Pulmonary and hematological inflammatory responses to intravenous cellulose micro-particles in broilers

Area of Science:

• Veterinary immunology
• Pulmonary pathology
• Avian inflammatory responses

Background:

• Intravenous injection of micro-particles leads to pulmonary arteriolar lodging.
• Understanding the inflammatory cascade following micro-particle exposure is crucial for avian health.

Purpose of the Study:

• To investigate the systemic and pulmonary inflammatory responses in broilers after intravenous cellulose micro-particle injection.
• To characterize the cellular composition of lung inflammatory aggregates and changes in circulating white blood cells.

Main Methods:

• Broilers were intravenously injected with cellulose micro-particles or saline (control).
• Pulmonary inflammation was assessed by counting granuloma/lymphocyte aggregates in lung tissue.
• Cellular components of aggregates were identified using immunohistochemistry.
• Circulating white blood cell (WBC) counts and proportions were analyzed at 3, 24, and 48 hours post-injection.

Main Results:

• Cellulose micro-particles induced localized inflammatory responses in the lung parenchyma, with monocytes and basophils surrounding the particles.
• T cell subsets (CD4, CD8, TCR1-3) and B cells were found in the outer regions of inflammatory aggregates.
• While total WBC concentrations remained similar, circulating eosinophil and basophil percentages increased at 48 hours post-injection in the particle group.
• Circulating monocyte concentration elevated within 24 hours post-injection.

Conclusions:

• Cellulose micro-particles trapped in pulmonary arterioles initiate acute focal inflammatory responses in broiler lungs.
• The proportions of circulating WBCs are modulated within 48 hours following micro-particle exposure.
• This study provides insights into the avian immune system's reaction to foreign micro-particle lodging in the pulmonary vasculature.