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Histone H4 aggravates inflammatory injury through TLR4 in chlorine gas-induced acute respiratory distress syndrome
Yanlin Zhang
Peking University Third Hospital
Corresponding Author
ORCiD: https://orcid.org/0000-0003-0078-3554
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This work is licensed under a CC BY 4.0 License. Read Full License
View the published version at Journal of Occupational Medicine and Toxicology.
Background: Chlorine gas (Cl 2 ) exposure remains a public health concern in household, occupational, and transportation accidents around the world. The death rate associated with acute respiratory distress syndrome (ARDS) caused by high concentrations of Cl 2 is very high, mainly because the pathogenesis of ARDS remains unclear. Histone H4 has been identified as an important endogenous pro-inflammatory molecule. The present study aimed to examine the pathogenic role of histone H4 in Cl 2 -induced ARDS.
Methods: ARDS was induced by Cl 2 exposure in male C57BL/6 mice. Circulating histone H4, blood gas, pulmonary edema, endothelial activation, and neutrophil infiltration were measured during acute lung injury (ALI). Histone H4 or anti-H4 antibody was administered through the tail vein 1 h prior to Cl 2 exposure to study the pathogenic role of histone H4. Toll-like receptor 2 knock-out ( Tlr2 -KO) and Tlr4 -KO mice were used in conjunction with blocking antibody against TLR1, TLR2, TLR4, or TLR6 to explore the mechanism involved in histone H4-mediated injury.
Results: Cl 2 exposure induced a concentration-dependent ALI. The levels of circulating histone H4 were positively correlated with Cl 2 concentrations. Pretreatment with intravenous histone H4 further aggravated lethality rate, blood gas, endothelial activation, and neutrophil infiltration, while anti-H4 antibody showed protective effects. Tlr4 deficiency improved lethality rate, blood gas, and pulmonary edema, and prevented endothelial and neutrophil activation caused by Cl 2 exposure. More importantly, Tlr4 gene deletion greatly diminished the effect of histone H4 or anti-H4 antibody observed in wild-type (WT) mice. The impact of Tlr2 on inflammatory injury was not significant. The role of TLRs was also validated by endothelial activation mediated by histone H4 in vitro.
Conclusions: Circulating histone H4 played a pro-inflammatory role in ARDS caused by Cl 2 . TLR4 was closely involved in histone H4-mediated inflammatory injury. Therefore, intervention targeting histone H4 is potentially protective.
Keywords
Chlorine gas, Acute respiratory distress syndrome, Histone H4, Toll-like receptor, Pulmonary inflammation
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Figure S1 Pathological changes in lung tissue after Cl2 exposure. Twenty four hours after exposure (30 min) to different concentrations (10 to 800 ppm) of Cl2, pulmonary histopathology was analyzed, including alveolar hemorrhage, interstitial edema, infiltration of inflammatory cells, and disruption of the alveolar wall. Lung sections were stained with hematoxylin and eosin (HE). N = 6 for all groups. Scale bars: 100 μm. Figure S2 Acetylation analysis of circulating histone H4 after Cl2 exposure. Twenty four hours after mice were treated (30 min) with different concentrations (10, 50, 200, and 800 ppm) of Cl2, the acetylation status of circulating histone H4 was analyzed by western blot. The concentration of histone H4 was measured with a histone H4 detection kit. Equal amounts of histone H4 were mixed with loading buffer and subjected to electrophoresis. Western blot was performed in triplicate.
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This preprint is under consideration at Journal of Occupational Medicine and Toxicology. A preprint is a preliminary version of a manuscript that has not completed peer review at a journal. Research Square does not conduct peer review prior to posting preprints. The posting of a preprint on this server should not be interpreted as an endorsement of its validity or suitability for dissemination as established information or for guiding clinical practice.
Learn more about In Review
Research
Histone H4 aggravates inflammatory injury through TLR4 in chlorine gas-induced acute respiratory distress syndrome
Yanlin Zhang
Peking University Third Hospital
Corresponding Author
ORCiD: https://orcid.org/0000-0003-0078-3554
Badges
Prescreen
This manuscript passed our Prescreen assessment
Complete author information
Appropriate declaration statements
Potential risks to human health
Prescreen
Peer Review Timeline
CURRENT STATUS: Published
Version 3
Posted 25 Sep, 2020
Published
On 08 Oct, 2020
No community comments so far
Editor assigned
On 24 Sep, 2020
Editorial decision: Accept
On 24 Sep, 2020
Submission checks complete
On 23 Sep, 2020
Editor invited
On 23 Sep, 2020
No comments provided
Editorial decision: Minor revision
On 09 Sep, 2020
Reviewer #3 agreed
On 14 Aug, 2020
Review #3 received
Received 14 Aug, 2020
Review #1 received
Received 14 Aug, 2020
Review #2 received
Received 14 Aug, 2020
Reviewer #1 agreed
On 13 Aug, 2020
Reviewer #2 agreed
On 13 Aug, 2020
Editor assigned
On 13 Aug, 2020
Reviewers invited
Invitations sent on 13 Aug, 2020
Submission checks complete
On 12 Aug, 2020
Editor invited
On 12 Aug, 2020
No comments provided
Editorial decision: Major revision
On 13 Jul, 2020
Review #3 received
Received 07 Jul, 2020
Review #2 received
Received 07 Jul, 2020
Reviewer #3 agreed
On 16 Jun, 2020
Reviewer #2 agreed
On 16 Jun, 2020
Review #1 received
Received 28 May, 2020
Reviewer #1 agreed
On 06 May, 2020
Reviewers invited
Invitations sent on 14 Apr, 2020
Editor assigned
On 07 Apr, 2020
Submission checks complete
On 06 Apr, 2020
Editor invited
On 06 Apr, 2020
First submitted
On 03 Apr, 2020
Metrics
Comments: 0
PDF Downloads: ...
HTML Views: ...
License:
This work is licensed under a CC BY 4.0 License. Read Full License
View the published version at Journal of Occupational Medicine and Toxicology.
Background: Chlorine gas (Cl 2 ) exposure remains a public health concern in household, occupational, and transportation accidents around the world. The death rate associated with acute respiratory distress syndrome (ARDS) caused by high concentrations of Cl 2 is very high, mainly because the pathogenesis of ARDS remains unclear. Histone H4 has been identified as an important endogenous pro-inflammatory molecule. The present study aimed to examine the pathogenic role of histone H4 in Cl 2 -induced ARDS.
Methods: ARDS was induced by Cl 2 exposure in male C57BL/6 mice. Circulating histone H4, blood gas, pulmonary edema, endothelial activation, and neutrophil infiltration were measured during acute lung injury (ALI). Histone H4 or anti-H4 antibody was administered through the tail vein 1 h prior to Cl 2 exposure to study the pathogenic role of histone H4. Toll-like receptor 2 knock-out ( Tlr2 -KO) and Tlr4 -KO mice were used in conjunction with blocking antibody against TLR1, TLR2, TLR4, or TLR6 to explore the mechanism involved in histone H4-mediated injury.
Results: Cl 2 exposure induced a concentration-dependent ALI. The levels of circulating histone H4 were positively correlated with Cl 2 concentrations. Pretreatment with intravenous histone H4 further aggravated lethality rate, blood gas, endothelial activation, and neutrophil infiltration, while anti-H4 antibody showed protective effects. Tlr4 deficiency improved lethality rate, blood gas, and pulmonary edema, and prevented endothelial and neutrophil activation caused by Cl 2 exposure. More importantly, Tlr4 gene deletion greatly diminished the effect of histone H4 or anti-H4 antibody observed in wild-type (WT) mice. The impact of Tlr2 on inflammatory injury was not significant. The role of TLRs was also validated by endothelial activation mediated by histone H4 in vitro.
Conclusions: Circulating histone H4 played a pro-inflammatory role in ARDS caused by Cl 2 . TLR4 was closely involved in histone H4-mediated inflammatory injury. Therefore, intervention targeting histone H4 is potentially protective.
Figure 1
Figure 2
Figure 3
Figure 4