In our study, the concentrations of acute phase proteins and cytokines were evaluated both in the calves with diarrhea caused by amoebiasis due to E. histolytica and in the control group. From the concentrations of acute phase proteins, SAA (235.86±14.77 µg/ml) and Hp (176.62±20.75 µg/ml) were statistically (p<0.001) higher in amoebiasis group in comparison to the control group’s SAA (9.82±1.43 µg/ml) and Hp (11.55±1.33 µg/ml) (Table 1). Besides, from the concentrations of cytokines, IL-1β (56.61±6.34 ng/ml), IL-6 (28.03±2.17 ng/ml) and TNF-α (0.42±0.03 ng/ml) in the calves with amoebiasis were statistically higher (p<0.05) than the control group’s IL-1β (25.15 ± 2.12 ng/ml), IL-6 (17.22 ± 2.93 ng/ml) and TNF-α (0.16 ± 0.02 ng/ml) (Table 1). In our study, the levels of AST, ALT, ALB, GLU, CHO, TP, GGT, BUN, D-BIL and T. BIL were assessed in both groups (Table 2). In the group with amoebiasis, serum AST (U/L), D-BIL (mg/dL), GGT (U/L) and BUN (mg/dL) concentrations were statistically higher (p<0.05) in comparison to the control group. However, no statistical difference was found between the amoebiasis groups and the control group regarding ALT (U/L), GLU (mg/dL), ALB (g/L), CHO (mg/dL), TP (g/L) and T.BIL (mg/dL) values (Table 2).
SAA and Hp concentrations have been proven to be highly significant in calves
(Mohammadi et al., 2021). Acute phase proteins (APPs) are blood proteins that synthesized primarily by liver as a part of acute phase response (APR). Their concentrations may increase (positive APPs) or decrease (negative APPs)
(Eckersall et al., 2001). Evaluation of inflammatory processes in cattle is more challenging than in other species due to the fact that the symptoms of the disease cannot be easily spotted and inflammation is not always accompanied by leukocytosis
(Hunter and Jones, 2015). Hence, more accurate and useful bioindicators for inflammation must be searched urgently. SAA and Hp are important acute phase proteins in cattle infections
(Cray, 2012).
(Choi et al., 2021) found a positive correlation between acute phase proteins and diarrhea.
Entamoeba histolytica is a major cause of amebic diarrhea. In their study on mice,
(Burgess et al., 2014) found that when they transplanted the feces containing segmented filamentous bacteria to recipient mice, the mice showed resistance to
E.
histolytica and that SAA increased along with intestinal concentrations of dendritic cells and neutrophils after infection. During rotavirus, coronavirus and
E.
coli infections, a significant increase in SAA concentrations as well as diarrhea were observed in calves
(Balikci and Al 2014). In case of naturally occurring rotavirus or coronavirus coinfection with Cryptosporidium versus mono-infection, significantly higher SAA concentration increase has been previously reported
(Eckersall et al., 2001; Kabu et al., 2016). In a previous study
(Molina et al., 2014) established that SAA concentration significantly increased in animals infected with bovine viral diarrhea virus. In our study, SAA concentration in calves with diarrhea caused by Amoebiasis (235.86±14.77 µg/ml) were found to be statistically higher (p<0.001) than in the control group (9.82±1.43 µg/ml). We are of the opinion that the increase in SAA, which is the major acute phase protein for the cattle, stems from systemic inflammation.
It was reported that serum Haptoglobin concentration due to calf diarrhea was in rise
(Albayrak and Kabu, 2016; Chae et al., 2019; Choi et al., 2021; Kabu and Uyarlar, 2022).
(Chae et al., 2019) reported that in diarrhea due to bovine coronavirus in calves, serum HP concentration was high. Another study reported that in experimental respiratory system infections induced by bovine herpes virus 1 and
Pasteurella haemolytica serotype A1, Hp concentration increased
(Petersen et al., 2004). (Choi et al., 2021) reported that Hp concentrations in calves with diarrhea significantly increased and there was a positive correlation between a 2-globulin and diarrhea. These results provide valuable information for clinicians who might use serum protein profiles and Hp to evaluate the diagnosis and prognosis of calves with diarrhea. Our study also established higher (p<0.001) Hp concentration in calves with diarrhea due to amoebiasis (176.62±20.75 µg/ml) than in the control group (11.55±1.33 µg/ml). Nevertheless, during hereditary diseases or infections haptoglobulin binds free hemoglobin that is secreted during various autoimmune diseases
(Cray, 2012). Now that haptoglobulin has that feature, we think that the rise in its concentration increases in proportion to the hemoglobin released after
Entamoeba lyses erythrocytes.
Studies reported an increase in HP and SAA in dairy calves as a response to
Cryptosporidium infections, especially in diarrhea
(Enemark et al., 2003a,b; Pourjafar et al., 2011). Entamoeba histolytica, like
Cryptosporidium, settles in the gastrointestinal tract. We suggest that this drastic difference was caused by the nature of the
E.
histolytica infection and probably due to the fact that localized damage to the small intestine was more prone to trigger an immunological response that increased HP rather than SAA concentrations.
TNF-α is one of the main cytokines which partake in systemic inflammation and contribute to acute phase reaction. Even though it is synthesized in and secreted from neutrophil, eosinophiland mast cells, its main source is activated macrophages
(Ankri, 2015). Additionally, TNF-α attracts entamoeba and enable them to penetrate interstitial extracellular matrix. Moreover, some intestinal cells act as a reservoir for TNF-α and might be active in the earlier stages of the infection
(Labruyere et al., 2019). (Peterson et al., 2010) demonstrated the correlation between high TNF-α concentration and
E.
histolytica in the study they conducted on the children with diarrhea caused by
E.
histolytica. Our study similarly determined that serum TNF-α concentration (0.42±0.03 ng/ml) in the calves with diarrhea caused by amoebiasis was higher (p<0.001) than in the control group (0.16±0.02 ng/ml). IL-1β is a potent pro-inflammatory cytokine that plays an important role in inflammation and the host defense against tissue damage; although it is produced and released in various cell types, it is produced by monocytes and macrophages, which are cells that initiate the immune response
(Lopez-Castejon and Brough, 2011).
(Macias-Perez et al., 2019) demonstrated thatIL-1β significantly increased in hamsters with amoebic hepatic abscess and decreased after the treatment. Similarly in our study, serum IL-1β concentration in the calves with diarrhea caused by amoebiasis (56.61±6.34 ng/ml) was higher (p<0.05) than in the control group (25.15±2.12 ng/ml).
As the parasite invasion process develops, the epithelium responds with a protective inflammatory response. However, as epithelial cell lysis occurs, pro-inflammatory cytokines such as pro-IL-1β are released. This cytokine is rendered to its active form by cysteine proteases, some of which are of parasite origin
(Sharma et al., 2005). A series of regulatory events may occur at this stage.These may include the interaction of surface and soluble parasite-derived molecules
(Yu and Chadee, 1997; Kammanadiminti et al., 2004; Maldonado-Bernal et al., 2005) with the host cell, resulting in the release of epithelium cytokines/chemokines such as IL-6, granulocyte/macrophage colony stimulating factor TNF-α.
(Espinosa-Cantellano and Martinez-Palomo, 2000). We suggest that the increase in the concentrations of TNF-α, IL-1β and IL-6 are related to this mechanism. Our results indicated that
E.
histolytica impact on the production of APP and associated clinical signs could be attributed to the
E.
histolytica infection.
In our study, there was no statistical difference in terms of alanine aminotransferase (ALT, U/L), glycose (GLU, mg/dL), albumin (ALB, g/L), cholesterol (CHO, mg/dL), total protein (TP, g/L) and total bilirubin (T.BIL, mg/dL) between the groups with Amoebiasis and the control group. In the group with Amoebiasis, serum aspartate aminotransferase (AST, U/L), direct bilirubin (D-BIL, mg/dL), Gamaglutamyl transferase (GGT, U/L) and blood urea nitrogen (BUN, mg/dL) were statistically higher (p<0.05) than the control group; these enzymatic parameters should not be disregarded while assessing hepatic damage.While AST is present in many tissues including brain, kidneys and muscles (heart, skeleton, face) and the presence of ALT in high concentration in hepatocytes and in low concentrations in other tissues indicates hepatic damage specifically
(Woreta and Alqahtani, 2014). It was reported that after trophozoites adhere to and lyse intestinal epithelium, they spread hematologically to peritoneum, liver, lung or brain through the vein
(Kantor et al., 2018). We suppose that serum AST concentration increases due to the hematologic spread of trophozoites to peritoneum, liver, lungs and brain as a result of the presence of AST in several tissues (brain, kidneys, muscles) and the damage this creates in the tissues and organs. D-BIL was reported to have increased during cholestatic diseases with impaired bile flow and hepatocellular infections
(Kwo et al., 2017). We assume from the increase in D-BIL value that
E.
histolytica might affect bile ducts. Moreover, GGT is a potent indicator for damage to bile ducts and liver and GGT has been reported to be mainly localized in biliary epithelial cells and the apical membrane of hepatocytes
(Woreta and Alqahtani, 2014). We suggest that the increase in GGT together with D-BIL supports the fact that bile ducts are affected. BUN parameter is often used in the diagnosis and follow-up of kidney diseases
(Hokamp and Nabity, 2016). Rodrigues
(Ferreira-Filho et al., 2011) reported in a conducted study that the prevalence of amoebiasis caused by
E.
histolytica/
dispar was approximately 8%. In the light of this study and measured BUN value, we assert that
E.
histolytica damages kidneys.