Effects of 1, 25-dihydroxy vitamin D3 on clinical symptoms, pro-inflammatory and inflammatory cytokines in calves with experimental pneumonia

Highlights

• Calf pneumonia caused by Pasteurella multocida.

• Different factors modified during pneumonia such as the respiratory scoring, the radiographic lung patterns, and production of cytokines.

• 1, 25-dihydroxycholecalciferol is a potent immunomodulatory action.

• Vitamin D injection following pneumonia revealed positive therapeutic effects on different measured parameters.

Abstract

1, 25-dihydroxycholecalciferol is recognized as a potent immune-modulator which can fight against the pathogens via the activation of vitamin D3 receptors (VDRs), as well as stimulating various cytokines in infectious diseases. In the present study, because of the vitamin D3 has an appropriate immunomodulatory, the effects of this vitamin on the levels of pre-inflammatory and anti-inflammatory cytokines have been investigated in calves with experimental pasteurellosis. This study was experimentally carried out on 10 Holstein crossbred male calves (2–4 months) that were divided into two groups. Prepared Pasteurella multocida (3 × 10⁹ CFU/mL) was inoculated in the trachea with a lavage catheter and then the treatment group was injected with 1, 25-dihydroxycholecalciferol after confirming pneumonia. Blood sampling, clinical symptoms scoring and radiological evaluation were recorded for both groups at different time intervals. The prescription of, vitamin D₃ to the treatment group caused a decline in clinical symptoms score and changed interstitial and alveolo-interstitial lung pattern to such a degree that it could recover in comparison with the control group.

The concentrations of pro-inflammatory cytokines (i.e., IL-1β, IL-6, and TNF-α) and the chemokine (IL-8) showed a significant decrease in the treatment group while the concentration of IL-10 increased in the treatment groups following the vitamin D₃ injection (P = .001). The evidence from the current study suggests that vitamin D3 exert the immunomodulatory effects in infectious diseases through the regulation of cytokines and activation of VDR pathways to produce antimicrobial peptides.

Introduction

Pneumonia, as the most common lung infectious diseases in dairy cattle, is considered as an economic problem especially in the calf breeding industries. Pneumonia is known as the inflammation of the lung tissue, which can also be accompanied with the inflammation of the bronchioles and the pleura, resulting in permanent damage and even death in severe lesions (Veit and Farrell, 1978).

The outbreak of pneumonia in different countries have been reported between 10% and 70% with a significant death that occurs in calves with lung infectious. Different economic aspects of this disease include treatment and prevention costs, reduction of food consumption and growth rate and an increase in mortality rate of herds (Gibbs, 2001; Mohammadi et al., 2006;). The mortality rate due to respiratory diseases in dairy cattle has been reported 2.2% to 9.4% (Waltner-Toews et al., 1986; Virtala et al., 1996). The morbidity and mortality rate in the herd, on the other hand, depends on the quality of the farm and hutches, management system especially the density of calves, bedding, ventilation and the presence of opportunistic pathogens in the environment and animals (Thomas et al., 1978).

In severe epidemics, 80–90% of the calves in the herd can be infected, however usually the mortality rate due to the disease is less than 5% (Bryson, 1985; Gevaert, 2006). The occurrence of disease during the growing time especially at the ages of 2 weeks until 5 months is most common (Lillie, 1974; Curtis et al., 1988; Constable et al., 2017). Whereas, the concentration of IgG1, IgG2, and IgA in nasal secretions between the ages of 2–4 weeks are at the lowest level, the highest incidence can be observed during these ages (Van Donkersgoed et al., 1993; Ganaba et al., 1995).

Additionally, the highest incidence occurs during the autumn and winter seasons when a closed husbandry system works in industrial farms (Bryson, 1985; Gevaert, 2006). Sex is another criterion that effects the occurrence of disease, so that the incidence of disease in males is more than that in females in the same conditions (Constable et al., 2017).

Based on previous studies, some risk factors including transportation, dehorning, weaning, pain, inappropriate bed, poor ventilation, changing the place of calves, imbalanced diet, abnormal noises, entry of new livestock to the herd, overcrowding, inadequate intake of colostrum, and the like can cause pneumonia due to the immune system weakness. (Constable et al., 2017).

Pasteurellosis pneumonia is one of the most common respiratory diseases that can cause severe outbreaks of acute pneumonia under mentioned conditions (Selvaraj et al., 2009; Smith, 2015). The endotoxin produced by Pasteurella multocida and Mannheimia haemolytica, which are Gram-negative and heterogeneous bacteria that coexists in the upper respiratory tract of large animals, can cause inflammation and pulmonary lesions (Mohammadi et al., 2007; Fatma et al., 2008; Selvaraj et al., 2009; Smith, 2015; Mosier, 2015).

Primary detection of calf pneumonia alongside the appropriate diagnosis of the etiological reason is considered as the main key for the effective control of the disease. Respiratory disease scoring was assigned as an appropriate diagnostic tool based on 4 categories of body temperature, type of nasal discharge, eye discharge or appearance of ear, and coughing; each of these clinical signs has a measurement from 0 (normal) to 3 (severe). The respiratory infection is scored based on the quantity of points from the mentioned classifications of clinical signs according which an upper grade represent the severity of disease (Panousis, 2009) (Table 1).

Radiographic interpretation of pulmonary disease is a critical example of veterinary diagnostic tools that attributable to respiratory system disease and increase or decrease in radiographic opacity of the lungs can be occurred. Whereas in most diseases, an enhancement in opacity can be observed that is usually characteristic of the pulmonary parenchymal component involved (alveolar, bronchial, interstitial, and vascular). These opacity changes are called lung patterns (Masseau et al., 2008; Awad Hussein et al., 2018; Spasov et al., 2018).

During pneumonia, the pattern of blood cells especially white blood cells is changed, subsequently under which the production of cytokines, chemokines, and antimicrobial peptides is modified (Mohammadi et al., 2006). For instance, pathogens be stimulate the monocytes and the macrophages, and subsequently the production and release of different cytokines such as interleukin 1, 6 and TNF will occur (Thacker, 2006). It is worthwhile to note that cytokines are a group of signaling molecules that interact with immune system cells and provide regular communication networks for interconnecting various components of the immune system, as well as the immune system and other body organs (Zhang and Jianxiong, 2007).

Interleukin -1β plays roles in promoting the immune regulation, during inflammation and fever process (Malazdrwich et al., 2001; Zhang and Jianxiong, 2007).

IL-6, as a pro-inflammatory cytokine, participates in diverse activities including stimulation of B cells, production of acute phase proteins and motivation of fever process as an endogenous pyrogen. Furthermore, this cytokine plays a key role in mediating the responses due to infections or injuries caused by pathogens (Ishihara and Hirano, 2002; Zhang and Jianxiong, 2007).

In the pathogenesis of bronchial inflammation and respiratory diseases, IL-8, as a chemokine, plays an important role (Malazdrwich et al., 2001; Zhang and Jianxiong, 2007), and IL-10, an anti-inflammatory and multi-active cytokine exerts a stimulatory or inhibitory effect on different cells. As a down-regulator of cellular immune response, it can suppress pro-inflammatory cytokines via the motivation of monocytes (Zhang and Jianxiong, 2007).

TNF-α acts as the main intermediary of acute inflammatory responses due to the presence of pathogens especially Gram-negative bacteria which are produced by activated agranulocyte phagocytes such as pulmonary macrophages as the main source (Malazdrwich et al., 2001; Zhang and Jianxiong, 2007).

As an essential fat-soluble vitamin Vitamin D₃ (1, 25-dihydroxycholecalciferol) can take different actions including regulation of the immune system and improvement of host resistance to intracellular infections, based on the type and situation of the cells (Bikle, 2009; Guillot et al., 2010; Lippolis et al., 2011; Sacco et al., 2012). Vitamin D₃ controls the expression of genes responsible for the production of proteins in the immune system. These proteins play a role in eliminating the exogenous and endogenous pathogens (Christakos et al., 2010; Heikkinen et al., 2011; Meyer et al., 2012; Handelt et al., 2013; Carmeliet et al., 2015).

Cellular studies and evidence indicated that vitamin D3 has immune-regulatory and anti-inflammatory effects. There is an increasing understanding that vitamin D3 exerts wide regulatory effects on cells of the adaptive and innate immune system. Vitamin D3 can be down-regulating the expression and production of several pro-inflammatory cytokines including TNF- α, IL-1β, IL-6, and IL-8. The cellular actions of 1,25(OH)2D3 are mediated by the VDR, a ligand-dependent transcription regulator molecule belonging to the superfamily of nuclear receptors. In the immune system, almost all immune cells, including T cells such as CD4 + and CD8 +, B cells, neutrophils, and antigen-providing cells (APCs), such as macrophages and dendritic cells (DCs), express VDR (Christakos et al., 2010; Hymoller and Jensen, 2010; Heikkinen et al., 2011; Meyer et al., 2012; Handelt et al., 2013; Carmeliet et al., 2015; Calton et al., 2015; Chirumbolo et al., 2017).

The present study aimed to investigate the moderating effects of vitamin D₃ on the levels of inflammatory and pro-inflammatory cytokines as alternative antibiotics and immunomodulating agents in experimental pasteurellosis.