(C) Densitometric anaysis of the blots showing the ratios of Beclin-1 and LC3-II to β-actin in Figure 10A. * and ** denote p < 0.05 and p < 0.01 respectively in Figure 10B and 10C (vs. control); # and ## denote p < 0.05 and p < 0.01 respectively in Figure 10B and 10C (vs. LPS). (D) Graph represents percentage of remaining E.coli at different time points in each group treated as described above. Data are mean values ± SD (n ≥3). * and ** denote p < 0.05 and p < 0.01 respectively (LPS vs. control); # and ## denote p < 0.05 and
p < 0.01 respectively (LPS + TLR4 siRNA vs. Selleck INK1197 LPS). Discussion Although aberrant autophagy is observed in many bacterial infectious diseases, the role of autophagy in PD-related peritonitis remains unknown. Our study has investigated the role of autophagy in PMCs against intracellular E.coli. We demonstrated that LPS could induce autophagy in HMrSV5 cells. LPS enhanced the intracellular bactericidal activity of HMrSV5 cells and promoted the co-localization of E.coli (K12-strain) with autophagosomes. Moreover, treatment with microtubule-disrupting agents such as 3-MA or Wm or Beclin-1 siRNA, markedly attenuated the A-1155463 nmr intracellular bactericidal activity of HMrSV5 cells and the co-localization of E. coli with autophagosomes induced by LPS treatment. Furthermore, knockdown of TLR4 vanished LPS-induced autophagy and bactericidal activity. These data collectively suggest
that autophagy activated by LPS via TLR4 represents an innate defense mechanism for inhibiting intracellular E. Glutathione peroxidase coli replication. Autophagy is a process traditionally known to contribute to cellular cleaning
via the removal of intracellular components in lysosomes . Recently, our colleagues reported that LPS stimulation led to autophagy in cultured peritoneal mesothelial cells . In keeping with their reports, our data revealed that LPS induced accumulation of LC3-II in a time- and dose-dependent manner in HMrSV5 cells, as indicated by an increased aggregation of GFP-LC3 puncta and a higher number of autophagosome-like MDC-labeled vacuoles. Furthermore, HMrSV5 cells pretreated with 3-MA, Wm or Beclin-1 siRNA displayed defective autophagy induction in response to LPS. These results indicate that LPS is a general stimulant of autophagic activity in PMCs. In addition, our study showed the viability of LPS-treated cells had no significant difference compared to the control group. It has been demonstrated that exposure of PMCs to LPS resulted first in autophagy and later, apoptosis . Apoptosis was only observed under higher concentrations of LPS (5 to 10 μg/ml) exposure for 48 hours in HMrSV5 cells . We could not detect apoptosis in HMrSV5 cells following the incubation with lower doses of LPS (0-5 μg/ml) for shorter time periods (0-24 h) in present study, which was consistent with the previous ICG-001 mouse report .