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Phenylbutyrate counteracts Shigella mediated downregulation of cathelicidin in rabbit lung and intestinal epithelia: a potential therapeutic strategy.

Sarker P, Ahmed S, Tiash S, Rekha RS, Stromberg R, Andersson J, Bergman P, Gudmundsson GH, Agerberth B, Raqib R - PLoS ONE (2011)

Bottom Line: Interestingly, reduced expression of CAP-18 was also noticed in the epithelia of lung and trachea, indicating a systemic effect of the infection.Oral treatment with PB resulted in reduced clinical illness and upregulation of CAP-18 in the epithelium of rectum.The drug effect is suggested to be systemic as intravenous administration of NaB could also upregulate CAP-18 in the epithelia of lung, rectum and colon.

View Article: PubMed Central - PubMed

Affiliation: International Centre for Diarrheal Disease Research, Bangladesh, Dhaka, Bangladesh.

ABSTRACT

Background: Cathelicidins and defensins are endogenous antimicrobial peptides (AMPs) that are downregulated in the mucosal epithelia of the large intestine in shigellosis. Oral treatment of Shigella infected rabbits with sodium butyrate (NaB) reduces clinical severity and counteracts the downregulation of cathelicidin (CAP-18) in the large intestinal epithelia.

Aims: To develop novel regimen for treating infectious diseases by inducing innate immunity, we selected sodium 4-phenylbutyrate (PB), a registered drug for a metabolic disorder as a potential therapeutic candidate in a rabbit model of shigellosis. Since acute respiratory infections often cause secondary complications during shigellosis, the systemic effect of PB and NaB on CAP-18 expression in respiratory epithelia was also evaluated.

Methods: The readouts were clinical outcomes, CAP-18 expression in mucosa of colon, rectum, lung and trachea (immunohistochemistry and real-time PCR) and release of the CAP-18 peptide/protein in stool (Western blot).

Principal findings: Significant downregulation of CAP-18 expression in the epithelia of rectum and colon, the site of Shigella infection was confirmed. Interestingly, reduced expression of CAP-18 was also noticed in the epithelia of lung and trachea, indicating a systemic effect of the infection. This suggests a causative link to acute respiratory infections during shigellosis. Oral treatment with PB resulted in reduced clinical illness and upregulation of CAP-18 in the epithelium of rectum. Both PB and NaB counteracted the downregulation of CAP-18 in lung epithelium. The drug effect is suggested to be systemic as intravenous administration of NaB could also upregulate CAP-18 in the epithelia of lung, rectum and colon.

Conclusion: Our results suggest that PB has treatment potential in human shigellosis. Enhancement of CAP-18 in the mucosal epithelia of the respiratory tract by PB or NaB is a novel discovery. This could mediate protection from secondary respiratory infections that frequently are the lethal causes in dysentery.

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CAP-18 immunoreactivity in various mucosal epithelia of healthy, infected, infected and treated with PB/NaB rabbits.Mucosal sections of rectum, distal colon, lung and trachea from healthy rabbits (n = 5), Shigella-infected rabbits (n = 5) and infected rabbits treated orally with NaB (n = 5) or PB (n = 5) were stained with CAP-18 specific antibody. Quantification of immunoreactive area relative to the total cell area of the epithelia was done by a computerized image-analysis technique, and the results are expressed as ACIA score, i.e., the total positively stained area×total mean intensity (1–256 levels/per pixel) of positive area divided by total cell area (See materials and methods). Data are given as mean ± standard deviation. One-way ANOVA (or ANOVA on ranks for data that were not normally distributed as assessed by Q-Q plot and histogram) was used in comparing different groups of rabbits. The differences are significant when P<0.05; ‡significant when compared to healthy, *significant when compared to infected. PB: Sodium 4-phenylbutyrate, NaB: Sodium butyrate.
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pone-0020637-g004: CAP-18 immunoreactivity in various mucosal epithelia of healthy, infected, infected and treated with PB/NaB rabbits.Mucosal sections of rectum, distal colon, lung and trachea from healthy rabbits (n = 5), Shigella-infected rabbits (n = 5) and infected rabbits treated orally with NaB (n = 5) or PB (n = 5) were stained with CAP-18 specific antibody. Quantification of immunoreactive area relative to the total cell area of the epithelia was done by a computerized image-analysis technique, and the results are expressed as ACIA score, i.e., the total positively stained area×total mean intensity (1–256 levels/per pixel) of positive area divided by total cell area (See materials and methods). Data are given as mean ± standard deviation. One-way ANOVA (or ANOVA on ranks for data that were not normally distributed as assessed by Q-Q plot and histogram) was used in comparing different groups of rabbits. The differences are significant when P<0.05; ‡significant when compared to healthy, *significant when compared to infected. PB: Sodium 4-phenylbutyrate, NaB: Sodium butyrate.

Mentions: Immunohistochemical analyses (Fig. 3 and 4) revealed significant downregulation of CAP-18 peptide/protein after Shigella infection in the epithelia of rectum (p = 0.008) and distal colon (p≤0.001) compared to healthy rabbits. This is in line with our previous result [11]. Interestingly, we also detected a significant downregulation of epithelial CAP-18 in the lung (p = 0.001) and trachea (p = 0.016) after Shigella infection compared to healthy rabbits. No obvious changes in CAP-18 peptide/protein expression were observed in the non-epithelial region of the organs investigated (Fig. 3).


Phenylbutyrate counteracts Shigella mediated downregulation of cathelicidin in rabbit lung and intestinal epithelia: a potential therapeutic strategy.

Sarker P, Ahmed S, Tiash S, Rekha RS, Stromberg R, Andersson J, Bergman P, Gudmundsson GH, Agerberth B, Raqib R - PLoS ONE (2011)

CAP-18 immunoreactivity in various mucosal epithelia of healthy, infected, infected and treated with PB/NaB rabbits.Mucosal sections of rectum, distal colon, lung and trachea from healthy rabbits (n = 5), Shigella-infected rabbits (n = 5) and infected rabbits treated orally with NaB (n = 5) or PB (n = 5) were stained with CAP-18 specific antibody. Quantification of immunoreactive area relative to the total cell area of the epithelia was done by a computerized image-analysis technique, and the results are expressed as ACIA score, i.e., the total positively stained area×total mean intensity (1–256 levels/per pixel) of positive area divided by total cell area (See materials and methods). Data are given as mean ± standard deviation. One-way ANOVA (or ANOVA on ranks for data that were not normally distributed as assessed by Q-Q plot and histogram) was used in comparing different groups of rabbits. The differences are significant when P<0.05; ‡significant when compared to healthy, *significant when compared to infected. PB: Sodium 4-phenylbutyrate, NaB: Sodium butyrate.
© Copyright Policy
Related In: Results  -  Collection

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getmorefigures.php?uid=PMC3108617&req=5

pone-0020637-g004: CAP-18 immunoreactivity in various mucosal epithelia of healthy, infected, infected and treated with PB/NaB rabbits.Mucosal sections of rectum, distal colon, lung and trachea from healthy rabbits (n = 5), Shigella-infected rabbits (n = 5) and infected rabbits treated orally with NaB (n = 5) or PB (n = 5) were stained with CAP-18 specific antibody. Quantification of immunoreactive area relative to the total cell area of the epithelia was done by a computerized image-analysis technique, and the results are expressed as ACIA score, i.e., the total positively stained area×total mean intensity (1–256 levels/per pixel) of positive area divided by total cell area (See materials and methods). Data are given as mean ± standard deviation. One-way ANOVA (or ANOVA on ranks for data that were not normally distributed as assessed by Q-Q plot and histogram) was used in comparing different groups of rabbits. The differences are significant when P<0.05; ‡significant when compared to healthy, *significant when compared to infected. PB: Sodium 4-phenylbutyrate, NaB: Sodium butyrate.
Mentions: Immunohistochemical analyses (Fig. 3 and 4) revealed significant downregulation of CAP-18 peptide/protein after Shigella infection in the epithelia of rectum (p = 0.008) and distal colon (p≤0.001) compared to healthy rabbits. This is in line with our previous result [11]. Interestingly, we also detected a significant downregulation of epithelial CAP-18 in the lung (p = 0.001) and trachea (p = 0.016) after Shigella infection compared to healthy rabbits. No obvious changes in CAP-18 peptide/protein expression were observed in the non-epithelial region of the organs investigated (Fig. 3).

Bottom Line: Interestingly, reduced expression of CAP-18 was also noticed in the epithelia of lung and trachea, indicating a systemic effect of the infection.Oral treatment with PB resulted in reduced clinical illness and upregulation of CAP-18 in the epithelium of rectum.The drug effect is suggested to be systemic as intravenous administration of NaB could also upregulate CAP-18 in the epithelia of lung, rectum and colon.

View Article: PubMed Central - PubMed

Affiliation: International Centre for Diarrheal Disease Research, Bangladesh, Dhaka, Bangladesh.

ABSTRACT

Background: Cathelicidins and defensins are endogenous antimicrobial peptides (AMPs) that are downregulated in the mucosal epithelia of the large intestine in shigellosis. Oral treatment of Shigella infected rabbits with sodium butyrate (NaB) reduces clinical severity and counteracts the downregulation of cathelicidin (CAP-18) in the large intestinal epithelia.

Aims: To develop novel regimen for treating infectious diseases by inducing innate immunity, we selected sodium 4-phenylbutyrate (PB), a registered drug for a metabolic disorder as a potential therapeutic candidate in a rabbit model of shigellosis. Since acute respiratory infections often cause secondary complications during shigellosis, the systemic effect of PB and NaB on CAP-18 expression in respiratory epithelia was also evaluated.

Methods: The readouts were clinical outcomes, CAP-18 expression in mucosa of colon, rectum, lung and trachea (immunohistochemistry and real-time PCR) and release of the CAP-18 peptide/protein in stool (Western blot).

Principal findings: Significant downregulation of CAP-18 expression in the epithelia of rectum and colon, the site of Shigella infection was confirmed. Interestingly, reduced expression of CAP-18 was also noticed in the epithelia of lung and trachea, indicating a systemic effect of the infection. This suggests a causative link to acute respiratory infections during shigellosis. Oral treatment with PB resulted in reduced clinical illness and upregulation of CAP-18 in the epithelium of rectum. Both PB and NaB counteracted the downregulation of CAP-18 in lung epithelium. The drug effect is suggested to be systemic as intravenous administration of NaB could also upregulate CAP-18 in the epithelia of lung, rectum and colon.

Conclusion: Our results suggest that PB has treatment potential in human shigellosis. Enhancement of CAP-18 in the mucosal epithelia of the respiratory tract by PB or NaB is a novel discovery. This could mediate protection from secondary respiratory infections that frequently are the lethal causes in dysentery.

Show MeSH
Related in: MedlinePlus