Superoxide-
hydrogen peroxide (S-HP), triggered by Val16Ala-SOD2 human polymorphism, may influence the risk of depression. Therefore, it is plausible that higher basal S-
anion levels and chronic inflammatory states associated with the VV-SOD2 genotype can negatively modulate the stress response associated with resilience in various species, from primitive species to humans. To test this hypothesis, Eisenia fetida earthworms were exposed for 24 h to 30 nM
rotenone, which causes
mitochondrial dysfunction by generating high S-
anion levels (known as the "VV-like phenotype"), and 10 μM
porphyrin, a SOD2-like compound, which generates elevated HP levels (known as the "AA-like phenotype"). The results suggested that both S-
anion and HP acted as signaling molecules, differentially altering the immune function and acute hydric stressful response. Although the AA-like phenotype improved the immune and stress response efficiencies, the VV-like phenotype showed a downregulated expression of the
toll-like receptor (EaTLR, JX898685) and
antimicrobial peptide (
AMP) (AF060552) genes, which triggered the impairment of encapsulation and earthworms extracellular trap (EET) processes used by earthworms to trap and destroy microorganisms. When exposed to adverse environments and dangerous hydric stress, VV-like earthworms exhibited an impulsive behavior and failed to quickly identify and migrate to a protected environment, unlike control earthworms and AA-like earthworms. All results corroborated that the S-
anion imbalance could concomitantly induce alterations in immune function and stress behavior related to earthworm survival. From a human perspective, this information may corroborate the potential specific role of
superoxide anion in the modulation of the stress response, resilience, and risk of depression.