Residential exposure associations with ALS risk, survival, and phenotype: a Michigan-based case-control study.

Background: Environmental exposures impact amyotrophic lateral sclerosis (ALS) risk and progression, a fatal and progressive neurodegenerative disease. Better characterization of these exposures is needed to decrease disease burden. Objective: To identify exposures in the residential setting that associate with ALS risk, survival, and onset segment. Methods: ALS and control participants recruited from University of Michigan completed a survey that ascertained exposure risks in the residential setting. ALS risk was assessed using logistic regression models followed by latent profile analysis to consider exposure profiles. A case-only analysis considered the contribution of the residential exposure variables via a Cox proportional hazards model for survival outcomes and multinomial logistic regression for onset segment, a polytomous outcome. Results: This study included 367 ALS and 255 control participants. Twelve residential variables were associated with ALS risk after correcting for multiple comparison testing, with storage in an attached garage of chemical products including gasoline or kerosene (odds ratio (OR) = 1.14, padjusted < 0.001), gasoline-powered equipment (OR = 1.16, padjusted < 0.001), and lawn care products (OR = 1.15, padjusted < 0.001) representing the top three risk factors sorted by padjusted. Latent profile analysis indicated that storage of these chemical products in both attached and detached garages increased ALS risk. Although residential variables were not associated with poorer ALS survival following multiple testing corrections, storing pesticides, lawn care products, and woodworking supplies in the home were associated with shorter ALS survival using nominal p values. No exposures were associated with ALS onset segment. Conclusion: Residential exposures may be important modifiable components of the ALS susceptibility and prognosis exposome.

Peripheral Immune Profiles Predict ALS Progression in an Age- and Sex-Dependent Manner.

BACKGROUND AND OBJECTIVES: Amyotrophic lateral sclerosis (ALS) is a fatal neurodegenerative disease whose pathobiology associates with peripheral blood immune cell levels and activation patterns in an age and sex-dependent manner. This study's objective was to identify immune profile associations with ALS progression, whether the associations are age and sex-specific, and whether immune profiles can predict a future disease course. METHODS: Flow cytometry immune profiles (a combination of 22 peripheral blood immune markers) were generated for 241 participants with ALS and linked to ALS progression, using progression-free survival, which is a composite combining the revised ALS Functional Rating Scale and survival. Participants were first grouped by immune profiles using unsupervised hierarchical clustering, and clusters were associated with subsequent progression-free survival. Next, individual immune markers were associated with progression-free survival using least absolute shrinkage and selection operator-Cox regression. Analyses were stratified by age and sex to identify demographic-specific immune mechanisms. Finally, random forest determined the predictive power of immune profiles on ALS progression in the whole population and again stratified by age and sex. RESULTS: Progression-free survival differed between clusters of participants with similar immune profiles, particularly reduced natural killer (NK)-cell activation associated with slower progression. Individual markers such as neutrophil levels and NK-cell NKp46 expression associated with faster ALS progression while overall NK-cell levels and NK-cell subpopulations associated with slower progression; the strength of these associations varied by age and sex. Adding these immune markers to prediction models dramatically increased short-term prediction compared with routine clinical prognostic variables alone, and the addition of NK-cell markers further improved the prediction accuracy in female participants. DISCUSSION: Specific immune profiles likely contribute to ALS progression in an age and sex-dependent manner, and peripheral immune markers enhance the prediction of short-term clinical outcomes. These findings suggest a complex milieu of immune profiles associated with ALS progression, and more detailed immunophenotyping in ALS will facilitate personalized immunotherapeutics in ALS.

Avocational exposure associations with ALS risk, survival, and phenotype: A Michigan-based case-control study.

INTRODUCTION: Environmental exposures strongly influence ALS risk and identification is needed to reduce ALS burden. Participation in hobbies and exercise may alter ALS risk and phenotype, warranting an assessment to understand their contribution to the ALS exposome. METHODS: Participants with ALS and healthy controls were recruited from University of Michigan and self-completed a survey to ascertain hobbies, exercise, and avocational exposures. Exposure variables were associated with ALS risk, survival, onset segment, and onset age. RESULTS: ALS (n = 400) and control (n = 287) participants self-reported avocational activities. Cases were slightly older (median age 63.0 vs. 61.1 years, p = 0.019) and had a lower educational attainment (p < 0.001) compared to controls; otherwise, demographics were well balanced. Risks associating with ALS after multiple comparison correction included golfing (odds ratio (OR) 3.48, padjusted = 0.004), recreational dancing (OR 2.00, padjusted = 0.040), performing gardening or yard work (OR 1.71, padjusted = 0.040) five years prior to ALS and personal (OR 1.76, padjusted = 0.047) or family (OR 2.21, padjusted = 0.040) participation in woodworking, and personal participation in hunting and shooting (OR 1.89, padjusted = 0.040). No exposures associated with ALS survival and onset. Those reporting swimming (3.86 years, padjusted = 0.016) and weightlifting (3.83 years, padjusted = 0.020) exercise 5 years prior to ALS onset had an earlier onset age. DISCUSSION: The identified exposures in this study may represent important modifiable ALS factors that influence ALS phenotype. Thus, exposures related to hobbies and exercise should be captured in studies examining the ALS exposome.

Tofacitinib Suppresses Natural Killer Cells In Vitro and In Vivo: Implications for Amyotrophic Lateral Sclerosis.

Amyotrophic lateral sclerosis (ALS) is a fatal and incurable neurodegenerative disease with few therapeutic options. However, the immune system, including natural killer (NK) cells, is linked to ALS progression and may constitute a viable therapeutic ALS target. Tofacitinib is an FDA-approved immunomodulating small molecule which suppresses immune cell function by blocking proinflammatory cytokine signaling. This includes the cytokine IL-15 which is the primary cytokine associated with NK cell function and proliferation. However, the impact of tofacitinib on NK activation and cytotoxicity has not been thoroughly investigated, particularly in ALS. We therefore tested the ability of tofacitinib to suppress cytotoxicity and cytokine production in an NK cell line and in primary NK cells derived from control and ALS participants. We also investigated whether tofacitinib protected ALS neurons from NK cell cytotoxicity. Finally, we conducted a comprehensive pharmacokinetic study of tofacitinib in mice and tested the feasibility of administration formulated in chow. Success was assessed through the impact of tofacitinib on peripheral NK cell levels in mice. We found tofacitinib suppressed IL-15-induced activation as measured by STAT1 phosphorylation, cytotoxicity, pro-inflammatory gene expression, and pro-inflammatory cytokine secretion in both an NK cell line and primary NK cells. Furthermore, tofacitinib protected ALS neurons from NK cell-mediated cytotoxicity. In mice, we found tofacitinib bioavailability was 37% in both male and female mice; using these data we formulated mouse containing low and high doses of tofacitinib and found that the drug suppressed peripheral NK cell levels in a dose-dependent manner. These results demonstrate that tofacitinib can suppress NK cell function and may be a viable therapeutic strategy for ALS.

NK cells associate with ALS in a sex- and age-dependent manner.

NK cells are innate immune cells implicated in ALS; whether NK cells impact ALS in a sex- and age-specific manner was investigated. Herein, NK cells were depleted in male and female SOD1G93A ALS mice, survival and neuroinflammation were assessed, and data were stratified by sex. NK cell depletion extended survival in female but not male ALS mice with sex-specific effects on spinal cord microglia. In humans, NK cell numbers, NK cell subpopulations, and NK cell surface markers were examined in prospectively blood collected from subjects with ALS and control subjects; longitudinal changes in these metrics were correlated to revised ALS functional rating scale (ALSFRS-R) slope and stratified by sex and age. Expression of NK cell trafficking and cytotoxicity markers was elevated in subjects with ALS, and changes in CXCR3+ NK cells and 7 trafficking and cytotoxicity markers (CD11a, CD11b, CD38, CX3CR1, NKG2D, NKp30, NKp46) correlated with disease progression. Age affected the associations between ALSFRS-R and markers NKG2D and NKp46, whereas sex impacted the NKp30 association. Collectively, these findings suggest that NK cells contribute to ALS progression in a sex- and age-specific manner and demonstrate that age and sex are critical variables when designing and assessing ALS immunotherapy.