Doxycycline-Induced Apoptosis in Brucella suis S2-Infected HMC3 Cells via Calreticulin Suppression and Activation of the IRE1/Caspase-3 Signaling Pathway

  • Infect Drug Resist. 2025 Apr 23:18:2005-2020. doi: 10.2147/IDR.S507193.
Zhao Wang  1 ,  Juan Yang  2 ,  Deng-Er Zhang  3 ,  Xia Qiao  4 ,  Shu-Long Yang  5 ,  Zhen-Hai Wang  2  6 ,  Qian Yang  1
Affiliations
  • 1. Department of Experimental Surgery, The Second Affiliated Hospital of Air Force Medical University, Xi'an, People's Republic of China.
  • 2. Neurology Center, The General Hospital of Ningxia Medical University, Yinchuan, People's Republic of China.
  • 3. The First Clinical Medical School, Ningxia Medical University, Yinchuan, People's Republic of China.
  • 4. Institute of Medical Science, The General Hospital of Ningxia Medical University, Yinchuan, People's Republic of China.
  • 5. Department of Orthopedics, The People's Hospital of Wuhai, Wuhai, People's Republic of China.
  • 6. Diagnosis and Treatment Engineering Technology Research Center of Nervous System Diseases of Ningxia Hui Autonomous Region, The General Hospital of Ningxia Medical University, Yinchuan, People's Republic of China.
PMID: 40290405 DOI: 10.2147/IDR.S507193
Abstract

Objective: This study aims to elucidate the apoptotic mechanism induced by doxycycline (Dox) in human microglial clone 3 (HMC3) cells infected with the Brucella suis S2 strain, with the goal of identifying potential therapeutic targets for neurobrucellosis.

Methods: The expression of calreticulin (CALR) at both the protein and mRNA levels was assessed using Western blot analysis and reverse transcription-quantitative polymerase chain reaction (RT-qPCR), respectively, following exposure of HMC3 cells to varying concentrations and treatment durations of Dox. Apoptosis rates were determined via flow cytometry. To investigate the involvement of the inositol-requiring enzyme-1 (IRE1)/Caspase-12/Caspase-3 pathway, CALR protein levels were analyzed through Western blot after a 12-hour treatment with 160 μM Dox. Endoplasmic reticulum (ER) stress and intracellular calcium (Ca²⁺) concentrations were evaluated using fluorescent staining. The same parameters were measured in B. suis S2-infected HMC3 cells following treatment with 160 μM Dox.

Results: Treatment with 160 μM Dox for 12 hours resulted in a reduction in CALR protein levels and the induction of Apoptosis in HMC3 cells. The downregulation of CALR activated the IRE1/Caspase-12/Caspase-3 signaling pathway, leading to Apoptosis. Similar apoptotic effects were observed in B. suis S2-infected HMC3 cells following Dox treatment.

Conclusion: Dox promotes Apoptosis in B. suis S2-infected HMC3 cells by suppressing CALR expression and activating the IRE1/Caspase-12/Caspase-3 signaling pathway. These findings suggest that CALR regulation may serve as a potential therapeutic target for neurobrucellosis.

Keywords
Brucella suis S2 strain; HMC3; IRE1/Caspase-12/Caspase-3 pathway; apoptosis; doxycycline.
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