Investigating LIM (Lin-11, Isl-1, and Mec-3) Kinases and Their Correlation with Pathological Events and Microtubule Dynamics in an Experimental Model of Spinal Cord Injury in Rats.

The spinal cord injury (SCI) and the neurodegenerative processes accompanying it follow an intricate pathway with very limited options for treatment strategies until now. Microtubules, essential for the growth and maintenance of neurons, are mostly disorganized and destabilized due to neurodegeneration. Regeneration or plasticity is restricted to the adult central nervous system (CNS) due to several intrinsic and extrinsic mechanisms. Some fundamental or injury-induced expressions of specific molecules can be inhibited or antagonized pharmacologically to protect neurons to a certain extent after neurodegeneration. Accordingly, these molecules offer an excellent target as a therapeutic approach to promote neuroprotection. LIM kinases (LIMKs) are one of these molecules that phosphorylates members of the actin-depolymerizing factor (ADF)/cofilin family of actin-binding and filament-severing proteins. The individual role of LIMKs has not yet been studied in the pathology of SCI. In this study, we targeted LIMK and checked its role in microtubule destabilization in vitro. LIMK1 was found to be upregulated after microtubule depolymerization and inhibition of LIMK with specific inhibitor-protected neurons. Then, we checked the expressions of individual LIMKs throughout different time points across SCI in a rat contusion model, correlating with established pathophysiological markers. The phosphorylated form of LIMK1 was found to be elevated at chronic time points after injury, where scar formation and diminution of neurons prevail. Finally, we targeted the LIMK pathway with its specific inhibitor BMS-5, which showed neuroprotection after SCI. Overall, our results provided a concept concerning how a small-molecule inhibitor of LIMK may offer a strategy to treat SCI-associated neurodegeneration.

Maresin-1 prevents blood-spinal cord barrier disruption associated with TRPV4 elevation in the experimental model of spinal cord injury.

Recently, we reported the TRPV4 ion channel activation and its association with secondary damage after spinal cord injury (SCI). TRPV4 activation is linked with blood-spinal cord barrier (BSCB) disruption, endothelial damage, and inflammation after SCI. Specialized pro-resolving mediators (SPM) are endogenous lipid mediators released for inflammation resolution. Studies suggest that SPM could act as an endogenous antagonist of ion channels directly or indirectly at the plasma membrane. Herein, we studied the effect of maresin-1, a docosahexaenoic acid (DHA)-derived SPM, in SCI-induced TRPV4 expression and subsequent associated damage. First, employing a particular agonist (4αPDD) in endothelial and neuronal cell lines, we examined the potential of maresin-1 to block TRPV4 activation. Then we quantify the DHA levels in plasma and epicenter of the spinal cord in sham and at 1, 3, 7, 14, 21, and 28-days post-injury (DPI) using LC-MS. Then, we exogenously administered maresin-1 using two dosing regimens i.e., single-dose (1 µg) and multiple-dose (1 µg/day for seven days), to confirm its role in the TRPV4 inhibition and its linked damage. After SCI, DHA levels decrease in the spinal cord epicenter area as well as in the plasma. Treatment with maresin-1 attenuates TRPV4 expression, inflammatory cytokines, and chemokines and impedes neutrophil infiltration. Furthermore, treatment with maresin-1 prevents BSCB disruption, alleviates glial scar formation, and improves functional recovery. Thus, our results suggest that maresin-1 could modulate TRPV4 expression and could be a safe and promising approach to target inflammation and BSCB damage after SCI.

Comparative Evaluation of Aldose Reductase Inhibition in Polycystic Ovarian Syndrome-Induced Rats.

Polycystic ovary syndrome (PCOS) represents a spectrum of disorders, associated with hyperandrogenism, oligoanovulation, and polycystic ovaries. Aldose reductase (AR), a rate-limiting enzyme of polyol pathway, is responsible for maintenance of intracellular osmotic balance, facilitation of oocyte development, and organization of the granulosa cells in the ovary. Cyclic changes in the aldose reductase level were found during the 4-5 days estrus cycle in rat, which is regulated by gonadotropin-releasing hormone (GnRH). Irregular GnRH secretion in PCOS patients may lead to altered aldose reductase expression and ovarian dysfunction. Treatment with a novel AR inhibitor, fidarestat, has been reported to improve erythrocyte sorbitol content in diabetic patients. Hence, the potential role AR in pathogenesis of PCOS was investigated by inhibiting AR with fidarestat in PCOS-induced rats. Pre-pubertal female Sprague-Dawley rats were divided into five groups. PCOS is induced either by administering letrozole or by feeding high-fat diet for 90 days. After induction of PCOS, fidarestat treatment was given for 28 days and various parameters were measured. In PCOS-induced rats, parameters like food intake, body weight, insulin, OGTT, triglycerides, cholesterol, prolonged diestrus phase, ovary weight, and immunohistological localization AR were found to be significantly altered. Fidarestat treatment significantly improved ovary weight, ovarian aldose reductase localization in PCOS-induced rats. Improvement in all these parameters suggest involvement of aldose reductase in the pathogenesis of PCOS.

Extra Cellular Matrix Remodeling: An Adjunctive Target for Spinal Cord Injury and Intervertebral Disc Degeneration.

The extracellular matrix (ECM) is a protein-and-carbohydrate meshwork that supports a variety of biological structures and processes, from tissue development and elasticity to the preservation of organ structures. ECM composition is different in each organ. It is a remarkably dynamic 3-dimensional structure that's constantly changing to maintain tissue homeostasis. This review aims to describe the involvement of ECM components in the remodeling process of spinal cord injury (SCI) and intervertebral disc degeneration (IVDD). Here, we have also described the current ECM-based therapeutic targets, which can be explored for ECM remodeling SCI is a neurological condition with intense influences resulting from a trauma inflicted on the spinal cord. SCI leads to damage to the intact ECM that leads to regeneration failure. IVDD mainly occurs due to aging and trauma. Various ECM components enable fragmentation of the disc and are thereby involved in disc degeneration. ECM manipulation can be used as an adjunct treatment in SCI and IVDD. Current treatment approaches for SCI and IVDD are conservative and unsatisfactory. Targeting ECM remodeling as an adjunct therapy may result in better disease outcomes.

Ethamsylate Attenuates Mutilated Secondary Pathogenesis and Exhibits a Neuroprotective Role in Experimental Model of Spinal Cord Injury.

Deficits in the neuronal connection that succumbs to the impairment of sensory and motor neurons are the hallmarks of spinal cord injury (SCI). Secondary pathogenesis, which initiates after the primary mechanical insult to the spinal cord, depicts a pivotal role in producing inflammation, lesion formation and ultimately causes fibrotic scar formation in the chronic period. This fibrotic scar formed acts as a major hindrance in facilitating axonal regeneration and is one of the root causes of motor impairment. Cascade of secondary events in SCI begins with injury-induced blood spinal cord barrier rupture that promotes increased migration of neutrophils, macrophages, and other inflammatory cells at the injury site to initiate the secondary damages. This phenomenon leads to the release of matrix metalloproteinase, cytokines and chemokines, reactive oxygen species, and other proteolytic enzymes at the lesion site. These factors assist in the activation of the TGF-ß1 signaling pathway, which further leads to excessive proliferation of perivascular fibroblast, followed by deposition of collagen and fibronectin matrix, which are the main components of the fibrotic scar. Subsequently, this scar formed inhibits the propagation of action potential from one neuron to adjacent neurons. Ethamsylate, an anti-hemorrhagic drug, has the potential to maintain early hemostasis as well as restore capillary resistance. Therefore, we hypothesized that ethamsylate, by virtue of its anti-hemorrhagic activity, reduces hemorrhagic ischemia-induced neuronal apoptosis, maintains the blood spinal cord barrier integrity, and decreases secondary damage severity, thereby reduce the extent of fibrotic scar formation, and demonstrates a neuroprotective role in SCI.

Tomographic Imaging and Correlation to Quantify Vascular and Inflammatory Changes in an Experimental Spinal Cord Injury.

Spinal cord injury (SCI) is a devastating condition causing the loss of sensory and motor functions. SCI pathology is multifaceted, encompassing inflammation, scarring, neuronal damage, and vascular and tissue remodeling. The dynamics of SCI rapidly transform from acute, sub-acute, and chronic phases. The rapidly changing environment necessitates the real-time monitoring of disease severity. Therefore, in this study, we used the IVIS spectrum, a noninvasive fluorescence imaging modality, to monitor the disease pathology in live animals. We used near-infrared fluorescence imaging agents including Angiosense 750 EX, a probe that detects vascular changes, and Cat B 680 FAST, a probe that detects inflammation at various day points post injury (DPI), that is, DPI-1, DPI-14, and DPI-28. We quantified the pathophysiological changes after SCI using IVIS in live animals. As a result, we observed distinct differences in the disease progression between injured and sham mice. Moreover, live imaging showed a good correlation with behavioral studies, protein expression, and immunohistological analysis. Hence, the goal of this study was to introduce a new optical imaging modality that offers a determination of disease severity and the advantage of accelerated imaging of the correlated biomarkers in a real-time and dynamic manner. This study concluded that Cat B 680 Fast and Angiosense 750 EX could be used to assess the disease severity after SCI. Furthermore, our study suggests that the noninvasive fluorescence optical imaging modality offers a unique approach in monitoring neuroinflammatory diseases in live animals.

Strategies to neutralize RhoA/ROCK pathway after spinal cord injury.

Regeneration is bungled following CNS injuries, including spinal cord injury (SCI). Inherent decay of permissive conditions restricts the regrowth of the mature CNS after an injury. Hypertrophic scarring, insignificant intrinsic axon-growth activity, and axon-growth inhibitory molecules such as myelin inhibitors and scar inhibitors constitute a significant hindrance to spinal cord repair. Besides these molecules, a combined absence of various mechanisms responsible for axonal regeneration is the main reason behind the dereliction of the adult CNS to regenerate. The neutralization of specific inhibitors/proteins by stymieing antibodies or encouraging enzymatic degradation results in improved axon regeneration. Previous efforts to induce regeneration after SCI have stimulated axonal development in or near lesion sites, but not beyond them. Several pathways are responsible for the axonal growth obstruction after a CNS injury, including SCI. Herein, we summarize the axonal, glial, and intrinsic factor which impedes the regeneration. We have also discussed the methods to stabilize microtubules and through this to maintain the proper cytoskeletal dynamics of growth cone as disorganized microtubules lead to the failure of axonal regeneration. Moreover, we primarily focus on diverse inhibitors of axonal growth and molecular approaches to counteract them and their downstream intracellular signaling through the RhoA/ROCK pathway.