Limits...
Heme oxygenase-1 promotes granuloma development and protects against dissemination of mycobacteria.

Regev D, Surolia R, Karki S, Zolak J, Montes-Worboys A, Oliva O, Guroji P, Saini V, Steyn AJ, Agarwal A, Antony VB - Lab. Invest. (2012)

Bottom Line: Inhibition of HO by zinc protoporphyrin-IX led to inhibition of MCP-1 and increased expression of CCR2, its cognate receptor.Mycobacteria were found only inside defined granulomas but not outside granuloma in the lungs of HO-1⁺/⁺ mice.Higher MCP-1 levels were found in bronchoalveolar lavage fluid of M. avium infected HO-1(-/-) mice and CCR2 expression was higher in HO-1⁻/⁻ alveolar macrophages when compared with HO-1⁺/⁺ mice.

View Article: PubMed Central - PubMed

Affiliation: Division of Pulmonary, Critical Care and Sleep Medicine, College of Medicine, University of Florida, Gainesville, FL, USA.

ABSTRACT
Non-tuberculous mycobacterial (NTM) infections occur in both immunocompromised and immunocompetent hosts and are an increasingly recognized cause of morbidity and mortality. The hallmark of pulmonary mycobacterial infections is the formation of granuloma in the lung. Our study focuses on the role of heme oxygenase-1 (HO-1), a cytoprotective enzyme, in the regulation of granuloma development and maturation following infection with Mycobacterium avium. We examined the role of HO-1 in regulating monocyte chemoattractant protein-1 (MCP-1) and chemokine receptor 2 (CCR2), two molecules involved in monocyte-macrophage cell trafficking after infection. We showed that RAW 264.7 mouse monocytes exposed to M. avium expressed HO-1 and MCP-1. Inhibition of HO by zinc protoporphyrin-IX led to inhibition of MCP-1 and increased expression of CCR2, its cognate receptor. HO-1⁻/⁻ mice did not develop organized granuloma in their lungs, had higher lung colony forming unit of M. avium when infected with intratracheal M. avium, and had loose collections of inflammatory cells in the lung parenchyma. Mycobacteria were found only inside defined granulomas but not outside granuloma in the lungs of HO-1⁺/⁺ mice. In HO-1⁻/⁻ mice, mycobacteria were also found in the liver and spleen and showed increased mortality. Peripheral blood monocytes isolated from GFP⁺ mice and given intravenously to HO-1⁺/⁺ mice localized into tight granulomas, while in HO-1⁻/⁻ mice they remained diffusely scattered in areas of parenchymal inflammation. Higher MCP-1 levels were found in bronchoalveolar lavage fluid of M. avium infected HO-1(-/-) mice and CCR2 expression was higher in HO-1⁻/⁻ alveolar macrophages when compared with HO-1⁺/⁺ mice. CCR2 expression localized to granuloma in HO-1⁺/⁺ mice but not in the HO-1⁻/⁻ mice. These findings strongly suggest that HO-1 plays a protective role in the control of M. avium infection.

Show MeSH

Related in: MedlinePlus

Mouse lung tissue showing differential granuloma formation in HO-1+/+ and HO-1-/- mice after 6 month M. avium infection or saline inoculationMouse lungs were harvested following 6 month M. avium inoculation and visually inspected for presence of granuloma. Alternatively, lung tissue was fixed and stained with H&E to confirm granuloma formation. (A) Absence of granuloma in HO-1+/+ control lung. (B) Presence of organized, mature granulomas in HO-1+/+ lung inoculated with M. avium for 6 months. (C) Absence of granuloma in HO-1-/- control lung. (D) Diffuse infection and unorganized granuloma formation in HO-1-/- lung inoculated with M. avium for 6 months. (E) 200× H&E stain of normal tissue from HO-1+/+ control lung. (F) 200× H&E stain showing organized granuloma formation in HO-1+/+ lung inoculated with M. avium for 6 months. (G) 200× H&E stain of normal tissue from HO-1-/- control lung. (H) 200× H&E stain of diffuse infection and dysfunctional granuloma formation in HO-1-/- lung inoculated with M. avium for 6 months. Five mice were included in each treatment group (lungs are not shown to scale).
© Copyright Policy
Related In: Results  -  Collection

License
getmorefigures.php?uid=PMC4017357&req=5

Figure 3: Mouse lung tissue showing differential granuloma formation in HO-1+/+ and HO-1-/- mice after 6 month M. avium infection or saline inoculationMouse lungs were harvested following 6 month M. avium inoculation and visually inspected for presence of granuloma. Alternatively, lung tissue was fixed and stained with H&E to confirm granuloma formation. (A) Absence of granuloma in HO-1+/+ control lung. (B) Presence of organized, mature granulomas in HO-1+/+ lung inoculated with M. avium for 6 months. (C) Absence of granuloma in HO-1-/- control lung. (D) Diffuse infection and unorganized granuloma formation in HO-1-/- lung inoculated with M. avium for 6 months. (E) 200× H&E stain of normal tissue from HO-1+/+ control lung. (F) 200× H&E stain showing organized granuloma formation in HO-1+/+ lung inoculated with M. avium for 6 months. (G) 200× H&E stain of normal tissue from HO-1-/- control lung. (H) 200× H&E stain of diffuse infection and dysfunctional granuloma formation in HO-1-/- lung inoculated with M. avium for 6 months. Five mice were included in each treatment group (lungs are not shown to scale).

Mentions: Our in vitro results suggested that HO-1 appeared to play a role in the regulation of both MCP-1 and CCR2 following infection with M. avium. To evaluate the role of HO-1 in granuloma formation in vivo, we used a mouse model of HO-1 deficiency and compared granuloma formation in HO-1+/+ mice and HO-1-/- mice following M. avium infection. We examined the lungs of HO-1+/+ and HO-1-/- mice, six weeks, sixteen weeks and at six months post M. avium infection and compared the results with lungs from control mice inoculated with saline at the same time period. We examined the lungs of HO-1+/+ and HO-1-/- mice six months post M. avium infection and compared the results with lungs from control mice inoculated with saline at the same time period. At the end of the experimental period, mice were euthanized and the lungs, spleen and liver were harvested for analysis. Lungs from HO-1+/+ infected mice showed organized, mature granulomas whereas, lungs from HO-1-/- infected mice presented unorganized, loose collections of mononuclear cells (Figure 3, B, D).


Heme oxygenase-1 promotes granuloma development and protects against dissemination of mycobacteria.

Regev D, Surolia R, Karki S, Zolak J, Montes-Worboys A, Oliva O, Guroji P, Saini V, Steyn AJ, Agarwal A, Antony VB - Lab. Invest. (2012)

Mouse lung tissue showing differential granuloma formation in HO-1+/+ and HO-1-/- mice after 6 month M. avium infection or saline inoculationMouse lungs were harvested following 6 month M. avium inoculation and visually inspected for presence of granuloma. Alternatively, lung tissue was fixed and stained with H&E to confirm granuloma formation. (A) Absence of granuloma in HO-1+/+ control lung. (B) Presence of organized, mature granulomas in HO-1+/+ lung inoculated with M. avium for 6 months. (C) Absence of granuloma in HO-1-/- control lung. (D) Diffuse infection and unorganized granuloma formation in HO-1-/- lung inoculated with M. avium for 6 months. (E) 200× H&E stain of normal tissue from HO-1+/+ control lung. (F) 200× H&E stain showing organized granuloma formation in HO-1+/+ lung inoculated with M. avium for 6 months. (G) 200× H&E stain of normal tissue from HO-1-/- control lung. (H) 200× H&E stain of diffuse infection and dysfunctional granuloma formation in HO-1-/- lung inoculated with M. avium for 6 months. Five mice were included in each treatment group (lungs are not shown to scale).
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4017357&req=5

Figure 3: Mouse lung tissue showing differential granuloma formation in HO-1+/+ and HO-1-/- mice after 6 month M. avium infection or saline inoculationMouse lungs were harvested following 6 month M. avium inoculation and visually inspected for presence of granuloma. Alternatively, lung tissue was fixed and stained with H&E to confirm granuloma formation. (A) Absence of granuloma in HO-1+/+ control lung. (B) Presence of organized, mature granulomas in HO-1+/+ lung inoculated with M. avium for 6 months. (C) Absence of granuloma in HO-1-/- control lung. (D) Diffuse infection and unorganized granuloma formation in HO-1-/- lung inoculated with M. avium for 6 months. (E) 200× H&E stain of normal tissue from HO-1+/+ control lung. (F) 200× H&E stain showing organized granuloma formation in HO-1+/+ lung inoculated with M. avium for 6 months. (G) 200× H&E stain of normal tissue from HO-1-/- control lung. (H) 200× H&E stain of diffuse infection and dysfunctional granuloma formation in HO-1-/- lung inoculated with M. avium for 6 months. Five mice were included in each treatment group (lungs are not shown to scale).
Mentions: Our in vitro results suggested that HO-1 appeared to play a role in the regulation of both MCP-1 and CCR2 following infection with M. avium. To evaluate the role of HO-1 in granuloma formation in vivo, we used a mouse model of HO-1 deficiency and compared granuloma formation in HO-1+/+ mice and HO-1-/- mice following M. avium infection. We examined the lungs of HO-1+/+ and HO-1-/- mice, six weeks, sixteen weeks and at six months post M. avium infection and compared the results with lungs from control mice inoculated with saline at the same time period. We examined the lungs of HO-1+/+ and HO-1-/- mice six months post M. avium infection and compared the results with lungs from control mice inoculated with saline at the same time period. At the end of the experimental period, mice were euthanized and the lungs, spleen and liver were harvested for analysis. Lungs from HO-1+/+ infected mice showed organized, mature granulomas whereas, lungs from HO-1-/- infected mice presented unorganized, loose collections of mononuclear cells (Figure 3, B, D).

Bottom Line: Inhibition of HO by zinc protoporphyrin-IX led to inhibition of MCP-1 and increased expression of CCR2, its cognate receptor.Mycobacteria were found only inside defined granulomas but not outside granuloma in the lungs of HO-1⁺/⁺ mice.Higher MCP-1 levels were found in bronchoalveolar lavage fluid of M. avium infected HO-1(-/-) mice and CCR2 expression was higher in HO-1⁻/⁻ alveolar macrophages when compared with HO-1⁺/⁺ mice.

View Article: PubMed Central - PubMed

Affiliation: Division of Pulmonary, Critical Care and Sleep Medicine, College of Medicine, University of Florida, Gainesville, FL, USA.

ABSTRACT
Non-tuberculous mycobacterial (NTM) infections occur in both immunocompromised and immunocompetent hosts and are an increasingly recognized cause of morbidity and mortality. The hallmark of pulmonary mycobacterial infections is the formation of granuloma in the lung. Our study focuses on the role of heme oxygenase-1 (HO-1), a cytoprotective enzyme, in the regulation of granuloma development and maturation following infection with Mycobacterium avium. We examined the role of HO-1 in regulating monocyte chemoattractant protein-1 (MCP-1) and chemokine receptor 2 (CCR2), two molecules involved in monocyte-macrophage cell trafficking after infection. We showed that RAW 264.7 mouse monocytes exposed to M. avium expressed HO-1 and MCP-1. Inhibition of HO by zinc protoporphyrin-IX led to inhibition of MCP-1 and increased expression of CCR2, its cognate receptor. HO-1⁻/⁻ mice did not develop organized granuloma in their lungs, had higher lung colony forming unit of M. avium when infected with intratracheal M. avium, and had loose collections of inflammatory cells in the lung parenchyma. Mycobacteria were found only inside defined granulomas but not outside granuloma in the lungs of HO-1⁺/⁺ mice. In HO-1⁻/⁻ mice, mycobacteria were also found in the liver and spleen and showed increased mortality. Peripheral blood monocytes isolated from GFP⁺ mice and given intravenously to HO-1⁺/⁺ mice localized into tight granulomas, while in HO-1⁻/⁻ mice they remained diffusely scattered in areas of parenchymal inflammation. Higher MCP-1 levels were found in bronchoalveolar lavage fluid of M. avium infected HO-1(-/-) mice and CCR2 expression was higher in HO-1⁻/⁻ alveolar macrophages when compared with HO-1⁺/⁺ mice. CCR2 expression localized to granuloma in HO-1⁺/⁺ mice but not in the HO-1⁻/⁻ mice. These findings strongly suggest that HO-1 plays a protective role in the control of M. avium infection.

Show MeSH
Related in: MedlinePlus