Short-Term Thermal Stress Affects Immune Cell Features in the Sea Urchin Paracentrotus lividus

Abstract

Due to global warming, animals are experiencing heat stress (HS), affecting many organic functions and species’ survival. In this line, some characteristics of immune cells in sea urchins subjected to short-term HS were evaluated. Paracentrotus lividus adult females were randomly divided into three groups and housed in tanks at 17 °C. In two of these tanks, the temperatures were gradually increased up to 23 and 28 °C. Celomatic fluid was collected after 3 and 7 days. The coelomocytes were morphologically typed and evaluated for their mitochondrial membrane potential (MMP), lipoperoxidation extent (LPO), and hydrogen peroxide content (H2O2). Respiratory burst was induced by treatment with phorbol 12-myristate 13-acetate (PMA). HS caused a significant change in the coelomocytes’ type distribution. MMP increased in the 23 °C-group and decreased in the 28 °C-group at both 3 and 7 days. LPO only increased in the 28 °C-group at 7 days. H2O2 progressively decreased together with the temperature increase. Respiratory burst was detected in all groups, but it was higher in the 17 °C group. In conclusion, the increase in temperature above the comfort zone for this animal species affects their immune cells with possible impairment of their functions.

Immune and Reproductive Biomarkers in Female Sea Urchins Paracentrotus lividus under Heat Stress

“…JC1 (5,5′,6,6′-Tetrachloro-1,1′,3,3′-tetraethyl-imidacarbocyanine iodide) (Life Technologies) was used to assess MMP, as previously reported [ 16 , 21 , 38 ]. In brief, 7.7 µM JC1 was added to 200 µL FNSW containing either 500 eggs or 4 × 10 5 coelomocytes.…”

“…MMP was expressed as the ratio between the absolute fluorescence intensity emission peaks at ~595 (F 0 B) and ~535 (F 0 A) nm wavelengths. A positive control was prepared by treating pre-loaded JC-1 eggs with 2 µM CCCP (carbonyl cyanide 3-chlorophenylhydrazone) [ 21 ].…”

“…as fluorescence emission peak intensity at ~525 nm wavelength setting the excitation wavelength at 488 nm. Positive controls were prepared by treating control coelomocytes and eggs with 25 μM hydrogen peroxide before staining [ 21 ].…”

“…The coelomocyte number and their cellular activity represent a good indicator of the immunological status of an organism and its ability to defend itself from pathogens [ 20 ]. Moreover, the immune cells of P. lividus have been proven to be a good bioindicator of abiotic stress such as seawater temperature increase [ 21 ]; thereby, they are a useful tool for marine global change research [ 22 ].…”

Marine diseases and the Anthropocene: Understanding microbial pathogenesis in a rapidly changing world

“…The increased exposure of an organism to environmental stressors, either in intensity or frequency, is generally regarded to reduce the ability of that organism to respond to a pathogen. For example, thermal stress associated with extreme heatwaves can dampen molecular and phenotypic immune processes in bivalves, echinoderms and macroalgae (Campbell et al., 2011 ; Masanja et al., 2023 ; Murano et al., 2023 ), while exposure to pollutants such as ammonia or heavy metals can compromise the integrity of the shrimp intestinal mucosa rendering it susceptible to infection (Duan et al., 2018 , 2021 ). However, there remains a paucity of detailed molecular knowledge regarding the immune physiology of many marine organisms and hence the mechanisms by which stress may render them susceptible to infection are not known.…”