Spleen tyrosine kinase facilitates neutrophil activation and worsens long-term neurologic deficits after spinal cord injury

Neutrophil-to-lymphocyte ratio at admission for early diagnosis, severity assessment, and prognosis of acute traumatic spinal cord injury

STUDY DESIGN

A retrospective study.

OBJECTIVE

This study examined the value of neutrophil-to-lymphocyte ratio at admission for early diagnosis, severity assessment, and prognosis of acute traumatic SCI.

SETTING

The First People's Hospital of Neijiang, China.

METHODS

This was a single-center, retrospective, cohort study of patients treated within 12 h of acute SCI between January 2018 and October 2022. Ninety-four SCI patients were selected as the Observation group, including 26 with complete injury (AIS grade A) and 68 with incomplete injury (AIS grade B-D), while 94 patients with simple spinal fracture were randomly selected as the Control group. Eighty-one observation group patients underwent surgical treatment, of which 33 had a higher AIS grade (Good prognosis subgroup) and 48 a lower or equal grade post-surgery (Poor prognosis subgroup). Univariate and multivariate analyses were performed to assess predictors of early diagnosis, severity, and 6-month outcome.

RESULTS

Initial white blood cell count, neutrophil count, monocyte count, and NLR were higher in the Observation group than the Control group, while lymphocyte count was lower in the Observation group. Multivariate logistic regression analysis identified NLR as an independent predictor of early diagnosis. Spinal canal encroachment ≥50%, neutrophil count, and NLR were higher in the complete injury subgroup, and spinal canal encroachment ≥50% was an independent predictor of complete injury, while NLR was not. The NLR was higher in the poor prognosis subgroup and was an independent risk factor.

CONCLUSIONS

Peripheral blood NLR is useful for early diagnosis of acute SCI and is predictive of clinical outcome.

Neutrophil biology in injuries and diseases of the central and peripheral nervous systems

The role of inflammation in nervous system injury and disease is attracting increased attention. Much of that research has focused on microglia in the central nervous system (CNS) and macrophages in the peripheral nervous system (PNS). Much less attention has been paid to the roles played by neutrophils. Neutrophils are part of the granulocyte subtype of myeloid cells. These cells, like macrophages, originate and differentiate in the bone marrow from which they enter the circulation. After tissue damage or infection, neutrophils are the first immune cells to infiltrate into tissues and are directed there by specific chemokines, which act on chemokine receptors on neutrophils. We have reviewed here the basic biology of these cells, including their differentiation, the types of granules they contain, the chemokines that act on them, the subpopulations of neutrophils that exist, and their functions. We also discuss tools available for identification and further study of neutrophils. We then turn to a review of what is known about the role of neutrophils in CNS and PNS diseases and injury, including stroke, Alzheimer's disease, multiple sclerosis, amyotrophic lateral sclerosis, spinal cord and traumatic brain injuries, CNS and PNS axon regeneration, and neuropathic pain. While in the past studies have focused on neutrophils deleterious effects, we will highlight new findings about their benefits. Studies on their actions should lead to identification of ways to modify neutrophil effects to improve health.

Spinal cord injury: molecular mechanisms and therapeutic interventions

Spinal cord injury (SCI) remains a severe condition with an extremely high disability rate. The challenges of SCI repair include its complex pathological mechanisms and the difficulties of neural regeneration in the central nervous system. In the past few decades, researchers have attempted to completely elucidate the pathological mechanism of SCI and identify effective strategies to promote axon regeneration and neural circuit remodeling, but the results have not been ideal. Recently, new pathological mechanisms of SCI, especially the interactions between immune and neural cell responses, have been revealed by single-cell sequencing and spatial transcriptome analysis. With the development of bioactive materials and stem cells, more attention has been focused on forming intermediate neural networks to promote neural regeneration and neural circuit reconstruction than on promoting axonal regeneration in the corticospinal tract. Furthermore, technologies to control physical parameters such as electricity, magnetism and ultrasound have been constantly innovated and applied in neural cell fate regulation. Among these advanced novel strategies and technologies, stem cell therapy, biomaterial transplantation, and electromagnetic stimulation have entered into the stage of clinical trials, and some of them have already been applied in clinical treatment. In this review, we outline the overall epidemiology and pathophysiology of SCI, expound on the latest research progress related to neural regeneration and circuit reconstruction in detail, and propose future directions for SCI repair and clinical applications.

Immunological Response to Exercise in Athletes with Disabilities: A Narrative Review of the Literature

For a person with a disability, participating in sports activities and/or competitions can be a challenge for the immune system. The relationship between exercise and immunity response in disabled athletes is, indeed, extremely complex for several reasons, including (1) the chronic low-grade inflammatory and immunodepression-"secondary immune deficiency"-state imposed by the disability/impairment; (2) the impact of the disability on an array of variables, spanning from physical fitness to well-being, quality of life, sleep, and nutritional aspects, among others, which are known to mediate/modulate the effects of exercise on human health; (3) the variability of the parameters related to the exercise/physical activity (modality, frequency, intensity, duration, training versus competition, etc.); and (4) the intra- and inter-individual variability of the immunological response to exercise. In able-bodied athletes, previously published data described several exercise-induced changes affecting various immunological subsets and subpopulations, ranging from neutrophils to lymphocytes, and monocytes. Broadly, moderate intensity workout is accompanied by optimal immunity and resistance to infections such as upper respiratory tract infections (URTI) in athletes. Periods of intense training with insufficient recovery can cause a temporary state of immunosuppression, which should end with a few days of rest/recovery from exercise. Disabled athletes are relatively overlooked and understudied with respect to their able-bodied counterparts. Findings from the few studies available on paralympic and disabled athletes are here summarized and analyzed utilizing a narrative approach to review and determine the major features of the immunological and inflammatory responses to exercise in this specific population. Moreover, a few studies have reported behavioral, dietary, and training strategies that can be adopted to limit exercise-induced immunosuppression and reduce the risk of infection in people with disabilities. However, given the paucity of data and contrasting findings, future high-quality investigations on paralympic and disabled athletes are urgently needed.

Biodegradable bilayer hydrogel membranes loaded with bazedoxifene attenuate blood-spinal cord barrier disruption via the NF-κB pathway after acute spinal cord injury

After spinal cord injury (SCI), blood-spinal cord barrier (BSCB) disruption and hemorrhage lead to blood cell infiltration and progressive secondary injuries. Therefore, early restoration of the BSCB represents a key step in the treatment of SCI. Bazedoxifene (BZA), a third-generation estrogen receptor modulator, has recently been reported to inhibit inflammation and alleviate blood-brain barrier disruption caused by traumatic brain injury, attracting great interest in the field of central nervous system injury and repair. However, whether BZA can attenuate BSCB disruption and contribute to SCI repair remains unknown. Here, we developed a new type of biomaterial carrier and constructed a BZA-loaded HSPT (hyaluronic acid (HA), sodium alginate (SA), polyvinyl alcohol (PVA), tetramethylpropane (TPA) material construction) (HSPT@Be) system to effectively deliver BZA to the site of SCI. We found that HSPT@Be could significantly reduce inflammation in the spinal cord in SCI rats and attenuate BSCB disruption by providing covering scaffold, inhibiting oxidative stress, and upregulating tight junction proteins, which was mediated by regulation of the NF-κB/MMP signaling pathway. Importantly, functional assessment showed the evident improvement of behavioral functions in the HSPT@Be-treated SCI rats. These results indicated that HSPT@Be can attenuate BSCB disruption via the NF-κB pathway after SCI, shedding light on its potential therapeutic benefit for SCI. STATEMENT OF SIGNIFICANCE: After spinal cord injury, blood-spinal cord barrier disruption and hemorrhage lead to blood cell infiltration and progressive secondary injuries. Bazedoxifene has recently been reported to inhibit inflammation and alleviate blood-brain barrier disruption caused by traumatic brain injury. However, whether BZA can attenuate BSCB disruption and contribute to SCI repair remains unknown. In this study, we developed a new type of biomaterial carrier and constructed a bazedoxifene-loaded HSPT (HSPT@Be) system to efficiently treat SCI. HSPT@Be could provide protective coverage, inhibit oxidative stress, and upregulate tight junction proteins through NF-κB/MMP pathway both in vivo and in vitro, therefore attenuating BSCB disruption. Our study fills the application gap of biomaterials in BSCB restoration.

Seleno-Metabolites and Their Precursors: A New Dawn for Several Illnesses?

Selenium (Se) is an essential element for human health as it is involved in different physiological functions. Moreover, a great number of Se compounds can be considered potential agents in the prevention and treatment of some diseases. It is widely recognized that Se activity is related to multiple factors, such as its chemical form, dose, and its metabolism. The understanding of its complex biochemistry is necessary as it has been demonstrated that the metabolites of the Se molecules used to be the ones that exert the biological activity. Therefore, the aim of this review is to summarize the recent information about its most remarkable metabolites of acknowledged biological effects: hydrogen selenide (HSe⁻/H₂Se) and methylselenol (CH₃SeH). In addition, special attention is paid to the main seleno-containing precursors of these derivatives and their role in different pathologies.

Effects of biological sex mismatch on neural progenitor cell transplantation for spinal cord injury in mice

Despite advancement of neural progenitor cell transplantation to spinal cord injury clinical trials, there remains a lack of understanding of how biological sex of transplanted cells influences outcomes after transplantation. To address this, we transplanted GFP-expressing sex-matched, sex-mismatched, or mixed donor cells into sites of spinal cord injury in adult male and female mice. Biological sex of the donor cells does not influence graft neuron density, glial differentiation, formation of the reactive glial cell border, or graft axon outgrowth. However, male grafts in female hosts feature extensive hypervascularization accompanied by increased vascular diameter and perivascular cell density. We show greater T-cell infiltration within male-to-female grafts than other graft types. Together, these findings indicate a biological sex-specific immune response of female mice to male donor cells. Our work suggests that biological sex should be considered in the design of future clinical trials for cell transplantation in human injury.

In this study, Pitonak et al. report that transplantation of neural progenitor cells derived from male donors trigger an immune rejection response following transplantation into sites of spinal cord injury in female mice.

The immune microenvironment and tissue engineering strategies for spinal cord regeneration

Regeneration of neural tissue is limited following spinal cord injury (SCI). Successful regeneration of injured nerves requires the intrinsic regenerative capability of the neurons and a suitable microenvironment. However, the local microenvironment is damaged, including insufficient intraneural vascularization, prolonged immune responses, overactive immune responses, dysregulated bioenergetic metabolism and terminated bioelectrical conduction. Among them, the immune microenvironment formed by immune cells and cytokines plays a dual role in inflammation and regeneration. Few studies have focused on the role of the immune microenvironment in spinal cord regeneration. Here, we summarize those findings involving various immune cells (neutrophils, monocytes, microglia and T lymphocytes) after SCI. The pathological changes that occur in the local microenvironment and the function of immune cells are described. We also summarize and discuss the current strategies for treating SCI with tissue-engineered biomaterials from the perspective of the immune microenvironment.