Sessions

In viral diseases of horses causing viremia, the early inflammatory response triggered by the infection plays a key role in the progression of the disease and its adverse effects on health, contributing to poor general condition and damage to certain organs, thereby significantly worsening the prognosis. The main objective of our research was to develop an equine primary in vitro model that is suitable for studying systemic inflammatory and oxidative stress responses, while preserving the interactions between blood cells and humoral components. In the present study, it was aimed to trigger pro-inflammatory cytokine response in the established cell model by exposing the cultured cells to the viral RNA analogue polyinosinic polycytidylic acid (poly I:C), and then to study the immunomodulatory and redox-modulating effects of curcumin.

Whole blood cultures were established from the blood of a healthy horse, and the cultures were incubated with 10 and 50 µg/mL poly I:C, as well as 0.3 and 30 µg/mL curcumin, and their combinations for 12 hours. Thereafter, lactate dehydrogenase (LDH) activity, concentrations of several inflammatory mediators and hydrogen peroxide levels were quantified in cell-free supernatants.

At both concentrations, poly I:C increased the release of interleukin (IL)-1β, interferon-γ-induced protein 10 (IP-10) and tumor necrosis factor-α (TNF-α), while it also increased the concentrations of IL-6 and interferon-γ (IFN-γ) at the higher dose, without causing an increase in extracellular LDH activity indicative of cellular damage. Thus, poly I:C elicited a consistent, marked inflammatory cytokine response without detectable cytotoxicity. In combination with poly I:C, curcumin further enhanced the IL-6 and TNF-α responses and in certain cases also increased the concentrations of IL-1β and IP-10. However, higher-dose curcumin treatment reduced the concentration of hydrogen peroxide in culture media when applied together with both poly I:C exposures.

Based on the results gained, an inflammatory response was successfully induced by poly I:C in the established equine primary whole blood culture. In this model, curcumin exhibited context-dependent immunomodulatory and redox-modulating activity: upon concurrent poly I:C exposure, it further increased pro-inflammatory cytokine peaks, while at higher dose it mitigated extracellular hydrogen peroxide concentrations, indicating an antioxidant effect. The established model thus proved suitable for studying the acute systemic inflammatory response observed in viremia-associated conditions in horses at the molecular level, as well as for in vitro testing of certain alternative, novel immunomodulatory and redox-modulating candidates.