Associations of postprandial ghrelin, liver-expressed antimicrobial peptide 2 and leptin levels with body composition, disease progression and survival in patients with amyotrophic lateral sclerosis

Abstract

Background and purpose: Loss of appetite contributes to weight loss and faster disease progression in amyotrophic lateral sclerosis (ALS). Impairment of appetite control in ALS may include altered production or action of orexigenic (i.e., ghrelin) and anorexigenic (i.e., liver-expressed antimicrobial peptide 2 [LEAP2] and leptin) hormones. We aimed to determine if postprandial circulating ghrelin levels, LEAP2 levels, LEAP2:ghrelin molar ratio and leptin levels differ in ALS patients compared to non-neurodegenerative disease controls, and whether they are associated with disease progression and body composition.

Methods: In this prospective natural history study, we assessed postprandial plasma levels of ghrelin, LEAP2 and leptin in patients with ALS (cases; n = 46) and controls (controls; n = 43). For cases, measures were compared to changes in body weight, body composition and clinical outcomes.

Results: Postprandial ghrelin level was decreased by 52% in cases compared to controls (p = 0.013). LEAP2:ghrelin molar ratio was increased by 249% (p = 0.009), suggesting greater ghrelin resistance. Patients with lower LEAP2:ghrelin tended to have better functional capacity at assessment, as inferred by the ALS Functional Rating Scale-Revised (τ = -0.179, p = 0.086). Furthermore, ghrelin and LEAP2:ghrelin molar ratio correlated with diagnostic delay (ghrelin, τ = 0.223, p = 0.029; LEAP2:ghrelin, τ = -0.213, p = 0.037). Baseline ghrelin level, LEAP2 level, LEAP2:ghrelin ratio and leptin level were, however, not predictive of change in functional capacity during follow-up. Also, patients with higher postprandial ghrelin levels (hazard ratio [HR] 1.375, p = 0.048), and lower LEAP2:ghelin ratios (HR 0.828, p = 0.051) had an increased risk of earlier death.

Conclusions: Reduced postprandial ghrelin levels, coupled with increased LEAP2:ghrelin molar ratios, suggests a loss of ghrelin action in patients with ALS. Given ghrelin's actions on appetite, metabolism and neuroprotection, reduced ghrelin and greater ghrelin resistance could contribute to impaired capacity to tolerate the physiological impact of disease. Comprehensive studies are needed to explain how ghrelin and LEAP2 contribute to body weight regulation and disease progression in ALS.

Keywords: LEAP2; amyotrophic lateral sclerosis; disease progression; functional decline; ghrelin; leptin.