Association between endotoxin levels in dust from indoor swine housing environments and the immune responses of pigs

Abstract

Indoor animal husbandry environments are inevitably contaminated with endotoxins. Endotoxin exposure is associated with various inflammatory illnesses in animals. This cross-sectional study evaluated the relationship between the degree of endotoxin exposure and the cellular and humoral immune profiles of fattening pigs. Blood samples were taken from the jugular vein of 47 pigs from ten pig farms in Korea. Whole blood cell counts and plasma immunoglobulin (Ig) classes were determined. Peripheral-blood mononuclear cells were stimulated in vitro with concanavalin A for 48 h, and cytokines released into culture supernatants were measured. The barns in which the pigs lived were assessed for endotoxin levels in the total and respirable dust by using the limulus amebocyte lysate kinetic QCL method. Low and high endotoxin exposures were defined as ≤ 30 and > 30 EU/m3, respectively. Compared to pigs with low endotoxin exposure (n = 19), highly exposed pigs (n = 28) had higher circulating neutrophil and lymphocyte (particularly B cells) counts, IgG and IgE levels, interferon-gamma (IFNγ) and interleukin (IL)-4 productions, and lower IgA levels and tumor necrosis factor-alpha (TNFα) production. The IL-4, IFNγ, and TNFα levels significantly correlated with endotoxin level and/or pig age. Constant exposure of pigs to high levels of airborne endotoxins can lead to aberrant immune profiles.

Influence of immune status on the airborne colonization of piglets with methicillin-resistant staphylococcus aureus (MRSA) clonal complex (CC) 398

“…MRSA alone (CG), the increase of the total leukocytes due to a significant increase of neutrophils detected in the EG is interpreted as being induced by endotoxin. Alterations in the peripheral blood of endotoxin-exposed pigs were also found by other groups [10,29]. Thereby, our data imply that the effect of airborne endotoxin in our aerosol chamber on the immune system is comparable to those in animals continuously exposed to high levels of endotoxin in pig barns.…”

“…Furthermore, in a field study, discrepancies were found in the immune response between pigs and broilers despite the equal endotoxin concentration in the environment of investigated barns [29]. Roque et al explained their findings with the longer endotoxin exposure of pigs (5-month fattening period) compared to broilers (1-month fattening period) [29]. The authors concluded that endotoxin weakens the piglets' immune defense against pathogens underlining that a possible role of airborne endotoxin favoring MRSA colonization in field cannot be neglected.…”

“…Jolie et al found a significantly higher neutrophil and alveolar macrophage concentration in the BAL after long-term endotoxin exposure (i.e., 15 weeks), indicating a systemic inflammatory response, though in the absence of clinical signs [30]. Furthermore, in a field study, discrepancies were found in the immune response between pigs and broilers despite the equal endotoxin concentration in the environment of investigated barns [29]. Roque et al explained their findings with the longer endotoxin exposure of pigs (5-month fattening period) compared to broilers (1-month fattening period) [29].…”

Every breath you take: Impacts of environmental dust exposure on intestinal barrier function–from the gut-lung axis to COVID-19

“…In comparison with pigs raised in barns with low-bacterial endotoxin levels, there was an increase of white blood cells in pigs exposed to high-endotoxin levels. In addition, peripheral blood mononuclear cells (PBMC) collected from high-exposure pigs had greater plasma immunoglobulin (Ig) G and IgE levels but lower IgA levels than that produced by PBMCs from low-exposure pigs ( 66 ). The inflammatory capabilities of SFD have also been demonstrated in various in vitro experiments using human bronchial epithelial cells and pulmonary carcinoma cell lines ( 19 , 72 ).…”

“…Moreover, endotoxins found in the dust collected from CAFOs act as the primary factor in the onset of asthma and other respiratory conditions (61)(62)(63). A considerable amount of research has shown that exposure to endotoxins is especially prevalent in swine farm workers (64)(65)(66). Raising swine is a lucrative agricultural enterprise for US farmers with sales generating 26.3 billion dollars in 2017 (67).…”