Experimental apical periodontitis alters salivary biochemical composition and induces local redox state disturbances in the salivary glands of male rats

OBJECTIVES

The objective was to evaluate the effects of experimental apical periodontitis on the inflammatory, functional, biochemical, and redox parameters of the parotid and submandibular glands in rats.

MATERIALS AND METHODS

Twenty 12-week-old male Wistar rats were randomly divided into two groups (n = 10): a control group and apical periodontitis group. After 28 days, the saliva was collected for salivary flow rate and biochemistry composition. Both glands were sampled for quantification of the tumor necrosis factor-alpha (TNF-α) and biochemical analyses of redox state.

RESULTS

TNF-α concentrations were higher in both salivary glands adjacent to the periapical lesions in animals with apical periodontitis and also compared to the control group. The apical periodontitis group increased the salivary amylase, chloride, potassium, calcium, and phosphate. The total oxidant capacity increased in the parotid gland adjacent to the periapical lesions in the same rat and compared to the control group. Conversely, the total antioxidant capacity of the parotid glands on both sides in the apical periodontitis group was lower than that in the control group. Furthermore, glutathione peroxidase activity increased in the submandibular gland adjacent to the apical periodontitis group compared to the control group.

CONCLUSIONS

Experimental apical periodontitis alters salivary biochemical composition, in addition to increasing inflammatory marker and inducing local disturbances in the redox state in the parotid and submandibular glands of male rats.

CLINICAL RELEVANCE

Apical periodontitis could exacerbate the decline in oral health by triggering dysfunction in the salivary glands.

Alterations in salivary biochemical composition and redox state disruption induced by the anticonvulsant valproic acid in male rat salivary glands

OBJECTIVE

To investigate the effects of the anticonvulsant valproic acid (VPA) on salivary glands in male rat using biochemical, functional, histomorphometric, and redox state parameters.

MATERIALS AND METHODS

Twenty-four male Wistar rats were randomly distributed into three groups (n = 8 per group): Control (0.9% saline solution), VPA100 (100 mg/kg), and VPA400 (400 mg/kg). After 21 consecutive days of treatment with by intragastric gavage. Pilocarpine-induced saliva was collected to determine salivary flow rate, pH, buffering capacity, and biochemical composition. Analyses of histomorphometric parameters and redox balance markers were performed on the parotid and submandibular glands.

RESULTS

Salivary flow rate, pH, buffering capacity, total protein, potassium, sodium, and chloride were similar between groups. However, phosphate and calcium were reduced in VPA400, while amylase was increased in both VPA100 and VPA400. We did not detect significant differences in the areas of acini, ducts, and connective tissue in the salivary glands between the groups. There were no significant changes in the redox status of the submandibular glands. In turn, in the parotid glands we detected reduced total oxidizing capacity and lipid peroxidation, measured as thiobarbituric acid reactive substances (TBARs) and higher uric acid concentration in both the VPA100 and VPA400 groups, and increased superoxide dismutase (SOD) in the VPA400 group.

CONCLUSION

Chronic treatment with VPA modified the salivary biochemical composition and caused disruption in the redox state of the parotid gland in rats.

Dual nanocarrier of chlorhexidine and fluconazole: Physicochemical characterization and effects on microcosm biofilms and oral keratinocytes

OBJECTIVES

This study assembled and characterized a dual nanocarrier of chlorhexidine (CHX) and fluconazole (FLZ), and evaluated its antibiofilm and cytotoxic effects.

METHODS

CHX and FLZ were added to iron oxide nanoparticles (IONPs) previously coated by chitosan (CS) and characterized by physical-chemical analyses. Biofilms from human saliva supplemented with Candida species were grown (72 h) on glass discs and treated (24 h) with IONPs-CS carrying CHX (at 39, 78, or 156 µg/mL) and FLZ (at 156, 312, or 624 µg/mL) in three growing associations. IONPs and CS alone, and 156 µg/mL CHX + 624 µg/mL FLZ (CHX156-FLZ624) were tested as controls. Next, microbiological analyses were performed. The viability of human oral keratinocytes (NOKsi lineage) was also determined (MTT reduction assay). Data were submitted to ANOVA or Kruskal-Wallis, followed by Fisher's LSD or Tukey's tests (α=0.05).

RESULTS

Nanocarriers with spherical-like shape and diameter around 6 nm were assembled, without compromising the crystalline property and stability of IONPs. Nanocarrier at the highest concentrations was the most effective in reducing colony-forming units of Streptococcus mutans, Lactobacillus spp., Candida albicans, and Candida glabrata. The other carriers and CHX156-FLZ624 showed similar antibiofilm effects, and significantly reduced lactic acid production (p<0.001). Also, a dose-dependent cytotoxic effect against oral keratinocytes was observed for the dual nanocarrier. IONPs-CS-CHX-FLZ and CHX-FLZ significantly reduced keratinocyte viability at CHX and FLZ concentrations ≥7.8 and 31.25 µg/mL, respectively (p<0.05).

CONCLUSION

The nanotherapy developed outperformed the effect of the combination CHX-FLZ on microcosm biofilms, without increasing the cytotoxic effect of the antimicrobials administered.

CLINICAL SIGNIFICANCE

The dual nanocarrier is a promising topically-applied therapy for the management of oral candidiasis considering that its higher antibiofilm effects allow the use of lower concentrations of antimicrobials than those found in commercial products.

Early life stress exacerbates bone resorption and inhibits anxiety-like behaviour induced by apical periodontitis in rats

AIM

To evaluate the influence of the early life stress (ELS) on the severity of the apical periodontitis (AP) in Wistar rats.

METHODOLOGY

Forty male Wistar rats were divided into four groups (n = 10): Control rats; AP-rats with AP; ELS-rats subject to ELS; AP + ELS-rats exposed to ELS and subject to AP. ELS was induced by maternal separation (MS) for a period of 3 h for 21 consecutive days. AP was induced via pulp exposure of the first and second right maxillary molars to the oral environment for 40 days. Three days before euthanasia, all rats underwent behavioural analysis to measure anxiety levels by elevated zero maze. Then, the rats were euthanized and the maxillas were removed to assess the occurrence and severity of AP. The periapical region was evaluated for the intensity of the inflammatory infiltrate and the extent of bone loss. The Mann-Whitney test was performed for nonparametric data, and the Tukey's or Student's t-test was performed for parametric data (p < .05).

RESULTS

The intensity of the inflammatory infiltrate was significantly larger in the AP + ELS group when compared with AP group (p < .05). The AP + ELS group exhibited significantly greater alveolar bone loss, with a periapical lesion size of 103.5 ± 29.88, compared with 72.3 ± 22.28 in the AP group (p < .05). Rats with AP displayed higher anxiety-like behaviour in relation to the control group (p < .05). However, exposure to ELS abolished the AP-induced increased anxiety-like 'behaviour' throughout, since that rats from AP + ELS group attended more the open arms than non-stressed rats with AP (p < .05).

CONCLUSION

Early life stress is predictive of the severity of AP exacerbating the inflammatory process and increasing periapical bone resorption.

Analysis of the femoral neck from rats in the periestropause treated with oxytocin and submitted to strength training

Among the interventions used to prevent osteoporosis in female organisms, strength training (ST) and oxytocin (OT) stand out, as a promising hormone with anabolic action on bone. This study aimed to verify whether the combined action of OT and ST, compared to isolated interventions, potentiates the bone remodeling process of the femoral neck of Wistar rats during periestropause. Forty Wistar rats (18 months) with irregular estrous cycle were randomly distributed into groups: 1-Vehicle (Veh; NaCl 0.15 mol/L ip); 2-Oxytocin (Ot; 134 μg/kg/ip); 3-Strength training (St); 4-Ot + St. The animals of the 1, 2 and 4 groups received two intraperitoneal injections with an interval of 12 h every 30 days, totaling 8 injections at the end of the experimental period (18 to 21 months). The animals in the St and Ot + St groups performed ST on a ladder 3 times a week, maximal voluntary carrying capacity (MVCC) test monthly. After 120 days, the animals were euthanized; the femur was collected for analysis of biomechanical testing, densitometry, bone microtomography, Raman spectroscopy, tissue PCR, and blood for analysis of bone biomarkers, liver damage, and oxidative stress. The main effects in the Ot group were observed in the maximum load and energy in the compression testing (femoral head), and stiffness and energy in the three-points bending testing (femur diaphysis). In addition, the main effects occurred on the bone mineral density (BMD), cortical thickness (Ct.Th), number of pores (Po.N), polar moment of inertia (J), trabecular thickness (Tb.Th), and connectivity density (Conn.Dn), Bone alkaline phosphatase (Alp), Tumor necrosis factor receptor superfamily member 11b (Opg), Tumor necrosis factor ligand superfamily member 11 (Rankl) and Cathepsin K (Ctsk) expression. There was an effect in the tartrate-resistant acid phosphatase (TRAP) and alkaline phosphatase (ALP). In the St group, the main effect was observed on the energy (compression and the three-points bending), stiffness, aBMD, BMD, cortical bone area (Ct.Ar), Po.N, trabecular bone volume (BV/TV), Tb.Th and in the mineralization ratio (ѵ₁PO₄/proline), Runt-related transcription factor 2 (Runx2), Bone morphogenetic protein 2 (Bmp2), Alp, Osteopontin/secreted phosphoprotein 1 (Opn/Spp1), Opg, Tumor necrosis factor receptor superfamily member 11ª (Rank), Rankl, Ctsk expression. There was an effect in the TRAP and ALP. The interaction in the combination of therapies in the Ot + St group was verified in energy to maximum load (compression and three-points bending testing), stiffness, BMD, Ct.Th, J, Tb.Th and ѵ₁PO₄/proline. In the gene analysis there was interaction in the Runx2, Osterix/Sp7 transcription factor (Osx/Sp7), Bmp2, Alp, Osteocalcin/Bone gamma-carboxyglutamate protein (Ocn/Bglap), Opg, Rankl and Acid phosphatase 5, tartrate resistant (Trap/Acp5) expression. In addition, the combination of OT and ST resulted in a higher maximum load compared to the Veh group, with higher BV/TV than the Ot group, higher Rankl and Ctsk expression than Veh and Ot groups, and lower Po.N and lower activity of TRAP than the other groups. In oxidative stress, total antioxidant capacity (TAC) was lower. These results showed that the combination of interventions is a promising anabolic strategy for the prevention of osteoporosis in the period of periestropause, standing out from the effects of isolated interventions.

Stress hormone norepinephrine incites resistance of oral cancer cells to chemotherapy

This study investigated whether norepinephrine (NE) and epinephrine (E) interfere in the response of head and neck squamous cell carcinoma (SCC) cell lines to cisplatin and explored the mechanisms of chemoresistance. Head and neck SCC-derived cell lines SCC-9, Cal27, SCC-25, and FaDu were stimulated with NE or E and treated with the inhibitory concentration of cisplatin for 24 h. As for adrenergic receptors (ADRB) inhibition, cells were treated with propranolol. The results showed that, when combined with NE, cisplatin effectiveness against SCC-9 and Cal27 but not SCC-25 and FaDu cells were notably reduced. E did not affect the response of the cells to cisplatin. Further experiments were performed with the responsive SCC-9 and SCC-25 cell lines and the hormone NE. The time course assay showed that stimulation of oral SCC cells with NE decreased the cleavage of caspase-3 and expression of multidrug resistance protein 1 (MDR-1) but only transiently affected ATP-binding cassette (ABC) subfamily G, isoform 2 protein (ABCG2) expression. The expression of cleaved caspase-3 and Bcl-2 were, respectively, decreased and increased by the combination of NE and cisplatin in SCC-9 and Cal27 cells. NE-induced resistance was reverted by previous treatment with propranolol. Expressions of ABCG2, and p-Akt but not of MDR-1, were enhanced by NE plus cisplatin when compared to cisplatin only in both cell lines. Migratory activity of oral SCC cells challenged with cisplatin was not affected by NE. These findings reveal for the first time that stress hormone NE induces resistance of oral cancer cells to cisplatin in vitro through the ADRB/Akt/ABCG2 pathway, pumping the drug out of the cell and inhibiting apoptosis.

Telmisartan impairs the in vitro osteogenic differentiation of mesenchymal stromal cells from spontaneously hypertensive male rats

Telmisartan (TELM) is an angiotensin II (Ang II) type 1 receptor (Agtr1) antagonist, with partial agonism for Pparg, and has been shown to affect bone metabolism. Therefore, the aim of this study was to investigate the effects of TELM in the in vitro osteogenic differentiation of bone marrow-derived mesenchymal stromal cells (BMSC) from spontaneously hypertensive rats (SHRs). BMSC were obtained from male SHR, and the osteogenic medium (OM) was added to the cells concomitantly with TELM (0.005, 0.05, and 0.5 μM). Undifferentiated BMSC, in control medium (CM), showed an increased viability, while the addition of OM reduced this parameter, and TELM did not show cytotoxicity in the concentrations used. BMSC in OM had an alkaline phosphatase (ALP) activity peak at d10, which decreased at d14 and d21, and TELM reduced ALP at d10 in a dose-dependent manner. Mineralization was observed in the OM at d14, which intensified at d21, but was inhibited by TELM. Agtr1b was increased in the OM, and TELM inhibited its expression. TELM reduced Opn, Ocn, and Bsp and increased Pparg expression, and at the higher concentration TELM also increased the expression of adipogenic markers, Fabp4 and Adipoq. In addition, TELM 0.5 μM increased Irs1 and Glut4, insulin and glucose metabolism markers, known to be regulated by Pparg and to be related to adipogenic phenotype. Our data shows that TELM inhibited the osteogenic differentiation and mineralization of SHR BMSC, by favoring an adipogenic prone phenotype due to Pparg upregulation.

β1-adrenergic receptor but not β2 mediates osteogenic differentiation of bone marrow mesenchymal stem cells in normotensive and hypertensive rats

The sympathetic nervous system regulates bone remodeling via adrenergic receptors on the surface of bone cells. Herein, we evaluated the role of beta-adrenergic receptors (ADRBs) in osteoblastic differentiation of bone marrow mesenchymal stem cells (BMSCs) derived from normotensive (Wistar) and spontaneously hypertensive rats (SHRs). BMSCs were cultured in a proliferation medium or osteogenic medium (OM). Cells cultured in OM were treated with carvedilol (Cv) or nebivolol (Nb).In OM, cell proliferation was decreased in both strains. In Wistar rats, Cv increased BMSC proliferation and increased alkaline phosphatase (ALP) activity in OM. Both Cv and Nb decreased ALP activity. In addition, Cv and Nb reduced mineral deposition in Wistar rats. Moreover, NB decreased mineralization in SHRs, exhibiting superior efficacy. In OM, cells from Wistar rats and SHRs showed Adrb1 and Adrb2 expression. On day 7, Nb, but not Cv, reduced Adrb1 levels in BMSCs from Wistar rats. Nb inhibited Adrb2 in both strains, and Cv demonstrated superior efficacy. In BMSCs from Wistar rats, both antagonists inhibited Runx2, osterix, and β-catenin; in SHRs, Cv and Nb inhibited only osterix. Cv decreased osteopontin (Opn), osteocalcin (Ocn), and bone morphogenetic protein (Bmp2) in BMSCs from Wistar rats, inhibiting only Opn in SHRs. Nb effectively inhibited Ocn, bone sialoprotein, and Bmp2, but not Ocn, in BMSCs from Wistar rats, while suppressing Opn in BMSCs from SHRs. In addition, Nb inhibited p-p38 in BMSCs from Wistar rats; Cv inhibited p-p38 in BMSCs from SHRs. In Wistar rats, both antagonists inhibited p-ERK and reduced p-JNK; Cv reduced these expressions only in SHRs. In conclusion, ADRB1, but not ADRB2, could be involved in the osteogenic differentiation of BMSCs from Wistar rats and SHRs. The high ADRB1 expression might suppress the effect of ADRB2 on BMSCs.

Stress hormones promote DNA damage in human oral keratinocytes

Chronic stress increases the systemic levels of stress hormones norepinephrine and cortisol. As well as tobacco-specific carcinogen NNK (4-(methylnitrosamine)-1-(3-pyridyl)-1-butanone), they can induce expressive DNA damage contributing to the cancer development. However, it is unknown whether stress hormones have genotoxic effects in oral keratinocytes. This study investigated the effects of stress hormones on DNA damage in a human oral keratinocyte cell line (NOK-SI). NOK-SI cells stimulated with norepinephrine or cortisol showed higher DNA damage compared to untreated cells. Norepinephrine-induced DNA damage was reversed by pre-treatment with beta-adrenergic blocker propranolol. Cells treated with NNK combined to norepinephrine displayed reduced levels of caspases 3 and 7. Cortisol also reduced the activity of pro-apoptotic enzymes. NNK or norepinephrine promoted single-strand breaks and alkali-label side breaks in the DNA of NOK-SI cells. Pre-treatment of cells with propranolol abolished these effects. Carcinogen NNK in the presence or absence of cortisol also induced DNA damage of these cells. The genotoxic effects of cortisol alone and hormone combined with NNK were blocked partially and totally, respectively, by the glucocorticoid receptor antagonist RU486. DNA damage promoted by NNK or cortisol and carcinogen combined to the hormone led to intracellular γH2AX accumulation. The effects caused by NNK and cortisol were reversed by propranolol and glucocorticoid receptor antagonist RU486, respectively. Propranolol inhibited the oxidation of basis induced by NNK in the presence of DNA-formamidopyrimidine glycosylase. DNA breaks induced by norepinephrine in the presence or absence of NNK resulted in higher 8OHdG cellular levels. This effect was also induced through beta-adrenergic receptors. Together, these findings indicate that stress hormones induce DNA damage of oral keratinocytes and could contribute to oral carcinogenesis.

Nanocarriers of Miconazole or Fluconazole: Effects on Three-Species Candida Biofilms and Cytotoxic Effects In Vitro

The contribution of different Candida species in oral fungal infections has stimulated the search for more effective therapies. This study assessed the antibiofilm effects of nanocarriers of miconazole (MCZ) or fluconazole (FLZ) on Candida biofilms, and their cytotoxic effects on murine fibroblasts. Three-species biofilms (Candida albicans/Candida glabrata/Candida tropicalis) were formed on 96-well plates, and they were treated with nanocarriers (iron oxide nanoparticles coated with chitosan—“IONPs-CS”) of MCZ or FLZ at 39/78/156 µg/mL; antifungals alone at 156 µg/mL and artificial saliva were tested as positive and negative controls, respectively. Biofilms were analyzed by colony forming units (CFU), biomass, metabolic activity, and structure/viability. The cytotoxicity (L929 cells) of all treatments was determined via 3-[4,5-dimethylthiazol-2-yl]-2,5 diphenyl tetrazolium bromide (MTT) reduction assay. Data were submitted to one- or two-way ANOVA, followed by Tukey’s or Fisher LSD’s tests (p < 0.05). IONPs-CS-MCZ at 78 µg/mL promoted similar antibiofilm and cytotoxic effects compared with MCZ at 156 µg/mL. In turn, IONPs-CS-FLZ at 156 µg/mL was overall the most effective FLZ antibiofilm treatment, surpassing the effects of FLZ alone; this nanocarrier was also less cytotoxic compared with FLZ alone. It can be concluded that both nanocarriers are more effective alternatives to fight Candida biofilms compared with their respective positive controls in vitro, being a promising alternative for the treatment of oral fungal infections.

Mast cells contribute to alveolar bone loss in Spontaneously Hypertensive Rats with periodontal disease regulating cytokines production

Mast cells (MCs) play a pivotal role in inflammatory responses and had been studied in inflammatory bone disorders, however, their role in alveolar bone loss induced by periodontal disease (PD) is not yet fully understood. We, therefore, aimed to evaluate the effects of MCs depletion in the PD-induced alveolar bone loss in Wistar (W) and Spontaneously Hypertensive Rats (SHRs). PD was induced by ligating the lower first molars with silk thread one day after the MCs depletion, by the pre-treatment with compound 48/80 for 4 days. After 15 days of PD induction, the hemi-mandibles were surgically collected for qRT-PCR, histological analyses, immunostaining, and ELISA. Systolic blood pressure (SBP) was verified by tail plethysmography to confirm the hypertensive status, and SHR presented SBP >150 mmHg, and previous MC depletion alone or associated with PD did not alter this parameter. SHRs showed a more severe alveolar bone loss compared to W, and MC depletion significantly inhibited this response in both strains, with a more significant response in SHRs. MCs were less abundant in 48/80+PD groups, thus validating the previous MCs depletion in our model. PD increased the number of MC in the gingival tissue of SHR. Cytokine production (TNF-α, IL-6, IL-1β, and CXCL3) was constitutively higher in SHR and increased further after PD, which was also significantly reduced in the MCs-depleted animals. PD led to an increased expression of Opn, Rankl, Rank, Vtn, Itga5, Itgb5, Trap, and Ctsk in the mandible of W and SHRs, which was reversed in MCs-depleted animals. These results suggest that MCs significantly contributes to the PD-induced alveolar bone resorption, especially in the SHR, which is associated with a more severe PD progression compared to Wistar, partly explained by these cells contribution to the inflammatory status and mediator production, stimulating osteoclast-related response markers, which were reduced after MC depletion in our experimental model.

Social isolation stress facilitates chemically induced oral carcinogenesis

Social isolation has affected a large number of people and may lead to impairment of physical and mental health. Although stress resulting from social isolation may increase cancer progression, its interference on tumorigenesis is poorly known. In this study, we used a preclinical model to evaluate the effects of social isolation stress on chemically induced oral carcinogenesis. Sixty-two 21-day-old male Wistar rats were divided into isolated and grouped groups. After 90 days of age, the rats from both groups underwent oral carcinogenesis with 4-nitroquinoline 1-oxide (4NQO) for 20 weeks. All rats were assessed for depressive-like behavior and euthanized for oral squamous cell carcinoma (OSCC) diagnosis and measurement of inflammatory mediators in the tumor microenvironment. Social isolation stress increased the OSCC occurrence by 20.4% when compared to control. Isolated rats also showed higher tumor volume and cachexia than the grouped rats. Social isolation did not induce changes in the depressive-like behavior after carcinogenic induction. Tumors from stressed rats had increased levels of the inflammatory mediators, TNF-alpha, IL1-beta and MCP-1. The concentrations of TNF-alpha and MCP-1 were significantly increased in the large tumors from isolated animals. Higher tumor levels of TNF-alpha, IL-6, IL1-beta and MCP-1 were positively correlated with OSCC growth. This study provides the first evidence that social isolation stress may facilitate OSCC occurrence and tumor progression, an event accompanied by increased local levels of inflammatory mediators.

Telmisartan Prevents Alveolar Bone Loss by Decreasing the Expression of Osteoclasts Markers in Hypertensive Rats With Periodontal Disease

Periodontal disease (PD) is a prevalent inflammatory disease with the most severe consequence being the loss of the alveolar bone and teeth. We therefore aimed to evaluate the effects of telmisartan (TELM), an angiotensin II type 1 receptor (Agtr1) antagonist, on the PD-induced alveolar bone loss, in Wistar (W) and Spontaneous Hypertensive Rats (SHRs). PD was induced by ligating the lower first molars with silk, and 10 mg/kg TELM was concomitantly administered for 15 days. The hemimandibles were subjected to microtomography, ELISA was used for detecting tumor necrosis factor (TNF-α), interleukin-1β (IL-1β), interleukin-6 (IL-6), CXCL3, and CCL2, while qRT-PCR was used for analyzing expression of components of renin-angiotensin system (RAS) (Agt, Ace, Agt1r, Agt2r, Ace2, and Masr), and bone markers (Runx2, Osx, Catnb, Alp, Col1a1, Opn, Ocn, Bsp, Bmp2, Trap, Rank, Rankl, CtsK, Mmp-2, Mmp-9, and osteoclast-associated receptor (Oscar)). The SHR + PD group showed greater alveolar bone loss than the W + PD group, what was significantly inhibited by treatment with TELM, especially in the SHR group. Additionally, TELM reduced the production of TNF-α, IL-1β, and CXCL3 in the SHR group. The expression of Agt increased in the groups with PD, while Agtr2 reduced, and TELM reduced the expression of Agtr1 and increased the expression of Agtr2, in W and SHRs. PD did not induce major changes in the expression of bone formation markers, except for the expression of Alp, which decreased in the PD groups. The bone resorption markers expression, Mmp9, Ctsk, and Vtn, was higher in the SHR + PD group, compared to the respective control and W + PD group. However, TELM attenuated these changes and increased the expression of Runx2 and Alp. Our study suggested that TELM has a protective effect on the progression of PD, especially in hypertensive animals, as evaluated by the resorption of the lower alveolar bone. This can be partly explained by the modulation in the expression of Angiotensin II receptors (AT1R and AT2R), reduced production of inflammatory mediators, the reduced expression of resorption markers, and the increased expression of the bone formation markers.

Novel Colloidal Nanocarrier of Cetylpyridinium Chloride: Antifungal Activities on Candida Species and Cytotoxic Potential on Murine Fibroblasts

Nanocarriers have been used as alternative tools to overcome the resistance of Candida species to conventional treatments. This study prepared a nanocarrier of cetylpyridinium chloride (CPC) using iron oxide nanoparticles (IONPs) conjugated with chitosan (CS), and assessed its antifungal and cytotoxic effects. CPC was immobilized on CS-coated IONPs, and the nanocarrier was physico-chemically characterized. Antifungal effects were determined on planktonic cells of Candida albicans and Candida glabrata (by minimum inhibitory concentration (MIC) assays) and on single- and dual-species biofilms of these strains (by quantification of cultivable cells, total biomass and metabolic activity). Murine fibroblasts were exposed to different concentrations of the nanocarrier, and the cytotoxic effect was evaluated by MTT reduction assay. Characterization methods confirmed the presence of a nanocarrier smaller than 313 nm. IONPs-CS-CPC and free CPC showed the same MIC values (0.78 µg mL⁻¹). CPC-containing nanocarrier at 78 µg mL⁻¹ significantly reduced the number of cultivable cells for all biofilms, surpassing the effect promoted by free CPC. For total biomass, metabolic activity, and cytotoxic effects, the nanocarrier and free CPC produced statistically similar outcomes. In conclusion, the IONPs-CS-CPC nanocarrier was more effective than CPC in reducing the cultivable cells of Candida biofilms without increasing the cytotoxic effects of CPC, and may be a useful tool for the treatment of oral fungal infections.

Antimicrobial, antibiofilm and cytotoxic effects of a colloidal nanocarrier composed by chitosan-coated iron oxide nanoparticles loaded with chlorhexidine

OBJECTIVES

This study evaluated the antimicrobial and antibiofilm effects of a colloidal nanocarrier for chlorhexidine (CHX) on Candida glabrata and Enterococcus faecalis, as well as tested its cytotoxic effect on murine fibroblasts.

METHODS

Iron oxide nanoparticles (IONPs) were coated with chitosan (CS) and loaded with CHX at 31.2, 78 and 156 μg/mL. Antimicrobial effects were assessed by determining the minimum inhibitory concentration (MIC), using the broth microdilution method, and fractional inhibitory concentration index (FICI). Preformed biofilms (48 h) were treated with different concentrations of the nanocarrier (24 h) and quantified by colony-forming units (CFUs), total biomass and metabolic activity. For cytotoxicity, the viability of L929 cells was evaluated by MTT assay after 24 and 48 h of exposure to the nanocarrier. Data were submitted to ANOVA and Fisher LSD or Tukey post-hoc tests (α = 0.05).

RESULTS

MIC and FICI results showed an indifferent interaction among the components of the nanocarrier for all strains evaluated. CHX alone and nanocarrier containing 156 μg/mL CHX did not differ from each other in reducing the number of CFUs. However, the nanocarrier containing 156 μg/mL CHX promoted the highest reductions in total biofilm biomass and metabolism, surpassing the effect of CHX alone. After 24 and 48 h of exposure, the nanocarrier reduced CHX toxicity to the L929 cell at low concentrations.

CONCLUSION

These findings suggest that the CHX nanocarrier has potential to be used in the control of oral diseases associated with C. glabrata and E. faecalis.

CLINICAL RELEVANCE

CHX has improved the antibiofilm effect and reduced the cytotoxicity (at low concentrations) when conjugated to CS-coated IONPs. This new colloidal formulation has potential as an alternative antimicrobial agent to pure CHX for the control of biofilm-related oral diseases, such as oral candidiasis and endodontic infections.

Pineal gland protects against chemically induced oral carcinogenesis and inhibits tumor progression in rats

Clinical investigations suggest that melatonin suppression and circadian dysfunction may be related to cancer development in shift workers. Studies also show that melatonin suppression after pinealectomy increases cancer incidence in preclinical models. However, no study evaluated the influence of pinealectomy on oral cancer development. In the current study, we investigated the effects of pinealectomy on oral squamous cell carcinoma (OSCC) occurrence and progression in rats. Rats submitted to sham surgery were used as control. Pinealectomy promoted an increase of 140% in OSCC occurrence when compared to sham animals. Tumors from pinealectomized rats displayed a higher volume and thickness than the tumors from sham-operated animals. Pinealectomy induced atrophy of the epithelium adjacent to the oral lesions. Pinealectomized rats showed higher mean number of tumor-associated macrophages and eosinophils in the invasive front of OSCC. In addition, nuclear overexpression of ERK1/2 and p53 was also observed in the front of carcinomas from pinealectomized rats. These results reveal that pineal gland plays a protective role against oral carcinogenesis. The melatonin suppression caused by the pinealectomy might contribute to oral cancer development by acting on ERK1/2 and p53 pathways and regulating tumor inflammation.

Effect of pre-treatment of strength training and raloxifene in periestropause on bone healing

BACKGROUND

There is evidence that strength training (ST) and raloxifene (Ral) treatment during periestropause promotes better bone quality. We wanted to determine whether the skeletal benefits of ST or Ral treatment, performed during periestropause, would persist after fracture. Therefore, the present study aimed to analyze the influence of pre-treatment with ST and administration of Ral during periestropause on bone healing after total unilateral osteotomy.

METHODS

Senescent female Wistar rats between 18 and 21 months of age, performed ST on a ladder three times per week, were administered Ral by gavage (2.3 mg/kg/day), or an association of both. After 120 days, the treatments were interrupted, and a total osteotomy was performed on the left tibia in all animals. They were euthanized 1 and 8 weeks post-osteotomy.

RESULTS

The administration of Ral during periestropause worsened the biochemical and oxidative profile, decreased gene expression of markers related to bone resorption and remodeling, which negatively affected the physicochemical properties; this lead to changes in the bone callus microarchitecture and mass, as well as a decrease in callus resistance to torsional deformation, resulting in lower tissue quality during bone healing. In contrast, ST performed prior to the osteotomy resulted in better bone healing, improvement of the biochemical and oxidative profile, alteration of the genetic profile in favor of bone formation and resorption, as well as the physic-ochemical properties of the callus. These changes led to better microarchitecture and bone mass and increased callus resistance to torsional deformation, confirming its beneficial effect on the quality of bone tissue, providing acceleration of bone consolidation. The combination of therapies at this exercise intensity and drug dosage showed a negative interaction, where the negative effect of Ral overcame the positive effect of ST, leading to decreased tissue quality in the bone healing process.

CONCLUSIONS

This study indicates that in addition to excellent non-pharmacological therapy and action in the prevention of osteoporosis, ST performed during the aging period may increase bone quality at the onset of healing and provide improved bone consolidation. Furthermore, the anti-osteoclastogenic effect of Ral shown in this model delayed the bone repair process, resulting in considerable clinical concern.

Soluble yerba mate (Ilex Paraguariensis) extract enhances in vitro osteoblastic differentiation of bone marrow-derived mesenchymal stromal cells

ETHNOPHARMACOLOGICAL RELEVANCE

Yerba mate (Ilex paraguariensis) consumption has been associated with beneficial effects on bone health.

AIM OF THE STUDY

The purpose of this study was to evaluate the mechanism by which soluble yerba mate (SYM) stimulates osteoblast differentiation of bone marrow-derived mesenchymal stromal cells (BM-MSCs).

MATERIALS AND METHODS

BM-MSCs from male Wistar rats were induced towards osteoblastic differentiation with different concentrations of SYM (10, 20, and 50 μg/mL). Osteoblastic differentiation was evaluated by measuring proliferation rates, alkaline phosphatase activity, MMP-2 activity, mineralization, and gene expression of Runx2, Osterix, β-catenin (Catnb), collagen type I (Col1a1), osteopontin (Opn), osteocalcin (Ocn), bone sialoprotein (Bsp), bone morphogenetic protein-2 (Bmp2), osteoprotegerin (Opg), and Rankl. We also analyzed cytokine production and MAP kinase pathways.

RESULTS

SYM (10 μg/mL) did not show a cytotoxic effect and induced a slight increase in ALP activity; however, a great increase in mineralization was observed. SYM was also able to reduce TNF-α and IL-10 production; increase the expression of transcription factors Runx2, Osterix, and Catnb; and increase matrix proteins Opn, Bsp, Ocn, and Bmp2. We also observed a decrease in intracellular signaling of ERK, JNK, and p38 MAPK, which seemed to be related to the SYM response.

CONCLUSIONS

Together, these results help to explain the promoting effect on osteoblast differentiation produced by a low SYM concentration. However, a higher SYM concentration presented deleterious effects, including cytotoxicity, decreased ALP activity, increased cytokine production, decreased bone marker gene expression, increased MAPK signaling, and significant mineralization reduction. In conclusion, our results suggest a concentration-specific direct stimulatory effect of SYM on osteoblastic differentiation in vitro.

Aliskiren Attenuates the Inflammatory Response and Wound Healing Process in Diabetic Mice With Periodontal Disease

The aim of this study was to characterize the role of local RAS (renin–angiotensin system) in the inflammatory response of normal (N) and diabetic (D) mice with periodontal disease (PD). Diabetes Mellitus (DM) was induced by peritoneal injection of streptozotocin in Balb/c mice. PD was induced by ligature around the first molar in both N and D, irrespective of whether they were treated with aliskiren (50 mg/kg, Alisk). Mandibles were harvested for histomorphometric analyses, and gingival tissue (GT) was collected to evaluate gene expression and extracellular matrix components (ECM). Immunohistochemical (IHC) analyses were used to localize RAS in GT. The production of C-reactive protein (CRP), IL-1β, CXCL2, and CCL8 was evaluated by enzyme-linked immunosorbent assay (ELISA). Renin was found to exacerbate the inflammation and periodontal bone loss at 14 days after PD, and Alisk inhibited this process in GT of N and D. PD increased CRP, CXCL2, CCL8, and IL-1β production in both animals. Alisk could inhibit CRP, CXCL2, and CCL8 primarily in D animals. However, only CCL8 was decreased in N animals after Alisk pretreatment. PD enhanced expression and production of AGT, ACE, AT1R, and AT2R in both N and D. AT1R expression was higher in D with PD, and AT2R expression was higher in N with PD. ACE2 and receptor Mas (MasR) expression and production was elevated in the control group of both animals. PD inhibited ACE2 in N but not in D. MasR expression was unaffected in both N and D with PD. Alisk reduced expression and production of all RAS components in GT of both animals, except for ACE2 in N. RAS staining was observed in all layers of epithelium, basal cell layer, and lamina propria and was higher in N with PD. Col1a1, Col1a2, Col3a1, and fibronectin (Fn1) were increased in both animals with PD. Alisk inhibited Col1a1 and Fn in both animals, Col1a2 was decreased only in D, while levels of Col3a1 remained unchanged in all animal groups. In conclusion, these data demonstrated the presence and functional role of local RAS in GT, exacerbating the inflammatory response, periodontal bone loss, and wound healing processes in both N and D animal groups. In addition, Alisk was able to significantly reduce gingival inflammation, excessive wound healing processes, and periodontal bone loss.

Oxytocin effects on osteoblastic differentiation of Bone Marrow Mesenchymal Stem Cells from adult and aging female Wistar rats

Recently, it has been suggested that oxytocin (OT) might play a role in the control of bone remodeling and in bone health of young and adult females. The purpose of this study was to evaluate the effect of osteogenic medium (OM) plus OT (OM + OT; 100 nmol/L) on osteoblastic differentiation of bone marrow mesenchymal stem cells (BMMSCs) from cyclic adult (12 months old) and acyclic aging (24 months old) female Wistar rats. After 14 days, OM + OT increased the oxytocin and oxytocin receptor in the BMMSCs from animals of both age groups relative to OM controls. Alkaline phosphatase activity was higher in the OM + OT than OM group in BMMSCs from 24-month-old female rats. OM + OT improved osteogenic differentiation, observed by anticipated mineralization and increased gene expression of bone morphogenetic protein 2, bone sialoprotein, osteopontin and osteocalcin in both aged relative to OM controls. These findings suggest a role for OT as an adjuvant to induce osteoblastic differentiation of BMMSCs from aged female rat.

l-arginine modulates inflammation and muscle regulatory genes after a single session of resistance exercise in rats

We investigated the skeletal muscle adaptation to l-arginine supplementation prior to a single session of resistance exercise (RE) during the early phase of muscle repair. Wistar rats were randomly assigned into non-exercised (Control), RE plus vehicle (RE); RE plus l-arginine (RE+L-arg) and RE plus aminoguanidine (RE+AG) groups. Animals received four doses of either vehicle (0.9% NaCl), l-arg (1 g/b.w.), or AG (iNOS inhibitor) (50 mg/b.w.). The animals performed a single RE session until the concentric failure (ladder climbing; 80% overload) and the skeletal muscles were harvested at 0, 8, 24, and 48 hours post-RE. The RE resulted in increased neutrophil infiltrate (24 hours post-RE) (3621 vs 11852; P<.0001) associated with enhanced TNF-α (819.49 vs 357.02; P<.005) and IL-6 (3.84 vs 1.08; P<.0001). Prior, l-arginine supplementation attenuates neutrophil infiltration (5622; P<.0001), and also TNF-α (506.01; P<.05) and IL-6 (2.51, P<.05) levels. AG pretreatment mediated an inhibition of iNOS levels similar to levels found in RE group. RE animals displayed increased of atrogin-1 (1.9 fold) and MuRF-1 (3.2 fold) mRNA levels, reversed by l-arg supplementation [atrogin-1 (0.6 fold; P<.001); MuRF-1 (0.8-fold; P<.001)] at 24 hours post-RE. MyoD up-regulated levels were restricted to l-arg treated animals at 24 hours (2.8 vs 1.5 fold; P<.005) and 48 hours post-RE (2.4 vs 1.1 fold; P<.001). AG pretreatment reversed these processes at 24 hours [atrogin-1 (2.1 fold; P<.0001); MuRF-1 (2.5 fold; P<.0001); MyoD (1.4 fold)]. l-arginine supplementation seems to attenuate the resolution of RE-induced muscle inflammation and up-regulates MyoD expression during the early phase of muscle repair.

Effects of strength training on osteogenic differentiation and bone strength in aging female Wistar rats

The effects of strength training (ST) on the mechanical bone strength and osteogenic differentiation of bone marrow mesenchymal stromal cells (BMSCs) from adult, aged and exercised aged rats were determined. The exercised aged animals displayed higher values of areal bone mineral density, compression test, alkaline phosphatase activity (ALP) and biological mineralization, while oil red O staining for adipocytes was lower. ST increased gene expression of runt-related transcription factor 2 (Runx2), osterix (Osx) as well as bone matrix protein expression, and reduced expression of peroxisome proliferator-activated receptor gamma (Pparγ). The production of pro-inflammatory cytokine tumor necrosis factor alpha (TNF-α) was lower in BMSCs of the aged exercised group. The ST practice was able to improve the bone mechanical properties in aged female rats, increasing the potential for osteogenic differentiation of BMSCs, reducing the adipogenic differentiation and pro-inflammatory cytokine level. In summary, the data achieved in this study showed that strength training triggers physiological responses that result in changes in the bone microenvironment and bring benefits to biomechanical parameters of bone tissue, which could reduce the risk of fractures during senescent.

Biocompatibility of primers and an adhesive used for implant-retained maxillofacial prostheses: An in vitro analysis

STATEMENT OF PROBLEM

Implant-retained maxillofacial prostheses should be biocompatible, regardless of the primers and adhesives used to bond the acrylic resin and facial silicone. The authors are unaware of any study evaluating the influence of these primers and adhesives on the biocompatibility of maxillofacial prostheses.

PURPOSE

The purpose of this in vitro study was to evaluate the cytotoxic effect of primers and an adhesive used to bond acrylic resin and facial silicone during the fabrication of implant-retained maxillofacial prostheses.

MATERIAL AND METHODS

Twenty-eight circular specimens made of resin and silicone were fabricated, either bonded or nonbonded with primer and adhesive. The specimens were divided into 7 groups: resin; silicone; resin+silastic medical adhesive type A+silicone; resin+DC 1205 primer silicone; resin+Sofreliner primer+silicone; resin+DC 1205 primer+silastic medical adhesive type A+silicone; and resin+Sofreliner primer+silastic medical adhesive type A+silicone. Eluates of the materials tested were prepared by setting 4 specimens of each experimental group in Falcon tubes with medium and incubating at 37°C for 24 hours. The eluate cytotoxicity was evaluated by an assay of survival/proliferation ((3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyl tetrazolium bromide [MTT] test) in cultures of human keratinocytes. The levels of IL1, IL6, TNFα, and the chemokine MIP-1α were evaluated by enzyme-linked immunosorbent assay. The mRNA expressions for MMP-9, TGF-β, and collagen type IV were analyzed by the real time polymerase chain reaction. Data were submitted to analysis of variance with Bonferroni post hoc tests (α=.05).

RESULTS

An increased cell proliferation was observed for the RAS group, with statistically significant differences (P<.001) compared with the unstimulated group. The RDCpS group showed the highest IL6 concentration values (P<.001). No significant statistical difference was found in the relative quantification of mRNA for collagen type IV, MMP9, or TGFβ between the groups (P>.05).

CONCLUSIONS

The RAS group showed the highest cell proliferation percentage, while the RDCpS group exhibited the highest IL6 concentration values. No detectable levels of IL1β, TNF α, or CCL3/MIP1α were observed. The tested materials showed no toxic effects on the HaCaT cell line.

Tracheal Smooth Muscle Cells Stimulated by Stem Cell Factor-c-Kit Coordinate the Production of Transforming Growth Factor-β1 and Fibroblast Growth Factor-2 Mediated by Chemokine (C-C Motif) Ligand 3

The aim of this study was to evaluate the mechanism involved in the stem cell factor (SCF)-induced production of fibroblast growth factor-2 (FGF-2), transforming growth factor-β1 (TGF-β1), and chemokine (C-C motif) ligand 3 (CCL3) in tracheal smooth muscle cells (tSMCs) and the signaling pathway involved in the process. tSMC primary cultures were stimulated with SCF and evaluated at 24 h. Cells treated with specific antibodies did not show any immunolabeling for cytokeratin or fibroblast activation protein, but were positive for α-smooth muscle actin, indicating the purity of the primary cell line. Western blot analysis showed constitutive phosphorylation of c-Kit, as well as increased total protein and phosphorylated c-Kit levels in tSMCs after SCF stimulation. Flow cytometry analysis also showed an increase in cell-surface c-Kit expression in the presence of SCF. SCF induced TGF-β mRNA expression in tSMCs, as well as the production of TGF-β1, CCL3, and FGF-2. Pretreatment with anti-CCL3 antibody blocked TGF-β1 expression and partially inhibited FGF-2 production. On the other hand, anti-c-Kit antibody blocked TGF-β1 expression and FGF-2 production. Thus, TGF-β1 and FGF-2 production were mediated by CCL3 production through c-Kit. Pretreatment with mitogen-activated protein kinase kinase 1, p38, and Jun N-terminal kinase inhibitors showed that the effects mediated by SCF were involved with the modulation of mitogen-activated protein kinase (MAPK) pathways. Development of inhibitors targeting CCL3 through MAPK activation could thus be an attractive strategy to inhibit tSMC activation during asthma.

In Vitro and In Vivo Toxicity Evaluation of Colloidal Silver Nanoparticles Used in Endodontic Treatments

INTRODUCTION

Silver nanoparticles have been used for different purposes in dentistry, including endodontic treatments. The aim of this study was to determine the cytotoxicity of different types of silver nanoparticles on mouse fibroblast cell line L929 and the reaction of subcutaneous connective tissue of Wistar rats to these nanoparticles.

METHODS

Silver nanoparticles of an average size of 5 nm were synthesized with ammonia (SNA) or polyvinylpyrrolidone (SNP). L929 was exposed to SNA and SNP (0.1-100 μg/mL), and 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide and enzyme-linked immunosorbent assays were performed after 6, 24, and 48 hours. Culture medium was used as the control. Sixteen rats received, individually, 3 polyethylene tubes filled with a fibrin sponge embedded in 100 μL SNA or SNP (1 μg/mL). A fibrin sponge with no embedding was the control. Tissue reaction was performed qualitatively and quantitatively after 7, 15, 30, and 90 days of implantation in the dorsal connective tissue of Wistar rats.

RESULTS

SNA and SNP were cytotoxic to L929 in higher concentrations, with SNA significantly more toxic than SNP. SNA and SNP did not induce significant interleukin-1β and interleukin-6 production. The release of stem cell factor by L929 increased 48 hours after the treatment with SNP at 5 μg/mL. Histologic examination showed that the inflammatory responses caused by SNA and SNP at 1 μg/mL were similar to the control in all experimental periods.

CONCLUSIONS

It was concluded that SNA and SNP were not cytotoxic at 25 μg/mL or lower concentrations. However, for safe clinical use, further studies establishing others points of its toxicologic profile are recommended.

Bone marrow mesenchymal stem cells stimulated by bFGF up-regulated protein expression in comparison with periodontal fibroblasts in vitro

OBJECTIVE

The aim of this study was to evaluate, in vitro, the role of bFGF in the proliferation and expression of collagen type I and fibronectin of dog bone marrow mesenchymal stem cells (dBMMSCs) in comparison with the expression of the same proteins in dog periodontal fibroblasts (dPLFs).

DESIGN

dBMMSCs from the iliac crest were cultivated in Dulbecco's Modified Eagle's Medium (DMEM). Flow cytometry analysis (FCA) was used to characterize dBMMSC. Cells were stimulated with bFGF (1, 5 and 10 ng/mL) after 24 and 48 h. Real time RT-PCR was performed to verify collagen type I and fibronectin expressions. MTT assay was used to confirm cellular proliferation. Statistical analyses were performed (ANOVA and Kruskal-Wallis tests; p<0.05).

RESULTS

FCA showed 55.98% of CD34+ and 32.67% of CD90+ after bone marrow aspiration; 3.33% of CD34+ and 33.0% of CD90+ before P1. After P2, 10.54% of dBMMSCs expressed CD90, whereas after P3, this number decreased to 1.58%. dPLFs presented 4.04% of CD90+ and 1.05% of CD34+ after P3. MTT evaluation showed increase in dBMSC proliferation with 5 ng/mL bFGF-stimulus after 24-h. Both collagen I and fibronectin expression were very similar between the two cells groups after 24-h stimulation with 1 ng/mL bFGF concentration. Fibronectin and collagen I expressions were higher after 24-h stimulation with 5 ng/mL bFGF.

CONCLUSION

dBMMSCs (1 ng/mL-bFGF stimulus after 24 h) are very similar to dPLFs as regards morphological and immunostaining characteristics, and collagen and/or fibronectin production. The dBMMSCs presented the highest protein expression rates with 5 ng/mL-bFGF stimulus after 24-h.

In vitro regulation of CCL3 and CXCL12 by bacterial by-products is dependent on site of origin of human oral fibroblasts

INTRODUCTION

Production of chemokines by tissue resident cells is one of the main mechanisms involved in the inflammatory infiltrate formation during inflammation. The specific ability of fibroblasts from different oral tissues such as gingiva, periodontal ligament, and dental pulp from permanent and deciduous teeth in producing the chemokines CCL3 and CXCL12 under stimulation by bacterial products commonly found in endodontic infections was investigated.

METHODS

Cultures of fibroblasts from gingiva and periodontal ligament as well as from dental pulp from permanent and deciduous teeth were established by using an explant technique and stimulated with increasing concentrations of Escherichia coli lipopolysaccharide (EcLPS) and Enterococcus faecalis lipoteichoic acid (EfLTA) for 1, 6, and 24 hours. Supernatants were tested for CCL3 and CXCL12 by enzyme-linked immunosorbent assay.

RESULTS

In general, CCL3 production was induced by EcLPS in the 4 fibroblast subtypes and by EfLTA in fibroblasts from gingiva and periodontal ligament. Constitutive CXCL12 synthesis decreased in all fibroblast subtypes especially under stimulation with EcLPS. Fibroblast from permanent deciduous teeth was the cell type presenting the most expressive reduction in CXCL12 release by both stimuli. On the basis of computational matching of CXCL12 mRNA with the microRNAs miR-141 and miR-200a, their expression was also investigated. Although detected in the fibroblasts, these molecules remained unaltered by bacterial by-product stimulation.

CONCLUSIONS

EcLPS and EfLTA induced the production of CCL3 and unbalanced the synthesis of CXCL12 in a manner dependent on the specific tissue origin of fibroblasts.

Characterization of a local renin-angiotensin system in rat gingival tissue

BACKGROUND

The systemic renin-angiotensin system (RAS) promotes the plasmatic production of angiotensin (Ang) II, which acts through interaction with specific receptors. There is growing evidence that local systems in various tissues and organs are capable of generating angiotensins independently of circulating RAS. The aims of this study were to investigate the expression and localization of RAS components in rat gingival tissue and evaluate the in vitro production of Ang II and other peptides catalyzed by rat gingival tissue homogenates incubated with different Ang II precursors.

METHODS

Reverse transcription-polymerase chain reaction assessed mRNA expression. Immunohistochemical analysis aimed to detect and localize renin. A standardized fluorimetric method with tripeptide hippuryl-histidyl-leucine was used to measure tissue angiotensin-converting enzyme (ACE) activity, whereas high performance liquid chromatography showed products formed after the incubation of tissue homogenates with Ang I or tetradecapeptide renin substrate (TDP).

RESULTS

mRNA for renin, angiotensinogen, ACE, and Ang II receptors (AT(1a), AT(1b), and AT(2)) was detected in gingival tissue; cultured gingival fibroblasts expressed renin, angiotensinogen, and AT(1a) receptor. Renin was present in the vascular endothelium and was intensely expressed in the epithelial basal layer of periodontally affected gingival tissue. ACE activity was detected (4.95 +/- 0.89 nmol histidyl-leucine/g/minute). When Ang I was used as substrate, Ang 1-9 (0.576 +/- 0.128 nmol/mg/minute), Ang II (0.066 +/- 0.008 nmol/mg/minute), and Ang 1-7 (0.111 +/- 0.017 nmol/mg/minute) were formed, whereas these same peptides (0.139 +/- 0.031, 0.206 +/- 0.046, and 0.039 +/- 0.007 nmol/mg/minute, respectively) and Ang I (0.973 +/- 0.139 nmol/mg/minute) were formed when TDP was the substrate.

CONCLUSION

Local RAS exists in rat gingival tissue and is capable of generating Ang II and other vasoactive peptides in vitro.

Neutrophil migration induced by IL-1beta depends upon LTB4 released by macrophages and upon TNF-alpha and IL-1beta released by mast cells

In the present study, we investigate whether mast cells and macrophages are involved in the control of IL-1beta-induced neutrophil migration, as well as the participation of chemotactic mediators. IL-1beta induced a dose-dependent neutrophil migration to the peritoneal cavity of rats which depends on LTB(4), PAF and cytokines, since the animal treatment with inhibitors of these mediators (MK 886, PCA 4248 and dexamethasone respectively) inhibited IL-1beta-induced neutrophil migration. The neutrophil migration induced by IL-1beta is dependent on mast cells and macrophages, since depletion of mast cells reduced the process whereas the increase of macrophage population enhanced the migration. Moreover, mast cells or macrophages stimulated with IL-1beta released a neutrophil chemotactic factor, which mimicked the neutrophil migration induced by IL-1beta. The chemotactic activity of the supernatant of IL-1beta-stimulated macrophages is due to the presence of LTB(4), since MK 886 inhibited its release. Moreover, the chemotactic activity of IL-1beta-stimulated mast cells supernatant is due to the presence of IL-1beta and TNF-alpha, since antibodies against these cytokines inhibited its activity. Furthermore, significant amounts of these cytokines were detected in the supernatant. In conclusion, our results suggest that neutrophil migration induced by IL-1beta depends upon LTB(4) released by macrophages and upon IL-1beta and TNFalpha released by mast cells.

Interleukin 4 induces the expression of inducible nitric oxide synthase in eosinophils

We investigated the effects of the Th2-like cytokines IL-4 and IL-13 and of IL-10 on the induction of iNOS and NO production in rat eosinophils. Addition of mIL-4 to the eosinophil culture increased iNOS activity and nitrite production but did not improve the stimulatory effect of IFN-gamma and LPS. In contrast to eosinophils, addition of mIL-4 to macrophage cultures inhibited the iNOS expression and nitrite production induced by IFN-gamma plus LPS. Addition of mIL-13 to the eosinophil cultures did not significantly change iNOS activity and nitrite production in cells stimulated or not with IFN-gamma plus LPS. On the other hand, IL-13 inhibited iNOS activity in IFN-gamma plus LPS-stimulated macrophages. In the presence of IL-10, iNOS activity in non-stimulated eosinophil or macrophage cultures was not significantly altered, but the enzyme expression was inhibited in IFN-gamma plus LPS-stimulated eosinophils or macrophages. The production of nitrite by eosinophils stimulated by IFN-gamma plus LPS was inhibited by the presence of IL-10 in the medium. In conclusion, eosinophils might exhibit differential modulation of the L-arginine/iNOS pathway depending on the profile of Th2 cytokines produced during allergic diseases. IL-4 appears to be an important Th2 cytokine involved in the induction of the L-arginine/iNOS pathway in eosinophils.

Macrophages and mast cells control the neutrophil migration induced by dentin proteins

Dentin sialoprotein (DSP) and dentin phosphoprotein (DPP), the major dentin proteins, have been shown to induce neutrophil migration through release of IL-1beta, TNF-alpha, MIP-2, and KC. However, the sources of these mediators were not determined. Here, the roles of macrophages and mast cells (MC) in dentin-induced neutrophil accumulation were investigated. Peritoneal MC depletion or the enhancement of macrophage population increased DSP- and DPP-induced neutrophil extravasation. Moreover, supernatants from DSP- and DPP-stimulated macrophages caused neutrophil migration. The release of neutrophil chemotactic factor by macrophages was inhibited by dexamethasone or the supernatant of DSP-treated MC. Consistently, dexamethasone and the MC supernatant inhibited the production of IL-1beta, TNF-alpha, and MIP-2 by macrophages. This inhibitory activity of the DSP-stimulated MC was neutralized by anti-IL-4 and anti-IL-10 antibodies. These results indicate that dentin induces the release of the neutrophil chemotactic substance(s) by macrophages, which are down-modulated by MC-derived IL-4 and IL-10.

Stem cell factor: a hemopoietic cytokine with important targets in asthma

We review evidence that Stem Cell Factor (SCF) plays an important role in the pathophysiology of asthma. SCF is produced by a wide variety of cells present in asthmatic lung, including mast cells and eosinophils. Its receptor, c-kit, is broadly expressed on mature mast cells and eosinophils. SCF promotes recruitment of mast cell progenitors into tissues, as well as their local maturation and activation. It also promotes eosinophil survival, maturation and functional activation. SCF enhances IgE-dependent release of mediators from mast cells, including histamine, leukotrienes, cytokines (TNF-alpha, IL-5, GM-CSF) and chemokines (RANTES/CCL5, MCP-1/CCL2, TARC/CCL17 e MDC/CCL22); it is required for IL-4 production in mast cells. SCF, acting in concert with IgE, also upregulates the expression and function of CC chemokine receptors in mast cells. Structural and resident airway cells express increased levels of SCF in the bronchus of asthmatic patients. In a murine model of asthma, allergen exposure increased production of SCF by epithelial cells and alveolar macrophages, which was transient and paralleled by histamine release. SCF induced long-lived airway hyperreactivity, which was prevented by local neutralization of SCF, as well as by inhibitors of the production or activity of cysteinyl-leukotrienes. Together, these observations suggest that SCF has an important role in asthma.

The role of chemokines and chemokine receptors in eosinophil activation during inflammatory allergic reactions

Chemokines are important chemotactic cytokines that play a fundamental role in the trafficking of leukocytes to sites of inflammation. They are also potent cell-activating factors, inducing cytokine and histamine release and free radical production, a fact that makes them particularly important in the pathogenesis of allergic inflammation. The action of chemokines is regulated at the level of agonist production and processing as well as at the level of receptor expression and coupling. Therefore, an analysis of the ligands must necessarily consider receptors. Eosinophils are target cells involved in the allergic inflammatory response since they are able to release a wide variety of mediators including CC and CXC chemokines and express their receptors. These mediators could damage the airway epithelial cells and might be important to stimulate other cells inducing an amplification of the allergic response. This review focuses on recently emerging data pertaining to the importance of chemokines and chemokine receptors in promoting eosinophil activation and migration during the allergic inflammatory process. The analysis of the function of eosinophils and their chemokine receptors during allergic inflammation might be a good approach to understanding the determinants of asthma severity and to developing novel therapies.

Sephadex induces eosinophil migration to the rat and mouse peritoneal cavity: involvement of mast cells, LTB4, TNF-alpha, IL-8 and PAF

OBJECTIVE AND DESIGN

In this study we investigated the chemotactic mediators involved in the Sephadex-induced eosinophil migration into the peritoneal cavities of rats and mice, and which resident peritoneal cells release these mediators.

MATERIALS AND METHODS

Sephadex suspension was injected into the peritoneal cavities of rats or mice which were pretreated, or not, with specific drugs that inhibit synthesis or production of the inflammatory mediators and eosinophil chemotactic activities were observed. To investigate the role of resident peritoneal cells as a source of these chemotactic factors, the macrophage population was enhanced or the mast cell population was depleted. The resident cells were also stimulated, in vitro, with Sephadex and the chemotactic activity of the supernatants was determined.

RESULTS

Sephadex induced dose and time dependent eosinophil migration in rats and mouse, which were inhibited by dexamethasone and MK 886. BN 52021 only affected the eosinophil migration into the mouse peritoneal cavity. An increase in the macrophage population did not alter the eosinophil migration induced by Sephadex in rat or mouse. However, mast cell population depletion reduced eosinophil migration in rats, but did not alter the migration in mice. Sephadex-stimulated rat mast cells released an eosinophil chemotactic factor whose release was inhibited by dexamethasone and MK 886. Anti-TNF-alpha and anti-IL-8 Abs inhibited the chemotactic activity of the mast cell supernatant.

CONCLUSION

Sephadex-induced eosinophil migration into the rat peritoneal cavity is dependent on mast cells, which release LTB4, TNF-alpha and CINC-1. Conversely, Sephadex-induced eosinophil migration into the mouse peritoneal cavity is mediated by PAF and LTB4, which are not released from resident macrophages or mast cells.