Liver parasites cause infections that can be lethal, especially by damaging the bile ducts and liver tissue. If we talk about parasites, the effects of parasitic agents are usually manifested as clinical symptoms such as weakness, loss of appetite, depression, malaise, edema under the chin and abdomen, anemia and jaundice and decreased milk production (Değer and Biçek, 2005; Doğanay, 2017; Acıöz and Aydın, 2020; Ertaş and Kırmızıgül, 2021). Such as the cases we observed in the present is in parallel with the mentioned studies. Parasitic invasions in ruminants cause severe economic losses in these animalsMany parasites similarly have a complex system of host immuno-modulation and immuno-avoidance, Here, a repertoire of proteins is secreted to simultaneously defend against and distract the host's immune reply (Calvani, 2022).
After any kind of tissue damage, whether it's caused by physical, mechanical, or chemical trauma, the body responds with an inflammatory reaction. This same response is also seen in conditions like autoimmune diseases and inflammatory bowel infections. The inflammatory stimuli produced by granulocytes, lymphocytes, and macrophages, such as prostaglandins, reactive oxygen species, and free radicals, can contribute to tissue damage. Additionally, oxidative stress has been linked to impaired immune response in several studies (Abd Ellah, 2013).
The immune response is crucial in protecting the host against parasitic diseases, but it comes with a cost. Building an immune defense requires energy that could otherwise be used for other important functions such as growth, reproductive performance, and sexual signaling. During an immune response, oxidants can be formed in two ways. Firstly, immune cells produce oxidants as part of their cytotoxic activity to eliminate the pathogen. Secondly, oxidants can also be by-products of oxygen consumption, which can contribute to the production of toxic oxidants in addition to the increased metabolic activity during the immune response (Van de Crommenacker et al., 2010).
Although metabolic activity and oxidant production are linked, the relationship is not always straightforward. Animals tend to use alternative methods for mitochondrial respiration to reduce oxidant production. Therefore, parasites may be responsible for oxidant synthesis directly through the degradation products of their own metabolism (Van de Crommenacker et al., 2012). According to a number of studies, levels of reactive oxygen species have been reported to rise in the cells of sick hosts attacked by parasites (Abd Ellah, 2013; Öner at al., 2022). The elevation of free radicals in parasite-infected cells is related to the host's diet, the amount of parasite infestation and the destructive effect on tissue. Parasitic diseases are associated with blood-borne protozoan agents such as Babesiosis, Theileriosis and Trypanosomosis. In addition, Fasciola sp., Eimeria sp. and Trichostrongylus sp. have been reported to be associated with lipid peroxidation, and this assessment provides a guide to parasitic diseases associated with oxidative stress and their deleterious effects (Abd Ellah, 2013).
AOPP is a marker of oxidative stress and an advanced oxidation protein product that identifies oxidative damage in proteins (Bottari et al., 2015). Although different results were obtained in studies in which the change in AOPP level was determined (Polat, et al., 2012). AOPP value was found to be significantly higher in parasitic diseases (Polat, et al., 2012; Bottari et al., 2015; Milanovic et al. 2018). In the currend study particularly Fasciola spp., Echinococcus spp., Dicrocoelium spp. affecting the liver, AOPP level was significantly higher in naturally infected sheep sera compared to the control group. This is in line with Bottari et al., (2015). It was concluded that oxidative stress in the liver increased and protein damage occurred with increasing AOPP level.
The acute phase response is a non-specific response of the individual to different tissue injuries. Acute phase proteins are a group of proteins of varying concentration in animals exposed to external or internal problem such as infection, inflammation, surgical trauma or stress (Nazifi et al., 2009). Ceruloplasmin concentrations are increased in some but not all spontaneous inflammatory diseases. Ceruloplasmin carry copper and are role in iron metabolism. Ceruloplasmin has been described as an acute phase protein in multiple species (Feldman et al., 2000). Ceruloplasmin has functions such as increasing various enzyme (cytochrome C oxidase and Cu-Zn superoxide dismutase) activities with copper, providing higher antimicrobial power in phagocytic cells and protecting against oxidative damage (Bayyit and Merhan, 2020). moreover, ceruloplasmin is an indicator of the presence of infection (Bozukluhan et al., 2016; Bayyit and Merhan, 2020).
Ceruloplasmin, which is involved in the antioxidant system, is a moderately important acute phase protein in addition to its functions such as protecting cells against oxidative damage and antimicrobial activity (Bozukluhan et al., 2020). Bozukluhan et al., (2020) reported that the value of ceruloplasmin was found to be high in sheep with toxoplasmosis, but this was statistically insignificant. Similarly, in another study, Nispet et al., (2008) compared the serum ceruloplasmin level in cattle with echinococcosis with the healthy group and reported that the difference in ceruloplasmin values was insignificant.
In Holstein cattle with bovine tropical theilerosis, it has been shown that there is an increase in serum ceruloplasmin levels as parasitemia increases (Nazifi et al., 2009). Mohammadi et al., (2021) showed that serum ceruloplasmin level was significantly increased in cattle with natural infection of Babesia bigemina in relation to the parasitemia load compared to the control group. In a study in humans with pulmonary cystic echinococcus, the serum ceruloplasmin level of infected humans was shown to be significantly higher compared to healthy controls, and it was reported that the serum ceruloplasmin level of infected constructs decreased significantly after surgical intervention compared to the value before surgery. It has been suggested that chronic inflammation may cause this increase and may be an immune response of the host (Mohammadi et al., 2021). In the study conducted by Nisper et al., (2009), although serum ceruloplasmin level was high in cattle with Echinococcus spp., this elevation was not found to be significant. They reported that elevated ceruloplasmin levels may be excreted from the liver into the circulation in response to tissue damage caused by echinococcosis host (Eser et al., 2013). In the current study, it was found that ceruloplasmin value was significantly high in liver parasitosis, but this high value was not significant in echinococcosis and dicrocoeliosis infected sheep. According to these results, liver damage and oxidative stress are thought to occur in liver parasitism.
There are antioxidant systems in the body that act as protectors against free radical damage at various rates. These antioxidants are negatively affected by impaired body balance and oxidative stress caused by free radicals (Yazıcı et al., 2002). Thiols, which are antioxidant molecules, constitute one of the important links in the extracellular defense system chain (Değirmençay et al., 2021). Thiol groups, which try to prevent the damaging effect of free radicals, can not maintain plasma and tissue levels during these effects. Proteins in the cell wall and extracellular fluid are oxidized by the cysteine residue of thiols in the presence of oxidant molecules. In this reversible reaction thiols are metabolized to disulfide bonds (Ulrich and Jakob, 2019; Değirmençay et al., 2021). It has been suggested that proteins are exposed to oxidative stress, resulting in a decrease in -SH groups and functional defects. In studies conducted in different structures and patients, a decrease in -SH groups is generally expected with oxidative stress (Yazıcı et al., 2002). Çetinkaya et al., (2020) reported that total thiol parameter was significantly lower in rat models of Alzheimer's disease compared to the control group. Similarly, Çamkerten et al., (2019) reported that total sulfhydryl group was importantly lower in pigs with sarcoptyx mange compared to healthy pigs. Değirmençay et al., (2021) revealed that thiol levels were low in dogs with canine distemper. In another study Tarhan et al., (2023) hey compared babesian dogs with a healthy group and measured total thiol levels. As a result, he stated that he found the level of this parameter to be low but not significant. This study is in parallel with the mentioned studies and is also similar to the study conducted by Tarhan et al., (2023) İn the present study total sulfhydryl level was found to be lower in the patient groups compared to the control group, but this value was not significant. Although this decrease is not significant, it is likely that the reduction of the sulfhydryl group indicates oxidative damage.