Lung immunity after complete thoracic spinal cord transection in female mice

DOI:10.34945/F52G69

DATASET CITATION

Mifflin K. A., Brennan F. H., Guan Z., Kigerl K. A., Filous A. R., Mo X., Schwab J. M., Popovich P. G. (2022) Lung immunity after complete thoracic spinal cord transection in female mice. ODC-SCI:735 http://doi.org/10.34945/F52G69

ABSTRACT

STUDY PURPOSE: Pulmonary infection is a leading cause of morbidity and mortality after spinal cord injury (SCI). Although SCI causes atrophy and dysfunction in primary and secondary lymphoid tissues with a corresponding decrease in the number and function of circulating leukocytes, it is unknown if this SCI-dependent systemic immune suppression also affects the unique tissue-specific antimicrobial defense mechanisms that protect the lung. Here, we test the hypothesis that SCI directly impairs pulmonary immunity and subsequently increases the risk for developing pneumonia.

DATA COLLECTED: The dataset includes n=242 C57/Bl6 female mice aged 9-13 weeks. Mice received a complete transection SCI at either the thoracic level 1 (T1Tx) or 3 (T3Tx). Sham mice underwent a laminectomy only at the appropriate thoracic level. Flow cytometry was used to assess lung immune cells (neutrophils, T- and B-lymphocytes, alveolar macrophages, CD45+ immune cells) at 12h ((n=8-12 T3Tx, n=8-12 T3 sham), 3d (n=12 T3Tx, n=12 T3 sham, n=7 T1Tx, n=7 T1 sham), and 28d (n=12 T3Tx, n=12 T3 sham) post- injury. Corresponding cultures of lung homogenate on blood agar (n=7 12h & 3dpi T3Tx and 3dpi T3 Sham, n=12-14 28dpi T3 Sham mice, n=12-14 28dpi T3Tx, n=18 T1Tx, n=13 T1 Sham) and CHROMagar ™ plates (n=18 T1Tx, n=13 T1 Sham) at these timepoints were also used to assess pulmonary bacterial burden after injury. The drug AMD3100, a CXCR4 antagonist (1mg/mouse given subcutaneously 1h post-injury then daily for either 3d or 7d), was also tested in T1Tx mice to see if the drug improved pulmonary immune function as measured by flow cytometry (n=10 T1Tx vehicle and n= 13 T1Tx AMD3100 mice), altered blood immune cell counts (n=8 T1 sham, n=9 T1Tx vehicle and n=10 T1Tx AMD3100) or reduced bacteria load (n=21 T1Tx vehicle and n=23 T1Tx AMD3100 for 3dpi studies, n=9 T1Tx vehicle and n=10 T1Tx AMD3100 for 7dpi studies). A subset of AMD3100 treated mice also underwent an induced pneumonia procedure (n=11 T3Tx vehicle + pneumonia and n=11 T3TxAMD3100 + pneumonia). Finally, n=4 mice were pooled from T3 Sham or T3Tx groups to perform a PCR array for lung immunity genes and RT-qPCR on 10 identified hub genes at 12h and 3d post-injury.

CONCLUSIONS: Using mouse models of severe high thoracic level 1 or 3 SCI, we find that recruitment of circulating leukocytes and transcriptional control of immune signaling in the lung is impaired after SCI, creating an environment that is permissive for infection. Specifically, we see a sustained loss of pulmonary leukocytes (up to ~60% loss), a loss of alveolar macrophages (30% loss) at chronic timepoints post-injury, and a decrease in immune modulatory genes, especially cytokines (e.g. Tnf, Il6, Infg), needed to eliminate pulmonary infections. Importantly, this injury-dependent impairment of pulmonary antimicrobial defense is only partially overcome by boosting the recruitment of immune cells to the lung with the drug AMD3100, an FDA-approved drug that mobilizes leukocytes and hematopoietic stem cells from bone marrow. Collectively, these data indicate that the immune suppressive effects of SCI extend to the lung, a unique site of mucosal immunity. Furthermore, preventing lung infection after SCI will likely require novel strategies, beyond the use of orthodox antibiotics, to reverse or block tissue-specific cellular and molecular determinants of pulmonary immune surveillance.

KEYWORDS

Spinal cord injury; lung; Pneumonia; pulmonary immunity; infection; immune surveillance; Bacteria; AMD3100

PROVENANCE / ORIGINATING PUBLICATIONS

RELEVANT LINKS

NOTES

DATASET INFO

Contact: Mifflin Katherine (katherine.mifflin@osumc.edu), Popovich Phillip (Phillip.Popovich@osumc.edu)

Lab: Phillip Popovich

ODC-SCI Accession:735

Records in Dataset: 242

Fields per Record: 52

Last updated: 2022-05-13

Date published:

Downloads: 12

Files: 2

LICENSE

Creative Commons Attribution License (CC-BY 4.0)

FUNDING AND ACKNOWLEDGEMENTS

Craig H. Neilsen Foundation grants 457267 to FHB, 647110 to KAM, 596764, to JMS, 457328 to ARF, The Ohio State University Presidential Postdoctoral Fellowship KAM, Wings for Life FHB, PGP,JMS, ARF, NINDS-NIH grants R01NS099532 to PGP, R01NS083942 to PGP, R35NS111582 to PGP, R01NS118200 to JMS, NIDILRR 90SI5020 to JMS, Ray W. Poppleton Endowment PGP, EU Era Net – Neuron Program, SILENCE Grant 01EW170A to JMS, William E. Hunt and Charlotte M. Curtis endowment JMS, The Ohio State University Discovery Theme Initiative Scholar (Chronic Brain Injury) JMS

CONTRIBUTORS

Mifflin, Katherine A. [ORCID:0000-0002-6323-4731]

Department of Neuroscience, Center for Brain and Spinal Cord Repair; Belford Center for Spinal Cord Injury, The Ohio State University Wexner Medical Center, Columbus, OH 43210

Brennan, Faith H. [ORCID:0000-0002-9201-2476]

Department of Neuroscience, Center for Brain and Spinal Cord Repair; Belford Center for Spinal Cord Injury, The Ohio State University Wexner Medical Center, Columbus, OH 43210

Guan, Zhen

Department of Neuroscience, Center for Brain and Spinal Cord Repair; Belford Center for Spinal Cord Injury, The Ohio State University Wexner Medical Center, Columbus, OH 43210

Kigerl, Kristina A. [ORCID:0000-0002-1652-0882]

Department of Neuroscience, Center for Brain and Spinal Cord Repair; Belford Center for Spinal Cord Injury, The Ohio State University Wexner Medical Center, Columbus, OH 43210

Filous, Angela R.

Department of Neurology, Center for Brain and Spinal Cord Repair; Belford Center for Spinal Cord Injury, The Ohio State University Wexner Medical Center, Columbus, OH 43210

Mo, Xiaokui [ORCID:0000-0002-9797-2687]

Department of Biomedical Informatics, The Ohio State University, Columbus, OH 43210

Schwab, Jan M. [ORCID:0000-0001-6784-4919]

Department of Neurology, Department of Neuroscience, Center for Brain and Spinal Cord Repair; Belford Center for Spinal Cord Injury, The Ohio State University Wexner Medical Center, Columbus, OH 43210

Popovich, Phillip G. [ORCID:0000-0003-1329-7395]

Department of Neuroscience, Center for Brain and Spinal Cord Repair; Belford Center for Spinal Cord Injury, The Ohio State University Wexner Medical Center, Columbus, OH 43210