Immunomodulatory Effects of Polysaccharides from Porphyra haitanensis in Hydrocortisone-Induced Immunocompromised Mice

This study investigated the immunomodulatory effect of polysaccharides from <i>Porphyra haitanensis</i> (PHP) using a hydrocortisone-induced immunosuppressive model. Immunocompromised mice were treated with varying doses of PHP and the effects on macroscopic indicators, macrophage function, and both cellular and humoral immune functions were comprehensively assessed. The results showed that PHP significantly increased the body weight and indexes of the spleen and thymus, improved the disorder of blood cell populations, and enhanced macrophage activity. Furthermore, PHP improved T lymphocyte subtypes and differentiation and regulated the CD4⁺/CD8⁺ ratio. PHP also promoted the expression of T-Bet and GATA-3 while maintaining immune homeostasis, alongside promoting cytokine secretion. PHP facilitated the production of antibody-generating cells, serum hemolysin, and antibodies. Western blot results revealed that PHP activates the TLR4/NF-κB pathway. These findings suggested that PHP exerts immunomodulatory effects on both the innate and adaptive immune systems.