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Enhanced production of bovine tumor necrosis factor-alpha during the periparturient period
L M Sordillo1, G M Pighetti, M R Davis
1Department of Veterinary Science, Pennsylvania State University, University Park 16802-3500, USA.
Insights
Periparturient dairy cows exhibit higher tumor necrosis factor-alpha (TNF-alpha) production by monocytes compared to lactating cows. This heightened TNF-alpha response, particularly in mammary lymph nodes, may increase susceptibility to coliform mastitis.
Area of Science:
- Veterinary immunology
- Dairy cattle health
- Infectious disease
Background:
- Periparturient dairy cows are susceptible to infections like coliform mastitis.
- Tumor necrosis factor-alpha (TNF-alpha) is a key inflammatory cytokine.
- Understanding immune responses in periparturient cows is crucial for disease prevention.
Purpose of the Study:
- To investigate TNF-alpha production by mononuclear cells in periparturient and lactating dairy cows.
- To compare TNF-alpha levels between peripheral blood and mammary lymph nodes.
- To explore the role of monocyte populations in immune responses during the periparturient period.
Main Methods:
- Isolation of mononuclear cells from peripheral blood and supramammary lymph nodes.
- Stimulation of cells with lipopolysaccharide (LPS) to induce cytokine production.
- Quantification of TNF-alpha concentrations and flow cytometric analysis of monocyte frequencies.
Main Results:
- Mononuclear cells from periparturient cows produced significantly higher TNF-alpha levels than those from lactating cows.
- Periparturient animals showed increased monocyte frequencies in tissue samples.
- Mammary lymph node cells produced more TNF-alpha than peripheral blood cells in periparturient cows, despite similar monocyte counts.
Conclusions:
- Elevated TNF-alpha production by monocytes in periparturient dairy cows may contribute to severe inflammatory responses.
- Differences in TNF-alpha production between tissue locations suggest variations in monocyte activation states.
- Modulating monocyte TNF-alpha production, especially in the mammary gland, could mitigate coliform mastitis severity.
Abstract:
This study examined the production of tumor necrosis factor (TNF-alpha) by mononuclear cells isolated from peripheral blood and supramammary lymph nodes of periparturient and mid to late lactating dairy cows. Monocyte-enriched cell populations were stimulated with lipopolysaccharide (LPS) and analyzed for TNF-alpha concentrations. Flow cytometric analysis was performed to determine the frequencies of relevant cell populations. Isolated mononuclear cells from periparturient dairy cows produced significantly higher levels of TNF-alpha than mid to late lactating dairy cows regardless of tissue location. A corresponding increase in the frequency of monocytes also was observed in tissue samples obtained from periparturient animals. The higher proportion of monocytes capable of producing TNF-alpha in the periparturient dairy cow may account for the increased levels of this potent mediator. Within the periparturient period, peripheral blood mononuclear cells were found to produce significantly less TNF-alpha than cells isolated from mammary lymph nodes. However, flow cytometric analysis revealed similar monocyte concentrations in both the peripheral blood and mammary lymph node. This indicates that the differences in cytokine production may be due to variations in monocyte activation state with respect to tissue location. It is possible that greater potential to produce TNF-alpha during the periparturient period may contribute to the severe acute phase response of the mammary gland to coliform infections during this time. Limiting TNF-alpha production by monocytes, particularly within the mammary gland, may reduce the severity of clinical coliform mastitis in periparturient dairy cattle.