaling axis. These results indicated that TINCR may play a tumor suppressive role in CMM.

Agonism of Gpr40 Protects the Capacities of Epidermal Stem Cells (ESCs) Against Ultraviolet-B (UV-B).

INTRODUCTION: Skin damage due to overexposure to ultraviolet B (UV-B) radiation can lead to the development of cancers and reduce the skin's functionality as a vital protective barrier. Epidermal stem cells (ESCs) are pluripotent cells responsible for skin regeneration and healing. Upon exposure to UV-B radiation, ESCs produce excess amounts of reactive oxygen species (ROS) and inflammatory cytokines. However, the functional protection of ESCs is not fully explored. G-protein coupled G protein-coupled receptor 40 (Gpr40) is a free fatty acid receptor that is emerging as a potential treatment target for various diseases. Gpr40 has been found to be expressed in various cell types. METHODS: ESCs were exposed to UV-B at the intensities of 25, 50, and 100 mJ/cm2 for 24 h using TL 20 W/12 RS UV lamps. ESCs were treated with UV-B at 50 mJ/cm2 in the presence or absence of 25 or 50 µM of the Gpr40 agonist GW9508 for 24 h. The gene expression of the Wnt1 pathway and proinflammatory cytokines were evaluated. To antagonize Gpr40 expression, ESCs were treated with 10 µM GW1100. RESULTS: Our findings demonstrate that Gpr40 agonism can reduce the production of ROS as well as the expression of interleukins 1ß and 8, two key proinflammatory cytokines. We demonstrate that agonism of Gpr40 can rescue the reduction in integrin ß1 and Krt19 induced by UV-B exposure, thereby improving the capacities of ESCs to resist UV-B damage. Moreover, we show that the effects of Gpr40 agonism observed in our experiments are mediated through the Wnt/ß-catenin canonical signaling pathway, as evidenced by the expression of Wnt1 and cyclin D1. CONCLUSION: Our findings present evidence of the role of Gpr40 agonism in mediating the protective capacities of ESCs against insult from UV-B radiation.

Ghrelin attenuates ultraviolet B radiation-induced impairment in capacities of epidermal stem cells.

Persistent exposure to solar ultraviolet radiation (UVR) causes continuous damages to skin, including progressive impairment of epidermal stem cells (ESCs) capacities. Ghrelin is the only known endogenous orexigenic hormone, which has displayed its various pharmacological functions. In the current study, we found that the specific receptor of ghrelin, growth hormone secretagogue receptor (GHS-R), is expressed in ESCs. Interestingly, GHS-R expression is significantly upregulated in response to ultraviolet B (UVB) radiation. We also found that ghrelin treatment prevented UVB radiation-induced reduction in cell viability and the release of lactate dehydrogenase (LDH). Additionally, ghrelin reduced UVB radiation-induced generation of reactive oxygen species (ROS) and restored the intracellular level of reduced glutathione (GSH). UVB radiation significantly suppressed the expressions of integrin ß1 and Krt19, the two major ESC markers, which were restored by ghrelin. Notably, knockdown of GHS-R abolished the effects of ghrelin on the expressions of integrin ß1 and Krt19, suggesting the involvement of GHS-R. Also, we found that ghrelin treatment inhibited UVB radiation- induced reduction of Wnt1, Wnt3a, Myc, and cyclin D1 at both the mRNA levels and the protein levels. Taken together, our findings identify a novel function of ghrelin on maintaining the capacities of ESCs against UVB radiation.