Elevated translocator protein in skull bone marrow is linked to human chronic pain
Mohammadian M, Efthimiou N, Gabriel K, Brusaferri L, Cooper-Hohn J, Kim M, Murphy JP, Alshelh Z, Grmek G, Schnieders JH, Chane CA, Carmichael TG, Yang D, Schubert JJ, Turkheimer FE, Cazuza RA, Grace PM, Catana C, Stufflebeam SM, Edwards RR, Napadow V, Sullivan K, Nahrendorf M, Price TJ, Gilman JM, Loggia ML. Elevated translocator protein in skull bone marrow is linked to human chronic pain. Sci Transl Med. 2026 Sep 2;18(865):eaed8729. doi: 10.1126/scitranslmed.aed8729. Epub 2026 Sep 2. PMID: 42685155.
I guess this is why I sometimes just look around online to see what’s going on with some researchers I know. In this case, I looked up what Vitaly Napadow has been doing. It turns out there is a whole new line of research using something called the translocator protein in chronic pain. Lo and behold it is found in skull bone. This is a brand new insight/development/avenue for future research.
Abstract
The skull bone marrow (SBM) is emerging as a critical hub for neuroimmune signaling, yet its role in chronic pain is unknown. Using integrated positron emission tomography/magnetic resonance imaging, here, we show that the levels of 18-kilodalton translocator protein (TSPO), a putative marker of immune cell density, are elevated in the SBM of individuals with chronic pain [n = 125; chronic low back pain (cLBP), n = 88; knee osteoarthritis (KOA), n = 37] compared with healthy controls (n = 22). These elevations were widespread, generally more pronounced for KOA than cLBP, associated with pain and pain-comorbid symptoms in partially segregated spatial patterns, and supported by preliminary immunohistochemical evidence in human SBM samples from a donor with a history of chronic pain (compared with a healthy donor). Because TSPO is highly expressed in myeloid cells, these results link SBM immune dysregulation with chronic pain and its associated psychological and functional impairments. These findings provide a strong rationale for investigating this previously overlooked structure, which remains largely underexplored in the context of pain.