New CDC recommendations: annual influenza vaccination recommended for individuals with spinal cord injuries

A Primary Care Provider's Guide to Managing Respiratory Health in Subacute and Chronic Spinal Cord Injury

Respiratory complications following spinal cord injury (SCI) have remained the leading cause of death across the lifespan and are one of the most common reasons for hospitalization. Complications from altered respiratory physiology after SCI include atelectasis, pneumonia, venous thromboembolic disease, and sleep-disordered breathing. The risk for complications is greater with higher SCI levels and severity, and mortality from pneumonia is heightened compared to the general population. Optimal primary care for individuals with SCI includes appropriate surveillance for SCI-specific respiratory disease, key preventive care including promotion of influenza immunization and respiratory muscle training, and early identification and treatment of pneumonia with institution of aggressive secretion management strategies. The respiratory physiology and specific management of respiratory complications after SCI is reviewed.

Chronic spinal cord injury impairs primary CD8 T cell antiviral immunity but does not affect generation or function of memory CD8 T cells

Antiviral immunity is severely compromised following trauma to the central nervous system. In mice with chronic spinal cord injury (SCI), primary infection with influenza virus leads to high mortality rates due to impaired expansion of virus-specific CD8 T cells. One strategy to increase resistance to viral infections is to generate memory immune cells that protect from recurrent infections. However, it is unknown if chronic SCI also impairs secondary immune responses to influenza challenge as it does primary responses. Here, we used a mouse model of chronic SCI and a clinically relevant influenza A infection to investigate CD8 T cell response. As shown previously, chronic SCI mice had impaired primary antiviral responses with high mortality rates and decreased expansion of virus-specific CD8 T cells following intranasal infection. To investigate CD8 T cell memory, we used two strains of influenza A virus [PR8(H1N1) and X31(H3N2)] that share internal proteins but differ in surface antigens. Chronic SCI mice immunized with live X31 were able to generate memory CD8 T cells that secreted IFNγ upon stimulation with viral peptides ex vivo, which was comparable to immunized uninjured mice. Importantly, immunization prior to challenge with a lethal dose of PR8 resulted in no mortality and significant CD8 T cell recall responses in both uninjured and chronic SCI mice. In addition, memory CD8 T cells generated before SCI remained functional up to 8 weeks after injury. These pre-existing memory CD8 T cells provided full protection from lethal PR8 challenge given at the chronic timepoint following injury. Overall, this study shows that memory CD8 T cells generated either before or after chronic SCI still remain functional. These results highlight the need for proper immunization of SCI patients and show the potential of memory T cells to confer protection against not only influenza, but other viral infections as well.

Chronic spinal cord injury attenuates influenza virus-specific antiviral immunity

Background

Individuals suffering from spinal cord injury (SCI) are at higher risk for respiratory-related viral infections such as influenza. In a previous study (Zha et al., J Neuroinflammation 11:65, 2014), we demonstrated that chronic spinal cord injury caused impairment in CD8⁺T cell function with increased expression of the immunosuppressive protein, programmed cell death 1 (PD-1). The present study was undertaken to establish whether chronic SCI-induced immune deficits would affect antiviral immunity directed against primary and secondary infections.

Methods

Six to seven weeks following a SCI contusion at thoracic level T9, mice were infected intranasally with influenza virus. Virus-specific immunity was analyzed at various time points post-infection and compared to uninjured controls.

Results

We report that chronic thoracic SCI impairs the ability of the animals to mount an adequate antiviral immune response. While all uninjured control mice cleared the virus from their lungs by day 10 post-infection, a significant number (approximately 70 %) of chronic SCI mice did not clear the virus and succumbed to infection-induced mortality. This was attributed to severe deficits in both virus-specific antibody production and CD8⁺ T cell response in injured mice after primary infection. We also determined that previously acquired humoral immunity was maintained after spinal cord injury as vaccination against influenza A prior to injury-protected mice from a homologous viral challenge. In contrast, prior immunization did not protect mice from a heterotypic challenge with a different strain of influenza virus.

Conclusions

Taken together, our data demonstrate that chronic SCI attenuates virus-specific humoral and cellular immunity during the establishment of primary response and impairs the development of memory CD8⁺ T cells. In contrast, B cell memory acquired through vaccination prior to SCI is preserved after injury which demonstrates that antigen-specific memory cells are refractory following injury. Our study defines important parameters of the deficits of chronic SCI-induced immune depression during a viral respiratory infection. Our objective is to better understand the mechanisms of spinal cord injury-induced immune depression with the goal of developing more effective therapies and reduce mortality due to complications from influenza and other infections.

Electronic supplementary material

The online version of this article (doi:10.1186/s12974-016-0574-y) contains supplementary material, which is available to authorized users.

Influenza infection control guidance provided to staff at Veterans Affairs facilities for veterans with spinal cord injury during a pandemic(†)

CONTEXT/OBJECTIVE

To assess guidance provided to staff at Veterans Affairs (VA) healthcare facilities on H1N1 influenza infection control for veterans with spinal cord injuries and disorders (SCI/D).

STUDY DESIGN

Cross-sectional qualitative semi-structured interviews.

SETTING

Thirty-three VA healthcare facilities from throughout the United States that provide care to veterans with SCI/D.

PARTICIPANTS

Thirty-three infection control key informants, each representing a VA healthcare facility.

INTERVENTIONS

None.

OUTCOME MEASURES

Infection control practices, including vaccination practices, hospital preparedness, and recommendations for future pandemics, both in general and specifically to SCI/D.

RESULTS

Most (n = 26, 78.8%) infection control key informants believed veterans with SCI/D were at increased risk for influenza and complications, but only 17 (51.5%) said veterans with SCI/D were treated as a priority group for vaccination at their facilities. There was little special guidance provided for treating veterans with SCI/D, and most (n = 28, 84.8%) informants said that infection control procedures and recommendations were applied universally. Yet, 10 key informants discussed 'unique challenges' to infection control in the SCI/D population. Informants discussed the potential for infectious agents to be spread through shared and common use equipment and the necessity of including caregivers in any vaccination or educational campaigns.

CONCLUSION

Greater input by experts knowledgeable about SCI/D is recommended to adequately address pandemic influenza within healthcare facilities where individuals with SCI/D receive care.

Guideline-recommended management of community-acquired pneumonia in veterans with spinal cord injury

BACKGROUND

Pneumonia is a leading cause of death in persons with spinal cord injuries and disorders (SCI/D), but little is known about guideline-based management for this disease in persons with SCI/D.

OBJECTIVES

The goal of this study was to describe guideline-based medical care for community-acquired pneumonia (CAP) in veterans with SCI/D.

METHODS

A retrospective medical record review was conducted at 7 Department of Veterans Affairs (VA) medical centers where veterans with SCI/D and CAP between 2005 and 2008 were included. Outcomes assessed were receipt of blood or sputum culture, antibiotic timeliness, appropriateness of empiric antibiotic treatment, and vaccination.

RESULTS

In 70 patients, 77 CAP episodes occurred and 83.1% were treated in the inpatient setting. The average age was 70.0 years and 64.9% had tetraplegia. Sputum culture was completed in 24.7% and blood culture in 59.7% of cases. Of inpatients, 79.7% had antibiotic treatment within 8 hours and 45.1% received guideline-recommended empirical antibiotics. More than 90% of inpatients received antibiotic treatment within 3 days of presentation and 78.1% received recommended treatment. The rates of pneumococcal pneumonia (89.9%) and influenza (79.7%) vaccinations were high in CAP cases.

CONCLUSIONS

Diagnostic testing and early guideline-recommended treatment is variable in veterans with SCI/D and CAP. However vaccination against influenza and pneumococcal pneumonia is high. Specific guidelines for management of CAP in SCI/D patients may be needed, which reflect the unique risk factors and needs of this population. These data can be used as a benchmark for improvements in care processes for treating and managing CAP in persons with SCI/D.

Stress hormones collaborate to induce lymphocyte apoptosis after high level spinal cord injury

Post-traumatic immune suppression renders individuals with spinal cord injury (SCI) susceptible to infection. Normally, proper immune function is regulated by collaboration between the sympathetic nervous system (SNS) and hypothalamic-pituitary-adrenal (HPA) axis and involves the controlled release of glucocorticoids (GCs) and norepinephrine (NE). Recently, we showed that after high thoracic (T3) SCI, aberrant levels of GCs and NE accumulate in the blood and spleen, respectively. These changes are associated with splenic atrophy, splenic leucopenia, increased intrasplenic caspase 3 levels, and suppressed B lymphocyte function. As GCs boost SNS function, in part by increasing the expression and affinity of beta2 adrenergic receptors (beta2ARs) while simultaneously preventing beta2AR down-regulation, we predicted that surges in stress hormones (i.e., GCs and NE) in the blood and spleen of mice with high-level SCI would act concurrently to adversely affect lymphocyte function and survival. Here, we show that post-SCI concentrations of GCs enhance the sensitivity of lymphocytes to beta2AR stimulation causing an increase in intracellular Bcl-2 interacting mediator of cell death (Bim) and subsequent apoptosis. In vivo, the combined antagonism of GC receptors and beta2ARs significantly diminished lymphocyte Bim levels and SCI-induced splenic lymphopenia. Together, these data suggest that pharmacological antagonists of the HPA/SNS axes should be considered as adjunct therapies for ameliorating post-traumatic immune suppression in quadriplegics and high paraplegics.

Acute respiratory infections in persons with spinal cord injury

Respiratory disorders are the leading cause of death for persons with both acute and chronic spinal cord injury (SCI), and much of the morbidity and mortality associated with respiratory disorders is related to acute respiratory infections. Pneumonia is the best recognized respiratory infection associated with mortality in this population. Recent evidence supports some management strategies that differ from those recommended for the general population. Upper respiratory tract infections and acute bronchitis may be precipitating factors in the development of pneumonia or ventilatory failure in patients with chronic SCI. This review emphasizes management principles for treatment and prevention of respiratory infections in persons with SCI.