Comprehensive immune profiling reveals substantial immune system alterations in a subset of patients with amyotrophic lateral sclerosis

Abstract

Amyotrophic lateral sclerosis (ALS) is a fatal neurodegenerative disease with a median lifespan of 2–3 years after diagnosis. There are few meaningful treatments that alter progression in this disease. Preclinical and clinical studies have demonstrated that neuroinflammation may play a key role in the progression rate of ALS. Despite this, there are no validated biomarkers of neuroinflammation for use in clinical practice or clinical trials. Biomarkers of neuroinflammation could improve patient management, provide new therapeutic targets, and possibly help stratify clinical trial selection and monitoring. However, attempts to identify a singular cause of neuroinflammation have not been successful. Here, we performed multi-parameter flow cytometry to comprehensively assess 116 leukocyte populations and phenotypes from lymphocytes, monocytes, and granulocytes in a cohort of 80 ALS patients. We identified 32 leukocyte phenotypes that were altered in ALS patients compared to age and gender matched healthy volunteers (HV) that included phenotypes of both inflammation and immune suppression. Unsupervised hierarchical clustering and principle component analysis of ALS and HV immunophenotypes revealed two distinct immune profiles of ALS patients. ALS patients were clustered into a profile distinct from HVs primarily due to differences in a multiple T cell phenotypes, CD3+CD56+ T cells and HLA-DR on monocytes. Patients clustered into an abnormal immune profile were younger, more likely to have a familial form of the disease, and survived longer than those patients who clustered similarly with healthy volunteers (344 weeks versus 184 weeks; p = 0.012). The data set generated from this study establishes an extensive accounting of immunophenotypic changes readily suitable for biomarker validation studies. The extensive immune system changes measured in this study indicate that normal immune homeostatic mechanisms are disrupted in ALS patients, and that multiple immune states likely exist within a population of patients with ALS.

Peripheral immune biomarkers and neurodegenerative diseases: A prospective cohort study with 20 years of follow‐up

“…[30][31][32] For example, ALS patients were shown to have altered levels of CD4+, CD8+, and natural killer T cells in the peripheral blood compared to healthy controls, and such alterations were shown to be associated with the progression rate of the disease. 30,31,33 The present study did not, however, reveal different associations of specific cell types with the risk of ALS or different concentrations of specific cell types between ALS patients and individuals without ALS during the 20 years before ALS diagnosis. The fact that previous studies compared leukocyte concentrations among clinical patients with ALS to healthy volunteers, whereas the present study examined leukocyte concentrations long before diagnosis of ALS patients to randomly selected population controls, might have contributed to part of the contrasting results pattern.…”

“…Studies directed at mapping peripheral adaptive immune profiles in ALS and associating immune alterations to clinical disease phenotypes have been conducted . For example, ALS patients were shown to have altered levels of CD4+, CD8+, and natural killer T cells in the peripheral blood compared to healthy controls, and such alterations were shown to be associated with the progression rate of the disease . The present study did not, however, reveal different associations of specific cell types with the risk of ALS or different concentrations of specific cell types between ALS patients and individuals without ALS during the 20 years before ALS diagnosis.…”

The Peripheral Immune System and Amyotrophic Lateral Sclerosis

“…The total leukocyte count is elevated in patients with ALS, and correlates with progression of disease (52). The ratio of neutrophils to monocytes was also shown to be increased (53), as was the total number of granulocytes (54). A micro-array study further confirmed evidence for mild neutrophilia in ALS patients (55).…”

High neutrophil-to-lymphocyte ratio predicts short survival duration in amyotrophic lateral sclerosis

“…Motor neuron degeneration in ALS occurs both cell-autonomously within motor neurons and non-cell-autonomously involving non-neuronal cells such as astrocytes and microglia 4,5 . Interestingly, alterations in peripheral immune cells as well as glial cells in the central nervous system (CNS) have been reported in humans and mouse models of ALS [6][7][8][9][10][11] . Leukocyte alterations in easily accessible peripheral blood may therefore be useful disease biomarkers.…”