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<p>Global warming elevates water temperatures, subjecting sturgeons, a cool-water fish species, to prolonged heat stress, particularly during summer months. This study investigated the effects of chronic heat stress on innate immune function and disease resistance in Siberian sturgeon (<i>Acipenser baerii</i>). Fish were acclimated stepwise from 21 to 26&#xa0;°C and maintained at 26&#xa0;°C for 21&#xa0;days, followed by an <i>Aeromonas hydrophila</i> (abbreviated <i>A. hydrophila</i>) challenge. Fish maintained at 21&#xa0;°C were used as the control group. Compared to the 21&#xa0;°C controls,sturgeons exposed to 26&#xa0;°C exhibited significantly reduced bacteridal activity, alternative complement hemolytic activity (ACH<sub>50</sub>), and myeloperoxidase (MPO) activity during heat exposure; in addition, following <i>A.hydeophila</i> challenge, the&#xa0;26&#xa0;°C group also showed significantly lower levels of ACH50, MPO, reactive oxygen species (ROS) production, and phagocyytic activity in peripheral blood leukocytes (PBLs). Serum immunoglobulin (IgM) and lysozyme levels fluctuated temporally but decreased markedly after bacterial infection in the 26&#xa0;°C group. In the post<i>-A. hydrophila</i> challenge, the 26&#xa0;°C group exhibited a significantly lower survival rate (25.93%) than the 21&#xa0;°C group (62.96%). Heat stressed sturgeons also displayed strong upregulation of pro-inflammatory cytokines including interleukin-1β (<i>IL-1β</i>), interleukin-6 (<i>IL-6</i>), and interleukin-8 (<i>IL-8</i>) in the spleen and head kidney after infection, while the expression of major histocompatibility complex class II β (<i>MHCIIβ</i>) was upregulated in the head kidney but downregulated in the liver. These results showed that chronic heat stress attenuates innate immunity in <i>Acipenser baerii</i> and exacerbates inflammatory dysregulation upon infection, ultimately weakening disease resistance. A water temperature of 25–26&#xa0;°C is commonly adopted in sturgeon aquaculture based on satisfactory short-time survival and growth performance. Nevertheless, our study suggests that under the experimental conditions, maintaining water temperatures below 26&#xa0;°C may be advantageous for Siberian sturgeon. At 26&#xa0;°C, innate immunity was significantly affected compared to the 21&#xa0;°C control.</p>

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Chronic heat stress attenuates innate immunity and increases susceptibility to Aeromonas hydrophila in Siberian sturgeon (Acipenser baerii)

  • 期刊论文

  • 发表日期：

    2026年3月27日

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  • Xiaowen Wang,
  • Huijuan Li,
  • Rong Zhang,
  • Lili Liu,
  • Wei Wang,
  • Hua Zhu

摘要

Global warming elevates water temperatures, subjecting sturgeons, a cool-water fish species, to prolonged heat stress, particularly during summer months. This study investigated the effects of chronic heat stress on innate immune function and disease resistance in Siberian sturgeon (Acipenser baerii). Fish were acclimated stepwise from 21 to 26 °C and maintained at 26 °C for 21 days, followed by an Aeromonas hydrophila (abbreviated A. hydrophila) challenge. Fish maintained at 21 °C were used as the control group. Compared to the 21 °C controls,sturgeons exposed to 26 °C exhibited significantly reduced bacteridal activity, alternative complement hemolytic activity (ACH50), and myeloperoxidase (MPO) activity during heat exposure; in addition, following A.hydeophila challenge, the 26 °C group also showed significantly lower levels of ACH50, MPO, reactive oxygen species (ROS) production, and phagocyytic activity in peripheral blood leukocytes (PBLs). Serum immunoglobulin (IgM) and lysozyme levels fluctuated temporally but decreased markedly after bacterial infection in the 26 °C group. In the post-A. hydrophila challenge, the 26 °C group exhibited a significantly lower survival rate (25.93%) than the 21 °C group (62.96%). Heat stressed sturgeons also displayed strong upregulation of pro-inflammatory cytokines including interleukin-1β (IL-1β), interleukin-6 (IL-6), and interleukin-8 (IL-8) in the spleen and head kidney after infection, while the expression of major histocompatibility complex class II β (MHCIIβ) was upregulated in the head kidney but downregulated in the liver. These results showed that chronic heat stress attenuates innate immunity in Acipenser baerii and exacerbates inflammatory dysregulation upon infection, ultimately weakening disease resistance. A water temperature of 25–26 °C is commonly adopted in sturgeon aquaculture based on satisfactory short-time survival and growth performance. Nevertheless, our study suggests that under the experimental conditions, maintaining water temperatures below 26 °C may be advantageous for Siberian sturgeon. At 26 °C, innate immunity was significantly affected compared to the 21 °C control.