Fish bioaccumulation and biomarkers in environmental risk assessment: a review

In the mid 1990s, immunoassays for C-reactive protein (CRP), with greater sensitivity than those previously in routine use, revealed that increased CRP values, even within the range previously considered normal, strongly predict future coronary events. These findings triggered widespread interest, especially, remarkably, in the US, where the clinical use of CRP measurement had been largely ignored for about 30 years. CRP production is part of the nonspecific acute-phase response to most forms of inflammation, infection, and tissue damage and was therefore considered not to provide clinically useful information. Indeed, CRP values can never be diagnostic on their own and can only be interpreted at the bedside, in full knowledge of all other clinical and pathological results. However, they can then contribute powerfully to management, just as universal recording of the patient’s temperature, an equally nonspecific parameter, is of great clinical utility.

The present torrent of studies of CRP in cardiovascular disease and associated conditions is facilitated by the ready commercial availability of automated CRP assays and of CRP itself as a research reagent. However, unlike the earlier rejection in the US of CRP as an empirical test because of its perceived lack of specificity, the current enthusiasm over CRP in cardiovascular disease is widely characterized by failure to recognize appropriately the nonspecific nature of the acute-phase response, and by lack of critical biological judgment. Quality control of the source, purity, and structural and functional integrity of the CRP, and the relevance of experimental design before ascribing pathophysiological functions, are also often ignored.

This article provides information about CRP as a protein and an acute-phase reactant, and a knowledge-based framework for interpretation and analysis of clinical observations of CRP in relation to cardiovascular and other diseases. We also review the properties of CRP, its possible role in pathogenesis of disease, and our own observations that identify it as a possible therapeutic target.

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C-reactive protein: a critical update

Cortisol is the principal corticosteriod in teleost fishes and its plasma concentrations rise dramatically during stress. The relationship between this cortisol increase and its metabolic consequences are subject to extensive debate. Much of this debate arises from the different responses of the many species used, the diversity of approaches to manipulate cortisol levels, and the sampling techniques and duration. Given the extreme differences in experimental approach, it is not surprising that inconsistencies exist within the literature. This review attempts to delineate common themes on the physiological and metabolic roles of cortisol in teleost fishes and to suggest new approaches that might overcome some of the inconsistencies on the role of this multifaceted hormone. We detail the dynamics of cortisol, especially the exogenous and endogenous factors modulating production, clearance and tissue availability of the hormone. We focus on the mechanisms of action, the biochemical and physiological impact, and the interaction with other hormones so as to provide a conceptual framework for cortisol under resting and/or stressed states. Interpretation of interactions between cortisol and other glucoregulatory hormones is hampered by the absence of adequate hormone quantification, resulting in correlative rather than causal relationships.

Cortisol in teleosts: dynamics, mechanisms of action, and metabolic regulation

Physiological changes in fish from stress in aquaculture with emphasis on the response and effects of corticosteroids

Innate immunity of fish (overview).

The role of phagocytes in the protective mechanisms of fish

C-reactive protein (CRP) was discovered by Tillett and Francis’ in the sera of patients with various infectious and inflammatory diseases as a material which precipitated pneumococcal C-polysaccharide (CPS). Subsequently Abernethy and Ave$ characterized CRP as a protein and identified the requirement for calcium ions in its interaction with CPS, while they and established that the appearance of CRP in the serum is a nonspecific response to infection, inflammation and tissue damage. Abernethy and Averf also introduced the term “acute phase sera” to designate samples obtained from patients in the acute phase of infectious diseases. CRP was called the “acute phase protein” and this term was subsequently applied to the large number of other plasma proteins, the concentrations of which are raised in acute phase sera. At an early stage Abernethy’ reported the presence of a precipitin comparable to CRP in acute phase monkey serum and, although he had been unable to find any in mouse or rabbit sera, Anderson and McCarty’later described the existence

Phylogenetic aspects of C-reactive protein and related proteins.

The effect of stress on the immune response of Atlantic salmon (Salmo salar L.) fed diets containing different amounts of vitamin C

Publisher Summary This chapter discusses phagocytosis in fish. Phagocytosis, the cellular ingestion and digestion of particulate matter, is probably the most widely distributed defense reaction occurring in virtually all animal phyla, As shown by primitive organisms, the process is directly related to nutrition and defense, but with the appearance of metazoan organization, cells specifically dedicated to the recognition and elimination of nonself material emerged. The presence of a vascular system also enhanced the speed with which these phagocytic cells could be mobilized at sites of injury, to dispose of invading bacteria and damaged cells from the organism itself. The phagocytic cells that play an important role in vertebrate defense mechanisms fall into two categories: (1) the granulocytes and (2) the mononuclear phagocytes. The phagocytic cells of fish can be generally considered within these groups. Studies on the behavior of phagocytic cells in fish exposed to pathogens can provide information on their effectiveness as defensive cells. A defect in phagocyte recognition, ingestion, or intracellular killing could be a contributory factor in the pathogenicity of some organisms.

Phagocytosis in fish

When plaice were injected intraperitoneally with either oyster glycogen or live Vibrio alginolyticus an acute cellular inflammatory response was observed. The duration of these responses, 7 and 15 days respectively, exceeded the time course of the mammalian cellular inflammatory reaction. Peak leucocyte numbers were found at 2–3 days and neutrophils, which were phagocytic, were more numerous than macrophages. Although the increase in macrophage numbers was less marked, these cells appeared more actively phagocytic than neutrophils. Cortisol injections and environmentally-induced stress caused a significant reduction in the extent of inflammatory cell infiltrates, while endotoxin significantly enhanced the response.

Thelma C. Fletcher

Papers

The role of phagocytes in the protective mechanisms of fish

Phylogenetic aspects of C-reactive protein and related proteins.

The effect of stress on the immune response of Atlantic salmon (Salmo salar L.) fed diets containing different amounts of vitamin C

Phagocytosis in fish

Peritoneal inflammatory cells in plaice, Pleuronectes platessa L.: effects of stress and endotoxin