4-Nonylphenol induces immunomodulation and apoptotic events in the clam Tapes philippinarum

Abstract

The effects of 4-nonylphenol (NP) on functional responses of haemocytes from the clamTapes philippinarum were investigated after 7 d exposure to sublethal NP concentrations (0, 0 + acetone, 0.025, 0.05, 0.1 and 0.2 mg l -1 NP). Haemocytes from both controls and exposed clams were collected, and the effects of NP on uptake of the vital dye Neutral Red (NR), superoxide dismutase (SOD) and lysozyme activities, total haemocyte count (THC) and volume of circulating cells were evaluated. The capability of NP to induce apoptosis was also investigated. Exposure of clams to 0.2 mg l -1 NP significantly increased (p < 0.05) NR uptake when compared with controls, suggesting that NP caused alterations in cell membrane stability. Significant decreases in both SOD and lysozyme activity were observed from 0.05 mg l -1 NP (p < 0.01 and p < 0.05, respectively) with respect to controls, indicating that NP causes oxidative stress and reduces the immunocompetence of the exposed clams. From 0.05 mg l -1 NP, the apoptotic index (percentage of haemocytes showing positivity to the TUNEL reaction) significantly increased (p < 0.001). Apoptotic haemocytes showed shrinkage and lost their amoeboid shape. Moreover, NP exposure significantly increased THC (p < 0.05 at 0.2 mg l -1 NP) and caused a different distribution in size frequency. On the basis of the threshold concentration values, the most sensitive endpoints for NP were SOD, lysozyme and apoptosis assays. Our results highlight a relationship between NP exposure and changes in the functional responses of haemocytes, suggesting that the contaminant induces immunomodulation in T. philippinarum, mainly by altering cell morphology, cell membrane stability and enzymatic activities, and by promoting oxidative stress and apoptotic events.

Haemocyte apoptosis as a general cellular immune response of the snail, Lymnaea stagnalis, to a toxicant

“…An increased fraction of spreading cells occurs concomitantly with the presence of apoptotic and necrotic cells in exposed snails. This observation suggests a facilitated turnover of those cells and/or the accompanied presence of haemocytes phagocytosing these cells (Matozzo and Marin 2005). Damaged cells are cleared but several aspects distinguish the engulfment of dying cells from the classical phagocytosis targeting foreign material: mainly, the uptake of apoptotic cells occurs without triggering the inflammatory response (Alibert and Chimini 2002).…”

“…A significant increase of circulating haemocytes has often been causally related to stress Pipe et al 1995Pipe et al , 1999Russo and Lagadic 2000;Matozzo et al 2001;Matozzo and Marin 2005). The higher number of blood cells in circulation may be attributable to migration from haematopoietic tissues rather than cell proliferation.…”

The Effects of 4-Nonylphenol on the Immune Response of The Pacific Oyster, Crassostrea Gigas, Following Bacterial Infection (Vibrio Campbellii)

“…This finding differs from previous studies, which reported an increase in THC in both clams (Matozzo and Marin, 2005) and cockles (Matozzo et al, 2008) exposed to nonylphenol (100 -200 μg/L for 7d). Perhaps the slight (although insignificant) increases we see in our salineinjected, 4-NP exposed oysters relative to the control oysters ( Fig.…”

“…Our observation that 4-NP disrupts the cellmediated immune response in oysters is corroborated by a number of other studies that have revealed rapid, functional effects of 4-NP on hemocyte parameters in bivalves. Matozzo and Marin (2005) found that exposure to 4-NP in clams (for similar duration and lengths as in the present study) led to a substantial increase in apoptotic activity in hemocytes. 4-NP has also been shown to decrease hemocyte lysosomal membrane stability in mussels (Canesi et al, 2004(Canesi et al, , 2007 and cockles (Matozzo et al, 2008), alter hemocytic phagocytosis in mussels (Canesi et al, 2007), decrease hemocyte membrane stability and, as mentioned above, increased hemocyte apoptosis in clams (Matozza and Marin, 2005).…”

“…Similar increases in lysozyme activity as a result of exposure to 4-NP were seen in cockles (Cerastoderma glaucum) and were hypothesized to be the result of altered lysosomal membrane stability and subsequent release of enzymes into the hemolymph (Matozzo et al, 2008). It has also been suggested that clams (Mercenaria mercenaria) experience immunosuppression when exposed to 4-NP due to decreased lysozyme activity in the hemocytes (Matozzo and Marin, 2005).…”