Oral Cadmium Intake Enhances Contact Allergen-induced Skin Reaction in Rats.

Objective: The effect of oral cadmium (Cd) intake to influence contact skin allergies was examined, since it is known that Cd is a heavy metal that affects many tissues, including the skin, in which it disturbs homeostasis, thus resulting in inflammation and injury. Methods: Male rats were evoked with experimental contact hypersensitivity reaction (CHS) to hapten dinitrochlorobenzene (DNCB), after prolonged (30 day) oral exposure to an environmentally relevant Cd dose (5 ppm). The ear cell population was analyzed with flow cytometry. Cytokine production by ear skin cells and the activity of skin-draining lymph node (DLN) cells were measured using enzyme-linked immunosorbent assay (ELISA). Results: Orally acquired Cd (5 ppm) increased CHS intensity only in Dark Agouti (DA) rats by affecting inflammatory responses in both the sensitization (an increase of IFN-γ and IL-17 cytokine production) and challenge (an increase of CD8 + and CD4 + cell number and TNF, IFN-γ and IL-17 cytokine production) phases. An increased CHS reaction was seen in Albino Oxford (AO) rats only at a high Cd dose (50 ppm), during the challenge phase (an increase of CD8 + and CD4 + cell number and TNF, IFN-γ and IL-17 cytokine production). Conclusion: These novel data indicate that oral Cd intensifies the skin response to sensitizing chemicals such as DNCB.

Dermatotoxicity of oral cadmium is strain-dependent and related to differences in skin stress response and inflammatory/immune activity.

Adverse effects of non-occupational exposure to cadmium (Cd) are increasingly acknowledged. Since our previous study has showed that orally acquired Cd affects skin, the contribution of genetic background to dermatotoxicity of oral cadmium was examined in two rat strains, Albino Oxford (AO) and Dark Agouti (DA), which differed in response to chemicals. While similar accumulation of Cd in the skin of both strains was noted, the skin response to the metal differed. DA rat individuals mounted antioxidant enzyme defense in the skin already at lower Cd dose, in contrast to AO rats which reacted to higher metal dose solely (and less pronounced), implying higher susceptibility of DA strain to Cd dermatotoxicity. Epidermal cells from both strains developed stress response, but higher intensity of antioxidant response in AO rats implied this strain`s better ability to defend against Cd insult. Cd induced epidermal cells' proinflammatory cytokine response only in DA rats. Increased IL-10 seems responsible for the lack of response in AO rats. Differences in the pattern of skin/epidermal cell responsiveness to cadmium give a new insight into repercussion of genetic variability to dermatotoxicity of orally acquired cadmium, bearing relevance for variations in the link between dietary cadmium and inflammation-based skin pathologies.

Pulmonary Aspergillus fumigatus infection in rats affects gastrointestinal homeostasis.

Microbiota inhabiting mucosal tissues is involved in maintenance of their immune homeostasis. Growing body of evidence indicate that dysbiosis in gut influence immune responses at distal sites including lungs. There are also reports concerning gut involvement with pulmonary injury/inflammation in settings of respiratory viral and bacterial infections. The impact of infections with other microorganisms on gut homeostasis is not explored. In this study, the rat model of sublethal pulmonary infection with Aspergillus fumigatus was used to investigate the effect of fungal respiratory infection on gut immune-mediated homeostasis. Signs of intestinal damage, intestinal and gut-draining lymphoid tissue cytokine responses and gut bacterial microbiota diversity were examined. Intestinal injury, inflammatory cell infiltration, as well as increased levels of intestinal interferon-γ (IFN-γ) and interleukin-17 (IL-17) (as opposed to unchanged levels of anti-inflammatory cytokine IL-10) during the two-week period depict intestinal inflammation in rats with pulmonary A. fumigatus infection. It could not be ascribed to the fungus as it was not detected in the intestine of infected rats. Increased production of pro-inflammatory cytokines by major gut-draining mesenteric lymph nodes point to these lymphoid organs as places of generation of cytokine-producing cells. No changes in spleen or systemic cytokine responses was observed, showing lack of the effects of pulmonary A. fumigatus infection outside mucosal immune system. Drop of intestinal bacterial microbiota diversity (disappearance of several bacterial bands) was noted early in infection with normalization starting from day seven. From day three, appearance of new bacterial bands (unique to infected individuals, not present in controls) was seen, and some of them are pathogens. Alterations in intestinal bacterial community might have affected intestinal immune tolerance contributing to inflammation. Disruption of gut homeostasis during pulmonary infection might render gastrointestinal tract more susceptible to variety of physiological and pathological stimuli. Data which showed for the first time gut involvement with pulmonary infection with A. fumigatus provide the baseline for future studies of the impact of fungal lung infections to gut homeostasis, particularly in individuals susceptible to these infections.

Oral cadmium exposure affects skin immune reactivity in rats.

Skin can acquire cadmium (Cd) by oral route, but there is paucity of data concerning cutaneous effects of this metal. Cd acquired by oral route can affect skin wound healing, but the effect of Cd on other activities involved in skin homeostasis, including skin immunity, are not explored. Using the rat model of 30-day oral administration of Cd (5 ppm and 50 ppm) in drinking water, basic aspects of immune-relevant activity of epidermal cells were examined. Dose-dependent Cd deposition in the the skin was observed (0.035 ±â€¯0.02 µg/g and 0.127 ±â€¯0.04 µg/g at 5 ppm and 50 ppm, respectively, compared to 0.012 ±â€¯0.009 µg/g at 0 ppm of Cd). This resulted in skin inflammation (oxidative stress at both Cd doses and dose-dependent structural changes in the skin and the presence/activation of innate immunity cells). At low Cd dose inflammatory response (nitric oxide and IL-1ß) was observed. Other inflammatory cytokines (IL-6 and TNF) response occurred at 50 ppm, which was increased further following skin sensitization with contact allergen dinitro-chlorobenzene (DNCB). Epidermal cells exposed to both Cd doses enhanced concanavalin A (ConA)-stimulated lymphocyte production of IL-17. This study showed for the first time the effect of the metal which gained access to the skin via gut on immune reactivity of epidermal cells. Presented data might be relevant for the link between dietary Cd and the risk of skin pathologies.

Oral warfarin intake affects skin inflammatory cytokine responses in rats.

Warfarin is an anticoagulant used in prevention/prophylaxis of thromboembolism. Besides the effects on coagulation, non-hemorrhagic reactions have also been documented. Although cutaneous reactions were reported in some patients, the impact on skin immunity was not explored. In the present paper, the effect of 30-day oral warfarin intake on skin cytokine responses in rats was analyzed. Increased release of inflammatory cytokines (TNF, IL-1ß and IL-10) was noted by skin explants from rats which received warfarin, but without effect on IL-6. No impact on epidermal cell cytokine secretion was seen, except a tendency of an increase of IL-6 response to stimulation with microbial product lipopolysaccharide (LPS). Topical application of contact allergen dinitrochlorobenzene (DNCB) resulted in slight (numerical solely) increase of TNF release by skin explants of warfarin-treated animals, while epidermal cells responded by increased secretion of all four cytokines examined. The data presented provide new information on the potential of oral warfarin to modulate skin innate immune activity.

Strain differences in intestinal toxicity of warfarin in rats.

Intestinal hemorrhage characterizes effectiveness of warfarin (WF) as rodenticide and is among adverse effects of therapy in humans. Having in mind genetic variations in the effectiveness of WF in wild rats and in the doses required for therapeutic effect, strain differences in the intestinal toxicity of oral warfarin in rats were examined in this study. High WF dose (3.5mg/l) led to mortality in Albino Oxford (AO) rats, with no lethality in Dark Agouti (DA) rats. Higher values of prothrombin time were noted at low WF dose (0.35mg/l) in the former strain. Leukocyte infiltration in intestine noted at this dose in both strains was associated with oxidative injury and more pronounced anti-oxidative response in AO rats. Suppression of mesenteric lymph node cell proliferation and IFN-γ and IL-10 production in AO rats and lack of these effects in DA rats, represent different strategies to protect vulnerable intestine from harmful immune responses.

Strain differences in toxicity of oral cadmium intake in rats.

Influence of genetic background on toxicity of oral cadmium (Cd) administration (30 days, in drinking water; 5 ppm and 50 ppm of cadmium) was examined in Albino Oxford (AO) and Dark Agouti (DA) rats. Similar cadmium deposition was noted in gut and draining mesenteric lymph nodes (MLN) of both strains but intensity and/or the pattern of responses to cadmium in these tissues differ. Less intense intestinal damage and leukocyte infiltration was observed in gut of cadmium-exposed AO rats. While gut-associated lymph node cells of DA rats responded to cadmium with an increase of cell proliferation, oxidative activity, IFN-γ, IL-17 production and expression, no changes of these activities of MLN cells of cadmium-treated AO rats were observed. Spleen, which accumulated cadmium comparable to MLN, responded to metal by drop in cell viability and by reduced responsiveness of proliferation and cytokine production to stimulation in DA rats solely, which suggest tissue dependence of cadmium effects. More pronounced cadmium effects on MLN and spleen cells of DA rats (which accumulated similar cadmium doses as AO rats), showed greater susceptibility of this strain to cadmium. The results presented, for the first time, depict the influence of genetic background to effects of oral cadmium administration.

Association of vascular endothelial growth factor expression with patohistological parameters of cutaneous melanoma.

BACKGROUND/AIM: Melanoma is the most aggresive malignant tumor of the skin. Contradictory data was published on vascular endothelial growth factor (VGEF) in tumor samples and its role in skin melanoma progression and prognosis. The aim of this study was to investigate the significance of VEGF expression as a prognostic parameter in melanoma. METHODS: The experimental group included 81 patients with primary skin melanomas treated from 2009 to 2013 at the Military Medical Academy, Belgrade. The control group included 20 patients with dysplastic and 20 with benign naevi. Stratification was done according to gender, age, clinical and patological stage, localization, histologic type, Clark's, Breslow, mitotic count, regression and ulceration, tumor infiltrating lymphocytes and metastatic spread.Immunohistochemical staining was performed on skin biopsies using DAKO anti-VEGF antibodies (Ab), LSAB+HRP, DAB and microvawe antigen (Ag) retrieval in DAKO pH 9.0 solution. For statistical data analysis was done with ANOVA, Bonferroni, Mann Whitney and Wilcox on test. RESULTS: The mean intensity of VEGF staining was statistically significantly higher in melanomas than in benign or dysplastic naevi. Furthermore, the highest recorded values were in Ia and IV clinical stages. The majority of melanomas with high intensity of VEGF staining were in pT1a pathological stage. Melanomas with the highest mitotic count (> 6) had a significantly higher intensity of VEGF staining than those with < 2 mitoses. The higest intensity of staining was in melanomas without significant lymphocytic infiltrate and the lowest was in those with brisk lymphocytic infiltrate, thus a statistical difference was siginifant. The mean intensity of VEGF staining was highest in melanomas with lymphovascular invasion. There was no statistically significant difference between VEGF and any other parameter. CONCLUSION: VEGF in primary skin melanomas plays an important role in tumor progression and is linked to the absence if tumor infiltrating lymphocytes and the presence of lymphovascular invasion. More detailed studies have to be done on VEGF prognostic value in melanoma on a larger number of patients.

Strain differences of cadmium-induced toxicity in rats: Insight from spleen and lung immune responses.

The impact of genetic background on effects of acute i.p. cadmium administration (0.5mg/kg and 1mg/kg) on basic immune activity of spleen and lungs was examined in two rat strains, Albino Oxford (AO) and Dark Agouti (DA), known to react differently to chemicals. More pronounced inhibition of Concanavalin A (ConA)-induced and Interleukin (IL)-2 stimulated spleen cell proliferation as well as higher levels of nitric oxide (known to decrease cell's proliferative ability) in DA rats at 1mg/kg, along with greater inhibition of ConA-induced Interferon (IFN-γ)-production by total and mononuclear (MNC) spleen cells and IL-17 production by spleen MNC in DA vs. AO rats at this dose show greater susceptibility of this strain to Cd effects on spleen cells response. More pronounced infiltration of neutrophils/CD11b(+) cells to lungs of DA rats treated with 1mg/kg of Cd and decreased IL-17 lung cell responses noted solely in DA rats speaks in favor of their higher susceptibility to this metal. However, lack of strain disparity in lung cells IFN-γ responses show that there are regional differences as well. Novel data from this study depict complexity of the influence of genetic background on the effects of cadmium on host immune reactivity.

Intestinal toxicity of oral warfarin intake in rats.

Though warfarin is extensively used in the prevention and treatment of thromboembolic processes in humans, adverse effects of warfarin therapy have been recognized. Intestinal hemorrhage is one of the hazards of anticoagulant therapy, but the mechanisms of warfarin toxicity are virtually unknown. In this work, the effects of 30 days oral warfarin (0.35 mg/l and 3.5 mg/l) intake on rat's gut were examined. Both doses resulted in prolongation of prothrombin time. Systemic effects of higher warfarin dose (increases in plasma AST, proteinuria, hematuria, changes in peripheral blood hematological parameters) were seen. Warfarin intake resulted in histologically evident tissue damage, leukocyte infiltration and intestinal inflammation [increases in myeloperoxidase activity, malondialdehyde content, superoxide dismutase and catalase activity, proinflammatory cytokine (IFN-γ, IL-17) concentrations in intestinal homogenates]. In contrast, suppression of gut-draining mesenteric lymph node (MLN) cell activity [proliferation responsiveness, production of IFN-γ and IL-17 to T lymphocyte mitogen Concanavalin A stimulation] was noted. Inhibition of regulatory cytokine IL-10 production by MLN cells, suggests commitment of MLN to the suppression of all inflammatory activities and creation of the microenvironment which is non-permissive for induction of potentially harmful immune response. These novel findings indicate the need of staying alert for (adverse) effects of warfarin therapy.

A subpopulation that may correspond to granulocytic myeloid-derived suppressor cells reflects the clinical stage and progression of cutaneous melanoma.

Seventy-eight melanoma patients and 10 healthy individuals were examined. Follow-up examinations of all melanoma patients were performed regularly every three months. Myeloid-derived suppressor cells (MDSC) were defined as lineage negative (CD3(-), CD19(-), CD56(-)), HLA-DR(-/low), CD11b(+) and CD33(+). Classification of granulocytic (GrMDSC) and monocytic (MoMDSC) subsets was based on the CD15 and CD14 expression, respectively. Unlike the MoMDSC, that were present in 60% of healthy controls and 15% of melanoma patients, the GrMDSC were present in all examined participants, and the melanoma patients were found to have statistically higher frequencies compared with healthy controls. Accordingly, we kept focused on GrMDSC frequencies in relation to the melanoma stages and course of the disease. The GrMDSC values are highest in stage IV melanoma patients, with statistical significance compared with stages IA, IB, IIA and IIB. Patients with progression had statistically higher GrMDSC counts comparing with those with stable disease (P = 0.0079). Patients who had progression-free interval (PFI) < 12 months showed significantly higher GrMDSC values compared with those with PFI > 12 months (P = 0.0333). GrMDSC showed significant negative correlation with PFI intervals (P = 0.0095). The GrMDSC subset was predominant in all our patients. We confirmed that GrMDSC do accumulate early in the peripheral blood of melanoma patients and their frequencies correlate narrowly with the clinical stage and the spread of the disease. The increase in GrMDSC frequencies correlates well with a progressive disease and could be considered a potential predictive biomarker of high-risk melanoma cases that are more likely to have a shorter PFI.

Skin response to epicutaneous application of anticoagulant rodenticide warfarin is characterized by differential time- and dose-dependent changes in cell activity.

CONTEXT: Skin is the target of both acute and chronic exposure to warfarin, coumarin anticoagulant. Single exposure of rat skin to this agent induces early (24 h following epicutaneous administration) local response which might be part of inflammatory/reparatory homeostatic program or introduction to pathological events in exposed skin. OBJECTIVE: To examine time-dependent changes in skin of rats exposed to epicutaneously applied warfarin. MATERIALS AND METHODS: The effect of low (10 µg) and high (100 µg) doses of warfarin on histologically evident changes of epidermis (epidermal thickness) and dermis (numbers of mesenchymal cells and dermal capillaries), skin cell proliferative activity (Ki67(+) and PCNA(+) cells) and apoptotic (TUNEL(+)) and necrotic (ultra structural appearance) cells was examined one, three and seven days after the application. RESULTS: Both warfarin doses affected the majority of skin cell activity, but with differential time-course of skin epidermal and dermal cells state/activity. The occurrence of necrotic/apoptotic epidermal and dermal cells was noted the first day after the application and the activities which point to tissue reparation/remodeling were observed seven days after skin exposure to this agent. DISCUSSION: The observed pattern of changes (early evidence of cell/tissue injury which was later followed by signs of cell activity characteristic for tissue reparation/remodeling) implied warfarin-induced toxicity in skin cells as stimulus for subsequent activities relevant for tissue homeostasis. CONCLUSION: The data presented provide new and additional information concerning skin responses to warfarin that gains access to this tissue.

Lymphoscintigraphy and sentinel lymph node biopsy, in cutaneous melanoma staging and treatment decisions.

OBJECTIVE: Sentinel lymph node biopsy (SLNB) is a widely accepted method in the management of clinically localized cutaneous melanomas. The aim of this study was to report the results on patients scheduled for preoperative lymphoscintigraphy and SLNB for staging and further treatment planning. SUBJECTS AND METHODS: Two hundred and one patients (115 male and 86 female, median age 57 years, range 9-81) with cutaneous melanoma having undergone SLB at Military Medical Academy between November 2010 and October 2014, were recruited for retrospective study. Dual labeling method (Tc-99m Nanocolloid (blue dye) was used. In order to delineate the relation between patients' tumors and scintigraphic characteristics with positive SLN findings, we examined all variables by univariate logistic regression with odd ratios representing the size effect. RESULTS: The overall identification rate of SLN was 98.5%. One or more positive SLN were seen in 47 (23.4%) of the patients. Drainage to one regional basin was noticed in 176 (88%) and multiple drainage regions, up to three, was noticed in 24 patients (12%). Transit lymph nodes were detected in 20 patients (10%). The characteristics that were assotiated significatly with sentinel lymph node metastases were Breslow thickness, nodular melanoma histological subtype and acral localization. CONCLUSION: Besides the well established primary tumor thickness being a predictor of SLN malignancy, we observed: acral body site location and nodular melanoma histological subtype to be significant independent factors in increasing the risk for regional metastases. Our results suport the clinical usefulness of SLNB within a multidisciplinary approach (dermatooncology, plastic/head and neck surgery, pathology, nuclear medicine), as a reliable method in staging and for treatment planning in melanoma patients.

Toxicity of oral cadmium intake: Impact on gut immunity.

Gastrointestinal tract is one of the main targets of cadmium (Cd), an important food and drinking water contaminant. In the present study, the effect of subchronic (30 days) oral (in water) intake of 5ppm and 50ppm of cadmium on immune responses in the gut was examined in rats. Cadmium consumption resulted in reduction of bacteria corresponding to Lactobacillus strain, tissue damage and intestinal inflammation [increases in high mobility group box 1 (HMGB1 molecules), superoxide dismutase (SOD) and catalase (CAT) activity and proinflammatory cytokine (TNF, IL-1ß, IFN-γ, IL-17) content]. Draining (mesenteric) lymph node (MLN) stress response was observed [elevation of MLN glutathione (GSH) and metallothionein (MT) mRNA levels] and stimulation of both adaptive [cellularity, proliferation, proinflammatory (IFN-γ and IL-17) MLN cell cytokine responses] as well as innate immune activity (increases in numbers of NK and CD68(+) cells, oxidative activities, IL-1ß). In contrast to proinflammatory milieu in MLN, decreased or unchanged antiinflammatory IL-10 response was observed. Stimulation of immune activities of MLN cells have, most probably, resulted from sensing of cadmium-induced tissue injury, but also from bacterial antigens that breached compromised intestinal barrier. These effects of cadmium should be taken into account when assessing dietary cadmium as health risk factor.

Interferon alpha-induced reduction in the values of myeloid-derived suppressor cells in melanoma patients.

BACKGROUND/AIM: Interaction between tumor cells and host's immunoregulatory cells in creation of microenvironment that supports tumor progression is the focus of numerous investigations in recent years. Myeloid-derived suppressor cells (MIDSCs) are heterogeneous population of immature dendritic cells, macrophages and granulocytes. In cancer patients, these cells accumulate in tumor microenvironment, tumor-draining lymph nodes, peripheral blood and the liver and their numbers correlate with the stage of the disease and the metastatic disease. The aim of the study was to investigate the effect of interferon alpha on MDSCs percentage in peripheral blood of melanoma patients. METHODS: The interferon treated melanoma patients were given subcutaneously interferon alpha, in optimal dose, for a period of at least 6 months before the analysis. Blood samples were collected from the melanoma patients (n=91) and the age/sex matched healthy controls (n=8). The following anti-human monoclonal antibodies were used for immunostaining: anti-CD15-FITC, anti-CD33-PE, anti-CD45-ECD, anti-HLA-DR PE/Cy5, anti-CD14-FITC, anti-CD16-PE and anti-CD11b-PE. RESULTS: Comparison of myeloid- derived suppressor cells values in the stage 2 melanoma patients with and without interferon alpha therapy did not show a significant difference. When we compared the MDSCs values in the patients within stage 3 melanoma, we found a significant difference in granulocytic subset values between the interferon alpha-treated and the untreated group. Comparison of values of all suppressor cells populations between the interferon alpha-treated patients and healthy controls showed a significant increase in suppressor cells percentage in the melanoma patients. The granulocytic and total MDSCs values were significantly lower in the interferon alpha treated melanoma patients with progression in comparison with untreated patients with stable disease. CONCLUSION: We confirmed that interferon alpha effect in stage 3 melanoma patients was reduction in MDSCs percentage. We also found an unexpected bounce back of these suppressor cells levels, many months after the discontinuation of interferon alpha therapy.

Proinflammatory cytokine responses in skin and epidermal cells following epicutaneous administration of anticoagulant rodenticide warfarin in rats.

CONTEXT: Dermal toxicity of coumarin anticoagulant rodenticides, such as warfarin, represents potential risk for workers handling these agents and for individuals applying easily available rodenticides in their households as well. OBJECTIVE: In this study, proinflammatory effects of repeated epicutaneous administration of warfarin in rats were explored by examining inflammatory cytokine skin responses. MATERIALS AND METHODS: Ex vivo production of IL-1ß, IL-6, TNF-α and IL-17 by skin explants and by epidermal cells isolated by enzyme (dispase/trypsin) digestion from skin repeatedly (once a day, three consecutive days) exposed to 10 µg of warfarin was measured 24 h and 72 h following the last warfarin application by ELISAs for respective rat cytokines. RESULTS: Warfarin treatment resulted in histological changes, but skin or epidermal cell viability were not compromised, judging by MTT reduction assay. Both skin and epidermal cells responded to administration of this agent by production of all examined inflammatory cytokines (skin explants by TNF-α and IL-17; epidermal cells by IL-1ß and TNF-α) except IL-6. DISCUSSION: Along with histomorphological changes, cytokines indicate functional consequences in treated skin. IL-1ß production, that precede production of TNF-α, might be responsible for production of the latter cytokine. Sustained production of IL-1ß suggests persistence of epidermal cell stimulation or existence of some amplification mechanisms. Requirements for T cells seem to exist concerning epidermal cell IL-17 production. CONCLUSION: Presented data provide additional new information concerning proinflammatory effects of warfarin.

Strain differences in contact hypersensitivity reaction to dinitrochlorobenzene (DNCB) in rats.

Genetic factors are among the most important determinants of susceptibility to induction of allergic contact dermatitis. A limited number of studies of experimental contact hypersensitivity (CHS) in animals has shown differences in the severity of CHS; however, the underlying mechanisms are unknown. In this study comparative analysis of CHS to low and high dinitrochlorobenzene (DNCB) doses regimen of sensitization/challenge in inbred Dark Agouti (DA) and Albino Oxford (AO) rats was examined. Basic aspects of draining lymph node (dLN) activity (cellularity, proliferation), proinflammatory (IFN-γ, IL-17) and anti-inflammatory (IL-10) cytokine gene expression and production, as well as IL-12 and IL-23 subunits mRNA expression, were examined in challenge and sensitization phase of CHS reaction. Lower (compared to DA) intensity of CHS in AO rats was associated with lack of (or negligible) dLN responses in challenge phase (ex vivo, hapten- or IL-2-stimulated cell proliferation and proinflammatory cytokine mRNA and production levels) but with lack of changes in IL-10 response. Less pronounced dLN activity of sensitized animals of this strain was observed as well. Higher proliferative activity and more pronounced proinflammatory cytokine response during challenge and sensitization phase suggest these activities as underlying mechanisms of higher susceptibility of DA rats to CHS response to DNCB.

Cadmium administration affects circulatory mononuclear cells in rats.

Although numerous investigations have demonstrated a direct effect of cadmium (Cd) on peripheral blood mononuclear cell (PBMC) activity in humans, there is virtually no data concerning the in vivo impact of this metal on circulatory mononuclear cells. In this study, the effects of a sub-lethal Cd (1 mg/kg) dose were examined in rats 48 h following a single intraperitoneal injection. Cd treatment resulted in increased total peripheral blood leukocyte levels; however, decreases in PBMC numbers were seen. These changes coincided with an accumulation of mononuclear cells in the lungs and an increase in mononuclear cells expressing CD11b. A lack of effect of Cd on spontaneous nitric oxide (NO) production and on iNOS mRNA levels in the PBMC was also noted. Differential effects of Cd on PBMC inflammatory cytokine (IL-1ß, TNFα, IL-6, IFNγ, and IL-17) gene expression and production were also seen. Specifically, except for IL-1ß (levels increased), there were decreases (relative to controls) in mRNA levels for all the other cytokines examined. While there were no Cd treatment-related changes in spontaneous production of the cytokines assessed, there seemed to be a trend (p = 0.06) toward a decrease in spontaneous IL-6 release. When these harvested cells were stimulated ex vivo, there was no effect from Cd exposure on LPS-stimulated IL-1ß and TNFα or on ConA-stimulated IFNγ or IL-17 production, but a decrease in IL-6 production in response to LPS was, again, noted. A preliminary study with a lower Cd dose (0.5 mg/kg) revealed some of the same outcomes noted here (mononuclear cell infiltration into lungs, increases in PBMC IL-1ß mRNA levels), but differential (increased IL-17 mRNA levels) or newly detected outcomes (increased levels of IL-1α mRNA) as well. The described effects of the single in vivo exposure to Cd on PBMC might contribute to a better overall understanding of the immunomodulatory potential of this environmental contaminant.

Acute cadmium administration to rats exerts both immunosuppressive and proinflammatory effects in spleen.

Conflicting data (both suppression and augmentation as well as lack of the effect) exist in respect to cadmium (Cd) and splenic T cell-based immune cell activity. Spleen is also the site of innate immune responses but impact of Cd on this type of immunity has been less explored. In the present study the effects of acute Cd administration on basic aspects of both T cell-based and innate immune spleen cell activity were examined in rats. Intraperitoneal injection of 1mg of Cd/kg resulted in decrease in concanavalin A (ConA) induced proliferation which seems to be more related to altered spleen cells responsiveness to IL-2 than to apoptosis. Differential effects on proinflammatory T cell derived cytokines were observed (decreases of IFN-γ gene expression and ConA-stimulated production, but increases in IL-17 mRNA levels with no effect on concentrations of protein product). Reduction of IFN-γ production seemed not to rely on IL-4 and IL-10, but at least partly on nitric oxide (NO). Increased activity relevant for innate immunity (granulocyte and CD11b(+) cell accumulation in the spleen, inducible nitric oxide synthase/iNOS expression and NO production by spleen cells) was observed, but there was a decrease in respiratory burst (dihydrorhodamine/DHR oxidation and nitroblue tetrazolium/NBT reduction). Increases of TNF-α and IL-1ß gene expression and IL-1ß protein product were noted as well. Administration of 0.5mg Cd/kg resulted in less pronounced (ConA-induced proliferation) or lack of the effect (IFN-γ production) on spleen T cell activities and on innate activities (granulocyte accumulation, NO production) as well. However, increases of spleen cell respiratory burst activity and IL-1ß production were observed. Effects of lower cadmium doses (5ppm and 50ppm) on several aspects of spleen cell immune activity were observed in intermediate period of exposure (30 days, oral intake) as well. Differential effects of Cd on immune activities of spleen cells might contribute to our understanding of the complexity of immunomodulatory effects of this metal.