Colostrum proinflammatory cytokines as biomarkers of bovine immune response to bovine tuberculosis (bTB)

In-depth systems biological evaluation of bovine alveolar macrophages suggests novel insights into molecular mechanisms underlying Mycobacterium bovis infection

Objective

Bovine tuberculosis (bTB) is a chronic respiratory infectious disease of domestic livestock caused by intracellular Mycobacterium bovis infection, which causes ~$3 billion in annual losses to global agriculture. Providing novel tools for bTB managements requires a comprehensive understanding of the molecular regulatory mechanisms underlying the M. bovis infection. Nevertheless, a combination of different bioinformatics and systems biology methods was used in this study in order to clearly understand the molecular regulatory mechanisms of bTB, especially the immunomodulatory mechanisms of M. bovis infection.

Methods

RNA-seq data were retrieved and processed from 78 (39 non-infected control vs. 39 M. bovis-infected samples) bovine alveolar macrophages (bAMs). Next, weighted gene co-expression network analysis (WGCNA) was performed to identify the co-expression modules in non-infected control bAMs as reference set. The WGCNA module preservation approach was then used to identify non-preserved modules between non-infected controls and M. bovis-infected samples (test set). Additionally, functional enrichment analysis was used to investigate the biological behavior of the non-preserved modules and to identify bTB-specific non-preserved modules. Co-expressed hub genes were identified based on module membership (MM) criteria of WGCNA in the non-preserved modules and then integrated with protein-protein interaction (PPI) networks to identify co-expressed hub genes/transcription factors (TFs) with the highest maximal clique centrality (MCC) score (hub-central genes).

Results

As result, WGCNA analysis led to the identification of 21 modules in the non-infected control bAMs (reference set), among which the topological properties of 14 modules were altered in the M. bovis-infected bAMs (test set). Interestingly, 7 of the 14 non-preserved modules were directly related to the molecular mechanisms underlying the host immune response, immunosuppressive mechanisms of M. bovis, and bTB development. Moreover, among the co-expressed hub genes and TFs of the bTB-specific non-preserved modules, 260 genes/TFs had double centrality in both co-expression and PPI networks and played a crucial role in bAMs-M. bovis interactions. Some of these hub-central genes/TFs, including PSMC4, SRC, BCL2L1, VPS11, MDM2, IRF1, CDKN1A, NLRP3, TLR2, MMP9, ZAP70, LCK, TNF, CCL4, MMP1, CTLA4, ITK, IL6, IL1A, IL1B, CCL20, CD3E, NFKB1, EDN1, STAT1, TIMP1, PTGS2, TNFAIP3, BIRC3, MAPK8, VEGFA, VPS18, ICAM1, TBK1, CTSS, IL10, ACAA1, VPS33B, and HIF1A, had potential targets for inducing immunomodulatory mechanisms by M. bovis to evade the host defense response.

Conclusion

The present study provides an in-depth insight into the molecular regulatory mechanisms behind M. bovis infection through biological investigation of the candidate non-preserved modules directly related to bTB development. Furthermore, several hub-central genes/TFs were identified that were significant in determining the fate of M. bovis infection and could be promising targets for developing novel anti-bTB therapies and diagnosis strategies.

Effects of lactation number and litter size on the chemical composition and immune components of goat colostrum

This study aimed to evaluate the effect of the number of lactations and litter size on the chemical composition, immunoglobulins, and cytokines of goat colostrum. The experiment was conducted at the Animal Research Base, Mianyang Academy of Agricultural Sciences, from February to March 2021. After delivery, 48 colostrum samples were obtained every 24 h by manual milking from both udders. The contents of colostrum proteins, IgA, and IgM increased markedly up to 48 h postpartum, reaching 250 and 1250 μg/mL, respectively (p < 0.01 compared with 0 h). However, the total Ig and IgG contents dropped quickly at 48 h postpartum to around 4.5 and 6 mg/mL, respectively, and continued to do so until 96 h postpartum (p < 0.01). As for litter size, the colostrum DM, fat, total Ig, IgG, INF-γ, and IL-2 of twin-birth goats were higher than those of single-birth goats at 0 h postpartum. Moreover, the colostrum of multiparous goats contained higher total Ig, IgA, IgG, and INF-γ concentrations than that of primiparous goats at 0 h postpartum (p < 0.01). However, the colostrum INF-α and IL-5 contents of multiparous goats were lower than those of primiparous goats at 0 h postpartum (p < 0.05). Available information indicates that colostrum secretion takes place until 48 h postpartum and that the effect of litter size and lactation number on colostrum quality is observed at 0 h postpartum.

Revisiting tuberculosis screening: An insight to complementary diagnosis and prospective molecular approaches for the recognition of the dormant TB infection in human and cattle hosts

Tuberculosis (TB) is defined as a chronic infection in both human and cattle hosts and many subclinical cases remain undetected. After the pathogen is inhaled by a host, phagocyted bacilli can persist inside macrophages surviving intracellularly. Hosts develop granulomatous lesions in the lungs or lymph nodes, limiting infection. However, bacilli become persister cells. Immunological diagnosis of TB is performed basically by routine tuberculin skin test (TST), and in some cases, by ancillary interferon-gamma release assay (IGRA). The concept of human latent TB infection (LTBI) by M. tuberculosis is recognized in cohorts without symptoms by routine clinical diagnostic tests, and nowadays IGRA tests are used to confirm LTBI with either active or latent specific antigens of M. tuberculosis. On the other hand, dormant infection in cattle by M. bovis has not been described by TST or IGRA testing as complications occur by cross-reactive immune responses to homolog antigens of environmental mycobacteria or a false-negative test by anergic states of a wained bovine immunity, evidencing the need for deciphering more specific biomarkers by new-generation platforms of analysis for detection of M. bovis dormant infection. The study and description of bovine latent TB infection (boLTBI) would permit the recognition of hidden animal infection with an increase in the sensitivity of routine tests for an accurate estimation of infected dairy cattle. Evidence of immunological and experimental analysis of LTBI should be taken into account to improve the study and the description of the still neglected boLTBI.

Tetrachlorobisphenol A induced immunosuppression and uterine injury in mice

Tetrachlorobisphenol A (TCBPA) is used as flame retardant, and it has been widely detected in the environmental and human samples. TCBPA is an endocrine disrupting chemical, but its effects on the immune system remains poorly understood. Here the effects of TCBPA on immune system were studied using combined in vivo and in vitro assays. Results showed that TCBPA could suppress the immune response in BALB/c mice via reducing the ratio of CD3⁺ T lymphocytes to regulatory T cells. Moreover, TCBPA exposure significantly induced the increasing secretion of four pro-inflammatory cytokines (IL-2, IL-12, IFN-γ, and TNF-α) and four anti-inflammatory cytokines (IL-4, IL-5, IL-10, GM-CSF) in mice serum. Interestingly, uterine edema was observed in over 80% TCBPA-treated mice after 14- day exposure. TCBPA was detected in 18.6% serum samples of 150 female volunteers in this study. Therefore, our findings provided evidence that TCBPA exposure may cause adverse outcomes on immune system and uterus, suggesting that environmental exposure of TCBPA, as well as its adverse effects on human health should be of concern.

Biomarkers as diagnostic tools for mycobacterial infections in cattle

Mycobacterial infections are widely distributed in animals and cause considerable economic losses, especially in livestock animals. Bovine paratuberculosis and bovine tuberculosis, which are representative mycobacterial infections in cattle, are difficult to diagnose using current-generation diagnostics due to their relatively long incubation periods. Thus, alternative diagnostic tools are needed for the detection of mycobacterial infections in cattle. A biomarker is an indicator present in biological fluids that reflects the biological state of an individual during the progression of a specific disease. Therefore, biomarkers are considered a potential diagnostic tool for various diseases. Recently, the number of studies investigating biomarkers as tools for diagnosing mycobacterial infections has increased. In human medicine, many diagnostic biomarkers have been developed and applied in clinical practice. In veterinary medicine, however, many such developments are still in the early stages. In this review, we summarize the current progress in biomarker research related to the development of diagnostic biomarkers for mycobacterial infections in cattle.

Low-molecular weight components of cow colostrum regulate bone marrow functions by modelling the redox-system of the organism

Colostrum is rich in various biologically active compounds such as immunotropic ones. Low molecular weight components were isolated from cow colostrum components (with a molecular weight of not more than 45 kDa). Their influence was investigated on intact Wistar Rattus norvegicus adult males in concentrations of 0.01, 0.1, 1.0 and 5.0 g/100 g of body weight. We determined content of lipid hydroperoxides and activity of serum glutathione peroxidase in blood serum, parameters of the bone marrow cells’ (BMCs) behaviour in the in vitro system (proliferation ability, morphologically identifiable and unidentifiable type of cells, lifespan of eosinophils). Morphological identifiable cells were stab neutrophils, segmented neutrophils, metamyelocytes, myelocytes, lymphocytes, basophils, neutrophils, eosinophils, monocytes. The low doses of colostrum components (0.01–0.10 g/100 g of body weight) did not affect the ratio of morphologically identifiable/unidentifiable cells. Administration of colostrum components at low doses (0.01 g/100 g of weight) increased the ability of BMCs to proliferate in the in vitro system. A super-large dose of colostrum components (5 g/100 g of body weight) was accompanied by a further loss of capacity for proliferation and cell death. Moreover, large doses of colostrum components resulted in change of balance to prooxidants (oxidants). The role of redox – system in BMCs functions was discussed. Large doses of colostrum components (1–5 g/100 g of body weight) were accompanied by a change of pro-antioxidant system balance. Only eosinophils were determined after administration of colostrum components in a large dose. It should be noted that the lifetime of eosinophils which developed under influence of colostrum components was greater than that of eosinophils obtained from control animals.

Biomarkers of cell-mediated immunity to bovine tuberculosis

Whole blood based assays, particularly interferon gamma (IFN-γ) release assays (IGRAs), are used for the diagnosis of both bovine and human tuberculosis (TB). The aim of the current study was to evaluate a panel of cytokines and chemokines for potential use as diagnostic readouts indicative of Mycobacterium bovis (M. bovis) infection in cattle. A gene expression assay was used to determine the kinetics of the response to M. bovis purified protein derivative and a fusion protein consisting of ESAT-6, CFP10, and Rv3615c upon aerosol infection with ∼10⁴ cfu of M. bovis. The panel of biomarkers included: IFN-γ, CXCL9, CXCL10, CCL2, CCL3, TNF-α, IL-1α, IL-1β, IL-1Ra, IL-22, IL-21 and IL-13. Protein levels of IFN-γ, CXCL9, and CXCL10 were determined by ELISA. Findings suggest that CXCL9, CXCL10, IL-21, IL-13, and several acute phase cytokines may be worth pursuing as diagnostic biomarkers of M. bovis infection in cattle.