IL-19(+) monocytes suppress neuroinflammation and promote neurological recovery in young individuals with traumatic brain injury

09/08/2026

AI Summary

IL-19+ cranial bone marrow monocytes infiltrate brain after TBI and suppress glial hyper-response, promoting neurological recovery in young individuals.
Therapeutic effect operates through the IL-19/IL-20R axis, which is impaired with age, reducing anti-inflammatory signalling after TBI.
Intracerebroventricular CX3CL1 increases cranial IL-19+ monocyte recruitment to brain and restores neurological recovery in aged TBI mice.

AI Summary

IL-19+ monocytes inhibit the glial hyper-response and promote neurological recovery after TBI through the IL-19/IL-20R axis, which is defective in aged patients.

Notably, intracerebroventricular injection of recombinant CX3CL1 inhibits excessive neuroinflammation and promotes neurological recovery of aged TBI mice by enhancing the output of cranial IL-19+ monocytes to the brain.

Our study demonstrates the important involvement of cranial bone marrow in the repair process after TBI and suggests that the characteristic recruitment of cranial bone marrow-derived regulatory myeloid cells may be an effective approach to improve outcomes of aged TBI.

Basic summary

Cell Rep. 2026 Aug 7;45(8):117805. doi: 10.1016/j.celrep.2026.117805. Online ahead of print.

ABSTRACT

Young patients with traumatic brain injury (TBI) have a better prognosis than the aged, but the underlying mechanisms are not clear. Here, we identified a population of IL-19⁺ monocytes derived from cranial bone marrow appearing in the brain after TBI. IL-19⁺ monocytes inhibit the glial hyper-response and promote neurological recovery after TBI through the IL-19/IL-20R axis, which is defective in aged patients. Further studies have proven that CX3CR1 on the IL-19⁺ monocytes is attracted by CX3CL1 after TBI, infiltrating the brain, and exerting immunoregulatory effects. Notably, intracerebroventricular injection of recombinant CX3CL1 inhibits excessive neuroinflammation and promotes neurological recovery of aged TBI mice by enhancing the output of cranial IL-19⁺ monocytes to the brain. Our study demonstrates the important involvement of cranial bone marrow in the repair process after TBI and suggests that the characteristic recruitment of cranial bone marrow-derived regulatory myeloid cells may be an effective approach to improve outcomes of aged TBI.

PMID:42570240 | DOI:10.1016/j.celrep.2026.117805

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