Systemic Immune Profile Predicts the Development of Infections in Patients with Spinal Cord Injuries

Multifaceted Pathophysiology and Secondary Complications of Chronic Spinal Cord Injury: Focus on Pressure Injury

Background/Objectives: Spinal cord injury (SCI) is a complex medical condition with widespread effects that extend beyond motor and sensory impairments. In addition to nervous system damage, SCI patients experience various secondary complications, including vascular dysfunction, altered body composition, and metabolic disturbances. Among the most common secondary pathologies is the development of pressure injuries (PIs), chronic wounds that significantly affect quality of life and can be challenging to treat. Understanding the physiological and cellular mechanisms behind these complications is crucial for improving care and therapeutic outcomes. Methods: We conducted a comprehensive literature search in PubMed, Scopus, and Google Scholar using keywords related to spinal cord injury, pressure ulcer/pressure injuries, metabolic and vascular dysfunction, biomechanics, and regenerative therapies. Studies were selected based on their relevance to the pathophysiology, risk factors, and novel therapeutic approaches for PIs in SCI patients. Results: Vascular dysfunction, characterized by impaired blood flow and microcirculatory issues, predisposes SCI patients to ischemia and tissue necrosis, particularly in areas subjected to prolonged pressure. Additionally, changes in body composition, such as increased adiposity and muscle atrophy, further compromise tissue integrity and healing capacity. The inflammatory response, mediated by cytokines such as IL-1, IL-6, and TNF-α, exacerbates these effects by sustaining a pro-inflammatory environment that delays the transition of macrophages to the M2 phenotype, critical for wound healing. External factors, such as poor nutrition, infections, and immobility, also play a significant role in worsening the wound healing process. Conclusions: Chronic SCI induces a cascade of physiological changes that predispose patients to the development of PIs and complicate their recovery. The intricate interplay of vascular, metabolic, and inflammatory responses creates a hostile environment for wound healing. A deeper understanding of these systemic effects is essential not only for developing targeted therapeutic strategies to improve chronic wound healing but also for refining preventive approaches that minimize their occurrence. Advancing this knowledge will ultimately help enhance the quality of life for individuals with SCI.

Spinal cord injury enhances lung inflammation and exacerbates immune response following exposure to LPS

Introduction

The severity of spinal cord injury (SCI) is closely tied to pulmonary function, especially in cases of higher SCI levels. Despite this connection, the underlying pathological mechanisms in the lungs post-SCI are not well understood. Previous research has established a connection between disrupted sympathetic regulation and splenocyte apoptosis in high thoracic SCI, leading to pulmonary dysfunction. The aim of this study was to investigate whether mice with low-level SCI exhibit increased susceptibility to acute lung injury by eliciting systemic inflammatory responses that operate independently of the sympathetic nervous system.

Methods

Here, we employed T9 contusion SCI and exposed mice to aerosolized lipopolysaccharide (LPS) to simulate lung inflammation associated with acute respiratory distress syndrome (ARDS). Twenty-four hours post-LPS exposure, lung tissues and bronchoalveolar lavage (BAL) fluid were analyzed.

Results

LPS markedly induced proinflammatory gene expression (SAA3, IRG1, NLRP3, IL-1beta, MCP-1) and cytokine release (IL-1beta, IL-6, MCP-1) in SCI mice compared to controls, indicating an exaggerated inflammatory response. Infiltration of Ly6G/C positive neutrophils and macrophages was significantly higher in SCI mice lungs post-LPS exposure. Interestingly, spleen size and weight did not differ between control and SCI mice, suggesting that T9 SCI alone does not cause spleen atrophy. Notably, bone-marrow-derived macrophages (BMDMs) from SCI mice exhibited hyper-responsiveness to LPS.

Discussions

This study demonstrated an increase in lung inflammation and immune responses subsequent to low-level T9 SCI, underscoring the widespread influence of systemic inflammation post-SCI, especially pronounced in specific organs like the lungs.

Plasma fibrinogen level is independent risk factor associated with the incidence of pulmonary infection in patients with spinal cord injury: a retrospective cohort study

BACKGROUND

Patients with spinal cord injury (SCI) are at higher risk of developing pulmonary infection (PI), and plasma fibrinogen level may be an independent risk factor for PI. However, the relationship between fibrinogen level and PI incidence in the SCI population remains unclear. This study aimed to elucidate the association between plasma fibrinogen level and the occurrence of PI among SCI patients.

METHODS

We conducted a retrospective analysis of 576 SCI patients admitted to the Rehabilitation Medicine Department between January 1, 2017, and December 31, 2021. Following exclusions, 491 patients were included in the final analysis, with 139 PI cases identified.

RESULTS

Surgery, level of injury and chest comorbidities were covariates in the relationship between fibrinogen level and PI incidence. Other identified potential risk factors for PI included age, D-dimer level, urinary tract infections (UTI), deep vein thrombosis (DVT), anticoagulant therapy, injury mechanism, and the American Spinal Injury Association Impairment Scale (AIS) grades. After adjusting for these factors, we found that for every 1 g/L increase in fibrinogen level, the risk of developing PI increased by 18% (HR = 1.18, P = 0.011), and indicating a positive linear relationship between fibrinogen level and PI incidence.

CONCLUSION

Plasma fibrinogen was an independent risk factor for PI in patients with SCI, especially for AIS-B and C grades. Proactive management of fibrinogen level after admission to rehabilitation medicine department could be crucial in reducing the incidence of PI in this vulnerable population.

CLINICAL TRIAL NUMBER

Not applicable.

Untargeted blood serum proteomics identifies novel proteins related to neurological recovery after human spinal cord injury

BACKGROUND

The discovery of new prognostic biomarkers following spinal cord injury (SCI) is a rapidly growing field that could help uncover the underlying pathological mechanisms of SCI and aid in the development of new therapies. To date, this search has largely focused on the initial days after the lesion. However, during the subacute stage of SCI (weeks to months after the injury), there remains potential for sensorimotor recovery, and numerous secondary events develop in various organs. Additionally, the confounding effects of early interventions after the injury are less likely to interfere with the results.

METHODS

In this study, we conducted an untargeted proteomics analysis to identify biomarkers of recovery in blood serum samples during the subacute phase of SCI patients, comparing those with strong recovery to those with no recovery between 30 and 120 days. We analyzed the fraction of serum that is depleted of the most abundant proteins to unmask proteins that would otherwise go undetected. Linear models were used to identify peptides and proteins related to neurological recovery and we validated changes in some of these proteins using Enzyme-linked Immunosorbent Assay (ELISA).

RESULTS

Our findings reveal that differences in subacute recovery after SCI (from 30 to 120 days) are associated with an enrichment in proteins involved in inflammation, coagulation, and lipid metabolism. Technical validation using commercial ELISAs further confirms that high levels of SERPINE1 and ARHGAP35 are associated with strong neurological recovery, while high levels of CD300a and DEFA1 are associated with a lack of recovery.

CONCLUSIONS

Our study identifies new candidates for biomarkers of neurological recovery and for novel therapeutic targets after SCI.

Screening the immune-related circRNAs and genes in mice of spinal cord injury by RNA sequencing

Spinal cord injury (SCI) is a pathological condition that leading to serious nerve damage, disability and even death. Increasing evidence have revealed that circular RNAs (circRNAs) and mRNA are widely involved in the regulation of the pathological process of neurological diseases by sponging microRNAs (miRNAs). Nevertheless, the potential biological functions and regulatory mechanisms of circRNAs in the subacute stage of SCI remain unclear. We analyzed the expression and regulatory patterns of circRNAs and mRNAs in SCI mice models using RNA-sequencing and bioinformatics analysis. A total of 24 circRNAs and 372 mRNAs were identified to be differentially expressed. Then we identifying the immune-related genes (IRGs) from them. The protein-protein interaction network were constructed based on the STRING database and Cytoscape software. Furthermore, Go and KEGG enrichment analysis were conducted to predict the functions of the IRGs and host genes of DECs. These findings will contribute to elucidate the pathophysiology of SCI and provide effective therapeutic targets for SCI patients.