No description available.

No description available.

No description available.

No description available.

The study investigated healthy claw samples from cross-bred heifers aged around 20 months. Histological studies adopted a novel sectioning approach along planes parallel to the wall, identifying dynamics of the keratinisation process, localisation of elastic fibres and anatomical features of cap papillae and horn. Structural molecules were investigated immunohistochemically, including cytokeratins, cytokeratin 14 (CK14) and β-actin. The results showed patterns of suprabasal keratin deposition and loss of signal for CK14 and β-actin markers in differentiating keratinocytes. Localisation of vimentin provided evidence of mesenchymal cells in laminar dermis. Transforming growth factor β1 (TGFβ1) and connective tissue growth factor (CTGF) were investigated immunohistochemically, by <i>in situ</i> hybridisation and RT-PCR. Immunohistochemistry showed signals in the dermis and epidermis, with mRNA presence solely in the dermis and high synthesis rates on comparison with internal control. Mean expression levels were higher in summer than in winter. Collagen I (COL1A2), elastin, estradiol receptor β, cyclin A and B were also investigated by RT-PCR and consistently amplified. Tissue cultures were carried out in order to study TGFβ1, CTGF and COL1A2 expression by RT-PCR in tissue explants incubated in presence of TGFβ1. Results identified a time effect but absence of a concentration effect. Proteomic analysis of fractions extracted from incubated and non-incubated (control) explants showed significant differences for a number of spots, mainly in the keratin region of the electrophoretic gels. In conclusion, the study has provided novel information on molecules of importance in the structure and regulation of epidermal and dermal cells and dermal extracellular matrix in the laminar region of the bovine claw.

Macrophages (M?) are widely distributed immune cells and can be phenotypically polarised by microenvironment to mount specific functional programs. M? polarised in vitro can be broadly classified in two main groups: classically activated (or Ml), and alternatively activated (or M2) M?. M1 exhibit potent microbicidal properties and induce pro-inflammatory responses, whilst M2 play a role in resolution of inflammation and reduce pro-inflammatory responses.

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In this thesis I show that macrophages (both cell lines and primary cultures) can be transfected by recombinant adenoviruses expressing -galactosidase (A-gal/Av1Bng), that the macrophages become activated by the transfection process and can be easily manipulated to localise to inflamed glomeruli after direct injection into the renal artery of rats with an experimentally induced glomerular inflammation caused by nephrotoxic nephritis. The injection of transfected macrophages reduces the severity of injury in this model of glomerulonephritis as shown by a reduction in the degree of albuminuria. This approach provides a favourable system for gene delivery in inflammatory disease and shows that both the functional properties of the transfected macrophage as well the transgene it is engineered to produce are relevant for in vivo gene transfer. This approach has also been used to determine the effect of macrophages expressing active TGF-1 on the development of glomerular inflammation. TGF-1 expressing macrophages localised efficiently to inflamed glomeruli and produced the cytokine in vivo. These cells produced a reduction in the level of albuminuria compared to unmodified disease but not in comparison to injection of macrophages transfected with adenovirus expressing -galactosidase. In addition there was no alteration in the infiltration by ED1 positive macrophages. Thus TGF-1 expressed in this manner appears unable to significantly modulate glomerular inflammatory disease and the potential reasons for this are discussed. The system I have developed of macrophage transfection and delivery provides a valuable approach to study and modulate inflammatory disease.

The presence of endotoxin in animals and humans triggers a sequence of acute phase responses, which include the synthesis and release of pro-inflammatory cytokines from immune cells, followed by the development of various symptoms of sickness including fever and an array of behavioural responses, commonly referred to as sickness behaviours. Most experimental investigations examining the mechanisms mediating fever and sickness behaviour responses have used purified lipopolysaccharide (LPS), the glycolipid pyrogenic moiety of the Gram-negative bacterial membrane, to trigger the innate immune system. Results obtained from studies using specific antagonists to block the action of cytokines synthesized following systemic administration of LPS, have uncovered important roles for pro-inflammatory cytokines, such as interleukin (IL)-1b, IL-6, tumour necrosis factor-alpha (TNF-a) and leptin, in mediating fever. Although it has been shown that administration of pro-inflammatory cytokines can induce sickness behaviour in experimental animals, no clear role has been identified for these cytokines as endogenous mediators of sickness behaviours induced following LPS administration. Using rats as experimental animals and endogenous cytokine antagonism, I therefore investigated whether endogenously released IL-1b, IL-6, TNF-a and leptin are physiologically active not only in the generation of fever, but also in the generation of two specific sickness behaviours, lethargy and anorexia, induced by subcutaneous (s.c.) administration of LPS. Lethargy, anorexia and fever were measured as changes in voluntary wheel-running, food intake and body temperature respectively. I antagonized the biological action of these cytokines in the periphery following s.c. administration of LPS by injecting rats intraperitoneally (i.p.) with specific anti-rat sera to one of the following: TNF-a, IL-1b, IL-6 or leptin. Peripherally-released leptin appeared to be an important mediator of both fever and anorexia, as the presence of leptin antibodies in the circulation abolished both the anorexia and fever induced by s.c. administration of LPS. In contrast though, whereas the presence of IL-6 antibodies in the circulation abolished the LPS-induced fever, suppression of voluntary activity was reversed by the presence of IL-6 antibodies only to the extent of 27%, and appetite also was not returned to normal levels in the presence of IL-6 antibodies. Thus, IL-6 may be an essential component of LPS-induced fever, but an additional factor or factors, possibly working in parallel with IL-6, may be required to mediate the lethargy and anorexia induced by s.c. administration of LPS. Injecting rats i.p. with TNF-a antiserum or IL-1b antiserum had no effect on LPS-induced lethargy and LPS-anorexia, indicating that if these cytokines are working with peripherally-released IL-6 to induce sickness behaviour, it is likely due to their synthesis in the brain. Injecting species-homologous rat IL-1β and IL-6 into the brains of conscious rats, I aimed to identify whether either of these two cytokines can act within the brain to induce lethargy and anorexia in the absence of an infection. Intracerebroventricular (i.c.v.) administration of either IL-1β or IL-6 before the night-time active period decreased voluntary activity in the rats in a dose-dependent fashion, whereas only IL-1β decreased food intake and body mass of the rats. It is possible therefore, that increased levels of IL-1β in the brain may be working in parallel with IL-6 released in the periphery to induce lethargy and anorexia following s.c. administration of LPS. Thus I antagonized the biological action of these cytokines endogenously by administering species-specific antiserum to IL-6 (IL-6AS) i.p., and a caspase-1 inhibitor, which prevents the cleavage of pro-IL-1β to biologically active IL-1β, i.c.v. and monitored the symptoms of sickness induced by LPS until they ceased, so as to determine the cytokine involvement not only in the induction of these responses, but also in the resolution of these responses. Pre-treating rats with either IL-6AS i.p. or a caspase-1 inhibitor i.c.v. attenuated the magnitude and the duration of the anorexia and lethargy induced by LPS administration. LPS-induced fever was completely abolished in rats pretreated i.p. with IL-6AS, while it was only partially attenuated in rats pre-treated i.c.v. with a caspase-1 inhibitor. In conclusion, there appears to be some distinct differences in the cytokine-mechanisms regulating fever and sickness behaviours induced by LPS. Identifying the physiological mechanisms mediating fever and sickness behaviours during illness may provide clinicians with more insight into managing not only the thermal, but also the non-thermal responses to infections, responses which may become detrimental to the host if they continue for a prolonged period. My observation that reducing either IL-6 in the circulation or IL-1β in the brain significantly enhances the resolution of anorexia and lethargy, but does not completely prevent them from occurring, appears to indicate that while individual cytokines are possible targets for therapies aimed at alleviating these sickness responses in patients with bacterial infections, to abolish them multiple cytokines may need to be targeted.

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