LINC00665 knockdown protects against cerebral ischemia-reperfusion injury

LINC00665 has been reported to participate in several human diseases. However, the role of LINC00665 in cerebral ischemia-reperfusion (CI/R) is still unknown. This study is designed to investigate the role of LINC00665 in rats with CI/R injury. We established middle cerebral artery occlusion/ reperfusion (MCAO/R) rats model in vivo. PC12 cells treated with oxygen-glucose deprivation/reperfusion (OGD/R) were used to establish in vitro I/R model. RT-qPCR assay was adopted to assess the mRNA expression of LINC00665 and miR-744-5p. MTT assay was used to determine cell viability. The protein expression of Bax and Bcl-2 were detected by Western blot assay. The relationship between LINC00665 and miR-744-5p was confirmed by dual luciferase reporter assay and RNA immunoprecipitation (RIP). In this study, we found that LINC00665 was sharply up regulated in MCAO/R rats and PC12 cells treated with I/R. Functionally, LINC00665 knockdown attenuated oxidative damage in PC12 cells treated with I/R. Moreover, LINC00665 knockdown promoted cell viability, while inhibited cell apoptosis in PC12 cells treated with I/R. In addition, miR-744-5p was confirmed to be a target of LINC00665. LINC00665 knockdown was validated to project CI/R injury by sponging miR-744-5p expression.

JAK2-IGF1 axis in osteoclasts regulates postnatal growth in mice

Osteoclasts are specialized cells of the hematopoietic lineage that are responsible for bone resorption and play a critical role in musculoskeletal disease. JAK2 is a key mediator of cytokine and growth factor signaling; however, its role in osteoclasts in vivo has yet to be investigated. To elucidate the role of JAK2 in osteoclasts, we generated an osteoclast-specific JAK2-KO (Oc-JAK2-KO) mouse using the Cre/Lox-P system. Oc-JAK2-KO mice demonstrated marked postnatal growth restriction; however, this was not associated with significant changes in bone density, microarchitecture, or strength, indicating that the observed phenotype was not due to alterations in canonical osteoclast function. Interestingly, Oc-JAK2-KO mice had reduced osteoclast-specific expression of IGF1, suggesting a role for osteoclast-derived IGF1 in determination of body size. To directly assess the role of osteoclast-derived IGF1, we generated an osteoclast-specific IGF1-KO mouse, which showed a similar growth-restricted phenotype. Lastly, overexpression of circulating IGF1 by human transgene rescued the growth defects in Oc-JAK2-KO mice, in keeping with a causal role of IGF1 in these models. Together, our data show a potentially novel role for Oc-JAK2 and IGF1 in the determination of body size, which is independent of osteoclast resorptive function.

Counselling Patients for Trial of Labour after Cesarean (TOLAC) and Invasive Placentation: Are We Missing the Mark? The Importance of Local Data and Informed Choice

OBJECTIVE

Rates of cesarean delivery are increasing, and these procedures carry potential complications, like the risk of invasive placentation, which increases with each cesarean. A trial of labour after cesarean (TOLAC) is a viable option for patients; however, it has been associated with uterine rupture, a complication with maternal and fetal risks. To better counsel patients considering TOLAC, we aimed to determine local uterine rupture rates and maternal and neonatal outcomes with TOLAC and compare these with outcomes related to invasive placentation.

METHODS

A 4-year retrospective chart review was conducted at our tertiary centre of all patients with a history of a previous cesarean delivery. We assessed rates of TOLAC, vaginal delivery after cesarean (VBAC), and uterine rupture, as well as maternal and neonatal outcomes associated with invasive placentation. Cases of uterine rupture from 1988 to the present were also reviewed, and their outcomes were compared with those of invasive placentation.

RESULTS

Our uterine rupture rate was 0.44% and VBAC rate was 73.8%. We identified 8 cases of uterine rupture since 1988 and 67 invasive placentas during the 4-year chart review. Invasive placentation was associated with a significantly increased risk of neonatal respiratory morbidity, hysterectomy, maternal complications, and longer length of maternal hospital stay when compared with uterine rupture.

CONCLUSION

While uterine rupture remains a potential complication of TOLAC, it is rare with overall excellent maternal and neonatal outcomes. Invasive placentation, the risk of which increases with cesarean delivery, carries potentially higher complication rates than uterine rupture. Local complication data is important for individual sites offering TOLAC. The implications of invasive placentation cannot be overlooked when counselling patients considering TOLAC.

The NLRP3 inflammasome contributes to sarcopenia and lower muscle glycolytic potential in old mice

The mechanisms underpinning decreased skeletal muscle strength and slowing of movement during aging are ill-defined. "Inflammaging," increased inflammation with advancing age, may contribute to aspects of sarcopenia, but little is known about the participatory immune components. We discovered that aging was associated with increased caspase-1 activity in mouse skeletal muscle. We hypothesized that the caspase-1-containing NLRP3 inflammasome contributes to sarcopenia in mice. Male C57BL/6J wild-type (WT) and NLRP3^-/- mice were aged to 10 (adult) and 24 mo (old). NLRP3^-/- mice were protected from decreased muscle mass (relative to body mass) and decreased size of type IIB and IIA myofibers, which occurred between 10 and 24 mo of age in WT mice. Old NLRP3^-/- mice also had increased relative muscle strength and endurance and were protected from age-related increases in the number of myopathic fibers. We found no evidence of age-related or NLRP3-dependent changes in markers of systemic inflammation. Increased caspase-1 activity was associated with GAPDH proteolysis and reduced GAPDH enzymatic activity in skeletal muscles from old WT mice. Aging did not alter caspase-1 activity, GAPDH proteolysis, or GAPDH activity in skeletal muscles of NLRP3^-/- mice. Our results show that the NLRP3 inflammasome participates in age-related loss of muscle glycolytic potential. Deletion of NLRP3 mitigates both the decline in glycolytic myofiber size and the reduced activity of glycolytic enzymes in muscle during aging. We propose that the etiology of sarcopenia involves direct communication between immune responses and metabolic flux in skeletal muscle.

Palmitate-induced inflammatory pathways in human adipose microvascular endothelial cells promote monocyte adhesion and impair insulin transcytosis

Obesity is associated with inflammation and immune cell recruitment to adipose tissue, muscle and intima of atherosclerotic blood vessels. Obesity and hyperlipidemia are also associated with tissue insulin resistance and can compromise insulin delivery to muscle. The muscle/fat microvascular endothelium mediates insulin delivery and facilitates monocyte transmigration, yet its contribution to the consequences of hyperlipidemia is poorly understood. Using primary endothelial cells from human adipose tissue microvasculature (HAMEC), we investigated the effects of physiological levels of fatty acids on endothelial inflammation and function. Expression of cytokines and adhesion molecules was measured by RT-qPCR. Signaling pathways were evaluated by pharmacological manipulation and immunoblotting. Surface expression of adhesion molecules was determined by immunohistochemistry. THP1 monocyte interaction with HAMEC was measured by cell adhesion and migration across transwells. Insulin transcytosis was measured by total internal reflection fluorescence microscopy. Palmitate, but not palmitoleate, elevated the expression of IL-6, IL-8, TLR2 (Toll-like receptor 2), and intercellular adhesion molecule 1 (ICAM-1). HAMEC had markedly low fatty acid uptake and oxidation, and CD36 inhibition did not reverse the palmitate-induced expression of adhesion molecules, suggesting that inflammation did not arise from palmitate uptake/metabolism. Instead, inhibition of TLR4 to NF-κB signaling blunted palmitate-induced ICAM-1 expression. Importantly, palmitate-induced surface expression of ICAM-1 promoted monocyte binding and transmigration. Conversely, palmitate reduced insulin transcytosis, an effect reversed by TLR4 inhibition. In summary, palmitate activates inflammatory pathways in primary microvascular endothelial cells, impairing insulin transport and increasing monocyte transmigration. This behavior may contribute in vivo to reduced tissue insulin action and enhanced tissue infiltration by immune cells.

Nucleotides released from palmitate-challenged muscle cells through pannexin-3 attract monocytes

Obesity-associated low-grade inflammation in metabolically relevant tissues contributes to insulin resistance. We recently reported monocyte/macrophage infiltration in mouse and human skeletal muscles. However, the molecular triggers of this infiltration are unknown, and the role of muscle cells in this context is poorly understood. Animal studies are not amenable to the specific investigation of this vectorial cellular communication. Using cell cultures, we investigated the crosstalk between myotubes and monocytes exposed to physiological levels of saturated and unsaturated fatty acids. Media from L6 myotubes treated with palmitate-but not palmitoleate-induced THP1 monocyte migration across transwells. Palmitate activated the Toll-like receptor 4 (TLR4)/nuclear factor-κB (NF-κB) pathway in myotubes and elevated cytokine expression, but the monocyte chemoattracting agent was not a polypeptide. Instead, nucleotide degradation eliminated the chemoattracting properties of the myotube-conditioned media. Moreover, palmitate-induced expression and activity of pannexin-3 channels in myotubes were mediated by TLR4-NF-κB, and TLR4-NF-κB inhibition or pannexin-3 knockdown prevented monocyte chemoattraction. In mice, the expression of pannexin channels increased in adipose tissue and skeletal muscle in response to high-fat feeding. These findings identify pannexins as new targets of saturated fatty acid-induced inflammation in myotubes, and point to nucleotides as possible mediators of immune cell chemoattraction toward muscle in the context of obesity.

Multiple environments of fluorinated anesthetics in intact tissues observed with 19F NMR spectroscopy

The incorporation of two fluorine-containing general anesthetic agents, halothane and methoxyflurane, into erythrocytes (from three different species), rabbit muscle and rabbit nerve, was followed with 19F NMR spectroscopy. Two major findings emerged from these studies: (1) multiple environments indicative of domain structure in the membrane can be observed depending on the anesthetic and the tissue type; and (2) the 19F chemical shifts of a given anesthetic were characteristic for the tissue examined. Halothane showed a single resonance in erythrocytes and multiple resonances in muscle and nerve, while methoxyflurane showed multiple resonances in both muscle and erythrocytes. The range of the 19F chemical shifts for the multiple peaks was as great as 6 ppm.