Review Immune Status of Individuals with Traumatic Spinal Cord Injury: A Systematic Review and Meta-Analysis, 2023, Valido et al.

[SNT Gatchaman]

Immune Status of Individuals with Traumatic Spinal Cord Injury: A Systematic Review and Meta-Analysis
Valido, Ezra; Boehl, Gabriela; Krebs, Jörg; Pannek, Jürgen; Stojic, Stevan; Atanasov, Atanas G.; Glisic, Marija; Stoyanov, Jivko

Individuals with spinal cord injury (SCI) have higher infection rates compared to those without SCI.

In this review, the immune status difference between individuals with and without traumatic SCI is investigated by examining their peripheral immune cells and markers. PubMed, Cochrane, EMBASE, and Ovid MEDLINE were searched without language or date restrictions. Studies reporting peripheral immune markers’ concentration and changes in functional capabilities of immune cells that compared individuals with and without SCI were included. Studies with participants with active infection, immune disease, and central nervous system (CNS) immune markers were excluded. The review followed the PRISMA guidelines. Effect estimates were measured by Weighted Mean Difference (WMD) using a random-effects model. Study quality was assessed using the National Heart, Lung, and Blood Institute Quality Assessment Tool. Fifty-four studies (1813 with SCI and 1378 without SCI) contributed to the meta-analysis. Leukocytes (n = 23, WMD 0.78, 95% CI 0.17; 1.38, I 2 83%), neutrophils (n = 11, WMD 0.76, 95% CI 0.09; 1.42, I 2 89%), C-reactive protein (CRP) (n = 12, WMD 2.25, 95% CI 1.14; 3.56, I 2 95%), and IL6 (n = 13, WMD 2.33, 95% CI 1.20; 3.49, I 2 97%) were higher in individuals with SCI vs. without SCI.

Clinical factors (phase of injury, completeness of injury, sympathetic innervation impairment, age, sex) and study-related factors (sample size, study design, and serum vs. plasma) partially explained heterogeneity. Immune cells exhibited lower functional capability in individuals with SCI vs. those without SCI. Most studies (75.6%) had a moderate risk of bias. The immune status of individuals with SCI differs from those without SCI and is clinically influenced by the phase of injury, completeness of injury, sympathetic innervation impairment, age, and sex. These results provide information that is vital for monitoring and management strategies to effectively improve the immune status of individuals with SCI.

Link | PDF (International Journal of Molecular Sciences)

 

[SNT Gatchaman]

Posting as spinal cord injury results in sympathectomy and this review discusses links between the autonomic nervous, endocrine and immune systems, which may be of relevance.

Having a complete or incomplete SCI affects the immune status. The subgroup analysis showed that the group with incomplete SCI had significantly higher concentrations of leukocytes and significantly lower concentrations of lymphocytes compared to those without SCI. Individuals with complete SCI have a higher probability of having sympathetic nerve plexus impairment. The sympathetic nervous plexus is at the thoraco-lumbar section of the spine, and it is crucial for hormonal balance, inhibitory bone marrow stimuli, and visceral organ innervation.

The loss of sympathetic control leads to an imbalance of hormonal releases, particularly norepinephrine and cortisol, that affects the immune cells’ maturation, leading to lower functional capabilities of these cells. A significantly lower immune cell function has been seen in the studies in this review at the chronic phase. The loss of inhibitory bone marrow control likewise results in the unregulated release and migration of immature immune cells. Moreover, the level of the injury also plays a role and has been observed in animal models as a modifier of immune response.

Individuals with tetraplegia have disrupted sympathetic innervation at a high level, while those with paraplegia have varying degrees of sympathetic innervation impairment at the thoraco-lumbar level. Results from the stratified analysis showed that individuals with tetraplegia had significantly higher CRP and IL6 concentrations and significantly lower granulocyte concentrations compared to those without SCI, and no significant differences were found in the immune markers tested with those with paraplegia vs. those without SCI.

 

[Ash]

Could a less severe spinal injury that doesn’t cause paralysis cause some of the same problems, and is there overlap with disruption to immune function of the type that can occur with TBIs?