Symposium: Animal welfare challenges for today and tomorrow.

The increasing separation of the public from production agriculture means there is often a lack of knowledge among consumers about current production practices and a perception that increased productivity and economic efficiency are necessarily associated with a decline in animal welfare. A symposium was organized to present information about animal welfare issues and the challenges they pose for both scientists and the poultry and allied industries. Companion papers provide information about understanding public attitudes and physiological/immunological approaches to welfare assessment, while this paper outlines current and future challenges to egg and meat production and industry responses to those challenges. For broiler chickens, increases in growth rate result in corollary increases in metabolic heat generation and water consumption, leading to the need for continuing improvements in housing, ventilation, and litter management. Stocking densities, lighting programs, muscle myopathies, and use of antibiotics are also areas that require research attention. In the layer industry, the key challenge is housing, with the industry undergoing a shift from conventional cage housing to alternatives like enriched colonies or cage-free. While these alternative systems have hen welfare advantages, there are also welfare disadvantages that require the development of mitigation strategies, and it is also essential to address associated issues including economic, environmental, egg safety, and worker health impacts. Concerns on the horizon include euthanasia of surplus male chicks and spent hens as well as beak-trimming. The humaneness of slaughter methods is an important welfare and consumer confidence issue, and the current regulations for poultry slaughter in the USA are discussed and compared to those for livestock. The poultry and allied industries, including retailers, are responding to these concerns by consulting with experts, developing science-based animal care standards and auditing programs, strengthening training and oversight programs, promoting research, and improving communication channels. In future, intensifying multi-disciplinary research efforts and developing mechanisms to improve communication between scientists and stakeholders, including the public, will be critical to addressing these issues.

High-anxious individuals show increased chronic stress burden, decreased protective immunity, and increased cancer progression in a mouse model of squamous cell carcinoma.

In spite of widespread anecdotal and scientific evidence much remains to be understood about the long-suspected connection between psychological factors and susceptibility to cancer. The skin is the most common site of cancer, accounting for nearly half of all cancers in the US, with approximately 2-3 million cases of non-melanoma cancers occurring each year worldwide. We hypothesized that a high-anxious, stress-prone behavioral phenotype would result in a higher chronic stress burden, lower protective-immunity, and increased progression of the immuno-responsive skin cancer, squamous cell carcinoma. SKH1 mice were phenotyped as high- or low-anxious at baseline, and subsequently exposed to ultraviolet-B light (1 minimal erythemal dose (MED), 3 times/week, 10-weeks). The significant strengths of this cancer model are that it uses a normal, immunocompetent, outbred strain, without surgery/injection of exogenous tumor cells/cell lines, and produces lesions that resemble human tumors. Tumors were counted weekly (primary outcome), and tissues collected during early and late phases of tumor development. Chemokine/cytokine gene-expression was quantified by PCR, tumor-infiltrating helper (Th), cytolytic (CTL), and regulatory (Treg) T cells by immunohistochemistry, lymph node T and B cells by flow cytometry, adrenal and plasma corticosterone and tissue vascular-endothelial-growth-factor (VEGF) by ELISA. High-anxious mice showed a higher tumor burden during all phases of tumor development. They also showed: higher corticosterone levels (indicating greater chronic stress burden), increased CCL22 expression and Treg infiltration (increased tumor-recruited immuno-suppression), lower CTACK/CCL27, IL-12, and IFN-γ gene-expression and lower numbers of tumor infiltrating Th and CTLs (suppressed protective immunity), and higher VEGF concentrations (increased tumor angiogenesis/invasion/metastasis). These results suggest that the deleterious effects of high trait anxiety could be: exacerbated by life-stressors, accentuated by the stress of cancer diagnosis/treatment, and mediate increased tumor progression and/or metastasis. Therefore, it may be beneficial to investigate the use of chemotherapy-compatible anxiolytic treatments immediately following cancer diagnosis, and during cancer treatment/survivorship.

Short-term stress enhances cellular immunity and increases early resistance to squamous cell carcinoma.

In contrast to chronic/long-term stress that suppresses/dysregulates immune function, an acute/short-term fight-or-flight stress response experienced during immune activation can enhance innate and adaptive immunity. Moderate ultraviolet-B (UV) exposure provides a non-invasive system for studying the naturalistic emergence, progression and regression of squamous cell carcinoma (SCC). Because SCC is an immunoresponsive cancer, we hypothesized that short-term stress experienced before UV exposure would enhance protective immunity and increase resistance to SCC. Control and short-term stress groups were treated identically except that the short-term stress group was restrained (2.5h) before each of nine UV-exposure sessions (minimum erythemal dose, 3-times/week) during weeks 4-6 of the 10-week UV exposure protocol. Tumors were measured weekly, and tissue collected at weeks 7, 20, and 32. Chemokine and cytokine gene expression was quantified by real-time PCR, and CD4+ and CD8+ T cells by flow cytometry and immunohistochemistry. Compared to controls, the short-term stress group showed greater cutaneous T-cell attracting chemokine (CTACK)/CCL27, RANTES, IL-12, and IFN-gamma gene expression at weeks 7, 20, and 32, higher skin infiltrating T cell numbers (weeks 7 and 20), lower tumor incidence (weeks 11-20) and fewer tumors (weeks 11-26). These results suggest that activation of short-term stress physiology increased chemokine expression and T cell trafficking and/or function during/following UV exposure, and enhanced Type 1 cytokine-driven cell-mediated immunity that is crucial for resistance to SCC. Therefore, the physiological fight-or-flight stress response and its adjuvant-like immuno-enhancing effects, may provide a novel and important mechanism for enhancing immune system mediated tumor-detection/elimination that merits further investigation.

Chronic stress and susceptibility to skin cancer.

BACKGROUND: Studies have shown that chronic stress or UV radiation independently suppress immunity. Given their increasing prevalence, it is important to understand whether and how chronic stress and UV radiation may act together to increase susceptibility to disease. Therefore, we investigated potential mediators of a stress-induced increase in emergence and progression of UV-induced squamous cell carcinoma. METHODS: SKH1 mice susceptible to UV-induced tumors were unexposed (naïve, n = 4) or exposed (n = 16) to 2240 J/m2 of UVB radiation three times a week for 10 weeks. Half of the UVB-exposed mice were left nonstressed (i.e., they remained in their home cages) and the other half were chronically stressed (i.e., restrained during weeks 4-6). UV-induced tumors were measured weekly from week 11 through week 34, blood was collected at week 34, and tissues were collected at week 35. mRNA expression of interleukin (IL)-12p40, interferon (IFN)-gamma, IL-4, IL-10, CD3epsilon, and CCL27/CTACK, the skin T cell-homing chemokine, in dorsal skin was quantified using real-time polymerase chain reaction. CD4+, CD8+, and CD25+ leukocytes were counted using immunohistochemistry and flow cytometry. All statistical tests were two-sided. RESULTS: Stressed mice had a shorter median time to first tumor (15 versus 16.5 weeks, difference = 1.5 weeks, 95% confidence interval [CI] = -3.0 to 3.3 weeks; P = .03) and reached 50% incidence earlier than controls (15 weeks versus 21 weeks). Stressed mice also had lower IFN-gamma ( mean = 0.03 versus mean = 0.07, difference = 0.04, 95% CI = 0.004 to 0.073; P = .02), CCL27/CTACK (mean = 101 versus mean = 142, difference = 41, 95% CI = 8.1 to 74.4; P = .03), and CD3epsilon (mean = 0.18 versus mean = 0.36, difference = 0.18, 95% CI = 0.06 to 0.30; P = .007) gene expression and lower numbers of infiltrating CD4+ cells (mean = 9.40 versus mean = 13.7, difference = 4.3, 95% CI = 2.36 to 6.32; P = .008) than nonstressed mice. In addition, stressed mice had more regulatory/suppressor CD25+ cells infiltrating tumors and more CD4+ CD25+ cells in circulation (mean = 0.36 versus mean = 0.17, difference = 0.19, 95% CI = 0.005 to 0.38; P = .03) than nonstressed mice. CONCLUSIONS: Chronic stress increased susceptibility to UV-induced squamous cell carcinoma in this mouse model by suppressing type 1 cytokines and protective T cells and increasing regulatory/suppressor T cell numbers.

Stress as an endogenous adjuvant: augmentation of the immunization phase of cell-mediated immunity.

Stress is thought to be immunosuppressive but paradoxically exacerbates inflammatory and autoimmune diseases. We initially showed that acute stress enhances skin immunity. Such immunoenhancement could promote immunoprotection in case of wounding, infection or vaccination but could also exacerbate immunopathological diseases. Here we identify the molecular and cellular mediators of the immunoenhancing effects of acute stress. Compared with non-stressed mice, acutely stressed animals showed significantly greater pinna swelling and leukocyte infiltration, and up-regulated macrophage chemoattractant protein-1, macrophage inflammatory protein-3alpha, IL-1alpha, IL-1beta, IL-6, tumor necrosis factor-alpha and IFN-gamma, but not IL-4 gene expression at the site of primary antigen exposure. Stressed animals also showed enhanced maturation and trafficking of dendritic cells (DCs) from skin to lymph nodes (LNs), higher numbers of activated macrophages in skin and LNs, increased T cell activation in LNs, and enhanced recruitment of surveillance T cells to skin. These findings show that important interactive components of innate (DCs and macrophages) and adaptive (surveillance T cells) immunity are mediators of the stress-induced enhancement of a primary immune response. Such enhancement during primary immunization may induce a long-term increase in immunologic memory resulting in subsequent augmentation of the immune response during secondary antigen exposure. Thus, the evolutionarily adaptive fight-or-flight stress response may protectively prepare the immune system for impending danger (e.g. infection and wounding by a predator), but may also contribute to stress-induced exacerbation of inflammatory and autoimmune diseases.