First Evidence of Altered Immune Responses and Resistance to Air Exposure in the Clam Chamelea gallina Exposed to Benzo(a)pyrene

Abstract

Effects of benzo(a)pyrene [B(a)P] (at a nominal concentration of 0.5 mg/L) on immune responses of the clam Chamelea gallina were investigated after 1, 7, and 12 days exposure. Total hemocyte count (THC), hemocyte volume, phagocytic activity, lysozyme-like activity in both hemocyte lysate (HL) and cell-free hemolymph (CFH) were measured. As unexpected alterations in hemocyte adhesion capability were observed in short-term hemocyte cultures for phagocytosis assays after a 1-day exposure, an adhesion test (not included in the original experimental setup) was performed after 7 and 12 days of exposure only. The survival-in-air test was carried out to evaluate general stress conditions in B(a)P-exposed clams. No alterations in THC was observed, whereas exposure for 7 and 12 days to B(a)P significantly decreased phagocytic activity and adhesion capability when compared with controls. Significant decreases in lysozyme activity were observed in CFH and HL, with respect to controls. B(a)P was also shown to alter the resistance to air exposure of clams. The LT(50) values fell from 9 days in control clams to 7 days in 1-day-exposed animals, and from 6 days in control clams to 5 days in 7-day-exposed bivalves. No significant variations in LT(50) values were recorded after 12 days of exposure. Results highlight a relationship between B(a)P exposure and alterations in hemocyte functionality and suggest that the contaminant induced irreversible immunosuppression in C. gallina, by altering phagocytic activity, adhesion capability, and enzymatic activity. Conversely, reduction in resistance to air exposure was reversible, suggesting that impairment of important physiological functions of clams occurred in the first phases of exposure only.

Immunotoxic effects of triclosan in the clam Ruditapes philippinarum

“…This result suggests that the hemocytes from TCS-exposed clams experienced cell shrinkage. Similarly, the fraction of smaller hemocytes markedly increased after 12 days of B(a)P exposure in C. gallina (Matozzo et al 2009). In addition, NP exposure for 7 days of R. philippinarum caused dose-dependent effects in the frequency distribution of hemocyte size: the fractions of smaller (\100 fl) and larger hemocytes ([400 fl) increased at the highest tested NP concentrations compared to controls (Matozzo and Marin 2005).…”

“…Results of previous studies that have investigated the contaminant effects on bivalve hydrolytic enzyme activity are often conflicting. For example, intracellular lysozyme activity was significantly decreased in C. gallina after B(a)P exposure for 1, 7 and 12 days (Matozzo et al 2009) and in R. philippinarum after NP exposure for 7 days (Matozzo and Marin, 2005). Conversely, Wootton et al (2003) have observed that exposure of M. edulis and E. siliqua to phenanthrene did not induce significant changes in the percentage of hemocytes showing non-specific esterase activity (another lysosomal hydrolytic enzyme), whereas hemocytes from C. edule showed a significant decrease in their enzyme activity after 7 days of exposure to 400 lg l -1 phenanthrene.…”

“…Conversely, phenanthrene did not induce a significant change in THC values in M. edulis, Cerastoderma edule and Ensis siliqua (Wootton et al 2003). No significant alterations were also observed in THC in the clam Chamelea gallina after 12 days of exposure to benzo(a)-pyrene [B(a)P] (Matozzo et al 2009). Conversely, a 7-day exposure to sublethal concentrations of B(a)P significantly decreased THC in the marine gastropod Haliotis diversicolor (Gopalakrishnan et al 2009).…”

The nonsteroidal anti-inflammatory drug, ibuprofen, affects the immune parameters in the clam Ruditapes philippinarum

“…In a recent study, exposure for 7 days to 4-nonylphenol (NP) significantly increased the THC values in R. philippinarum (Matozzo and Marin, 2005). On the contrary, no significant alterations in THC were observed in the clam Chamelea gallina after 12 days of exposure to benzo(a)pyrene [B(a)P] (Matozzo et al, 2009). As in our previous studies (Matozzo and Marin, 2005;Matozzo et al, 2009Matozzo et al, , 2012, during the present survey, the effects of IBU on THC were assessed to ascertain whether the immunotoxic effects of the contaminant can primarily be related to changes in the number of circulating haemocytes.…”

“…Conversely, the exposure of clams to Triclosan (TCS) significantly decreased the diameter and volume of haemocytes, suggesting cell shrinkage (Matozzo et al, 2012). Similarly, the fraction of smaller haemocytes markedly increased in C. gallina after 12 days of exposure to B(a)P (Matozzo et al, 2009). In addition, exposure of R. philippinarum to NP for 7 days affected the frequency distribution of haemocyte size: the fractions of smaller (<100 fL) and larger haemocytes (>400 fL) increased at the highest tested NP concentrations compared to controls (Matozzo and Marin, 2005).…”