Bovine Gamma Delta T Cells Contribute to Exacerbated IL-17 Production in Response to Co-Infection with Bovine RSV and Mannheimia haemolytica

Circulating T cell subpopulations in dairy calves infected with Bovine viral diarrhea virus 2 and Bovine herpes virus 1 following modified-live virus booster vaccination: Effects of the administration route and trace mineral supplementation

The objective of this study was to evaluate the effects of the vaccine administration route and the concurrent use of injectable trace minerals (ITM) with booster vaccination on the circulating leukocyte counts and T cell subpopulations in dairy calves challenged with Bovine viral diarrhea virus 2 (BVDV2) and Bovine herpes virus 1 (BHV1). A total of 60 Holstein male calves were used in this study. Forty-eight calves were administered a MLV intranasal (IN) vaccine containing BHV1, BRSV, BPI3V (Inforce 3®), and randomly assigned to subcutaneous (SC) administration of injectable trace minerals (ITM, n = 24) or saline (SAL, n = 24). Ten weeks later, the calves received booster vaccination using either SC or IN route and a second dose of ITM, or saline, according to previous groups [ITM-SC (n = 12), ITM-IN (n = 12), SAL-SC (n = 12), and SAL-IN (n = 12)]. Additionally, 12 calves did not receive vaccine or treatment (UNVAC, n = 12). Seven weeks after booster all calves were challenged with BVDV2 and seven days later with BHV1. Blood samples were collected on days -7, 0, 3, 6, 7, 10, 12 and 14 for determination of leukocyte counts and T cell subpopulations (CD4+, CD8+, WC1+ and CD25+). Unvaccinated calves had a significant leukopenia, compared to the vaccinated calves. There was a significant decrease of CD4+ CD8+ T cells over time after BVDV2 challenge, being more pronounced in the UNVAC calves. Calves receiving SC vaccination appeared to have greater CD4+ T cell number compared to the UNVAC calves. Calves treated with ITM had greater CD8+ T cells count than the other groups. Calves in the ITM-IN group had the greatest CD8+ T cell count on days 6 and 7 (P < 0.01). All vaccinated groups had steady response of CD4+CD25+ T cells and a slight increase of CD8+CD25+ T cells. In contrast, UNVAC calves had a significant increase of CD4+CD25+, CD8+CD25+ and WC1+CD25+ T cells on day 14. In conclusion, vaccine administration route and use of injectable trace minerals concurrent with vaccination affected the number CD4+ and CD8+ T cells in response to BVDV2 +BHV1 infection. Trace minerals supplementation concurrent with MLV vaccination might generate an improved cellular immunity against viral infections involved in respiratory disease.

Dietary Zinc Supplementation in Steers Modulates Labile Zinc Concentration and Zinc Transporter Gene Expression in Circulating Immune Cells

Zinc (Zn) is critical for immune function, and marginal Zn deficiency in calves can lead to suboptimal growth and increased disease susceptibility. However, in contrast to other trace minerals such as copper, tissue concentrations of Zn do not change readily in conditions of supplementation or marginal deficiency. Therefore, the evaluation of Zn status remains challenging. Zinc transporters are essential for maintaining intracellular Zn homeostasis, and their expression may indicate changes in Zn status in the animal. Here, we investigated the effects of dietary Zn supplementation on labile Zn concentration and Zn transporter gene expression in circulating immune cells isolated from feedlot steers. Eighteen Angus crossbred steers (261 ± 14 kg) were blocked by body weight and randomly assigned to two dietary treatments: a control diet (58 mg Zn/kg DM, no supplemental Zn) or control plus 150 mg Zn/kg DM (HiZn; 207 mg Zn/kg DM total). After 33 days, Zn supplementation increased labile Zn concentrations (as FluoZin-3 fluorescence) in monocytes, granulocytes, and CD4 T cells (P < 0.05) but had the opposite effect on CD8 and γδ T cells (P < 0.05). Zn transporter gene expression was analyzed on purified immune cell populations collected on days 27 or 28. ZIP11 and ZnT1 gene expression was lower (P < 0.05) in CD4 T cells from HiZn compared to controls. Expression of ZIP6 in CD8 T cells (P = 0.02) and ZnT7 in B cells (P = 0.01) was upregulated in HiZn, while ZnT9 tended (P = 0.06) to increase in B cells from HiZn. These results suggest dietary Zn concentration affects both circulating immune cell Zn concentrations and Zn transporter gene expression in healthy steers.

The ex vivo infection model of the peripheral bovine mononuclear cells (PBMCs) and the bovine spleen cells with the bovine coronavirus (BCoV) induced a differential expression of the host cytokine genes profiles and modulates the virus replication

The adaptive immune response during BCoV infection of peripheral blood mononuclear cells (PBMCs), the bovine spleen cells, and their isolated T lymphocytes was not studied well. Our study confirmed successful BCoV infection in PBMCs and spleen T cells. The BCoV replication was evidenced by measuring genome copy numbers using real-time PCR and expression levels of BCoV spike and nucleocapsid proteins via western blot and immunofluorescence assays. In infected PBMCs, CD4 T-cell levels were 1.45-fold higher, and CD8 T-cell levels were 1.6-fold lower compared to sham-infected cells. Conversely, infected splenocytes showed a 0.88-fold decrease in CD4 T-cells and a 1.88-fold increase in CD8 T-cells. The cytokine gene expression analysis revealed that BCoV infection activated type I interferon and upregulated IL-6 expression in PBMCs and splenocytes. These findings demonstrate that BCoV successfully infects immune cells from PBMCs and spleen, inducing differential host cytokine gene expression that favors virus replication.

The Effect of Saccharomyces cerevisiae Fermentation Product Supplementation on Pro-Inflammatory Cytokines in Holstein Friesian Cattle Experimentally Inoculated with Digital Dermatitis

Digital dermatitis (DD) poses a major animal welfare concern for the dairy industry, with even broader economic implications for the agricultural industry worldwide. The postbiotic, a Saccharomyces cerevisiae fermentation product (SCFP), has had a positive influence on the innate immune system of cattle, which makes it a potential candidate as a feed supplement as part of a prevention strategy for DD. This study investigated the effect of a commercial SCFP feed supplement compared to a control feed supplement on the production of pro-inflammatory cytokines (IL-1β and IL-6) by peripheral blood mononuclear cells (PBMCs) in Holstein Friesian steers experimentally infected with DD. The results showed that SCFP supplementation was associated with an overall reduced IL-1β production (p = 0.005), particularly prior to experimental inoculation with a DD lesion homogenate. However, the results of the analysis suggest that the innate immune system in the SCFP group became prepared to respond more rapidly to DD infection post-inoculation. During active (M2), chronic (M4), and focal flare-ups (M4.1) of DD, SCFP supplementation resulted in a more rapid secretion of IL-1β (M2: p = 0.038; M4/M4/1: p = 0.034). A more rapid response to DD infection for IL-6 was only found for chronic (M4) and focal flare-ups (M4.1) of DD (p = 0.006). These findings emphasize the difference in cytokine response between various stages of DD in the SCFP group compared to the control, highlighting implications for DD prevention and treatment.

Interactions Between Bovine Respiratory Syncytial Virus and Cattle: Aspects of Pathogenesis and Immunity

Bovine respiratory syncytial virus (BRSV) is a major respiratory pathogen in cattle and is relevant to the livestock industry worldwide. BRSV is most severe in young calves and is often associated with stressful management events. The disease is responsible for economic losses due to lower productivity, morbidity, mortality, and prevention and treatment costs. As members of the same genus, bovine and human RSV share a high degree of homology and are similar in terms of their genomes, transmission, clinical signs, and epidemiology. This overlap presents an opportunity for One Health approaches and translational studies, with dual benefits; however, there is still a relative lack of studies focused on BRSV, and the continued search for improved prophylaxis highlights the need for a deeper understanding of its immunological features. BRSV employs different host-immunity-escaping mechanisms that interfere with effective long-term memory responses to current vaccines and natural infections. This review presents an updated description of BRSV's immunity processes, such as the PRRs and signaling pathways involved in BRSV infection, aspects of its pathogeny, and the evading mechanisms developed by the virus to thwart the immune response.

Evidence of innate training in bovine γδ T cells following subcutaneous BCG administration

The Bacillus Calmette Guerin (BCG) vaccine has been shown to induce non-specific protection against diseases other than tuberculosis in vaccinated individuals, attributed to the induction of trained immunity. We have previously demonstrated that BCG administration induces innate immune training in mixed peripheral blood mononuclear cells and monocytes in calves. Gamma Delta (γδ) T cells are non-conventional T cells that exhibit innate and adaptive immune system features. They are in higher proportion in the peripheral blood of cattle than humans or rodents and play an essential role in bovine immune response to pathogens. In the current study, we determined if BCG administration induced innate immune training in bovine γδ T cells. A group of 16 pre-weaned Holstein calves (2-4 d age) were enrolled in the study and randomly assigned to vaccine and control groups (n=8/group). The vaccine group received two doses of 106 colony forming units (CFU) BCG Danish strain subcutaneously, separated by 2 weeks. The control group remained unvaccinated. Gamma delta T cells were purified from peripheral blood using magnetic cell sorting three weeks after receiving the 1st BCG dose. We observed functional changes in the γδ T cells from BCG-treated calves shown by increased IL-6 and TNF-α cytokine production in response to in vitro stimulation with Escherichia coli LPS and PAM3CSK4. ATAC-Seq analysis of 78,278 regions of open chromatin (peaks) revealed that γδ T cells from BCG-treated calves had an altered epigenetic status compared to cells from the control calves. Differentially accessible peaks (DAP) found near the promoters of innate immunity-related genes like Siglec14, Irf4, Ifna2, Lrrfip1, and Tnfrsf10d were 1 to 4-fold more accessible in cells from BCG-treated calves. MOTIF enrichment analysis of the sequences within DAPs, which explores transcription factor binding motifs (TFBM) upstream of regulatory elements, revealed TFBM for Eomes and IRF-5 were among the most enriched transcription factors. GO enrichment analysis of genes proximal to the DAPs showed enrichment of pathways such as regulation of IL-2 production, T-cell receptor signaling pathway, and other immune regulatory pathways. In conclusion, our study shows that subcutaneous BCG administration in pre-weaned calves can induce innate immune memory in the form of trained immunity in γδ T cells. This memory is associated with increased chromatin accessibility of innate immune response-related genes, thereby inducing a functional trained immune response evidenced by increased IL-6 and TNF-α cytokine production.

Effects of increasing supplemental zinc to non-implanted and implanted finishing steers

The effects of supplemental Zn within steroidal implant strategy on performance, carcass characteristics, trace mineral status, and muscle gene expression were tested in a 59-d study using 128 Angus-crossbred steers (492 ± 29 kg) in a 2 × 4 complete randomized design. Implant strategies included no implant (NoIMP) or Component TE-200 (TE200; Elanco, Greenfield, IN) administered on day 0. Zinc was supplemented at 0, 30, 100, or 150 mg Zn/kg dry matter (Zn0, Zn30, Zn100, Zn150, respectively) from ZnSO4. Steers were stratified by body weight (BW) to pens (n = 5 or 6 steers/pen) equipped with GrowSafe bunks (GrowSafe Systems Ltd., Airdrie, AB, Canada) and assigned treatments (n = 15, 16, or 17 steers/treatment). Cattle were weighed on days -1, 0, 18, and 59 with blood collected on days -1, 18, 40, and 59. Muscle samples were collected from the longissimus thoracis on day 11 and liver samples were collected on day 55 or 56. Data were analyzed using the Mixed Procedure of SAS via contrast statements testing the linear and quadratic response to Zn supplementation within implant treatment and NoIMP vs. TE200 for performance, carcass, blood, and liver parameters. Specific contrast statements were formed for the analysis of gene expression in muscle including: Zn0 vs. Zn150 within NoIMP and TE200, NoIMP vs. TE200 (Zn0 and Zn150 only), and the linear effect of supplementing Zn0, Zn100, and Zn150 within TE200. Steer was the experimental unit. Day 18 BW and days 0 to 18 average daily gain (ADG) were linearly increased due to Zn supplementation within TE200 (P ≤ 0.002) in conjunction with a linear increase from Zn in day 11 muscle epidermal growth factor receptor, matrix metalloproteinase 2, and phosphodiesterase 4B gene expression of TE200 steers (P ≤ 0.05). Plasma Zn on days 18 and 40 linearly increased with increasing Zn supplementation regardless of implant treatment (P ≤ 0.03) and was lesser for TE200 than NoIMP steers on day 18 (P = 0.001). Day 59 BW and hot carcass weight (HCW) were greater for TE200 vs. NoIMP (P ≤ 0.002) and HCW of implanted steers tended to linearly increase with increasing Zn supplementation (P = 0.09). No effects of Zn supplementation were observed in NoIMP for HCW, BW, or ADG (P ≥ 0.17). Yield grade and 12th rib fat tended to quadratically decrease within NoIMP (P ≤ 0.09), with Zn100 being the most lean. These data indicate increasing supplemental Zn influences steroidal implant signaling machinery while increasing the Zn status and implant-induced growth of feedlot cattle.

The influence of steroidal implants and manganese sulfate supplementation on growth performance, trace mineral status, hepatic gene expression, hepatic enzyme activity, and circulating metabolites in feedlot steers

Angus-cross steers (n = 144; 359 kg ± 13.4) were used to assess the effect of dietary Mn and steroidal implants on performance, trace minerals (TM) status, hepatic enzyme activity, hepatic gene expression, and serum metabolites. Steers (n = 6/pen) were stratified by BW in a 3 × 2 factorial. GrowSafe bunks recorded individual feed intake (experimental unit = steer; n = 24/treatment). Dietary treatments included (MANG; 8 pens/treatment; Mn as MnSO4): (1) no supplemental Mn (analyzed 14 mg Mn/kg DM; Mn0); (2) 20 mg supplemental Mn/kg DM (Mn20); (3) 50 mg supplemental Mn/kg DM (Mn50). Within MANG, steers received a steroidal implant treatment (IMP) on day 0: (1) no implant; NO; or (2) combination implant (Revalor-200; REV). Liver biopsies for TM analysis and qPCR, and blood for serum glucose, insulin, non-esterified fatty acids, and urea-N (SUN) analysis were collected on days 0, 20, 40, and 77. Data were analyzed as a randomized complete block with a factorial arrangement of treatments including fixed effects of Mn treatment (MANG) and implant (IMP) using PROC MIXED of SAS 9.4 using initial BW as a covariate. Liver TM, serum metabolite, enzyme activity, and gene expression data were analyzed as repeated measures. No MANG × IMP effects were noted (P ≥ 0.12) for growth performance or carcass characteristic measures. Dietary Mn did not influence final body weight, overall ADG, or overall G:F (P ≥ 0.14). Liver Mn concentration increased with supplemental Mn concentration (MANG; P = 0.01). An IMP × DAY effect was noted for liver Mn (P = 0.01) where NO and REV were similar on day 0 but NO cattle increased liver Mn from days 0 to 20 while REV liver Mn decreased. Relative expression of MnSOD in the liver was greater in REV (P = 0.02) compared to NO and within a MANG × IMP effect (P = 0.01) REV increased liver MnSOD activity. These data indicate current NASEM Mn recommendations are adequate to meet the demands of finishing beef cattle given a steroidal implant. Despite the roles of Mn in metabolic pathways and antioxidant defense, a basal diet containing 14 mg Mn/kg DM was sufficient for the normal growth of finishing steers. This study also provided novel insight into how implants and supplemental Mn influence genes related to arginine metabolism, urea synthesis, antioxidant capacity, and TM homeostasis as well as arginase and MnSOD activity in hepatic tissue of beef steers.

Immune phenotype is differentially affected by changing the type of bovine respiratory disease vaccine administered at revaccination in beef heifers

During preconditioning, modified-live vaccines are frequently administered to beef calves before weaning. In this study, we began to characterize the immune phenotype of calves that received a modified-live vaccination at 3-4 months of age and then either received the same modified-live or an inactivated vaccine upon arrival at the feedlot (weaning) and 28 days post-arrival (booster). Innate and adaptive immune measures were assessed before revaccination and 14 and 28 days post. Heifers that received three doses of the modified-live vaccine exhibited a relatively balanced immune response based on increases in mean cytokine concentrations (IL-17, IL-21) and total immunoglobulin-G (IgG) and subsets IgG1 and IgG2, which are related to both arms of the adaptive immune system. Conversely, heifers that received one dose of modified live and two doses of the inactivated vaccine had a more robust neutrophil chemotactic response and greater serum-neutralizing antibody titers, resulting in an enhanced innate immune and a skewed proinflammatory response. These results indicate that the revaccination protocol used after initial vaccination with a modified-live vaccine differentially influences the immune phenotype of beef calves, with three doses of modified live inducing potentially immune homeostasis and a combination of modified live and inactivated vaccines inducing a skewed immune phenotype. However, more research is needed to determine the protective efficacy of these vaccination protocols against disease.

Effects of feeding a Saccharomyces cerevisiae fermentation product and ractopamine hydrochloride to finishing beef steers on growth performance, immune system, and muscle gene expression

The objective of this study was to determine impacts on immune parameters, anti-oxidant capacity, and growth of finishing steers fed a Saccharomyces cerevisiae fermentation product (SCFP; NaturSafe; Diamond V, Cedar Rapids, IA) and ractopamine hydrochloride (RAC; Optaflexx; Elanco Animal Health, Greenfield, IN). Angus-crossbred steers (N = 288) from two sources were utilized in this 90-d study. Steers were blocked by source, stratified by initial body weight to pens of six steers, and pens randomly assigned to treatments (16 pens per treatment). Three treatments compared feeding no supplemental SCFP (control; CON) and supplemental SCFP for 57 d (SCFP57), and 29 d (SCFP29) before harvest. Supplementation of SCFP was 12 g per steer per d, and all steers were fed RAC at 300 mg per steer per d for 29 d before harvest. Blood samples were collected from3 steers per pen, and muscle samples were collected from 1 steer per pen at 57, 29 (start of RAC), and 13 (midRAC) days before harvest. Blood was analyzed from 2 steers per pen for ferric reducing anti-oxidant power (FRAP). Muscle gene expression of myokines, markers of anti-oxidant and growth signaling were assessed. Individual animal BW were also collected on 57, 29, 13, and 1 d before being harvested at a commercial facility (National Beef, Tama, IA). Data were analyzed using the Mixed procedure of SAS 9.4 (Cary, NC) with pen as the experimental unit. The model included fixed effects of treatment and group. Increased BW compared to CON was observed days -29, -13, and -1 in SCFP57 steers (P ≤ 0.05), with SCFP29 being intermediate days -13 and -1. Overall G:F was improved in SCFP29 and SCFP57 (P = 0.01). On day -29, FRAP was greater in SCFP57 than CON (P = 0.02). The percent of gamma delta T cells and natural killer cells in both SCFP29 and SCFP57 was greater than CON on day -13 (P = 0.02). There were no treatment × day effects for muscle gene expression measured (P ≥ 0.25). Interleukin 6 tended to decrease in SCFP29 and SCFP57 on day -13 (P = 0.10). No other treatment effects were observed for muscle gene expression. Muscle gene expression of interleukin 15 was increased (P = 0.01), and expression of interleukin 8 was decreased (P = 0.03) due to RAC feeding. Increased growth in SCFP-fed cattle may be related to changes in anti-oxidant capacity and the immune system.

The trehalose glycolipid C18Brar promotes antibody and T-cell immune responses to Mannheimia haemolytica and Mycoplasma ovipneumoniae whole cell antigens in sheep

Bronchopneumonia is a common respiratory disease in livestock. Mannheimia haemolytica is considered the main causative pathogen leading to lung damage in sheep, with Mycoplasma ovipneumoniae and ParaInfluenza virus type 3, combined with adverse physical and physiological stress, being predisposing factors. A balance of humoral and cellular immunity is thought to be important for protection against developing respiratory disease. In the current study, we compared the ability of the trehalose glycolipid adjuvant C18Brar (C18-alkylated brartemicin analogue) and three commercially available adjuvant systems i.e., Quil-A, Emulsigen-D, and a combination of Quil-A and aluminium hydroxide gel, to stimulate antibody and cellular immune responses to antigens from inactivated whole cells of M. haemolytica and M. ovipneumoniae in sheep. C18Brar and Emulsigen-D induced the strongest antigen-specific antibody responses to both M. haemolytica and M. ovipneumoniae, while C18Brar and Quil-A promoted the strongest antigen-specific IL-17A responses. The expression of genes with known immune functions was determined in antigen-stimulated blood cultures using Nanostring nCounter technology. The expression levels of CD40, IL22, TGFB1, and IL2RA were upregulated in antigen-stimulated blood cultures from animals vaccinated with C18Brar, which is consistent with T-cell activation. Collectively, the results demonstrate that C18Brar can promote both antibody and cellular responses, notably Th17 immune responses in a ruminant species.

Impact of preweaning vaccination on host gene expression and antibody titers in healthy beef calves

The impact of preweaning vaccination for bovine respiratory viruses on cattle health and subsequent bovine respiratory disease morbidity has been widely studied yet questions remain regarding the impact of these vaccines on host response and gene expression. Six randomly selected calves were vaccinated twice preweaning (T1 and T3) with a modified live vaccine for respiratory pathogens and 6 randomly selected calves were left unvaccinated. Whole blood samples were taken at first vaccination (T1), seven days later (T2), at revaccination and castration (T3), and at weaning (T4), and utilized for RNA isolation and sequencing. Serum from T3 and T4 was analyzed for antibodies to BRSV, BVDV1a, and BHV1. Sequenced RNA for all 48 samples was bioinformatically processed with a HISAT2/StringTie pipeline, utilizing reference guided assembly with the ARS-UCD1.2 bovine genome. Differentially expressed genes were identified through analyzing the impact of time across all calves, influence of vaccination across treatment groups at each timepoint, and the interaction of time and vaccination. Calves, regardless of vaccine administration, demonstrated an increase in gene expression over time related to specialized proresolving mediator production, lipid metabolism, and stimulation of immunoregulatory T-cells. Vaccination was associated with gene expression related to natural killer cell activity and helper T-cell differentiation, enriching for an upregulation in Th17-related gene expression, and downregulated genes involved in complement system activity and coagulation mechanisms. Type-1 interferon production was unaffected by the influence of vaccination nor time. To our knowledge, this is the first study to evaluate mechanisms of vaccination and development in healthy calves through RNA sequencing analysis.

Understanding the mechanisms of viral and bacterial coinfections in bovine respiratory disease: a comprehensive literature review of experimental evidence

Bovine respiratory disease (BRD) is one of the most important diseases impacting the global cattle industry, resulting in significant economic loss. Commonly referred to as shipping fever, BRD is especially concerning for young calves during transport when they are most susceptible to developing disease. Despite years of extensive study, managing BRD remains challenging as its aetiology involves complex interactions between pathogens, environmental and host factors. While at the beginning of the twentieth century, scientists believed that BRD was only caused by bacterial infections ("bovine pasteurellosis"), we now know that viruses play a key role in BRD induction. Mixtures of pathogenic bacteria and viruses are frequently isolated from respiratory secretions of animals with respiratory illness. The increased diagnostic screening data has changed our understanding of pathogens contributing to BRD development. In this review, we aim to comprehensively examine experimental evidence from all existing studies performed to understand coinfections between respiratory pathogens in cattle. Despite the fact that pneumonia has not always been successfully reproduced by in vivo calf modelling, several studies attempted to investigate the clinical significance of interactions between different pathogens. The most studied model of pneumonia induction has been reproduced by a primary viral infection followed by a secondary bacterial superinfection, with strong evidence suggesting this could potentially be one of the most common scenarios during BRD onset. Different in vitro studies indicated that viral priming may increase bacterial adherence and colonization of the respiratory tract, suggesting a possible mechanism underpinning bronchopneumonia onset in cattle. In addition, a few in vivo studies on viral coinfections and bacterial coinfections demonstrated that a primary viral infection could also increase the pathogenicity of a secondary viral infection and, similarly, dual infections with two bacterial pathogens could increase the severity of BRD lesions. Therefore, different scenarios of pathogen dynamics could be hypothesized for BRD onset which are not limited to a primary viral infection followed by a secondary bacterial superinfection.

Effect of increasing zinc supplementation on post-transit performance, behavior, blood and muscle metabolites, and gene expression in growing beef feedlot steers

Fifty-four Angus-cross steers (297 kg ± 12) were stratified by body weight (BW) to pens (six steers per pen) to determine the effects of supplemental Zn on posttransit growth performance and blood and muscle metabolites. Dietary treatments started 25 d before trucking: control (CON; analyzed 54 mg Zn/kg DM), industry (IND; CON + 70 mg supplemental Zn/kg DM), and supranutritional Zn (SUPZN; CON + 120 mg supplemental Zn/kg DM). Supplemental Zn was bis-glycinate bound Zn (Plexomin Zn; Phytobiotics North America, Cary, NC). On day 0, steers were loaded onto a commercial trailer and transported in 18 h (1,822 km). Individual BW was recorded on days –26, –25, –1, and 0 (pre-transit), 1 (posttransit), 6, 27, and 28. Blood was collected on days –1, 1, 6, and 27. Longissimus thoracis biopsies were collected on days –1, 1, and 28. Daily individual feed disappearance was recorded via GrowSafe bunks. Data were analyzed using Proc Mixed of SAS with fixed effect of diet and steer as the experimental unit (growth performance, blood: n = 18 steers per treatment; muscle: n = 12 steers per treatment). Individual initial BW was used as a covariate in BW analysis. Contrast statements to test linear, quadratic, and Zn effects were used to analyze performance and blood parameters. Repeated measures analysis was used for posttransit DMI recovery and weekly posttransit DMI and Zn intake with the repeated effect of time. MetaboAnalyst 5.0 was utilized for statistical analysis of day 1 (off truck) muscle metabolites. Plasma Zn linearly increased due to Zn on days 1, 6, and 27 (P = 0.01), and off-truck (day 1) serum lactate increased over day –1 by 20%, 0%, and 20% in CON, IND, and SUPZN, respectively (Quadratic: P = 0.01). Muscle lactate tended to increase posttransit in CON and IND (P ≤ 0.07) but not SUPZN. Muscle metabolites relating to amino acid and nitrogen metabolism were increased in all treatments posttransit (P ≤ 0.02), and alanine-glucose cycle metabolites tended to increase in CON and IND (P ≤ 0.07). Steers supplemented with Zn recovered pretransit DMI quicker than CON (by d 2: P = 0.01), while IND had greater overall posttransit DMI than CON with SUPZN intermediate (P = 0.04), and Zn-fed steers had greater ADG posttransit (P = 0.04). Zinc supplementation mitigated muscle or serum lactate increases due to transit and increased posttransit ADG.

Transcriptional programming and gene regulation in WC1+ γδ T cell subpopulations

γδ T cells represent a high proportion of lymphocytes in the blood of ruminants with the majority expressing lineage-specific glycoproteins from the WC1 family. WC1 receptors are coded for by a multigenic array whose genes have variegated but stable expression among cells in the γδ T cell population. WC1 molecules function as hybrid pattern recognition receptors as well as co-receptors for the TCR and are required for responses by the cells. Because of the variegated gene expression, WC1⁺ γδ T cells can be divided into two main populations known as WC1.1⁺ and WC1.2⁺ based on monoclonal antibody reactivity with the expressed WC1 molecules. These subpopulations differ in their ability to respond to specific pathogens. Here, we showed these populations are established in the thymus and that WC1.1⁺ and WC1.2⁺ subpopulations have transcriptional programming that is consistent with stratification towards Tγδ1 or Tγδ17. WC1.1⁺ cells exhibited the Tγδ1 phenotype with greater transcription of Tbx21 and production of more IFNγ while the WC1.2⁺ subpopulation tended towards Tγδ17 programming producing higher levels of IL-17 and had greater transcription of Rorc. However, when activated both WC1⁺ subpopulations' cells transcribed Tbx21 and secreted IFNγ and IL-17 reflecting the complexity of these subpopulations defined by WC1 gene expression. The gene networks involved in development of these two subpopulations including expression of their archetypal genes wc1-3 (WC1.1⁺) and wc1-4 (WC1.2⁺) were unknown but we report that SOX-13, a γδ T cell fate-determining transcription factor, has differential occupancy on these WC1 gene loci and suggest a model for development of these subpopulations.

Use of Thoracic Ultrasonography to Improve Disease Detection in Experimental BRD Infection

Bovine respiratory disease (BRD) is caused by complex interactions between viral and bacterial pathogens, host immune status, and environmental stressors. In both clinical and research settings, current methods for detecting BRD in calves commonly focus on visual indicators such as attitude, nasal discharge, and cough, in addition to vital signs such as rectal temperature and respiration rate. Recently, thoracic ultrasonography (TUS) has become more commonly used in clinical settings, in addition to physical examination to diagnose BRD. To assess the value of performing TUS during experimental BRD infection, 32 calves were challenged with bovine respiratory syncytial virus, to mimic a viral infection, and 30 calves were infected with Mannheimia haemolytica, to mimic a bacterial infection. TUS was performed at regular intervals using a standardized method and scoring system in addition to daily clinical scoring. Although overall correlations between clinical scores and TUS scores were generally weak (maximum R2 = 0.3212), TUS identified calves with abnormal lung pathology that would have otherwise been misclassified on the basis of clinical scoring alone, both on arrival and throughout the studies. In addition, TUS had an increased correlation with gross lung pathology on necropsy (maximum R2 = 0.5903), as compared to clinical scoring (maximum R2 = 0.3352). Our results suggest that TUS can provide additional information on calf health at enrollment and throughout a study and may provide an alternative to terminal studies, due to the high correlation with lung pathology at necropsy.

The Effects of Ursolic Acid Treatment on Immunopathogenesis Following Mannheimia haemolytica Infections

Bovine respiratory disease complex (BRDC) is a costly economic and health burden for the dairy and feedlot cattle industries. BRDC is a multifactorial disease, often involving viral and bacterial pathogens, which makes it difficult to effectively treat or vaccinate against. Mannheimia haemolytica (MH) are common commensal bacteria found in the nasopharynx of healthy cattle; however, following environmental and immunological stressors, these bacteria can rapidly proliferate and spread to the lower respiratory tract, giving rise to pneumonic disease. Severe MH infections are often characterized by leukocyte infiltration and dysregulated inflammatory responses in the lungs. IL-17A is thought to play a key role in this inflammatory response by inducing neutrophilia, activating innate and adaptive immune cells, and further exacerbating lung congestion. Herein, we used a small molecule inhibitor, ursolic acid (UA), to suppress IL-17A production and to determine the downstream impact on the immune response and disease severity following MH infection in calves. We hypothesized that altering IL-17A signaling during MH infections may have therapeutic effects by reducing immune-mediated lung inflammation and improving disease outcome. Two independent studies were performed (Study 1 = 32 animals and Study 2 = 16 animals) using 4-week-old male Holstein calves, which were divided into 4 treatment group including: (1) non-treated and non-challenged, (2) non-treated and MH-challenged, (3) UA-treated and non-challenged, and (4) UA-treated and MH-challenged. Based on the combined studies, we observed a tendency (p = 0.0605) toward reduced bacterial burdens in the lungs of UA-treated animals, but did not note a significant difference in gross (p = 0.3343) or microscopic (p = 0.1917) pathology scores in the lungs. UA treatment altered the inflammatory environment in the lung tissues following MH infection, reducing the expression of IL-17A (p = 0.0870), inflammatory IL-6 (p = 0.0209), and STAT3 (p = 0.0205) compared to controls. This reduction in IL-17A signaling also appeared to alter the downstream expression of genes associated with innate defenses (BAC5, DEFB1, and MUC5AC) and lung remodeling (MMP9 and TIMP-1). Taken together, these results support our hypothesis that IL-17A signaling may contribute to lung immunopathology following MH infections, and further understanding of this inflammatory pathway could expand therapeutic intervention strategies for managing BRDC.

Initial Liver Copper Status in Finishing Beef Steers Fed Three Dietary Concentrations of Copper Affects Beta Agonist Performance, Carcass Characteristics, Lipolysis Response, and Muscle Inflammation Markers

Simple Summary

Beta agonists are commonly used in the United States beef industry, offering improved performance in the days leading up to harvest by influencing energy metabolism. Copper has been shown to regulate the biological pathway leading to increased lipid mobilization. However, this connection has not been evaluated in cattle. Therefore, the objective of this study was to determine how Cu influences beta agonist-induced performance, energy metabolism and inflammation in feedlot cattle. Supplementation of Cu resulted in increased liver Cu concentrations, while cattle performance, lipolysis, and some markers of inflammation responded to Cu supplementation differently, depending on whether or not cattle were fed a beta agonist. Therefore, strategic supplementation of Cu may help optimize growth of cattle receiving a beta agonist.

Abstract

Ninety-three Angus-crossbred steers (470 ± 35 kg) were assigned to a 3 × 2 factorial to determine the effects of Cu status and beta agonist (BA) on performance, carcass characteristics, lipolytic rate, and muscle inflammation. Factors included Cu supplementation (mg Cu/kg dry matter (DM)) at: 0 (LO), 10 (MED), or 20 (HI) from Cu amino acid complex (Availa Cu; Zinpro) with no BA (NoRAC) or 300 mg·steer⁻¹·day⁻¹ of ractopamine hydrochloride (RAC; Optaflexx; Elanco) for final 28 days of 88-day trial. Linear and quadratic effects of Cu status within BA treatment were tested. Pre-BA gain was not affected by Cu supplementation (p ≥ 0.57), although day 53 liver Cu quadratically increased (p = 0.01). Average daily gain and muscle IL-8 gene expression quadratically increased (p ≤ 0.01), with MED having greatest gain and gene expression. Ribeye area tended to quadratically increase with Cu supplementation within RAC (p = 0.08). In vitro basal lipolytic rate tended to quadratically increase with Cu supplementation within RAC (p = 0.11), while stimulated lipolytic rate tended to linearly increase within NoRAC (p = 0.10). These data suggest lipolysis and the BA response of steers are influenced by dietary and liver Cu concentrations.

Effect of bis-glycinate bound zinc or zinc sulfate on zinc metabolism in growing lambs

To assess the efficacy of bis-glycinate bound Zn, 36 crossbred wethers (34 ± 2 kg) were sorted by body weight into three groups and stagger started on a Zn-deficient diet (18 mg Zn/kg dry matter [DM]; 22.5% neutral detergent fiber [NDF]) for 45 d prior to a 15-d metabolism period (10 d adaptation and 5 d collection). On day 46, lambs were randomly assigned to dietary treatments (four lambs treatment⁻¹group⁻¹): no supplemental Zn (CON) or 15 mg supplemental Zn/kg DM (ZINC) as Zn sulfate (ZS) or bis-glycinate (GLY; Plexomin Zn, Phytobiotics). Blood was collected from all lambs on days 1, 44, 56, and 61. Liver, jejunum, and longissimus dorsi samples were collected after euthanasia on day 61. Gene expression was determined via quantitative real-time polymerase chain reaction. Data were analyzed using ProcMixed of SAS (experimental unit = lamb; fixed effects = treatment, group, and breed) and contrast statements assessed the effects of supplemental Zn concentration (ZINC vs. CON) and source (GLY vs. ZS). After 15 d of Zn supplementation, plasma Zn concentrations were greater for ZINC vs. CON and GLY vs. ZS (P ≤ 0.01); tissue Zn concentrations were unaffected (P ≥ 0.27). Liver Cu concentrations were lesser for ZINC vs. CON (P = 0.03). Longissimus dorsi Mn concentrations were greater for ZINC vs. CON (P = 0.05) and tended to be lesser for GLY vs. ZS (P = 0.09). Digestibility of DM, organic matter (OM), and NDF was lesser for ZINC vs. CON (P ≤ 0.05); acid detergent fiber digestibility tended to be greater for GLY vs. ZS (P = 0.06). Nitrogen retention (g/d) tended to be greater for GLY vs. ZS (P = 0.10), and N apparent absorption was lesser for ZINC vs. CON (P = 0.02). Zinc intake, fecal output, retention, and apparent absorption were greater for ZINC vs. CON (P ≤ 0.01). Apparent absorption of Zn was −5.1%, 12.8%, and 15.0% for CON, ZS, and GLY, respectively. Nitrogen and Zn retention and apparent absorption were not correlated for CON (P ≥ 0.14) but were positively correlated for ZINC (retention: P = 0.02, r = 0.52; apparent absorption: P < 0.01, r = 0.73). Intestinal expression of Zn transporter ZIP4 was lesser for ZINC vs. CON (P = 0.02). Liver expression of metallothionein-1 (MT1) tended to be greater for GLY vs. ZS (P = 0.07). Although Zn apparent absorption did not differ between sources (P = 0.71), differences in post-absorptive metabolism may be responsible for greater plasma Zn concentrations and liver MT1 expression for GLY-supplemented lambs, suggesting improved bioavailability of GLY relative to ZS.

Mucosal IFNγ production and potential role in protection in Escherichia coli O157:H7 vaccinated and challenged cattle

Shiga-toxin producing Escherichia coli O157:H7 (O157)-based vaccines can provide a potential intervention strategy to limit foodborne zoonotic transmission of O157. While the peripheral antibody response to O157 vaccination has been characterized, O157-specific cellular immunity at the rectoanal junction (RAJ), a preferred site for O157 colonization, remains poorly described. Vaccine induced mucosal O157-specific antibodies likely provide some protection, cellular immune responses at the RAJ may also play a role in protection. Distinct lymphoid follicles were increased in the RAJ of vaccinated/challenged animals. Additionally, increased numbers of interferon (IFN)γ-producing cells and γδ + T cells were detected in the follicular region of the RAJ of vaccinated/challenged animals. Likewise, adjuvanted-vaccine formulation is critical in immunogenicity of the O157 parenteral vaccine. Local T cell produced IFNγ may impact epithelial cells, subsequently limiting O157 adherence, which was demonstrated using in vitro attachment assays with bovine epithelial cells. Thus, distinct immune changes induced at the mucosa of vaccinated and challenged animals provide insight of mechanisms associated with limiting O157 fecal shedding. Enhancing mucosal immunity may be critical in the further development of efficacious vaccines for controlling O157 in ruminants and thus limiting O157 transmission to humans.

The Bacterial and Viral Agents of BRDC: Immune Evasion and Vaccine Developments

Bovine respiratory disease complex (BRDC) is a multifactorial disease of cattle which presents as bacterial and viral pneumonia. The causative agents of BRDC work in synergy to suppress the host immune response and increase the colonisation of the lower respiratory tracts by pathogenic bacteria. Environmental stress and/or viral infection predispose cattle to secondary bacterial infections via suppression of key innate and adaptive immune mechanisms. This allows bacteria to descend the respiratory tract unchallenged. BRDC is the costliest disease among feedlot cattle, and whilst vaccines exist for individual pathogens, there is still a lack of evidence for the efficacy of these vaccines and uncertainty surrounding the optimum timing of delivery. This review outlines the immunosuppressive actions of the individual pathogens involved in BRDC and highlights the key issues in the development of vaccinations against them.

Special features of γδ T cells in ruminants

Ruminant γδ T cells were discovered in the mid-1980's shortly after a novel T cell receptor (TCR) gene from murine cells was described in 1984 and the murine TCRγ gene locus in 1985. It was possible to identify γδ T cell populations early in ruminants because they represent a large proportion of the peripheral blood mononuclear cells (PBMC). This null cell population, γδ T cells, was designated as such by its non-reactivity with monoclonal antibodies (mAb) against ovine and bovine CD4, CD8 and surface immunoglobulin (Ig). γδ T cells are non-conventional T cells known as innate-like cells capable of using both TCR as well as other types of receptor systems including pattern recognition receptors (PRR) and natural killer receptors (NKR). Bovine γδ T cells have been shown to respond to stimulation through toll-like receptors, NOD, and NKG2D as well as to cytokines alone, protein and non-protein antigens through their TCR, and to pathogen-infected host cells. The two main populations of γδ T cells are distinguished by the presence or absence of the hybrid co-receptor/PRR known as WC1 or T19. These two populations not only differ by their proportional representation in various tissues and organs but also by their migration into inflamed tissues. The WC1⁺ cells are found in the blood, skin and spleen while the WC1^- γδ T cells predominate in the gut, mammary gland and uterus. In ruminants, γδ T cells may produce IFNγ, IL-17, IL-10 and TGFβ, have cytotoxic activity and memory responses. The expression of particular WC1 family members controls the response to particular pathogens and correlates with differences in cytokine responses. The comparison of the WC1 gene families in cattle, sheep and goats is discussed relative to other multigenic arrays that differentiate γδ T cells by function in humans and mice.

Single-Shot Vaccines against Bovine Respiratory Syncytial Virus (BRSV): Comparative Evaluation of Long-Term Protection after Immunization in the Presence of BRSV-Specific Maternal Antibodies

The induction of long-lasting clinical and virological protection is needed for a successful vaccination program against the bovine respiratory syncytial virus (BRSV). In this study, calves with BRSV-specific maternally derived antibodies were vaccinated once, either with (i) a BRSV pre-fusion protein (PreF) and Montanide^TM ISA61 VG (ISA61, n = 6), (ii) BRSV lacking the SH gene (ΔSHrBRSV, n = 6), (iii) a commercial vaccine (CV, n = 6), or were injected with ISA61 alone (n = 6). All calves were challenged with BRSV 92 days later and were euthanized 13 days post-infection. Based on clinical, pathological, and proteomic data, all vaccines appeared safe. Compared to the controls, PreF induced the most significant clinical and virological protection post-challenge, followed by ΔSHrBRSV and CV, whereas the protection of PreF-vaccinated calves was correlated with BRSV-specific serum immunoglobulin (Ig)G antibody responses 84 days post-vaccination, and the IgG antibody titers of ΔSHrBRSV- and CV-vaccinated calves did not differ from the controls on this day. Nevertheless, strong anamnestic BRSV- and PreF-specific IgG responses occurred in calves vaccinated with either of the vaccines, following a BRSV challenge. In conclusion, PreF and ΔSHrBRSV are two efficient one-shot candidate vaccines. By inducing a protection for at least three months, they could potentially improve the control of BRSV in calves.

A multifunctional nanoparticle as a prophylactic and therapeutic approach targeting respiratory syncytial virus

Respiratory Syncytial Virus (RSV) has been a major health concern globally for decades, yet no effective prophylactic or treatment regimen is available. The key viral proteins responsible for RSV pathology include the fusion protein (F), the immunomodulatory non-structural-protein 1 (NS1) and the phosphoprotein (P) involved in viral replication. Herein, we developed a novel shell-core multifunctional nanosystem with dual payload: a plasmid construct encoding for shRNAs against NS1 and P, and an anti-fusion peptide (HR2D). Anti-ICAM1 antibody conjugated on the nanoparticle (NP) surface is used to target RSV infected cells. Our data show the potential of this nanosystem as a prophylactic and/or a therapeutic regimen against RSV infection. Furthermore, therapy of RSV infected mice with this nanosystem, in addition to reducing viral load, modulated expression of Th2 and allergy-associated cytokines such as IL4, IL-13 and IL-17 indicating a direct role of this nanosystem in the mechanisms involved in the immunoregulation of disease pathogenesis.

Effect of aerosolized bacterial lysate on development of naturally occurring respiratory disease in beef calves

Background

Bovine respiratory disease (BRD) is a major problem affecting beef cattle after arrival to feedlots. Alternatives to antibiotics are needed for prevention.

Hypothesis

Stimulation of pulmonary innate immune responses at the time of arrival to a feedlot reduces the occurrence and severity of BRD.

Animals

Sixty beef steers at high risk of BRD.

Methods

Randomized, double‐blinded, placebo‐controlled study. Calves received saline or a lysate of Staphylococcus aureus and Escherichia coli by aerosol, at 16 hours after feedlot arrival. Calves were monitored for 28 days for disease outcomes and levels of Mycoplasma bovis and Mannheimia haemolytica in nasal swabs.

Results

Death from M bovis pneumonia was significantly greater in lysate‐treated animals (6/29, 24%) compared to controls (1/29, 3%; odds ratio = 10.2; 95% confidence interval [CI] = 1.1‐96.0; P = .04). By 28 days after arrival, 29/29 lysate‐treated calves had ultrasonographic pulmonary consolidation compared to 24/29 control calves (P = .05). Lysate‐treated calves had lower weight gain compared to control calves (−8.8 kg, 95% CI = −17.1 to −0.5; P = .04), and higher body temperatures on days 4, 7, and 21 (0.19°C; 95% CI = 0.01‐0.37; P = .04). Nasal M bovis numbers increased over time and were higher in lysate‐treated calves (0.76 log CFU, 95% CI = 0.3‐1.2; P = .001).

Conclusions and Clinical Importance

Aerosol administration of a bacterial lysate exacerbated BRD in healthy high‐risk beef calves, suggesting that respiratory tract inflammation adversely affects how calves respond to subsequent natural infection with M bovis and other respiratory pathogens.

Common and Differential Dynamics of the Function of Peripheral Blood Mononuclear Cells between Holstein and Jersey Cows in Heat-Stress Environment

Simple Summary

Seasonal change, particularly changing to hot and humid season, has a negative effect on dairy cows in various ways, including productivity, reproduction, metabolism, and immunity. In high-temperature and humid weather, dairy cows are vulnerable to diseases by weakened immune system. However, the cause of this has not been fully described. Therefore, this study aims to understand changes of specific gene expression and immune pathways based on transcriptome analysis from peripheral blood mononuclear cells of Holstein and Jersey dairy cows between normal and heat-stress environmental conditions. We observed that the two breeds of dairy cow have common and different immune shifts according to the changes of temperature and humidity condition. Overall, the findings of this study improve the understanding of the underlying mechanisms by which seasonal changes affect dairy cow immunity.

Abstract

Heat stress has been reported to affect the immunity of dairy cows. However, the mechanisms through which this occurs are not fully understood. Two breeds of dairy cow, Holstein and Jersey, have distinct characteristics, including productivity, heat resistance, and disease in high-temperature environments. The objective of this study is to understand the dynamics of the immune response of two breeds of dairy cow to environmental change. Ribonucleic acid sequencing (RNA-seq) results were analyzed to characterize the gene expression change of peripheral blood mononuclear cells (PBMCs) in Holstein and Jersey cows between moderate temperature-humidity index (THI) and high THI environmental conditions. Many of the differentially expressed genes (DEGs) identified are associated with critical immunological functions, particularly phagocytosis, chemokines, and cytokine response. Among the DEGs, CXCL3 and IL1A were the top down-regulated genes in both breeds of dairy cow, and many DEGs were related to antimicrobial immunity. Functional analysis revealed that cytokine and chemokine response-associated pathways in both Holstein and Jersey PBMCs were the most important pathways affected by the THI environmental condition. However, there were also breed-specific genes and pathways that altered according to THI environmental condition. Collectively, there were both common and breed-specific altered genes and pathways in Holstein and Jersey cows. The findings of this study expand our understanding of the dynamics of immunity in different breeds of dairy cow between moderate THI and high THI environmental conditions.

Supplementing a Saccharomyces cerevisiae fermentation product modulates innate immune function and ameliorates bovine respiratory syncytial virus infection in neonatal calves

The objectives of this study were to determine the effects of oral supplementation with Saccharomyces cerevisiae fermentation products (SCFP; SmartCare and NutriTek; Diamond V, Cedar Rapids, IA) on immune function and bovine respiratory syncytial virus (BRSV) infection in preweaned dairy calves. Twenty-four Holstein × Angus, 1- to 2-d-old calves (38.46 ± 0.91 kg initial body weight [BW]) were assigned two treatment groups: control or SCFP treated, milk replacer with 1 g/d SCFP (SmartCare) and calf starter top-dressed with 5 g/d SCFP (NutriTek). The study consisted of one 31-d period. On days 19 to 21 of the supplementation period, calves were challenged via aerosol inoculation with BRSV strain 375. Calves were monitored twice daily for clinical signs, including rectal temperature, cough, nasal and ocular discharge, respiration effort, and lung auscultation. Calves were euthanized on day 10 postinfection (days 29 to 31 of the supplementation period) to evaluate gross lung pathology and pathogen load. Supplementation with SCFP did not affect BW (P = 0.762) or average daily gain (P = 0.750), percentages of circulating white blood cells (P < 0.05), phagocytic (P = 0.427 for neutrophils and P = 0.460 for monocytes) or respiratory burst (P = 0.119 for neutrophils and P = 0.414 for monocytes) activity by circulating leukocytes either before or following BRSV infection, or serum cortisol concentrations (P = 0.321) after BRSV infection. Calves receiving SCFP had reduced clinical disease scores compared with control calves (P = 0.030), reduced airway neutrophil recruitment (P < 0.002), reduced lung pathology (P = 0.031), and a reduced incidence of secondary bacterial infection. Calves receiving SCFP shed reduced virus compared with control calves (P = 0.049) and tended toward lower viral loads in the lungs (P = 0.051). Immune cells from the peripheral blood of SCFP-treated calves produced increased (P < 0.05) quantities of interleukin (IL)-6 and tumor necrosis factor-alpha in response to toll-like receptor stimulation, while cells from the bronchoalveolar lavage (BAL) of SCFP-treated calves secreted less (P < 0.05) proinflammatory cytokines in response to the same stimuli. Treatment with SCFP had no effect on virus-specific T cell responses in the blood but resulted in reduced (P = 0.045) virus-specific IL-17 secretion by T cells in the BAL. Supplementing with SCFP modulates both systemic and mucosal immune responses and may improve the outcome of an acute respiratory viral infection in preweaned dairy calves.

Type 3 immunity: a perspective for the defense of the mammary gland against infections

Type 3 immunity encompasses innate and adaptive immune responses mediated by cells that produce the signature cytokines IL-17A and IL-17F. This class of effector immunity is particularly adept at controlling infections by pyogenic extracellular bacteria at epithelial barriers. Since mastitis results from infections by bacteria such as streptococci, staphylococci and coliform bacteria that cause neutrophilic inflammation, type 3 immunity can be expected to be mobilized at the mammary gland. In effect, the main defenses of this organ are provided by epithelial cells and neutrophils, which are the main terminal effectors of type 3 immunity. In addition to theoretical grounds, there is observational and experimental evidence that supports a role for type 3 immunity in the mammary gland, such as the production of IL-17A, IL-17F, and IL-22 in milk and mammary tissue during infection, although their respective sources remain to be fully identified. Moreover, mouse mastitis models have shown a positive effect of IL-17A on the course of mastitis. A lot remains to be uncovered before we can safely harness type 3 immunity to reinforce mammary gland defenses through innate immune training or vaccination. However, this is a promising way to find new means of improving mammary gland defenses against infection.

Host Tolerance to Infection with the Bacteria that Cause Bovine Respiratory Disease

Calves vary considerably in their pathologic and clinical responses to infection of the lung with bacteria. The reasons may include resistance to infection because of pre-existing immunity, development of effective immune responses, or infection with a minimally virulent bacterial strain. However, studies of natural disease and of experimental infections indicate that some calves develop only mild lung lesions and minimal clinical signs despite substantial numbers of pathogenic bacteria in the lung. This may represent "tolerance" to pulmonary infection because these calves are able to control their inflammatory responses or protect the lung from damage, without necessarily eliminating bacterial infection. Conversely, risk factors might predispose to bovine respiratory disease by triggering a loss of tolerance that results in a harmful inflammatory and tissue-damaging response to infection.

Sequential exposure to bovine viral diarrhea virus and bovine coronavirus results in increased respiratory disease lesions: clinical, immunologic, pathologic, and immunohistochemical findings

Bovine coronaviruses (BoCVs) have been found in respiratory tissues in cattle and frequently associated with bovine respiratory disease (BRD); however, pathogenesis studies in calves are limited. To characterize the pathogenesis and pathogenicity of BoCV isolates, we used 5 different BoCV strains to inoculate colostrum-deprived calves, ~ 2-5 wk of age. Later, to determine if dual viral infection would potentiate pathogenicity of BoCV, calves were inoculated with BoCV alone, bovine viral diarrhea virus (BVDV) alone, or a series of dual-infection (BVDV-BoCV) schemes. A negative control group was included in all studies. Clinical signs and body temperature were monitored during the study and samples collected for lymphocyte counts, virus isolation, and serology. During autopsy, gross lesions were recorded and fixed tissues collected for histopathology and immunohistochemistry; fresh tissues were collected for virus isolation. Results suggest increased pathogenicity for isolate BoCV OK 1776. Increased body temperature was found in all virus-inoculated groups. Lung lesions were present in calves in all dual-infection groups; however, lesions were most pronounced in calves inoculated with BVDV followed by BoCV inoculation 6 d later. Lung lesions were consistent with mild-to-moderate interstitial pneumonia, and immunohistochemistry confirmed the presence of BoCV antigen. Our studies demonstrated that BVDV-BoCV dual infection may play an important role in BRD pathogenesis, and timing between infections seems critical to the severity of lesions.

Regulatory T cells and T helper 17 cells in viral infection

CD4⁺ T cells are the central element of the adaptive immune responses and protect the body from a variety of pathogens. Starting from naive cells, CD4⁺ T cells can differentiate into various effector cell subsets with specialized functions including T helper (Th) 1, Th2, Th17, regulatory T (Treg) and T follicular helper (Tfh) cells. Among them, Tregs and Th17 cells show a strong plasticity allowing the functional adaptation to various physiological and pathological environments during immune responses. Although they are derived from the same precursor cells and their differentiation pathways are interrelated, the terminally differentiated cells have totally opposite functions. Studies have shown that Tregs and Th17 cells have rather complex interplays in viral infection: Th17 cells may contribute to immune activation and disease progression while Tregs may inhibit this process and play a key role in the maintenance of immune homoeostasis, possibly at the cost of compromised viral control. In this review, we take respiratory syncytial virus (RSV), hepatitis B virus (HBV)/hepatitis C virus (HCV) and human immunodeficiency virus (HIV) infections as examples to discuss these interplays and their impacts on disease progression in viral infection.

Adaptive immunity in the postpartum uterus: Potential use of vaccines to control metritis

After parturition, dairy cows rely on an effective innate immune response, through the actions of neutrophils, macrophages, and antimicrobial peptides, to clear the uterus from pathogenic bacteria, such as E. coli, Bacteroides spp, F. necrophorum and T. pyogenes. However, the role of adaptive immunity in the postpartum uterus is less understood. In this review, we explore concepts of mucosal adaptive immunity and discuss recent findings regarding the efficacy of vaccines to reduce metritis in dairy cows. Areas of lymphocytic aggregates are seen throughout the bovine reproductive tract after parturition, but it is unknown if their development is influenced by previous exposure to pathogens or other intrinsic factors. Through the actions of Treg cells and γδ T cells, the uterus is an immune-tolerant environment during pregnancy. After parturition, the dynamics in the endometrial and circulating lymphocytic populations differ among cows that develop uterine diseases and healthy counterparts. However, the functionality of those cells has not yet been determined. It has been hypothesized that cows that fail to switch their uterine environment from an anti-inflammatory state prior to parturition to a pro-inflammatory state after calving are more susceptible to uterine infections. Given the nature of metritis related pathogens and the importance of innate immunity to uterine defense mechanisms, we speculate that an adaptive immunity biased towards a Th1/Th17 cellular response will provide best protection against uterine infections. Few studies have evaluated the efficacy of immunization in reducing the incidence of metritis in dairy cows revealing inconsistent findings.

Gamma Delta T Cell Function in Ruminants

Gamma delta (γδ) T cells constitute a major lymphocyte population in peripheral blood and epithelial surfaces. They play nonredundant roles in host defense against diverse pathogens. Although γδ T cells share functional features with other cells of the immune system, their distinct methods of antigen recognition, rapid response, and tissue tropism make them a unique effector population. This review considers the current state of our knowledge on γδ T cell biology in ruminants and the important roles played by this nonconventional T cell population in protection against several infectious diseases of veterinary and zoonotic importance.

γδ T cells in livestock: Responses to pathogens and vaccine potential

The immediate objective of our research is to understand the molecular mechanisms underlying activation and potentiation of the protective functional response of WC1⁺ γδ T cells to pathogens afflicting livestock species. The long-term goal is to incorporate stimulation of these cells into the next generation of vaccine constructs. γδ T cells have roles in the immune response to many infectious diseases including viral, bacterial, protozoan and worm infections, and their functional responses overlap with those of canonical αβ T cells, for example they produce cytokines including interferon-γ and IL-17. Stimulation of non-conventional lymphocytes including γδ T cells and αβ natural killer T (NKT) cells has been shown to contribute to protective immunity in mammals, bridging the gap between the innate and adaptive immune responses. Because of their innate-like early response, understanding how to engage γδ T-cell responses has the potential to optimize strategies of those that aim to induce pro-inflammatory responses as discussed here.

Co-infection of epithelial cells established from the upper and lower bovine respiratory tract with bovine respiratory syncytial virus and bacteria

Bovine respiratory disease complex is a major disease affecting the global cattle industry. Multiple infections by viruses and bacteria increase disease severity. Previously, we reported that bovine respiratory syncytial virus (BRSV) infection increases adherence of Pasteurella multocida to human respiratory and bovine kidney epithelial cells. To examine the interaction between the virus and bacteria in bovine respiratory cells, we generated respiratory epithelial cell lines from bovine trachea (bTEC), bronchus (bBEC), and lung (bLEC). Although all established cell lines were infected by BRSV and P. multocida susceptibility differed according to site of origin. The cells derived from the lower respiratory tract (bBEC and bLEC) were significantly more susceptible to BRSV than those derived from the upper respiratory tract (bTEC). Pre-infection of bBEC and bLEC with BRSV increased adherence of P. multocida; this was not the case for bTEC. These results indicate that BRSV may reproduce better in the lower respiratory tract and encourage adherence of bacteria. Thus, we identify one possible mechanism underlying severe pneumonia.

Current Animal Models for Understanding the Pathology Caused by the Respiratory Syncytial Virus

The human respiratory syncytial virus (hRSV) is the main etiologic agent of severe lower respiratory tract infections that affect young children throughout the world, associated with significant morbidity and mortality, becoming a serious public health problem globally. Up to date, no licensed vaccines are available to prevent severe hRSV-induced disease, and the generation of safe-effective vaccines has been a challenging task, requiring constant biomedical research aimed to overcome this ailment. Among the difficulties presented by the study of this pathogen, it arises the fact that there is no single animal model that resembles all aspects of the human pathology, which is due to the specificity that this pathogen has for the human host. Thus, for the study of hRSV, different animal models might be employed, depending on the goal of the study. Of all the existing models, the murine model has been the most frequent model of choice for biomedical studies worldwide and has been of great importance at contributing to the development and understanding of vaccines and therapies against hRSV. The most notable use of the murine model is that it is very useful as a first approach in the development of vaccines or therapies such as monoclonal antibodies, suggesting in this way the direction that research could have in other preclinical models that have higher maintenance costs and more complex requirements in its management. However, several additional different models for studying hRSV, such as other rodents, mustelids, ruminants, and non-human primates, have been explored, offering advantages over the murine model. In this review, we discuss the various applications of animal models to the study of hRSV-induced disease and the advantages and disadvantages of each model, highlighting the potential of each model to elucidate different features of the pathology caused by the hRSV infection.

Prophylactic digoxin treatment reduces IL-17 production in vivo in the neonatal calf and moderates RSV-associated disease

Respiratory syncytial virus (RSV) is a leading cause of morbidity and mortality in human infants. Bovine RSV infection of neonatal calves is pathologically and immunologically similar to RSV infection in infants, and is therefore a useful preclinical model for testing novel therapeutics. Treatment of severe RSV bronchiolitis relies on supportive care and may include use of bronchodilators and inhaled or systemic corticosteroids. Interleukin-17A (IL-17) is an inflammatory cytokine that plays an important role in neutrophil recruitment and activation. IL-17 is increased in children and rodents with severe RSV infection; and in calves with severe BRSV infection. It is currently unclear if IL-17 and Th17 immunity is beneficial or detrimental to the host during RSV infection. Digoxin was recently identified to selectively inhibit IL-17 production by antagonizing its transcription factor, retinoid-related orphan receptor γ t (RORγt). Digoxin inhibits RORγt binding to IL-17 and Th17 associated genes, and suppresses IL-17 production in vitro in human and murine leukocytes and in vivo in rodent models of autoimmune disease. We demonstrate here that in vitro and in vivo digoxin treatment also inhibits IL-17 production by bovine leukocytes. To determine the role of IL-17 in primary RSV infection, calves were treated prophylactically with digoxin and infected with BRSV. Digoxin treated calves demonstrated reduced signs of clinical illness after BRSV infection, and reduced lung pathology compared to untreated control calves. Digoxin treatment did not adversely affect virus shedding or lung viral burden, but had a significant impact on pulmonary inflammatory cytokine expression on day 10 post infection. Together, our results suggest that exacerbated expression of IL-17 has a negative impact on RSV disease, and that development of specific therapies targeting Th17 immunity may be a promising strategy to improve disease outcome during severe RSV infection.

Optimized protocols for γδ T cell expansion and lentiviral transduction

γδ T cells are a subset of unconventional T cells that serve a critical role in infectious diseases and various types of cancer. Cell therapy with genetically‑modified γδ T cells is regarded as a promising tool for tumor treatment. However, since γδ T cells constitute a minority of T cells, their large‑scale expansion is difficult to realize in an efficient and cost‑effective manner. In the present study, based on previous studies, culture protocols for γδ T cells were tested using different combinations of isopentenyl pyrophosphate and interleukin 2 in order to satisfy different experimental purposes. One protocol was demonstrated to be the most suitable for lentiviral transduction. These results greatly reinforce the promising prospects of using γδ T cells in basic research and for clinical applications.

Aerosol vaccination with Bacille Calmette-Guerin induces a trained innate immune phenotype in calves

Mycobacterium bovis Bacillus Calmette-Guérin (BCG) is a live attenuated vaccine for use against tuberculosis (TB); however, it is known to reduce childhood mortality from infections other than TB. The unspecific protection induced by BCG vaccination has been associated with the induction of memory-like traits of the innate immune system identified as ‘trained’ immunity. In humans and mouse models, in vitro and in vivo BCG training leads to enhanced production of monocyte-derived proinflammatory cytokines in response to secondary unrelated bacterial and fungal pathogens. While BCG has been studied extensively for its ability to induce innate training in humans and mouse models, BCG’s nonspecific protective effects have not been defined in agricultural species. Here, we show that in vitro BCG training induces a functional change in bovine monocytes, characterized by increased transcription of proinflammatory cytokines upon restimulation with the toll-like receptor agonists. Importantly, in vivo, aerosol BCG vaccination in young calves also induced a ‘trained’ phenotype in circulating peripheral blood mononuclear cells (PBMCs), that lead to a significantly enhanced TLR-induced proinflammatory cytokine response and changes in cellular metabolism compared to PBMCs from unvaccinated control calves. Similar to the long-term training effects of BCG reported in humans, our results suggest that in young calves, the effects of BCG induced innate training can last for at least 3 months in circulating immune populations. Interestingly, however, aerosol BCG vaccination did not ‘train’ the innate immune response at the mucosal level, as alveolar macrophages from aerosol BCG vaccinated calves did not mount an enhanced inflammatory response to secondary stimulation, compared to cells isolated from control calves. Together, our results suggest that, like mice and humans, the innate immune system of calves can be ‘trained’; and that BCG vaccination could be used as an immunomodulatory strategy to reduce disease burden in juvenile food animals before the adaptive immune system has fully matured.

A Single-Step Gold Nanoparticle-Blood Serum Interaction Assay Reveals Humoral Immunity Development and Immune Status of Animals from Neonates to Adults

A well-developed, functional immune system is paramount to combat harmful attacks from pathogenic organisms and prevent infectious diseases. Newborn animals and humans have only limited immunity upon birth, but their immune functions are expected to develop within weeks to months and eventually to reach a maturity that will provide full protection. Despite the importance of immune activity in animal and human health management, there is no convenient test available that allows for rapid assessment of the state of immune function in nonlaboratory settings. Here we report an extremely simple and rapid blood test that may be used in point-of-care clinics or field settings to evaluate the humoral immune status of animals. The test detects a cooperative interaction between a gold nanoparticle and arguably the three most important proteins involved in the immune system: immunoglobulin M (IgM), immunoglobulin G (IgG), and at least one complement protein, C3, in the blood serum. Such interactions cause the gold nanoparticles to form clusters and aggregates. The average particle size of the gold nanoparticle-serum mixture, measured by dynamic light scattering, corresponds positively to the immune status and activity of the subject. Our study demonstrates that the test may be used not only for monitoring the immune function development from neonates to adults, but also for detecting active immune responses during infection. Although data reported here are largely based on murine and bovine models, it is likely that this test will be applicable to humans as well.

Utility of the Neonatal Calf Model for Testing Vaccines and Intervention Strategies for Use against Human RSV Infection

Respiratory syncytial virus (RSV) is a significant cause of pediatric respiratory tract infections. It is estimated that two-thirds of infants are infected with RSV during the first year of life and it is one of the leading causes of death in this age group worldwide. Similarly, bovine RSV is a primary viral pathogen in cases of pneumonia in young calves and plays a significant role in bovine respiratory disease complex. Importantly, naturally occurring infection of calves with bovine RSV shares many features in common with human RSV infection. Herein, we update our current understanding of RSV infection in cattle, with particular focus on similarities between the calf and human infection, and the recent reports in which the neonatal calf has been employed for the development and testing of vaccines and therapeutics which may be applied to hRSV infection in humans.

Bovine respiratory syncytial virus infection enhances Pasteurella multocida adherence on respiratory epithelial cells

Primary infection with bovine respiratory syncytial virus (BRSV) predisposes cattle to secondary infection with bacteria that cause bovine respiratory disease complex (BRDC). However, the interaction between BRSV and bacteria is unclear. This in vitro study examined the adherence of Pasteurella multocida (PM) to BRSV-infected cells was assessed in colony forming unit assays, by flow cytometry analysis, and by indirect immunofluorescence analysis (IFA) of epithelial cells (A549, HEp-2, and MDBK). An in vitro model based on infection of BRSV-infected epithelial cells revealed that PM adherence to BRSV-infected cells was 2- to 8-fold higher than uninfected cells. This was confirmed by flow cytometry analysis and IFA. Epithelial cell expression of mRNA encoding cytokines and chemokines increased after exposure to PM, but increased further after co-infection with BRSV and PM. BRSV-mediated adherence of PM to epithelial cells may underlie the serious symptoms of BRDC.

Efficacy of mucosal polyanhydride nanovaccine against respiratory syncytial virus infection in the neonatal calf

Human respiratory syncytial virus (HRSV) is a leading cause of severe acute lower respiratory tract infection in infants and children worldwide. Bovine RSV (BRSV) is closely related to HRSV and a significant cause of morbidity in young cattle. BRSV infection in calves displays many similarities to RSV infection in humans, including similar age dependency and disease pathogenesis. Polyanhydride nanoparticle-based vaccines (i.e., nanovaccines) have shown promise as adjuvants and vaccine delivery vehicles due to their ability to promote enhanced immunogenicity through the route of administration, provide sustained antigen exposure, and induce both antibody- and cell-mediated immunity. Here, we developed a novel, mucosal nanovaccine that encapsulates the post-fusion F and G glycoproteins from BRSV into polyanhydride nanoparticles and determined the efficacy of the vaccine against RSV infection using a neonatal calf model. Calves receiving the BRSV-F/G nanovaccine exhibited reduced pathology in the lungs, reduced viral burden, and decreased virus shedding compared to unvaccinated control calves, which correlated with BRSV-specific immune responses in the respiratory tract and peripheral blood. Our results indicate that the BRSV-F/G nanovaccine is highly immunogenic and, with optimization, has the potential to significantly reduce the disease burden associated with RSV infection in both humans and animals.

Specific immune response in neonate Holstein heifer calves fed fresh or frozen colostrum

ABSTRACT: The objective of this study was to evaluate the influence of viable cells from colostrum on immune development in dairy heifer calves during the first 28 days of life. The animals were distributed between 2 groups: COL+ (n=9) receiving fresh whole colostrum from their own damns; and COL- (n=10) receiving pooled frozen colostrum, containing no viable cells, from a pool of donor cows. These calves were assessed before colostrum intake (D0), 48 hours of age (D2), and weekly from D7 to D28. The development of immunity was evaluated by assessment of the phenotype of blood leukocyte subsets, and induced cytokine production after 72 hours of stimulation in culture with concanavalin A (ConA), killed Staphylococcus aureus (S.aureus) and killed Escherichia coli (E. coli) by peripheral blood mononuclear cell (PBMC). The clinical history of these calves was marked by a high frequency of diarrhea in both groups. However, COL- had greater diarrhea intensity scores (fecal score~3 of 4), and rectal temperature on D7 than COL+ calves. Moreover, bronchopneumonia (n=1) and navel inflammation were observed only in COL- calves. COL- had a lower concentration of serum iron, and a higher absolute number of lymphocytes on D7 than COL+. COL- also had a higher percentage of anemic calves than the COL+ calves on D21 and D28. In general, the percent of cells within each subset of leukocytes was similar between the groups over the experiment, except on week 1 when COL- calves had a higher percentage of lymphocytes expressing CD45RO+ (P=0.07). A steady increase in CD45RO+ and concomitant decline in CD45RO- leukocytes was observed over the course of the study, indicating the development of immune memory. The proportion of CD14MHCII+ leukocytes increased with age (P≤0.05). The median background cytokine production by PBMC that were not stimulated was below the level of detection of the assays used for both groups. The PBMC from COL+ calves stimulated with ConA secreted a larger quantity of IL-17 week 2 (COL+=2060.0pg/mL and COL-=0.0pg/mL, P=0.00). PBMC from COL+ calves stimulated with killed S. aureus whole cell antigen (P=0.05) and killed E. coli whole cell antigen (P=0.05) also secreted higher levels of IL17 than COL- calves at week 4. Clear production of IL17 was observed in PBML from COL+ calves at week 2, but the difference was not statistical different between groups. In conclusion, calves fed fresh and frozen colostrum showed no difference in cells subset profile overall. The increased percentage of leukocytes expressing the memory CD45RO+ or CD14MHCII+ over the course of the experiment indicated a maturation of the adaptive immune response after natural exposure to pathogens in the environment of the calf. The enhanced IL17 secretion by COL+ calves indicated that viable maternal cells modulated T-cell Th17 production that was primed by bacterial antigens. This mechanism could be responsible for quick and efficient activation of neutrophils for bacterial clearance. The differences in cytokine production observed between groups may help to explain the different clinical pictures observed for calves COL+ and COL- calves.

Measuring bovine γδ T cell function at the site of Mycobacterium bovis infection

Bovine γδ T cells are amongst the first cells to accumulate at the site of Mycobacterium bovis infection; however, their role in the developing lesion remains unclear. We utilized transcriptomics analysis, in situ hybridization, and a macrophage/γδ T cell co-culture system to elucidate the role of γδ T cells in local immunity to M. bovis infection. Transcriptomics analysis revealed that γδ T cells upregulated expression of several novel, immune-associated genes in response to stimulation with M. bovis antigen. BCG-infected macrophage/γδ T cell co-cultures confirmed the results of our RNAseq analysis, and revealed that γδ T cells from M. bovis-infected animals had a significant impact on bacterial viability. Analysis of γδ T cells within late-stage M. bovis granulomas revealed significant expression of IFN-γ and CCL2, but not IL-10, IL-22, or IL-17. Our results suggest γδ T cells influence local immunity to M. bovis through cytokine secretion and direct effects on bacterial burden.

A glycosylated recombinant subunit candidate vaccine consisting of Ehrlichia ruminantium major antigenic protein1 induces specific humoral and Th1 type cell responses in sheep

Heartwater, or cowdriosis, is a tick-borne disease of domestic and wild ruminants that is endemic in the Caribbean and sub-Saharan Africa. The disease is caused by an intracellular pathogen, Ehrlichia ruminantium and may be fatal within days of the onset of clinical signs with mortality rates of up to 90% in susceptible hosts. Due to the presence of competent tick vectors in North America, there is substantial risk of introduction of heartwater with potentially devastating consequences to the domestic livestock industry. There is currently no reliable or safe vaccine for use globally. To develop a protective DIVA (differentiate infected from vaccinated animals) subunit vaccine for heartwater, we targeted the E. ruminantium immunodominant major antigenic protein1 (MAP1) with the hypothesis that MAP1 is a glycosylated protein and glycans contained in the antigenic protein are important epitope determinants. Using a eukaryotic recombinant baculovirus expression system, we expressed and characterized, for the first time, a glycoform profile of MAP1 of two Caribbean E. ruminantium isolates, Antigua and Gardel. We have shown that the 37–38 kDa protein corresponded to a glycosylated form of the MAP1 protein, whereas the 31–32 kDa molecular weight band represented the non-glycosylated form of the protein frequently reported in scientific literature. Three groups of sheep (n = 3–6) were vaccinated with increasing doses of a bivalent (Antigua and Gardel MAP1) rMAP1 vaccine cocktail formulation with montanide ISA25 as an adjuvant. The glycosylated recombinant subunit vaccine induced E. ruminantium-specific humoral and Th1 type T cell responses, which are critical for controlling intracellular pathogens, including E. ruminantium, in infected hosts. These results provide an important basis for development of a subunit vaccine as a novel strategy to protect susceptible livestock against heartwater in non-endemic and endemic areas.

Frequency of Th17 cells correlates with the presence of lung lesions in pigs chronically infected with Actinobacillus pleuropneumoniae

Porcine contagious pleuropneumonia caused by Actinobacillus pleuropneumoniae (APP) remains one of the major causes of poor growth performance and respiratory disease in pig herds. While the role of antibodies against APP has been intensely studied, the porcine T cell response remains poorly characterized. To address this, pigs were intranasally infected with APP serotype 2 and euthanized during the acute phase [6-10 days post-infection (dpi)] or the chronic phase of APP infection (27-31 dpi). Lymphocytes isolated from blood, tonsils, lung tissue and tracheobronchial lymph nodes were analyzed by intracellular cytokine staining (ICS) for IL-17A, IL-10 and TNF-α production after in vitro stimulation with crude capsular extract (CCE) of the APP inoculation strain. This was combined with cell surface staining for the expression of CD4, CD8α and TCR-γδ. Clinical records, microbiological investigations and pathological findings confirmed the induction of a subclinical APP infection. ICS-assays revealed the presence of APP-CCE specific CD4⁺CD8α^dim IL-17A-producing T cells in blood and lung tissue in most infected animals during the acute and chronic phase of infection and a minor fraction of these cells co-produced TNF-α. APP-CCE specific IL-17A-producing γδ T cells could not be found and APP-CCE specific IL-10-producing CD4⁺ T cells were present in various organs but only in a few infected animals. The frequency of identified putative Th17 cells (CD4⁺CD8α^dimIL-17A⁺) in lung and blood correlated positively with lung lesion scores and APP-specific antibody titers during the chronic phase. These results suggest a potential role of Th17 cells in the immune pathogenesis of APP infection.

Study on the effect and mechanism of the dysfunction of CD4(+) T cells in the disease process of chronic cardiac failure

OBJECTIVE

To study the effect and mechanism of the dysfunction of CD4(+) T cells in the disease process of chronic cardiac failure (CHF).

METHODS

According to different group technologies, 100 CHF patients were divided into the following groups: ischemia group and non-ischemia group, heart function Ⅲ-Ⅳ group and heart function Ⅰ-Ⅱ group, event group and non-event group, and 50 healthy volunteers were included in the control group. Real-time PCR was used to detect transcription factors T-bet and GATA-3 of Th1 and Th2; flow cytometry was applied to determine the ratio of Th17 and Treg cells; ELISA was employed to test cytokines IFN-γ, IL-4, IL-17 and IL-10 of peripheral blood Th1, Th2, Th17 and Treg cells, respectively; ultrasonic cardiogram was used to exploit to LVEF and LVEDd; and electrochemilu minescene immunoassay was used to examine plasma BNP. The differences of all indexes of all groups were analyzed and the correlation between CD4 T cells and clinical indexes was analyzed by Pearson correlation analysis.

RESULTS

As compared to the control group, the transcription factors T-bet and GATA-3 of Th1 and Th2, the ratio of cytokines Th17 and IFN-γ, cytokines IL-17, T-bet/GATA-3, IFN-γ/IL-4, Th17 cells/Treg cells, IL-17/IL-10 of the ischemia group and non-ischemia group, heart function Ⅲ-Ⅳ group and heart function Ⅰ-Ⅱ group, event group and non-event group were all increased significantly, while their transcription factor GATA-3 of Th2, cytokines IL-4, Treg cells ratio, cytokines IL-10 were decreased obviously. The differences showed statistical significance (P < 0.05). The increase or decrease of the partial CD4+ T cells of the ischemia group, heart function Ⅲ-Ⅳ group and event group was more distinctly. The results of Pearson correlation analysis showed that IFN-γ and IL-17 were significantly positively correlated with LVEDd and BNP, IL-4 and IL-10 were also significantly positively correlated with LVEF, but correlated negatively with BNP, and IL-17 was negatively correlative with LVEF.

CONCLUSIONS

There was a correlation between CHF and the dysfunction of CD4(+) T cells showing immune activation phenomenons of deviations from the Th1/Th2 balance towards Th1 and from the Th17/Treg balance towards Th17, which was also related to the types, severity and prognosis of the disease.