Protein signatures of aging in the hemolymph of marbled crayfish: Insights into crustacean immune aging

Aging is accompanied by progressive physiological declines in body functions. However, the molecular mechanisms of aging remain poorly understood in decapod crustaceans, a diverse group of invertebrates. We investigated age-related differences in the hemolymph proteomes of marbled crayfish using label-free protein quantification (LC-MS/MS), applying a significance threshold of p < 0.05 and a fold change >2 to elucidate molecular mechanisms underpinning aging. Two groups including young (n = 6) and old (n = 7) crayfish were used. Results showed a downregulation of superoxide dismutase in the hemolymph of older individuals. At the same time, glutathione peroxidase and transketolase were upregulated, which may reflect age-dependent changes in oxidative stress regulation and potential compensatory responses. Aging crayfish exhibited changes in levels of the ProPO system and phagocytosis-related proteins that suggest a possible shift from melanization to phagocytosis in the aging immune system. Additionally, the lower levels of some other immune-related proteins in the old individuals may be consistent with a decline in the crayfish immune system with age. Proteins associated with wound healing and regeneration were higher in young individuals, which may suggest an age-based decline in regenerative capacity. Cytoskeletal and extracellular matrix proteins were upregulated in older crayfish, which could potentially influence immune cell functions. Age-related alterations in the quantities of vitellogenins, hemocyanins, and metabolic enzymes maybe associated with changes in reproductive investment, respiratory capacity, and energy metabolism. Together, these findings highlight the complex molecular basis by which aging reshapes the hemolymph composition and alters immune system characteristics in an invertebrate, revealing molecular signatures that may represent aging mechanisms. Data are available via ProteomeXchange with identifier PXD065434.