Haemophilus parasuis infection in 3D4/21 cells induces autophagy through the AMPK pathway

Abstract

Haemophilus parasuis (H. parasuis) is a common commensal in the upper respiratory tract of pigs, but causes Glässer's disease in stress conditions. To date, many studies focused on the immune evasion and virulence of H. parasuis; very few have focused on the role autophagy played in H. parasuis infection, particularly in porcine alveolar macrophages (PAMs). In this study, a PAM cell line, 3D4/21 cells were used to study the role of autophagy in H. parasuis infection. 3D4/21 cells tandemly expressing GFP, mCherry, and LC3 were infected with H. parasuis serovar 5 (Hps5). Western blot analysis and confocal and transmission electron microscopy showed that H. parasuis infection effectively induces autophagy. Using Hps strains of varying virulence (Hps4, Hps5, and Hps7) and UV-inactivated Hps5, we demonstrated that autophagy is associated with the internalisation of living virulent strains into cells. In 3D4/21 cells pretreated with rapamycin and 3-MA then infected by Hps4, Hps5, and Hps7, we demonstrated that autophagy affects invasion of H. parasuis in cells. AMPK signal results showed that Hps5 infection can upregulate the phosphorylation level of AMPK, which is consistent with the autophagy development. 3D4/21 cells pretreated with AICAR or Compound C then infected by Hps5 revealed that the autophagy induced by Hps5 infection is associated with the AMPK pathway. Our study contributes to the theoretical basis for the study of H. parasuis pathogenesis and development of novel drugs target for prevention Glässer's disease.

Macrophage Mitochondrial Biogenesis and Metabolic Reprogramming Induced by Leishmania donovani Require Lipophosphoglycan and Type I Interferon Signaling

“…Similar findings were previously reported for L. infantum -infected BMM ( 9 ). This contrasts with several pathogens, including Mycobacterium tuberculosis , Haemophilus parasuis , Staphylococcus aureus , and Plasmodium falciparum , whose survival and replication were impaired by AICAR pretreatment of their host cells ( 88 – 90 ). Strikingly, the avirulent LPG-defective L. donovani Δ lpg1 mutant, which does not induce mitochondrial biogenesis, survived in BMM pretreated with AICAR.…”

Incomplete autophagy promotes the proliferation of Mycoplasma hyopneumoniae through the JNK and Akt pathways in porcine alveolar macrophages

“…Some studies have examined the signalling pathway of autophagy induced by other porcine respiratory pathogenic bacteria. For example, in an in vitro study, Glaesserella parasuis ( Haemophilus parasuis ) was found to induce autophagy in 3D4/21 cells via the AMPK signalling pathway [ 37 ]. Some Mycoplasma species induce autophagy via the MAPK signalling pathway.…”

Characterization and protective activity of monoclonal antibodies directed against Fe (3+) ABC transporter substrate-binding protein of Glaesserella parasuis

“…Sterile coverslips were placed into the bottom of 24-well plates and then inoculated with 3D4/21 cells (60% cell well confluency). Each cell well was inoculated with G. parasuis -5 at a dose of 400 MOI, and the cell plate was centrifuged at 800 × g for 10 min and then incubated at 37 °C for 1 h [ 13 ]. After washing 3 times with PBS, the infected cells on the coverslip were fixed with 4% formaldehyde.…”