MicroRNA miR-155 Activity in Mouse Choline Acetyltransferase-Positive Neurons Is Critical for the Rate of Early and Late Paraplegia After Transient Aortic Cross-Clamping

Aortic aneurism open repair surgery can cause spinal cord (SC) injury with 5–15% of patients developing paraparesis or paraplegia. Using a mouse model of transient aortic cross-clamping (ACC), we have previously found that the expression of proinflammatory microRNA miR-155 increases in motoneurons (MNs) and endothelial cells (ECs) of ischemic SCs, and that global miR-155 deletion decreases the percentage of paraplegia by 37.4% at 48-h post-ACC. Here, we investigated the cell-specific contribution of miR-155 in choline acetyltransferase-positive (ChAT+) neurons (that include all MNs of the SC) and ECs to SC injury after ACC. Mice lacking miR-155 in ChAT+ neurons (MN-miR-155-KO mice) developed 24.6% less paraplegia than control mice at 48-h post-ACC. In contrast, mice lacking miR-155 in ECs (ECs-miR-155-KO mice) experienced the same percentage of paraplegia as control mice, despite presenting smaller central cord edema. Unexpectedly, mice overexpressing miR-155 in ChAT+ neurons were less likely than control mice to develop early paraplegia during the first day post-ACC, however they reached the same percentage of paraplegia at 48-h. In addition, all mice overexpressing miR-155 in ECs (ECs-miR-155-KI mice) were paraplegic at 48-h post-ACC. Altogether, our results suggest that miR-155 activity in ChAT+ neurons protects the SC against ischemic injury during the first day post-ACC before becoming deleterious during the second day, which indicates that early and late paraplegias arise from different molecular malfunctions. These results point to the need to develop specific protective therapeutics aimed at inhibiting both the early and late deleterious events after open repair surgery of aortic aneurisms.

Endovascular repair and open repair surgery of thoraco-abdominal aortic aneurysms cause drastically different types of spinal cord injury

Both endovascular repair (EVR) and open repair (OR) surgery of thoraco-abdominal aortic aneurysms cause spinal cord (SC) injury that can lead to paraparesis or paraplegia. It has been assumed that mechanisms responsible for SC damage after EVR are similar to those after OR. This pilot study compared the pathophysiology of SC injury after EVR versus OR using a newly developed EVR dog model. An increasing number of stents similar to those used in patients were inserted in the aorta of three dogs to ensure thoracic or thoracic plus lumbar coverage. The aorta of OR dogs was cross-clamped for 45 min. Behavior assessment demonstrated unique patterns of proprioceptive ataxia and evolving paraparesis in EVR versus irreversible paraplegia in OR. MRI showed posterior signal in lumbar SC after EVR versus central cord edema after OR. Histopathology showed white matter edema in L3-L5 localized to the dorsal column medial lemniscus area associated with loss of myelin basic protein but not neurons after EVR, versus massive neuronal loss in the gray matter in L3-L5 after OR. Metabolome analysis demonstrates a distinctive chemical fingerprint of cellular processes in both interventions. Our results call for the development of new therapeutics tailored to these distinct pathophysiologic findings.

[The effect of various multimodal analgesia regimens during surgical treatment of patients with spinal stenosis on the rate of failed back surgery syndrome]

OBJECTIVE

To determine the effect of various methods of perioperative analgesia on the rate of failed back surgery syndrome in patients operated on for spinal stenosis.

MATERIAL AND METHODS

A total of 122 patients were operated on for spinal stenosis in 2010-2016. The patients were assigned to groups according to the type of received analgesia: Group K (n=19) underwent analgesia on-demand. Patients in the PMA group (n=21) received preventive multimodal analgesia (PMA) with ketoprofen, paracetamol and morphine. Patients in the PMA+PG (n=20) and PMA+N (n=20) groups additionally received pregabalin and nefopam, respectively. Patients in the PMA+E group (n=22) received continuous epidural analgesia with a combination of ropivacaine and morphine. In patients in the PMA+I group (n=20), the wound was infiltrated with ropivacaine and ketorolac.

RESULTS AND CONCLUSION

In Group K, analgesia was not adequate during five postoperative days. Analgesia with PMA resulted in significant pain reduction during three postoperative days compared to Group K. Wound infiltration in addition to PMA was followed by more significant pain relief during six postoperative hours (compared to the PMA group). Administration of pregabalin or nefopam, as well as epidural analgesia, did not improve quality of postoperative analgesia. Five to seven months after the surgery, 66% (57; 75%) of patients had low back and/or leg pain; 41% (32; 50%) of patients had leg pain. Among patients suffering from pain, 32-41% patients had the severe chronic pain syndrome that resulted in sleep disorder, disability and significant deterioration of quality of life. The rate of failed back surgery syndrome did not depend on the perioperative analgesia regimen.

miR-155 expression in antitumor immunity: The higher the better?

MicroRNAs are small noncoding RNAs that modulate gene expression either directly, by impairing the stability and/or translation of transcripts that contain their specific target sequence, or indirectly through the targeting of transcripts that encode transcription factors, factors implicated in signal transduction pathways, or epigenetic regulators. Abnormal expression of micro-RNAs has been found in nearly all types of pathologies, including cancers. MiR-155 has been the first microRNA to be implicated in the regulation of the innate and adaptative immune responses, and its expression is either increased or decreased in a variety of liquid and solid malignancies. In this review, we examine the oncogenic and antitumor potentials of miR-155, with special emphasize on its dose-dependent effects. We describe the impact of miR-155 levels on antitumor activity of lymphocytes and myeloid cells. We discuss miR-155 dose-dependent effects in leukemias and analyze results showing that miR-155 intermediate levels tend to be detrimental, whereas high levels of miR-155 expression usually prove beneficial. We also examine the beneficial effects of high levels of miR-155 expression in solid tumors. We discuss the possible causal involvement of miR-155 in leukemias and dementia in individuals with Down's syndrome. We finally propose that increasing miR-155 levels in immune cells might increase the efficiency of newly developed cancer immunotherapies, due to miR-155 ability to target transcripts encoding immune checkpoints such as cytotoxic T lymphocyte antigen-4 or programmed death-ligand 1.

[Prognostic models of the severity of acute dynamic pain on the first postoperative day and the likelihood of chronic postoperative pain in spine surgery]

The risk factors for acute pain as well as chronic pain syndrome (CPS) in spine surgery have not been defined to date.

PURPOSE

To define the prognostic parameters of acute pain severity and the risk of CPS in patients operated on for spinal diseases and injuries.

MATERIAL AND METHODS

The study included 291 patients operated on for degenerative diseases and injuries of the spine at the Sklifosovsky Research Institute of Emergency Medicine in 2010-2016. Sociodemographic and clinical data and the psychological status of patients were evaluated. A mechanical algometer was used to measure the pain threshold (PT) and pain tolerance. The movement pain intensity was assessed by using a visual analog scale (VAS) on the day of surgery. Pain was considered minor at a median score of 0-4 cm and severe at a median score of 5-10 cm. The presence of CPS was assessed during a telephone survey 5-7 months after surgery.

RESULTS

The gender, PT, dynamic pain intensity before surgery, and expectation of postoperative pain are risk factors for severe acute postoperative pain. A multinomial logit regression model (Hosmer-Lemeshow test - 4.322; p=0.827) predicts minor dynamic pain on the 1^st postoperative day with an accuracy of 70% (95% CI 63-76). The age and dynamic pain intensity on the 1^st postoperative are the risk factors for CPS; the multinomial logit regression model (Hosmer-Lemeshow test - 3.1; p=0.928) predicts CPS with an accuracy of 65% (95% CI 59-71) 5-7 months after surgery.

CONCLUSION

The developed software in the form of MS Excel calculators provides a particular patient with preoperative assessment of the risk for minor acute dynamic pain on the 1^st postoperative day and CPS 5-7 months after surgery.

[Expression of genes coding NGF and BDNF human proteins in embryos of transgenic stocks of Drosophila melanogaster]

Transgenic Drosophila stocks were selected. These stocks contained human ngf and bdnf genes under Drosophila heat-shock promoter. The expression of foreign genes during Drosophila development was demonstrated with Northern and whole mount hybridization.