Immunotoxicity and disease resistance in Japanese quail (Corturnix coturnix japonica) exposed to malathion

Organophosphate-Pesticide-Mediated Immune Response Modulation in Invertebrates and Vertebrates

Organophosphate pesticides (OPs) have greatly facilitated food production worldwide, and their use is not limited to agriculture and the control of pests and disease vectors. However, these substances can directly affect the immune response of non-target organisms. In this sense, exposure to OPs can have negative effects on innate and adaptive immunity, promoting deregulation in humoral and cellular processes such as phagocytosis, cytokine expression, antibody production, cell proliferation, and differentiation, which are crucial mechanisms for host defense against external agents. This review focuses on the scientific evidence of exposure to OPs and their toxic effects on the immune system of non-target organisms (invertebrates and vertebrates) from a descriptive perspective of the immuno-toxic mechanisms associated with susceptibility to the development of bacterial, viral, and fungal infectious diseases. During the exhaustive review, we found that there is an important gap in the study of non-target organisms, examples of which are echinoderms and chondrichthyans. It is therefore important to increase the number of studies on other species directly or indirectly affected by Ops, to assess the degree of impact at the individual level and how this affects higher levels, such as populations and ecosystems.

Stocking density: a clue for improving social behavior, welfare, health indices along with productivity performances of quail (Coturnix coturnix)-a review

The quail populations are considered to be one of the largest among the poultry species. Although quail egg and meat production are growing rapidly, still, quail farming practices and welfare aspects are not well established. Stocking density is one of the factors that can significantly affect the welfare, health, and performance of birds, but according to The Expert Group for Technical Advice on Organic Production, no allowed space standards have been reported for new hybrids and different breeds of quail. This review presents an overview of 1) the benefits of egg and meat of quail, 2) the global market of quail products, 3) the factors affecting the stocking density rate, and 4) the effects of stocking density rates and housing systems on the social behavior, welfare, physiological indices, and performance parameters of broiler and laying quail. Conclusively, larger space and enriched aviaries reduce aggressive behavior, and improve the quail welfare and immunological indices. However, the effect of stocking density on some blood biochemical indices and growth performance parameters showed mixed results. A better understanding of the relationship between housing, health, growth performance, and welfare aspects would assist in the implementation of welfare-economic standards for quail production. According to available data, stocking density ranges for broiler and laying Japanese quail are suggested; however, these stocking rates should be tested under different conditions.

Immunotoxic role of organophosphates: An unseen risk escalating SARS-CoV-2 pathogenicity

Consistent gathering of immunotoxic substances on earth is a serious global issue affecting people under pathogenic stress. Organophosphates are among such hazardous compounds that are ubiquitous in nature. They fuel oxidative stress to impair antiviral immune response in living entities. Aside, organophosphates promote cytokine burst and pyroptosis in broncho-alveolar chambers leading to severe respiratory ailments. At present, we witness COVID-19 outbreak caused by SARS-CoV-2. Infection triggers cytokine storm coupled with inflammatory manifestations and pulmonary disorders in patients. Since organophosphate-exposure promotes necroinflammation and respiratory troubles hence during current pandemic situation, additional exposure to such chemicals can exacerbate inflammatory outcome and pulmonary maladies in patients, or pre-exposure to organophosphates might turn-out to be a risk factor for compromised immunity. Fortunately, antioxidants alleviate organophosphate-induced immunosuppression and hence under co-exposure circumstances, dietary intake of antioxidants would be beneficial to boost immunity against SARS-CoV-2 infection.

Malathion induced cancer-linked gene expression in human lymphocytes

BACKGROUND

Malathion is the most widely used organophosphate pesticide in agriculture. Increasing cancer incidence in agricultural workers and their children links to the exposure of malathion. Identification of genes involved in the process of carcinogenesis is essential for exploring the role of malathion. The alteration in gene expression by malathion in human lymphocytes has not been explored yet, although hematological malignancies are rampant in humans.

OBJECTIVE

This study investigates the malathion induced expression of cancer associated genes in human lymphocytes.

METHODS

Human lymphocyte viability and colony-forming ability were analyzed in malathion treated and control groups. Gene expression profile in control and malathion treated human lymphocytes were performed using a microarray platform. The genes which have significant functions and those involved in different pathways were analyzed using the DAVID database. Differential gene expression upon malathion exposure was validated by quantitative real-time (qRT)-PCR.

RESULTS

Malathion caused a concentration-dependent reduction in human lymphocyte viability. At low concentration (50 μg/mL) of malathion treatment, human lymphocytes were viable indicating that low concentration of malathion is not cytotoxic and induces the colony formation. Total of 659 genes (15%) were up regulated and 3729 genes (85%) were down regulated in malathion treated human lymphocytes. About 57 cancer associated genes related to the growth and differentiation of B and T cells, immunoglobulin production, haematopoiesis, tumor suppression, oncogenes and signal transduction pathways like MAPK and RAS were induced by malathion.

CONCLUSION

This study evidences the carcinogenic nature of malathion. Low concentration of this pesticide is not cytotoxic and induces differentially regulated genes in human lymphocytes, which are involved in the initiation, progression, and pathogenesis of cancer.

Population genomic data reveal genes related to important traits of quail

Background

Japanese quail (Coturnix japonica), a recently domesticated poultry species, is important not only as an agricultural product, but also as a model bird species for genetic research. However, most of the biological questions concerning genomics, phylogenetics, and genetics of some important economic traits have not been answered. It is thus necessary to complete a high-quality genome sequence as well as a series of comparative genomics, evolution, and functional studies.

Results

Here, we present a quail genome assembly spanning 1.04 Gb with 86.63% of sequences anchored to 30 chromosomes (28 autosomes and 2 sex chromosomes Z/W). Our genomic data have resolved the long-term debate of phylogeny among Perdicinae (Japanese quail), Meleagridinae (turkey), and Phasianinae (chicken). Comparative genomics and functional genomic data found that four candidate genes involved in early maturation had experienced positive selection, and one of them encodes follicle stimulating hormone beta (FSHβ), which is correlated with different FSHβ levels in quail and chicken. We re-sequenced 31 quails (10 wild, 11 egg-type, and 10 meat-type) and identified 18 and 26 candidate selective sweep regions in the egg-type and meat-type lines, respectively. That only one of them is shared between egg-type and meat-type lines suggests that they were subject to an independent selection. We also detected a haplotype on chromosome Z, which was closely linked with maroon/yellow plumage in quail using population resequencing and a genome-wide association study. This haplotype block will be useful for quail breeding programs.

Conclusions

This study provided a high-quality quail reference genome, identified quail-specific genes, and resolved quail phylogeny. We have identified genes related to quail early maturation and a marker for plumage color, which is significant for quail breeding. These results will facilitate biological discovery in quails and help us elucidate the evolutionary processes within the Phasianidae family.

Malathion induced oxidative stress leads to histopathological and biochemical toxicity in the liver of rohu (Labeo rohita, Hamilton) at acute concentration

Organophosphorus pesticides form a diverse group of chemicals, having a wide range of physicochemical properties with crucial toxicological actions and endpoints. These are extensively used to control pests of different food (fruits, vegetables, tea, etc.) and non-food (tobacco, cotton, etc.) crops. Malathion is an important widely used organophosphorus pesticide but its hepatotoxic effects on fish are not well studied. Therefore, the current study was designed to investigate the hepatotoxic effects of Malathion on rohu (Labeo rohita) fish in a semi-static system using different parameters. The LC₅₀ of Malathion was found to be 5 µg/L for rohu for 96 h through Probit analysis and was used for further toxicity testing. To find the hepatotoxic effects of Malathion, changes in different biochemical indices including protein contents, Lipid Peroxidation (LPO), activities of four protein metabolic enzymes [Aspartate Aminotransferase (AAT), Lactate Dehydrogenase (LDH), Alanine Aminotransferase (AlAT), and Glutamate Dehydrogenase (GDH)], seven antioxidant enzymes [Catalase (CAT), Superoxide Dismutase (SOD), Peroxidase (POD), Glutathione (GSH), Glutathione Reductase (GR), Glutathione-s-transferase (GST), and Glutathione Peroxidase (GSH-Px)], DNA damage [in term of comet tail length, tail moment, DNA percentage in tail, and olive tail moment], reactive oxygen species (ROS), and Histopathological alterations were assayed. Malathion exposure led to a time-reliant significant (P < 0.05) decrease in protein contents and a significant (P < 0.05) increase in ROS, LPO, enzymatic activities, and DNA damage. The histopathological examination of the liver showed different changes including hepatic necrosis, fatty infiltration, hemorrhage vacuolation, glycogen vacuolation, congestion, and cellular swelling. The current study clearly revealed Malathion as a potent hepatotoxic pesticide; therefore the injudicious, indiscriminate and extensive use of Malathion should be prohibited or at least reduced and strictly monitored.

The association between non-Hodgkin lymphoma and organophosphate pesticides exposure: A meta-analysis

Several epidemiological studies show the association between organophosphate pesticides (OPs) and the risk of non-Hodgkin lymphoma (NHL), yet various research results remain controversial. To explore the hazard of OPs exposure to human health, three kinds of OPs (Terbufos, Malathion, and Diazinon) that are non-halogenated aliphatic compounds were included in the meta-analysis. We searched PubMed and Web of Science Databases for articles published from 1985 to February 2017. The databases were also searched for eligible studies through a manual references search. The random-effect model was utilized to compute the odds ratios (ORs) and 95% confident intervals (CIs). A total of ten observational studies (five cohort, four case-control, and one nested case-control) were included in our meta-analysis, with a pooled OR of 1.22 (95% CI 1.04 to 1.43) of Malathion, Terbufos and Diazinion. The general heterogeneity for OR was moderate (P_h = 0.032, I² = 41.2%). The OR estimates in the subset analyses were utilized to compare the association between the three kinds of OPs and NHL; Terbufos (OR = 1.07, 95% CI 0.85 to 1.36) and Malathion (OR = 1.17, 95% CI 0.82 to 1.67) had a statistically non-significant relationship, whereas Diazinon (OR = 1.39, 95% CI 1.11 to 1.73) was significantly associated with an increased NHL risk. Because immune dysfunction was thought to increase NHL risk, the toxicity levels in the immune system of the three types of OPs were compared. Malathion attacked immune cells via a direct effect and Diazinon disrupted the neuro-immune system, which involves the cholinergic system of lymphocytes via indirect immune damage, whereas an immunotoxic effect involving Terbufos was not reported. Overall, the present meta-analysis indicated a statistically significant association between Diazinon exposure and NHL risk.

A comparative study on toxicity induced by carbosulfan and malathion in Wistar rat liver and spleen

Organophosphorus (OP) and carbamate (CM) pesticides are widely used in agriculture. These pesticides are highly toxic to humans and their residues in food pose potential threat to human health. In this comparative study, we investigated the effect of subchronic exposure of OPs (malathion, MAL) and CM (Carbosulfan, CB) on rat liver and spleen. Biochemical analysis showed that levels of hepatic enzymes (ALT, ALP, LDH and PAL) changed after exposure to the pesticides. In the liver extracts, lipid peroxidation index increased after the treatment by pesticides. Our results indicated that exposure to MAL and CB leads to alteration of liver redox status. Both pesticides induced focal inflammation and fibrosis in the liver. After subchronic administration of MAL (200 mg/kg) and CB (25 mg/kg), systemic inflammation, as depicted by the increase in IFN-δ activity in liver, was observed in both malathion and carbosulfan treated animals. In addition, the results showed that MAL significantly increased TCD4+ and TCD8+ lymphocyte number. It also decreased INF-δ and IL-4 production. However, CB induced a reduction of TCD8+ number and cytokine production in spleen cells. In conclusion, malathion and carbosulfan had significant immunomodulatory properties in the spleen with inflammation and oxidative stress induction in the liver.

Changes in glucose metabolism and reversion of genes expression in the liver of insulin-resistant rats exposed to malathion. The protective effects of N-acetylcysteine

Organophosphorus pesticides are known to disturb glucose homeostasis and increase incidence of metabolic disorders and diabetes via insulin resistance. The current study investigates the influence of malathion on insulin signaling pathways and the protective effects of N-acetylcysteine (NAC). Malathion (200 mg/kg) and NAC (2 g/l) were administered orally to rats, during 28 consecutive days. Malathion increases plasma glucose, plasma insulin and glycated hemoglobin levels. Further, we observed an increase of insulin resistance biomarkers and a decrease of insulin sensitivity indices. The GP, GSK3β and PEPCK mRNA expressions were amplified by malathion while, the expression of glucokinase gene is down-regulated. On the basis of biochemical and molecular findings, it is concluded that malathion impairs glucose homeostasis through insulin resistance and insulin signaling pathways disruptions in a way to result in a reduced function of insulin into hepatocytes. Otherwise, when malathion-treated rats were compared to NAC supplemented rats, fasting glucose and insulin levels, as well as insulin resistance indices were reduced. Furthermore, NAC restored liver GP and PEPCK expression. N-acetylcysteine showed therapeutic effects against malathion-induced insulin signaling pathways disruption in liver. These data support the concept that antioxidant therapies attenuate insulin resistance and ameliorate insulin sensitivity.

Association of inflammatory response and oxidative injury in the pathogenesis of liver steatosis and insulin resistance following subchronic exposure to malathion in rats

Insulin resistance and risk of type 2 diabetes are the most important complications following exposure to organophosphorous (OPs) pesticides. Regarding the importance of liver on metabolic pathways regulation, in particular blood glucose homeostasis, we focused on liver inflammation and oxidative damages in a subchronic model of toxicity by malathion. Adult male Wistar rats of body weight 200-250g were used for the study. Malathion (200mg/kg b.w./day) was administered to rats by oral intubation for 28 days. Glycemic and insulin resistance indices, markers of liver injury, markers of inflammation and oxidative stress were assessed. Malathion-treated rats showed increased glycemia, insulinemia and glycated hemoglobin level, HOMA-IR and HOMA-β indices, plasma activities of hepatocellular enzymes, lipid peroxidation index, CD3(+)/CD4(+) and CD3(+)/CD4(+) and pro-inflammatory cytokines when decreased antioxidant status in liver was noted. Most of our study indicates that malathion promotes insulin resistance, inflammation and Hepatosteatosis in subchronic model of exposure. On the basis of biochemical and molecular findings, it is concluded that insulin resistance induced by malathion occurs through oxidative stress and related pro-inflammatory markers in a way to result in a reduced function of insulin in liver cells.

Antioxidant and anti-inflammatory effects of N-acetylcysteine against malathion-induced liver damages and immunotoxicity in rats

AIMS

Occupational exposure to organophosphate pesticides is becoming a common and increasingly alarming world-wide phenomenon. The present study is designed to investigate the preventive effect of N-acetylcysteine on malathion-induced hepatic injury and inflammation in rats.

MAIN METHODS

Adult male Wistar rats of body weight 200-230 g were used for the study. Malathion (200mg/kg b.w./day) was administered to rats by oral intubation and N-acetylcysteine (2g/l) in drinking water for 28 days. Rats were sacrificed on the 28th day, 2h after the last administration. Markers of liver injury (aspartate transaminase, alanine transaminase, alkaline phosphatase and lactate desyhdogenase), inflammation (leukocyte counts, myeloperoxidase, immunophenotyping of CD4(+) and CD8(+), interleukin-1β, interleukin-6 and interferon-γ expression) and oxidative stress (lipid peroxidation, reduced glutathione and antioxidant status) were assessed.

KEY FINDINGS

Malathion induced an increase in activities of hepatocellular enzymes in plasma, lipid peroxidation index, CD3(+)/CD4(+) and CD3(+)/CD4(+) percent and pro-inflammatory cytokines, when decreased antioxidant status in liver was noted. When malathion-treated rats were compared to NAC supplemented rats, leukocytosis, T cell count and IL-1β, IL-6, INF-γ expression were reduced. Furthermore, NAC restored liver enzyme activities and oxidative stress markers.

SIGNIFICANCE

Malathion induces hepatotoxicity, oxidative stress and liver inflammation. N-acetylcysteine showed therapeutic effects against malathion toxicity.

Immunomodulation and hormonal disruption without compromised disease resistance in perfluorooctanoic acid (PFOA) exposed Japanese quail

This study evaluated the impact of oral perfluorooctanoic acid (PFOA) on Japanese quail at concentrations found in American and Belgian workers at PFOA manufacturing facilities. Three arms of the immune system were tested; T cell, B cell, and innate immunity. After 6 weeks exposure, quail were challenged with E. coli infection to test the ultimate measure of immunotoxicity, disease resistance. The T cell response was lower in the high exposure groups. Antibody mediated, and innate immune responses were not different. Growth rate was higher, whereas thyroid hormone levels were lower in PFOA-exposed birds. Morbidity/mortality from disease challenge was not different among the control and PFOA-exposed groups, and no overt PFOA toxicity was observed pre-disease challenge. Although PFOA at 'worst case scenario' levels caused T cell immunosuppression, this did not translate into increased disease susceptibility, demonstrating that immunotoxicity testing must be interpreted with caution since disease resistance is the ultimate concern.

Natural stressors and ranavirus susceptibility in larval wood frogs (Rana sylvatica)

Chronic exposure to stressors has been shown to suppress immune function in vertebrates, making them more susceptible to pathogens. It is less clear, however, whether many natural stressors are immunosuppressive. Moreover, whether stressors make disease more likely or more severe in populations is unclear because animals respond to stressors both behaviorally and physiologically. We tested whether chronic exposure to three natural stressors of wood frog tadpoles-high-densities, predator-cues, and low-food conditions-influence their susceptibility to a lethal ranavirus both individually in laboratory experiments, and collectively in outdoor mesocosms. Prior to virus exposure, we observed elevated corticosterone only in low-food treatments, although other treatments altered rates of growth and development as well as tadpole behavior. None of the treatments, however, increased susceptibility to ranavirus as measured by the proportion of tadpoles that became infected or died, or the time to death compared to controls. In fact, mortality in the mesocosms was actually lower in the high-density treatment even though most individuals became infected, largely because of increased rates of metamorphosis. Overall we find no support for the hypothesis that chronic exposure to common, ecologically relevant challenges necessarily elevates corticosterone levels in a population or leads to more severe ranaviral disease or epidemics. Conditions may, however, conspire to make ranavirus infection more common in metamorphosing amphibians.

Quantification of interferon, interleukin, and Toll-like receptor 7 mRNA in quail splenocytes using real-time PCR

Japanese quail (Coturnix japonica) are farmed worldwide as poultry. Quail have been used as experimental animals in various scientific fields, but their immunological characteristics have not been well characterized. In this study, to develop a method for analyzing the innate immune response of quail to infectious pathogens, we determined the nucleotide sequences of major interleukins (IL) and Toll-like receptor (TLR)-7 of quail and developed quantitative real-time PCR assays. The nucleotide sequences of quail IL-1β, IL-4, IL-6, IL-8, IL-10, IL-12a, IL-12b, IL-13, IL-18, and TLR-7 were determined based on the sequences of the chicken genes. Specific primers for each of these genes and previously reported interferon (IFN)-α, IFN-γ, and IL-2 genes were designed for quantitative real-time PCR. Standard curves for quantification were established using serial dilutions of external standard plasmids containing real-time PCR products. Then, real-time PCR was performed to monitor the kinetics of quail immune-related gene expression induced in splenocytes stimulated with concanavalin A. After amplification, the r(2) values of the standard curves for all target genes were above 0.980. Melting analysis of real-time PCR revealed specific amplification of each gene that could be visualized clearly as a single peak of melting temperature in a melt peak chart. These data show that the mRNA expressions of quail immune-related genes can be accurately quantified using this real-time PCR assay. In this study, we showed the nucleotide sequences of several quail cytokine mRNA and constructed the quantitative real-time PCR for quail immune-related genes.

Acephate immunotoxicity in White Leghorn cockerel chicks upon experimental exposure

Immunotoxicity for subacute exposure to acephate (O,S-dimethyl-acetylphosphoramidothioate) was assessed in day old White Leghorn (WLH) cockerel chicks. The chicks were divided into five groups. Groups C1 and C2 served as plain control and vehicle control respectively. Chicks of groups T1, T2 and T3 were administered acephate suspended in groundnut oil at 21.3mg/kg, 28.4mg/kg and 42.6mg/kg respectively orally for 28 days. A non-significant reduction in total leukocyte count was observed. Although, anti-Newcastle Disease Virus (NDV) antibody titer, serum total protein (TP), serum globulin, serum albumin and organ:body weight ratios of immune organs were significantly suppressed. The delayed type hypersensitivity response to 2,4-dinitro-1-chlorobenzene (DNCB) was not significantly altered. Histopathologically, bursa and spleen showed mild depletion of lymphocytes. Furthermore, DNA fragmentation assay was performed and detected ladder pattern (180bp) in DNA. It was concluded that subacute acephate exposure at low concentrations may affect immune responses in avian species.

Relative sensitivities of Japanese quail to foreign red blood cell challenges for immunotoxicity testing

Given evidence that the immune system is sensitive to environmental contaminants, evaluating immunocompetence in toxicology studies is increasingly important. By incorporating a test of humoral response into controlled reproductive and developmental studies, more comprehensive results can be gathered to assess the potential for disease. The foreign red blood cells (RBC) challenge is a minimally invasive method for evaluating humoral responses to a foreign antigen. Typically, antibody response is assessed following injections of sheep erythrocytes; however, Japanese quail (Coturnix japonica) are only minimally sensitive to sheep RBC. In the present study, adult Japanese quail were treated with 5% solutions of RBC from goose, goat, cow, donkey, or pig in primary and secondary challenges. After each treatment, plasma samples were taken and antibody responses were measured for total immunoglobulins (Ig), IgG, and IgM. Overall, goose RBC generated the poorest responses in both primary and secondary challenges, while the strongest antibody responses were to pig and donkey RBC. Therefore, pig RBC appear to be a superior antigen for testing humoral response in Japanese quail.