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DUOX-Mediated Signaling Is Not Required for LPS-Induced Neutrophilic Response in the Airways.

Chang S, Linderholm A, Harper R - PLoS ONE (2015)

Bottom Line: We found that LPS induced profound neutrophilic lung inflammation in both Duoxa(+/+)and Duoxa(-/-) mice between 3h and 24h.Duoxa(-/-) mice had significantly higher neutrophil influx 24h after LPS instillation despite similar cytokine levels (KC, MIP-2, or TGF-α) between the two groups.These findings suggest that LPS-TLR-4-induced KC or MIP-2 cytokine induction and subsequent neutrophil recruitment in the airway does not require DUOX-derived hydrogen peroxide from airway epithelium.

View Article: PubMed Central - PubMed

Affiliation: Department of Internal Medicine, Division of Pulmonary and Critical Care Medicine, School of Medicine, University of California at Davis, Davis, California 95616, United States.

ABSTRACT
Oxidant production from DUOX1 has been proposed to lead to neutrophil recruitment into the airways when lung homeostasis is compromised. The objective of this study was to determine whether DUOX-derived hydrogen peroxide is required for LPS-induced neutrophil recruitment, using a functional DUOX knock out mouse model. We found that LPS induced profound neutrophilic lung inflammation in both Duoxa(+/+)and Duoxa(-/-) mice between 3h and 24h. Duoxa(-/-) mice had significantly higher neutrophil influx 24h after LPS instillation despite similar cytokine levels (KC, MIP-2, or TGF-α) between the two groups. These findings suggest that LPS-TLR-4-induced KC or MIP-2 cytokine induction and subsequent neutrophil recruitment in the airway does not require DUOX-derived hydrogen peroxide from airway epithelium.

No MeSH data available.


Related in: MedlinePlus

Cytokine levels are similar between LPS-exposed Duoxa+/+ and Duoxa-/- mice.BALF was collected at various timepoints from Duoxa+/+ (+/+) and Duoxa-/- (-/-) mice followed by measurement of KC (A) or MIP-2 (B) cytokine levels in the supernatant by ELISA. Cytokine concentration was determined by comparison to standard controls for each cytokine. Data from six animals in each group are shown. Mean cytokine values from Duoxa+/+ (+/+) and Duoxa-/- (-/-) mice are shown as a vertical line. Cytokine levels for LPS treatment differed significantly than PBS controls at three hours in both groups of mice (data not shown).
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pone.0131810.g004: Cytokine levels are similar between LPS-exposed Duoxa+/+ and Duoxa-/- mice.BALF was collected at various timepoints from Duoxa+/+ (+/+) and Duoxa-/- (-/-) mice followed by measurement of KC (A) or MIP-2 (B) cytokine levels in the supernatant by ELISA. Cytokine concentration was determined by comparison to standard controls for each cytokine. Data from six animals in each group are shown. Mean cytokine values from Duoxa+/+ (+/+) and Duoxa-/- (-/-) mice are shown as a vertical line. Cytokine levels for LPS treatment differed significantly than PBS controls at three hours in both groups of mice (data not shown).

Mentions: Typically, the binding of LPS to the TLR-4 receptor activates a signaling cascade that leads to increased IL-8 production and subsequent neutrophil recruitment[17], and DUOX-derived hydrogen peroxide has been shown to play a role in LPS-induced IL-8 production[10,11,13]. Therefore, we measured changes in the IL-8 mouse homologs KC and MIP-2[18] in BALF from Duoxa-/- and Duoxa+/+ mice after LPS instillation to evaluate the impact of DUOX-derived hydrogen peroxide in neutrophil chemotaxis. Both KC and MIP-2 levels peaked at 3h consistent with the canonical LPS-TLR4-IL-8 signaling pathway. Surprisingly, LPS induced similar levels of IL-8 homologues in the Duoxa-/- mice compared with the Duoxa+/+ mice (Fig 4). Alternatively, previous studies suggested LPS initiates DUOX-dependent upregulation of TGF-α signaling in airway epithelium, which may be primarily responsible for neutrophil influx into the airway[10,11,13,14]. To evaluate this possibility, we compared TGF-α levels in BALF from Duoxa-/- and Duoxa+/+ mice and found no induction of TGF-α in Duoxa-/- or Duoxa+/+ mice (data not shown). This supported our observation that LPS-induced neutrophil recruitment occurred through modulated expression of KC and MIP-2 independent of TGF-α signaling.


DUOX-Mediated Signaling Is Not Required for LPS-Induced Neutrophilic Response in the Airways.

Chang S, Linderholm A, Harper R - PLoS ONE (2015)

Cytokine levels are similar between LPS-exposed Duoxa+/+ and Duoxa-/- mice.BALF was collected at various timepoints from Duoxa+/+ (+/+) and Duoxa-/- (-/-) mice followed by measurement of KC (A) or MIP-2 (B) cytokine levels in the supernatant by ELISA. Cytokine concentration was determined by comparison to standard controls for each cytokine. Data from six animals in each group are shown. Mean cytokine values from Duoxa+/+ (+/+) and Duoxa-/- (-/-) mice are shown as a vertical line. Cytokine levels for LPS treatment differed significantly than PBS controls at three hours in both groups of mice (data not shown).
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pone.0131810.g004: Cytokine levels are similar between LPS-exposed Duoxa+/+ and Duoxa-/- mice.BALF was collected at various timepoints from Duoxa+/+ (+/+) and Duoxa-/- (-/-) mice followed by measurement of KC (A) or MIP-2 (B) cytokine levels in the supernatant by ELISA. Cytokine concentration was determined by comparison to standard controls for each cytokine. Data from six animals in each group are shown. Mean cytokine values from Duoxa+/+ (+/+) and Duoxa-/- (-/-) mice are shown as a vertical line. Cytokine levels for LPS treatment differed significantly than PBS controls at three hours in both groups of mice (data not shown).
Mentions: Typically, the binding of LPS to the TLR-4 receptor activates a signaling cascade that leads to increased IL-8 production and subsequent neutrophil recruitment[17], and DUOX-derived hydrogen peroxide has been shown to play a role in LPS-induced IL-8 production[10,11,13]. Therefore, we measured changes in the IL-8 mouse homologs KC and MIP-2[18] in BALF from Duoxa-/- and Duoxa+/+ mice after LPS instillation to evaluate the impact of DUOX-derived hydrogen peroxide in neutrophil chemotaxis. Both KC and MIP-2 levels peaked at 3h consistent with the canonical LPS-TLR4-IL-8 signaling pathway. Surprisingly, LPS induced similar levels of IL-8 homologues in the Duoxa-/- mice compared with the Duoxa+/+ mice (Fig 4). Alternatively, previous studies suggested LPS initiates DUOX-dependent upregulation of TGF-α signaling in airway epithelium, which may be primarily responsible for neutrophil influx into the airway[10,11,13,14]. To evaluate this possibility, we compared TGF-α levels in BALF from Duoxa-/- and Duoxa+/+ mice and found no induction of TGF-α in Duoxa-/- or Duoxa+/+ mice (data not shown). This supported our observation that LPS-induced neutrophil recruitment occurred through modulated expression of KC and MIP-2 independent of TGF-α signaling.

Bottom Line: We found that LPS induced profound neutrophilic lung inflammation in both Duoxa(+/+)and Duoxa(-/-) mice between 3h and 24h.Duoxa(-/-) mice had significantly higher neutrophil influx 24h after LPS instillation despite similar cytokine levels (KC, MIP-2, or TGF-α) between the two groups.These findings suggest that LPS-TLR-4-induced KC or MIP-2 cytokine induction and subsequent neutrophil recruitment in the airway does not require DUOX-derived hydrogen peroxide from airway epithelium.

View Article: PubMed Central - PubMed

Affiliation: Department of Internal Medicine, Division of Pulmonary and Critical Care Medicine, School of Medicine, University of California at Davis, Davis, California 95616, United States.

ABSTRACT
Oxidant production from DUOX1 has been proposed to lead to neutrophil recruitment into the airways when lung homeostasis is compromised. The objective of this study was to determine whether DUOX-derived hydrogen peroxide is required for LPS-induced neutrophil recruitment, using a functional DUOX knock out mouse model. We found that LPS induced profound neutrophilic lung inflammation in both Duoxa(+/+)and Duoxa(-/-) mice between 3h and 24h. Duoxa(-/-) mice had significantly higher neutrophil influx 24h after LPS instillation despite similar cytokine levels (KC, MIP-2, or TGF-α) between the two groups. These findings suggest that LPS-TLR-4-induced KC or MIP-2 cytokine induction and subsequent neutrophil recruitment in the airway does not require DUOX-derived hydrogen peroxide from airway epithelium.

No MeSH data available.


Related in: MedlinePlus