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Published on: March 18, 2014
Effects of Lactobacillus casei on Pseudomonas aeruginosa infection in normal and dexamethasone-treated mice
Abstract:
A single intraperitoneal injection of Lactobacillus casei YIT 0003 into normal or dexamethasone-treated mice led to nonspecific resistance against intraperitoneal challenge with lethal doses of Pseudomonas aeruginosa PAO 3047. The enhanced resistance was retained for 14 days (P less than 0.05) after injection with living L. casei. In contrast, the statistically significant duration of the enhanced resistance in mice treated intraperitoneally with living L. acidophilus YIT 0075 was only 5 days. The in vivo killing activity of peritoneal exudate cells (PECs) against P. aeruginosa 5 and 7 days after intraperitoneal injection of living L. casei was significantly higher than in the case of PECs elicited by L. acidophilus. In the case of intravenous injection of heat-killed L. casei before intraperitoneal challenge with P. aeruginosa, there were no survivors in the late period after administration of L. casei. A high correlation existed between the patterns of in vivo killing of P. aeruginosa by PECs and survival rate of mice injected intravenously with heat-killed L. casei. The reduced in vivo killing activity of PECs from dexamethasone-treated mice against P. aeruginosa infection was also augmented by the intraperitoneal injection of heat-killed L. casei. These results indicate that L. casei possesses a resistance-enhancing capacity against P. aeruginosa infection in vivo. Differences in the duration of the enhanced resistance caused by L. casei and by L. acidophilus may be due to differences in chemical composition and/or physicochemical properties of the cell walls of the two kinds of bacteria.
Insights
Lactobacillus casei enhances resistance against Pseudomonas aeruginosa infection in mice for up to 14 days. This probiotic effect, mediated by immune cells, offers a potential strategy for combating bacterial infections.
Area of Science:
- Immunology
- Microbiology
- Probiotics
Background:
- Probiotics, such as Lactobacillus species, are known to modulate the immune system.
- Pseudomonas aeruginosa is an opportunistic pathogen that can cause severe infections.
Purpose of the Study:
- To investigate the resistance-enhancing capacity of Lactobacillus casei against Pseudomonas aeruginosa infection in mice.
- To compare the duration and efficacy of resistance induced by Lactobacillus casei and Lactobacillus acidophilus.
Main Methods:
- Mice were injected intraperitoneally with living Lactobacillus casei or Lactobacillus acidophilus.
- Peritoneal exudate cells (PECs) were collected and their in vivo killing activity against Pseudomonas aeruginosa was assessed.
- Survival rates and the effect of heat-killed bacteria were evaluated.
Main Results:
- Lactobacillus casei conferred significant resistance against Pseudomonas aeruginosa for 14 days, while Lactobacillus acidophilus provided resistance for only 5 days.
- Lactobacillus casei significantly enhanced the in vivo killing activity of PECs against Pseudomonas aeruginosa.
- Heat-killed Lactobacillus casei also augmented the immune response in dexamethasone-treated mice.
Conclusions:
- Lactobacillus casei possesses a notable resistance-enhancing capacity against Pseudomonas aeruginosa infection in vivo.
- Differences in resistance duration may be attributed to variations in the cell wall composition of different Lactobacillus species.
- Lactobacillus casei represents a promising probiotic for enhancing host defense against bacterial pathogens.
