Detection of cytokine activated chondrocytes in arthritic joints from pigs infected with Erysipelothrix rhusiopathiae

The mononuclear phagocyte system of the pig as a model for understanding human innate immunity and disease

The biology of cells of the mononuclear phagocyte system has been studied extensively in the mouse. Studies of the pig as an experimental model have commonly been consigned to specialist animal science journals. In this review, we consider some of the many ways in which the innate immune systems of humans differ from those of mice, the ways that pigs may address the shortcomings of mice as models for the study of macrophage differentiation and activation in vitro, and the biology of sepsis and other pathologies in the living animal. With the completion of the genome sequence and the characterization of many key regulators and markers, the pig has emerged as a tractable model of human innate immunity and disease that should address the limited, predictive value of rodents in preclinical studies.

Periparturient cortisol, acute phase cytokine, and acute phase protein profiles of gilts housed in groups or stalls during gestation

Use of gestation stalls in pork production remains a controversial topic in animal welfare. Immune status and measures are frequently used to assess stress levels and thus well-being of confined animals. The important welfare issue of close confinement among gestating gilts was tested by quantifying cortisol, acute phase cytokine, and acute phase protein pro-files before and after farrowing of gilts housed in 2 systems. Landrace x Yorkshire crossbred gilts housed in groups of 4 (group, n = 8) in pens (3.9 x 2.4 m with 4 individual feeding spaces, 9.36 m(2) total or 2.34 m(2)/gilt) were compared with gilts housed in standard industry stalls (stall, n = 16; 2.2 x 0.6 m, 1.32 m(2)/gilt). Floors were fully slatted, and a substrate was not provided for either system. Cortisol was determined from saliva on d 105 of gestation, 1 h after moving the gilts into farrowing stalls (d 111), and 24 h and 7 d after farrowing. Cortisol was greater (P = 0.04) for group gilts compared with stall gilts 1 h after moving them into farrowing stalls and 24 h after farrowing. Cortisol concentrations decreased (P = 0.001) over time. Leukocyte mRNA expression of IL-1, IL-1 receptor antagonist, and tumor necrosis factor-alpha was determined by quantitative, reverse transcription PCR on d 35, 63, and 91 of gestation and 72 h after farrowing. Cytokine mRNA expression of peripheral blood mononuclear cells did not differ between housing systems for IL-1, its receptor antagonist, or for tumor necrosis factor-alpha. Acute phase proteins, including fibrinogen, haptoglobin, and alpha(1)-acid glycoprotein were determined for plasma samples taken at d 35, 63, and 91 of gestation and 72 h and 14 d after farrowing. In contrast to cortisol, plasma fibrinogen concentrations increased (P < 0.005) over time. Haptoglobin did not differ between treatments (P > 0.10). Stall gilts tended to have greater (P = 0.07) plasma alpha(1)-acid glycoprotein concentrations than group animals at d 35 of gestation and d 14 after farrowing. These data showed a trend (P < 0.07) for alpha(1)-acid glycoprotein concentrations to return to baseline more quickly in group-housed gilts, which did not appear to be directly related to increased cortisol just before farrowing. In conclusion, few differences in the acute phase response were detected between housing systems, suggesting that the resting immunological responses are only mildly affected by gestation stalls.

Molecular cloning of porcine interleukin-1beta converting enzyme and differential gene expression of IL-1beta converting enzyme, IL-1beta, and IL-18 in porcine alveolar macrophages

We have cloned and sequenced a cDNA that contains the coding sequence of porcine interleukin-1beta (IL-1beta) converting enzyme (ICE). Using degenerate oligonucleotide primers based on the amino acid sequences of the human, murine, and rat ICE, we performed the reverse transcription polymerase chain reaction (RT-PCR) with total RNA prepared from porcine alveolar macrophages stimulated with lipopolysaccharide (LPS) to clone the cDNA of porcine ICE. The open reading frame (ORF) of the porcine ICE cDNA is 1215 base pairs (bp) in length and encodes 404 amino acids. The predicted amino acid sequence is 72.5%, 62.6%, and 64.1% homologous to the human, murine, and rat amino acid sequences, respectively. The kinetics of mRNA expression of ICE, IL-1beta, and IL-18 in porcine alveolar macrophages after LPS stimulation revealed that ICE transcripts were weakly expressed in nonstimulated condition and upregulated after LPS stimulation. Moreover, IL-1beta and IL-18 transcripts were differently expressed after LPS stimulation.

Localization of viable bacteria and bacterial antigens in arthritic joints of Erysipelothrix rhusiopathiae-infected pigs

Chronic polyarthritis was induced in pigs by infection with Erysipelothrix rhusiopathiae (serovar 2, strain T28). Viable bacteria could be reisolated as long as 5 months post-infection from synovial fluid, synovial tissue and from isolated chondrocytes. The number of viable bacteria could be increased by hypotonic shock of the chondrocytes indicating a substantial intracellular amount of bacteria. Bacterial antigens were shown by immunohistochemistry to be present on the surface of both chondrocytes and synovial cells in arthritic joints. Neither viable bacteria nor bacterial antigen were detected in unaffected joints.

Pathogenesis of degenerative joint disease in the human temporomandibular joint

The wide range of disease prevalences reported in epidemiological studies of temporomandibular degenerative joint disease reflects the fact that diagnoses are frequently guided by the presence or absence of non-specific signs and symptoms. Treatment is aimed at alleviating the disease symptoms rather than being guided by an understanding of the underlying disease processes. Much of our current understanding of disease processes in the temporomandibular joint is based on the study of other articular joints. Although it is likely that the molecular basis of pathogenesis is similar to that of other joints, additional study of the temporomandibular joint is required due to its unique structure and function. This review summarizes the unique structural and molecular features of the temporomandibular joint and the epidemiology of degenerative temporomandibular joint disease. As is discussed in this review, recent research has provided a better understanding of the molecular basis of degenerative joint disease processes, including insights into: the regulation of cytokine expression and activation, arachidonic acid metabolism, neural contributions to inflammation, mechanisms of extracellular matrix degradation, modulation of cell adhesion in inflammatory states, and the roles of free radicals and heat shock proteins in degenerative joint disease. Finally, the multiple cellular and molecular mechanisms involved in disease initiation and progression, along with factors that may modify the adaptive capacity of the joint, are presented as the basis for the rational design of new and more effective therapy.

Intercellular adhesion molecule-1 (ICAM-1) and MHC class II on chondrocytes in arthritic joints from pigs experimentally infected with Erysipelothrix rhusiopathiae

This study set out to investigate the in vivo expression and distribution of the porcine homologues of the intercellular adhesion molecule-1 (ICAM-1) and MHC Class II as markers of chondrocyte activation during the development of chronic polyarthritis, which was experimentally induced in Landrace pigs by intra-articular injection of Erysipelothrix rhusiopathiae. ICAM-1 was found to be strongly expressed in vivo on chondrocytes and synovial cells in arthritic joints but was not detected in cartilage from unaffected joints. Although the majority of ICAM-1 positive chondrocytes did not co-express MHC Class II, chondrocyte-type cells expressing both molecules were detected in the transition zone as the disease progressed, particularly at 5 months post-infection. At this stage infiltration of CD4+ T lymphocytes into the damaged cartilage was also apparent. ICAM-1 and MHC Class II are not constitutively expressed on porcine chondrocytes but appeared to be induced as arthritis progressed. The detection of these markers in the pig helps to establish the validity of this animal model for immunopathological studies.

Porcine cytokines

Cytokines play a central role in modulation of immunological and physiological processes in animals under both homeostatic and abnormal conditions. Currently available information from a variety of species indicates that interleukins, interferons and tumor necrosis factor mobilize immune responses, activate inflammatory reactions and communicate with organ systems; colony stimulating factors regulate hematopoiesis and hematopoietic cell function; transforming growth factor beta affects wound healing, bone remodeling and cellular differentiation. Our understanding of cytokine biology in pigs is selective and based largely on effects of human proteins in porcine models of human diseases. However, knowledge of the nature and role of cytokines in swine immunology and physiology is increasing rapidly due to the application of molecular cloning techniques to porcine cytokines. This review summarizes the current state of knowledge of porcine cytokines and focuses on biological processes in which the porcine proteins have been investigated in swine.

Upregulation of complement regulators MCP (CD46), DAF (CD55) and protectin (CD59) in arthritic joint disease

CD46, CD55 and CD59 are cell surface glycoproteins which are widely distributed on normal tissue, where they function in the prevention of complement-mediated damage. In this study we have investigated the altered expression of these molecules under inflammatory conditions both in vitro and in vivo. By using immunocytochemical techniques we demonstrated marked but disparate upregulation of these molecules in IL1-treated cartilage and in diseased cartilage from arthritic joints compared to normal cartilage in both humans and pigs. Expression of these proteins was restricted to the chondrocyte surface, and was also demonstrated on isolated chondrocytes grown in monolayer culture and stimulated with IL1. It is suggested that the elevated levels of these regulatory proteins may be necessary to ameliorate the multiple damaging effects of the inflammatory processes associated with destructive joint diseases.