Emerging Cerebrospinal Fluid Biomarkers of Disease Activity and Progression in Multiple Sclerosis.

Importance: Biomarkers distinguishing nonrelapsing progressive disease biology from relapsing biology in multiple sclerosis (MS) are lacking. Cerebrospinal fluid (CSF) is an accessible fluid that most closely reflects central nervous system biology. Objective: To identify CSF biological measures associated with progressive MS pathobiology. Design, Setting, and Participants: This cohort study assessed data from 2 prospective MS cohorts: a test cohort provided serial CSF, clinical, and imaging assessments in a multicenter study of patients with relapsing MS (RMS) or primary progressive MS (PPMS) who were initiating anti-CD20 treatment (recruitment: 2016-2018; analysis: 2020-2023). A single-site confirmation cohort was used to assess CSF at baseline and long-term (>10 year) clinical follow-up (analysis: 2022-2023). Exposures: Test-cohort participants initiated standard-of-care ocrelizumab treatment. Confirmation-cohort participants were untreated or received standard-of-care disease-modifying MS therapies. Main Outcomes and Measures: Twenty-five CSF markers, including neurofilament light chain, neurofilament heavy chain, and glial fibrillary acid protein (GFAP); 24-week confirmed disability progression (CDP24); and brain magnetic resonance imaging measures reflecting focal injury, tissue loss, and progressive biology (slowly expanding lesions [SELs]). Results: The test cohort (n = 131) included 100 patients with RMS (mean [SD] age, 36.6 [10.4] years; 68 [68%] female and 32 [32%] male; Expanded Disability Status Scale [EDSS] score, 0-5.5), and 31 patients with PPMS (mean [SD] age, 44.9 [7.4] years; 15 [48%] female and 16 [52%] male; EDSS score, 3.0-6.5). The confirmation cohort (n = 68) included 41 patients with RMS and 27 with PPMS enrolled at diagnosis (age, 40 years [range, 20-61 years]; 47 [69%] female and 21 [31%] male). In the test cohort, GFAP was correlated with SEL count (r = 0.33), greater proportion of T2 lesion volume from SELs (r = 0.24), and lower T1-weighted intensity within SELs (r = -0.33) but not with acute inflammatory measures. Neurofilament heavy chain was correlated with SEL count (r = 0.25) and lower T1-weighted intensity within SELs (r = -0.28). Immune markers correlated with measures of acute inflammation and, unlike GFAP, were impacted by anti-CD20. In the confirmation cohort, higher baseline CSF GFAP levels were associated with long-term CDP24 (hazard ratio, 2.1; 95% CI, 1.3-3.4; P = .002). Conclusions and Relevance: In this study, activated glial markers (in particular GFAP) and neurofilament heavy chain were associated specifically with nonrelapsing progressive disease outcomes (independent of acute inflammatory activity). Elevated CSF GFAP was associated with long-term MS disease progression.

Short, thin asbestos fibers contribute to the development of human malignant mesothelioma: pathological evidence.

Based on animal studies, long and thin asbestos fibers (> or =8 microm in length and < or = 0.25 microm in width) have been postulated to be strongly carcinogenic inducing pleural malignant mesothelioma, while shorter, thicker fibers have been postulated to pose a lesser risk (Stanton hypothesis). The objective of this study is to test the validity of the Stanton hypothesis through direct pathologic analysis of human mesothelioma tissue. Digested bulk tissue samples, or ashed 25 microm thick sections, or both, were prepared from lung and mesothelial tissues taken from 168 cases of human malignant mesothelioma. In these tissues, 10,575 asbestos fibers (4820 in the lung and 5755 in mesothelial tissues (1259 in fibrotic serosa and 4496 in mesotheliomatous tissue)) were identified by high-resolution analytical electron microscopy. Dimensions of these asbestos fibers were measured in printed electron micrographs. Results were as follows: (1) long, thin asbestos fibers consistent with the Stanton hypothesis comprised only 2.3% of total fibers (247 / 10,575) in these tissues; (2) the majority (89.4%) of the fibers in the tissues examined were shorter than or equal to 5 microm in length (9454 of 10,575), and generally (92.7%) smaller than or equal to 0.25 microm in width (9808 of 10,575). (3) Among asbestos types detected in the lung and mesothelial tissues, chrysotile was the most common asbestos type to be categorized as short, thin asbestos fibers. (4) Compared with digestion technique of the bulk tissue, ashing technique of the tissue section was more effective to detect short, thin fibers. We conclude that contrary to the Stanton hypothesis, short, thin, asbestos fibers appear to contribute to the causation of human malignant mesothelioma. Such fibers were the predominant fiber type detected in lung and mesothelial tissues from human mesothelioma patients. These findings suggest that it is not prudent to take the position that short asbestos fibers convey little risk of disease.

Asbestos fibers contributing to the induction of human malignant mesothelioma.

UNLABELLED: To elucidate the features of the asbestos fibers contributing to the induction of human malignant mesothelioma, we used high-resolution analytical electron microscopy to determine the type, number, and dimensions of asbestos fibers in lung and mesothelial tissues in 168 cases of mesothelioma. RESULTS: 1. Asbestos fibers were present in almost all of the lung and mesothelial tissues from the mesothelioma cases. 2. The most common types of asbestos fibers in lung were either an admixture of chrysotile with amphiboles, amphibole alone, and occasionally chrysotile alone. In mesothelial tissues, most asbestos fibers were chrysotile. 3. In lung, amosite fibers were greatest in number followed by chrysotile, crocidolite, tremolite/actinolite, and anthophyllite. In mesothelial tissues, chrysotile fibers were 30.3 times more common than amphiboles. 4. In some mesothelioma cases, the only asbestos fibers detected in either lung or mesothelial tissue were chrysotile fibers. 5. The average number of asbestos fibers in both lung and mesothelial tissues was two orders of magnitude greater than the number found in the general population. 6. The majority of asbestos fibers in lung and mesothelial tissues were shorter than 5 micro m in length. CONCLUSIONS: 1) Fiber analysis of both lung and mesothelial tissues must be done to determine the types of asbestos fibers associated with the induction of human malignant mesothelioma; 2) short, thin asbestos fibers should be included in the list of fiber types contributing to the induction of human malignant mesothelioma; 3) RESULTS support the induction of human malignant mesothelioma by chrysotile.