Soluble beta-1,3/1,6-glucan from yeast inhibits experimental periodontal disease in Wistar rats

Yeast β-glucan-based nanoparticles loading methotrexate promotes osteogenesis of hDPSCs and periodontal bone regeneration under the inflammatory microenvironment

The regeneration of absorbed alveolar bone and reconstruction of periodontal support tissue are huge challenges in the clinical treatment of periodontitis due to the limited regenerative capacity of alveolar bone. It is essential to regulate inflammatory reaction and periodontal cell differentiation. Based on the anti-inflammatory effect of baker's yeast β-glucan (BYG) with biosafety by targeting macrophages, the BYG-based nanoparticles loading methotrexate (cBPM) were fabricated from polyethylene glycol-grafted BYG through chemical crosslinking for treatment of periodontitis. In our findings, cBPM promoted osteogenesis of human dental pulp stem cells (hDPSCs) under inflammatory microenvironment, characterized by the enhanced expression of osteogenesis-related Runx2 and activation of mitogen-activated protein kinase/extracellular signal-regulated protein kinase (MAPK/Erk) pathway in vitro. Animal experiments further demonstrate that cBPM effectively promoted periodontal bone regeneration and achieved in a better effect of recovery indicated by 19.2 % increase in tissue volume, 7.1 % decrease in trabecular separation, and a significant increase in percent bone volume and trabecular thickness, compared with the model group. Additionally, cBPM inhibited inflammation and repaired alveolar bone by transforming macrophage phenotype from inflammatory M1 to anti-inflammatory M2. This work provides an alternative strategy for the clinical treatment of periodontitis through BYG-based delivery nanoplatform of anti-inflammatory drugs.

Microbiota-immune-brain interactions: A new vision in the understanding of periodontal health and disease

This review highlights the significance of interactions between the microbiota, immune system, nervous and hormonal systems, and the brain on periodontal health and disease. Microorganisms in the microbiota, immune cells, and neurons communicate via homeostatic nervous and hormonal systems, regulating vital body functions. By modulating pro-inflammatory and anti-inflammatory adaptive immune responses, these systems control the composition and number of microorganisms in the microbiota. The strength of these brain-controlled responses is genetically determined but is sensitive to early childhood stressors, which can permanently alter their responsiveness via epigenetic mechanisms, and to adult stressors, causing temporary changes. Clinical evidence and research with humans and animal models indicate that factors linked to severe periodontitis enhance the responsiveness of these homeostatic systems, leading to persistent hyperactivation. This weakens the immune defense against invasive symbiotic microorganisms (pathobionts) while strengthening the defense against non-invasive symbionts at the gingival margin. The result is an increased gingival tissue load of pathobionts, including Gram-negative bacteria, followed by an excessive innate immune response, which prevents infection but simultaneously destroys gingival and periodontal tissues. Thus, the balance between pro-inflammatory and anti-inflammatory adaptive immunity is crucial in controlling the microbiota, and the responsiveness of brain-controlled homeostatic systems determines periodontal health.

Role of prebiotic dietary fiber in periodontal disease: A systematic review of animal studies

Background

Periodontitis is a chronic inflammatory condition affecting the supporting structures of a tooth in the oral cavity. The relationship between dietary fiber and periodontitis is poorly understood. The objective of this systematic review is to investigate if an intake of dietary fiber modulates periodontal disease in animal models and any concomitant effects on systemic inflammation, microbiota and their metabolites.

Methods

Animal studies using periodontitis models with any form of fiber intervention were included. Studies with comorbidities that were mutually inclusive with periodontitis and animals with physiological conditions were excluded. Search strategy with MeSH and free-text search terms were finalized and performed on the 22nd of September 2021.CINAHL Complete, EMBASE, MEDLINE, SciVerse Scopus® and Web of Science Core Collection databases were used to identify studies. SYRCLE’s risk of bias tool and CAMARADES were used for quality assessment. Results were synthesized utilizing Covidence© web-based platform software to remove duplicates, and the remaining studies were manually filtered.

Results

A total of 7,141 articles were retrieved from all databases. Out of 24 full-text articles assessed for eligibility, four studies (n = 4) were included. Four studies involved the use of β-(1,3/1,6)-glucan (n = 3) and mannan oligosaccharide (n = 1) at differing dosages for different study durations. All studies utilized a ligature-induced model of periodontitis in rats, either Wistar (n = 3) or Sprague–Dawley (n = 1). A dose-dependent relationship between the increased fiber intake and decrease in alveolar bone loss and pro-inflammatory markers was observed.

Conclusion

The number of included studies is limited and narrow in scope. They highlight the importance of pre-clinical trials in this field with broader dietary fiber intervention groups before proceeding to clinical trials. The use of dietary fiber as an intervention shows promise in the reduction of inflammatory conditions like periodontitis. However, further research is required to delineate the relationship between diet and its effects on microbiota and their metabolites such as short chain fatty acids in animal models of periodontitis.

Brewer's yeast polysaccharides - A review of their exquisite structural features and biomedical applications

Recent advances on brewer's yeast cell wall polysaccharides have unraveled exquisite structural features and diverse composition with (β1→3), (β1→6), (α1→4), (β1→4)-mix-linked glucans that are recognized to interact with different cell receptors and trigger specific biological responses. Herein, a comprehensive showcase of structure-biofunctional relationships between yeast polysaccharides and their biological targets is highlighted, with a focus on polysaccharide features that govern the biomedical activity. The insolubility of β-glucans is a crucial factor for binding and activation of Dectin-1 receptor, operating as adjuvants of immune responses. Contrarily, soluble low molecular weight β-glucans have a strong inhibition of reactive oxygen species production, acting as antagonists of Dectin-1 mediated signaling. Soluble glucan-protein moieties can also act as antitumoral agents. The balance between mannoproteins-TLR2 and β-glucans-Dectin-1 receptors-activation is crucial for osteogenesis. Biomedical applications value can also be obtained from yeast microcapsules as oral delivery systems, where highly branched (β1→6)-glucans lead to higher receptor affinity.

Dose-response effect of prebiotic ingestion (β-glucans isolated from Saccharomyces cerevisiae) in diabetic rats with periodontal disease

BACKGROUND

Periodontal disease is one of the most frequent comorbidities in diabetic patients and can contribute to poor blood glucose control.

OBJECTIVE

To evaluate the effects of ingesting different doses of beta-glucans (BG) isolated from Saccharomyces cerevisiae on alveolar bone loss (ABL) and inflammatory/metabolic parameters in normal and diabetic rats with ligature-induced periodontal disease (PD).

DESIGN

Sixty male rats were assigned into two groups: non-diabetic or diabetic (i.p. 70 mg/kg streptozotocin) with PD. Then, groups were subdivided into five subgroups according BG doses: 0 mg/Kg; 10 mg/Kg; 20 mg/Kg; 40 mg/Kg or 80 mg/Kg. Animals received BG for 28 days and ligatures were placed on lower first molars during the last 14 days.

RESULTS

ABL of diabetic and non-diabetic animals receiving BG 40 mg/kg (1.33 ± 0.03 mm and 0.77 ± 0.07 mm, respectively) and 80 mg/kg (1.26 ± 0.07 mm and 0.78 ± 0.05 mm, respectively) doses was lower (p < 0.05) in comparison to respective controls (1.59 ± 0.11 mm and 0.90 mm ±0.08). COX-2 (Control: 1.66 ± 0.12; 40 mg/kg: 1.13 ± 0.07; 80 mg/kg: 0.92 ± 0.18) and RANKL expressions (Control: 1.74 ± 0.34; 40 mg/kg: 1.03 ± 0.29 ;80 mg/kg: 0.75 ± 0.21), together with the RANKL/OPG ratio (Control: 1.17 ± 0.08; 40 mg/kg: 0.67 ± 0.09; 80 mg/kg: 0.63 ± 0.28) were attenuated above the same dose (p < 0.05). BG did not influence (p > 0.05) metabolic parameters in non-diabetic rats. In diabetic animals, doses above 40 mg/kg reduced IL-1β (Control: 387 ± 66; 40 mg/kg: 309 ± 27; 80 mg/kg: 300 ± 14) and TNF-α (Control: 229 ± 19; 40 mg/kg: 128 ± 53; 80 mg/kg: 71 ± 25), blood glucose levels (Control: 402 ± 49; 40 mg/kg: 334 ± 32; 80 mg/kg: 287 ± 56), total cholesterol (Control: 124 ± 8; 40 mg/kg: 120 ± 10; 80 mg/kg: 108 ± 9), LDL-c + VLDL-c (Control: 106 ± 8; 40 mg/kg: 103 ± 10; 80 mg/kg: 87 ± 10) and triacylglycerols (Control: 508 ± 90; 40 mg/kg: 301 ± 40; 80 mg/kg: 208 ± 61), whereas increased HDL-c (Control: 18 ± 0.5; 40 mg/kg: 19 ± 1; 80 mg/kg: 21 ± 1) (p < 0.05). Optimal dose needed to reduce ABL was higher in diabetic animals with PD.

CONCLUSIONS

BG ingestion reduced ABL and improved inflammatory profile in a dose-dependent manner. Best effects were achieved with doses above 40 mg/kg.

Phenotypes, roles, and modulation of regulatory lymphocytes in periodontitis and its associated systemic diseases

Periodontitis is a common chronic inflammatory disease that can result in tooth loss and poses a risk to systemic health. Lymphocytes play important roles in periodontitis through multiple mechanisms. Regulatory lymphocytes including regulatory B cells (Bregs) and T cells (Tregs) are the main immunosuppressive cells that maintain immune homeostasis, and are critical to our understanding of the pathogenesis of periodontitis and the development of effective treatments. In this review, we discuss the phenotypes, roles, and modulating strategies of regulatory lymphocytes including Bregs and Tregs in periodontitis and frequently cooccurring inflammatory diseases such as rheumatoid arthritis, Alzheimer disease, diabetes mellitus, and stroke. The current evidence suggests that restoring immune balance through therapeutic targeting of regulatory lymphocytes is a promising strategy for the treatment of periodontitis and other systemic inflammatory diseases.

Biological Effects of β-Glucans on Osteoclastogenesis

Although the anti-tumor and anti-infective properties of β-glucans have been well-discussed, their role in bone metabolism has not been reviewed so far. This review discusses the biological effects of β-glucans on bone metabolisms, especially on bone-resorbing osteoclasts, which are differentiated from hematopoietic precursors. Multiple immunoreceptors that can recognize β-glucans were reported to be expressed in osteoclast precursors. Coordinated co-stimulatory signals mediated by these immunoreceptors are important for the regulation of osteoclastogenesis and bone remodeling. Curdlan from the bacterium Alcaligenes faecalis negatively regulates osteoclast differentiation in vitro by affecting both the osteoclast precursors and osteoclast-supporting cells. We also showed that laminarin, lichenan, and glucan from baker’s yeast, as well as β-1,3-glucan from Euglema gracilisas, inhibit the osteoclast formation in bone marrow cells. Consistent with these findings, systemic and local administration of β-glucan derived from Aureobasidium pullulans and Saccharomyces cerevisiae suppressed bone resorption in vivo. However, zymosan derived from S. cerevisiae stimulated the bone resorption activity and is widely used to induce arthritis in animal models. Additional research concerning the relationship between the molecular structure of β-glucan and its effect on osteoclastic bone resorption will be beneficial for the development of novel treatment strategies for bone-related diseases.

Favourable effect of β-glucan treatment against cisplatin-induced reproductive system damage in male rats

The aim of this study was to investigate the potential beneficial effects of β-glucan treatment against oxidative, histological and spermatological damage caused by cisplatin on the male reproductive system. Twenty-eight Sprague Dawley male rats were used in the study. The rats were randomly divided into four equal-sized groups: a control group, cisplatin group (7 mg/kg in a single-dose cisplatin administered intraperitoneally), β-glucan group (β-glucan given at a dose of 50 mg kg^-1  d^-1 for 14 day) and a cisplatin plus β-glucan group (cisplatin and β-glucan administered together at the same dose). Cisplatin administration induced an increase in the level of thiobarbituric acid-reactive substances, a lipid peroxidation indicator. It induced a decrease in enzymatic (superoxide dismutase, catalase and glutathione peroxidase) activities and nonenzymatic (reduced glutathione) antioxidant levels. In addition, cisplatin caused both histological and spermatological damage, as shown by a decrease in sperm motility and epididymal sperm concentrations and an increase in abnormal sperm rates. The β-glucan treatment improved cisplatin-induced oxidative, histological and spermatological damage. This study revealed that β-glucan treatment provided prevention against male reproductive system damage caused by cisplatin. These preventative effects were likely due to its antioxidant properties.

Glucan and Mannan-Two Peas in a Pod

In recent decades, various polysaccharides isolated from algae, mushrooms, yeast, and higher plants have attracted serious attention in the area of nutrition and medicine. The reasons include their low toxicity, rare negative side effects, relatively low price, and broad spectrum of therapeutic actions. The two most and best-studied polysaccharides are mannan and glucan. This review focused on their biological properties.

Effects of β-Glucans Ingestion on Alveolar Bone Loss, Intestinal Morphology, Systemic Inflammatory Profile, and Pancreatic β-Cell Function in Rats with Periodontitis and Diabetes

This study aimed to evaluate the effects of β-glucan ingestion (Saccharomyces cerevisiae) on the plasmatic levels of tumor necrosis factor-α (TNF-α) and interleukin-10 (IL-10), alveolar bone loss, and pancreatic β-cell function (HOMA-BF) in diabetic rats with periodontal disease (PD). Besides, intestinal morphology was determined by the villus/crypt ratio. A total of 48 Wistar rats weighing 203 ± 18 g were used. Diabetes was induced by the intraperitoneal injection of streptozotocin (80 mg/kg) and periodontal inflammation, by ligature. The design was completely randomized in a factorial scheme 2 × 2 × 2 (diabetic or not, with or without periodontitis, and ingesting β-glucan or not). The animals received β-glucan by gavage for 28 days. Alveolar bone loss was determined by scanning electron microscopy (distance between the cementoenamel junction and alveolar bone crest) and histometric analysis (bone area between tooth roots). β-glucan reduced plasmatic levels of TNF-α in diabetic animals with PD and of IL-10 in animals with PD (p < 0.05). β-glucan reduced bone loss in animals with PD (p < 0.05). In diabetic animals, β-glucan improved β-cell function (p < 0.05). Diabetic animals had a higher villus/crypt ratio (p < 0.05). In conclusion, β-glucan ingestion reduced the systemic inflammatory profile, prevented alveolar bone loss, and improved β-cell function in diabetic animals with PD.

Animal models for periodontal regeneration and peri-implant responses

Translation of experimental data to the clinical setting requires the safety and efficacy of such data to be confirmed in animal systems before application in humans. In dental research, the animal species used is dependent largely on the research question or on the disease model. Periodontal disease and, by analogy, peri-implant disease, are complex infections that result in a tissue-degrading inflammatory response. It is impossible to explore the complex pathogenesis of periodontitis or peri-implantitis using only reductionist in-vitro methods. Both the disease process and healing of the periodontal and peri-implant tissues can be studied in animals. Regeneration (after periodontal surgery), in response to various biologic materials with potential for tissue engineering, is a continuous process involving various types of tissue, including epithelia, connective tissues and alveolar bone. The same principles apply to peri-implant healing. Given the complexity of the biology, animal models are necessary and serve as the standard for successful translation of regenerative materials and dental implants to the clinical setting. Smaller species of animal are more convenient for disease-associated research, whereas larger animals are more appropriate for studies that target tissue healing as the anatomy of larger animals more closely resembles human dento-alveolar architecture. This review focuses on the animal models available for the study of regeneration in periodontal research and implantology; the advantages and disadvantages of each animal model; the interpretation of data acquired; and future perspectives of animal research, with a discussion of possible nonanimal alternatives. Power calculations in such studies are crucial in order to use a sample size that is large enough to generate statistically useful data, whilst, at the same time, small enough to prevent the unnecessary use of animals.

Current and emerging therapies in the management of diabetic foot ulcers

BACKGROUND

Diabetic foot ulcers are one of the major causes of mortality in diabetic patients. Very few drugs and therapies have regulatory approval for this indication and several agents from diverse pharmacological classes are currently in various phases of clinical trials for the management of diabetic foot ulcers.

SCOPE

The purpose of this review is to provide concise information of the drugs and therapies which are approved and present in clinical trials.

REVIEW METHODS

This review was carried out by systematic searches of relevant guidelines, patents, published articles, reviews and abstracts in PubMed/Medline, Web of Science, clinicaltrials.gov, Cochrane Central Register of Controlled Trials, Cochrane Database of Systematic Reviews and Google Scholar of all English language articles up to 1 March 2015. The following search terms were used: diabetes, diabetic foot, diabetic foot ulcer, diabetic wound, diabetic foot infections, wound management, randomized controlled trials, approved treatments, new treatments and clinical trials.

CONCLUSIONS

The various drugs and therapies for the management of diabetic foot ulcers comprise antibiotics, neuropathic drugs, wound dressings, skin substitutes, growth factors and inflammatory modulators. The majority of these therapies target the treatment of diabetic foot ulcers to address the altered biochemical composition of the diabetic wound. However, no single treatment can be definitively recommended for the treatment of diabetic foot ulcers.

β-Glucans (Saccharomyces cereviseae) Reduce Glucose Levels and Attenuate Alveolar Bone Loss in Diabetic Rats with Periodontal Disease

The objective of this study was to assess the effects of oral ingestion of β-glucans isolated from Saccharomyces cereviseae on the metabolic profile, expression of gingival inflammatory markers and amount of alveolar bone loss in diabetic rats with periodontal disease. Diabetes mellitus was induced in 48 Wistar rats by intraperitoneal injection of streptozotocin (80 mg/kg). After confirming the diabetes diagnosis, the animals were treated with β-glucans (by gavage) for 28 days. On the 14^th day of this period, periodontal disease was induced using a ligature protocol. β-glucans reduced the amount of alveolar bone loss in animals with periodontal disease in both the diabetic and non-diabetic groups (p < 0.05). β-glucans reduced blood glucose, cholesterol and triacylglycerol levels in diabetic animals, both with and without periodontal disease (p < 0.05). Furthermore, treatment with β-glucans reduced the expression of cyclooxygenase-2 and receptor activator of nuclear factor kappa-B ligand and increased osteoprotegerin expression in animals with diabetes and periodontal disease (p < 0.05). It was concluded that treatment with β-glucans has beneficial metabolic and periodontal effects in diabetic rats with periodontal disease.

Effect of the probiotic Saccharomyces cerevisiae on ligature-induced periodontitis in rats

BACKGROUND AND OBJECTIVE

This study assessed the effects of the local use of Saccharomyces cerevisiae as monotherapy and as an adjuvant to the mechanical treatment of ligature-induced periodontitis in rats.

MATERIAL AND METHODS

Periodontitis was induced in 72 rats via the installation of a ligature around the mandibular first molar. After 7 d, the ligature was removed and the rats were placed in one of the following groups: no treatment (C; n = 18); scaling and root planing (SRP; n = 18); local irrigation with probiotics (PRO; n = 18); and SRP followed by local irrigation with probiotics (SRP/PRO; n = 18). Six rats from each group were killed at 7, 15 and 30 d. The histological characteristics, alveolar bone loss (ABL) and immunolabeling of tumor necrosis factor alpha (TNF-α), interleukin-1beta (IL-1β), interleukin-10 (IL-10) and TRAP on the furcation area of the first molar were assessed.

RESULTS

The PRO group showed features of acceleration of the tissue-repair process during the entire experiment. On day 15, there was less ABL in the SRP/PRO group compared with the C group. There were fewer TRAP-positive cells in the SRP and SRP/PRO groups at 30 d. There was less immunostaining for TNF-α in the PRO and SRP/PRO groups and less immunostaining for IL-1β in the PRO group. However, there was more immunostaining for IL-10 in the PRO group on day 15.

CONCLUSION

Local use of the probiotic did not result in any adverse effects on periodontal tissues. When used as monotherapy or as an adjuvant, the probiotic was effective at controlling periodontitis in rats.

Maternal Deprivation of Lewis Rat Pups Increases the Severity of Experi-mental Periodontitis in Adulthood

Background and Objective:

Early life adverse events may influence susceptibility/resistance to chronic inflammatory diseases later in life by permanently dysregulating brain-controlled immune-regulatory systems. We have investigated the impact of infant-mother separation during early postnatal life on the severity of experimental periodontitis, as well as systemic stress and immune responses, in adulthood.

Material and Methods:

Pups of periodontitis resistant Lewis rats were separated from their mothers for 3 h daily during postnatal days 2-14 (termed maternal deprivation; MD), separated for 15 min daily during the same time period (termed handling; HD), or left undisturbed. As adults, their behaviour was tested in a novel stressful situation, and ligature-induced periodontitis applied for 21 days. Two h before sacrifice all rats were exposed to a gram-negative bacterial lipopolysaccharide (LPS) challenge to induce a robust immune and stress response.

Results:

Compared to undisturbed controls, MD rats developed significantly more periodontal bone loss as adults, whereas HD rats showed a tendency to less disease. MD and HD rats exhibited depression-like behaviour in a novel open field test, while MD rats showed higher glucocorticoid receptor (Gr) expression in the hippocampus, and HD rats had altered methylation of genes involved in the expression of hippocampal Gr. LPS provoked a significantly lower increase in circulating levels of the cytokine TGF-1β in MD and HD rats, but there were no significant differences in levels of the stress hormone corticosterone.

Conclusion:

Stressful environmental exposures in very early life may alter immune responses in a manner that influences susceptibility/resistance to periodontitis.

Effects of long-term exposure of 3,4-methylenedioxymethamphetamine (MDMA; "ecstasy") on neuronal transmitter transport, brain immuno-regulatory systems and progression of experimental periodontitis in rats

The present study was designed to investigate the effects of long-term exposure (4 weeks) to the widely used narcotic drug and putative neurotoxicant 3,4-methylenedioxymetamphetamine (MDMA; "ecstasy") on neuronal transmitter transport and progression of experimental periodontitis in male Wistar rats. The rats were exposed to MDMA (10mg/kg/day i.p.) or saline five days a week for four consecutive weeks. Exposure to MDMA induced a significant reduction in the synaptosomal reuptake of serotonin, while the uptake of dopamine was significantly increased 24h after the last injection of MDMA. In contrast, the synaptosomal uptake of noradrenaline and the vesicular uptake through the vesicular monoamine transporter 2 were not affected. In the experiments of periodontitis development, ligature-induced periodontitis was induced three days prior to MDMA administration. Compared to controls, MDMA-treated rats developed significantly more periodontitis. In conclusion, our results show that long-term exposure to MDMA affects the serotonergic and dopaminergic transport systems in the rat brain and increased the susceptibility to the psychosomatic ailment periodontitis following disturbances of brain immune-regulatory systems. These results are interesting with respect to recent research showing that changes in neurotransmitter signalling may alter the reactivity of brain-controlled immunoregulatory systems controlling pathogenic microorganisms colonizing mucosal surfaces.

Macrophage stimulating agent soluble yeast β-1,3/1,6-glucan as a topical treatment of diabetic foot and leg ulcers: A randomized, double blind, placebo-controlled phase II study

AIMS/INTRODUCTION

Dysregulated inflammatory response is believed to be an important factor in the pathogenesis of several late complications of diabetes mellitus. β-Glucans are potent inducers of immune function. The present randomized, double blind, two-center, placebo-controlled study was undertaken to explore safety, tolerability and efficacy of soluble β-1,3/1,6-glucan (SBG) as a local treatment of diabetic foot ulcers.

MATERIALS AND METHODS

A total of 60 patients with type 1 or 2 diabetes and lower extremity ulcers (Wagner grade 1-2, Ankle/Brachial Index ≥0.7) received SBG or a comparator product (methylcellulose) locally three times weekly up to 12 weeks in addition to conventional management scheme. A total of 54 patients completed the study.

RESULTS

A tendency for shorter median time to complete healing in the SBG group was observed (36 vs 63 days, P = 0.130). Weekly percentage reduction in ulcer size was significantly higher in the SBG group than in the methylcellulose group between weeks 1-2, 3-4 and 5-6 (P < 0.05). The proportion of ulcers healed by week 12 was also in favor of SBG (59% vs 37%, P = 0.09), with a significantly higher healing incidence in the SBG group at week 8 (44% vs 17%, P = 0.03). SBG was safe and well tolerated. There was a clinically significant difference regarding the incidence of serious adverse events in favor of the SBG treatment.

CONCLUSIONS

Local treatment of diabetic lower extremity ulcers with β-1,3/1,6-polyglucose shows good safety results. This β-glucan preparation shows promising potential as a treatment accelerating cutaneous healing. Further studies are required to confirm this effect. This trial was registered with ClinicalTrials.gov (no. NCT00288392).

The influence of chronic stress imposed on pregnant rats on the induced bone loss in their adult offspring

BACKGROUND AND OBJECTIVE

Stress during pregnancy may alter offspring susceptibility to diseases during adulthood. In the present study, female Lewis rats were subjected to chronic stress during the gestational period, and the effect of this stress was evaluated histometrically on the progression of ligature-induced bone loss in their adult offspring.

MATERIAL AND METHODS

After confirming pregnancy, half of the pregnant rats were randomly designated as control animals (no stress regimen was imposed), and the other half was submitted to a chronic stress model (immobilization at cold temperature) between the 7th and the 18th gestational day. After birth, 12 male rats delivered by stressed mothers - Group 1 (G1) - and 12 male rats delivered by non-stressed mothers - Group 2 (G2) - were selected. When birthed rats reached 250 g of body weight, a silk ligature was placed around their maxillary right second molar in order to induce bone loss. The non-ligated left side served as a control. Sixty days later, these animals were sacrificed by anaesthetic overdose. After routine laboratorial processing, images of the histological sections were digitized and submitted for histometric measurement using two parameters: histological attachment loss and bone loss.

RESULTS

On the ligated side, G1 presented with greater histological attachment and bone loss than G2 (p<0.05). On the non-ligated control side, neither of the groups presented with alterations in these parameters (p>0.05).

CONCLUSION

The chronic stress regimen imposed on pregnant rats produced a greater progression of ligature-induced bone loss in their adult offspring.

Oral treatment with complement factor C5a receptor (CD88) antagonists inhibits experimental periodontitis in rats

BACKGROUND AND OBJECTIVE

The complement activation product 5a (C5a) is a potent mediator of the innate immune response to infection, and may thus also importantly determine the development of periodontitis. The present study was designed to explore the effect of several novel, potent and orally active C5a receptor (CD88) antagonists (C5aRAs) on the development of ligature-induced periodontitis in an animal model.

MATERIAL AND METHODS

Three different cyclic peptide C5aRAs, termed PMX205, PMX218 and PMX273, were investigated. Four groups of Wistar rats (n = 10 in each group) were used. Starting 3 d before induction of experimental periodontitis, rats either received one of the C5aRas (1-2 mg/kg) in the drinking water or received drinking water only. Periodontitis was assessed when the ligatures had been in place for 14 d.

RESULTS

Compared with control rats, PMX205- and PMX218-treated rats had significantly reduced periodontal bone loss.

CONCLUSION

The findings suggest that complement activation, and particularly C5a generation, may play a significant role in the development and progression of periodontitis. Blockade of the major C5a receptor, CD88, with specific inhibitors such as PMX205, may offer novel treatment options for periodontitis.

Systemic chemical desensitization of peptidergic sensory neurons with resiniferatoxin inhibits experimental periodontitis

Background and objective:

The immune system is an important player in the pathophysiology of periodontitis. The brain controls immune responses via neural and hormonal pathways, and brain-neuro-endocrine dysregulation may be a central determinant for pathogenesis. Our current knowledge also emphasizes the central role of sensory nerves. In line with this, we wanted to investigate how desensitization of peptidergic sensory neurons influences the progression of ligature-induced periodontitis, and, furthermore, how selected cytokine and stress hormone responses to Gram-negative bacterial lipopolysaccharide (LPS) stimulation are affected.

Material and methods:

Resiniferatoxin (RTX; 50 μg/kg) or vehicle was injected subcutaneously on days 1, 2, and 3 in stress high responding and periodontitis-susceptible Fischer 344 rats. Periodontitis was induced 2 days thereafter. Progression of the disease was assessed after the ligatures had been in place for 20 days. Two h before decapitation all rats received LPS (150 μg/kg i.p.) to induce a robust immune and stress response.

Results:

Desensitization with RTX significantly reduced bone loss as measured by digital X-rays. LPS provoked a significantly higher increase in serum levels of the pro-inflammatory cytokine tumour necrosis factor (TNF)-α, but lower serum levels of the anti-inflammatory cytokine interleukin (IL)-10 and the stress hormone corticosterone.

Conclusions:

In this model RTX-induced chemical desensitization of sensory peptidergic neurons attenuated ligature-induced periodontitis and promoted a shift towards stronger pro-inflammatory cytokine and weaker stress hormone responses to LPS. The results may partly be explained by the attenuated transmission of immuno-inflammatory signals to the brain. In turn, this may weaken the anti-inflammatory brain-derived pathways.

Chicken lines divergently selected for antibody responses to sheep red blood cells show line-specific differences in sensitivity to immunomodulation by diet. Part I: Humoral parameters

Individual differences in nutrient sensitivity have been suggested to be related with differences in stress sensitivity. Here we used layer hens divergently selected for high and low specific antibody responses to SRBC (i.e., low line hens and high line hens), reflecting a genetically based differential immune competence. The parental line of these hens was randomly bred as the control line and was used as well. Recently, we showed that these selection lines differ in their stress reactivity; the low line birds show a higher hypothalamic-pituitary-adrenal (HPA) axis reactivity. To examine maternal effects and neonatal nutritional exposure on nutrient sensitivity, we studied 2 subsequent generations. This also created the opportunity to examine egg production in these birds. The 3 lines were fed 2 different nutritionally complete layer feeds for a period of 22 wk in the first generation. The second generation was fed from hatch with the experimental diets. At several time intervals, parameters reflecting humoral immunity were determined such as specific antibody to Newcastle disease and infectious bursal disease vaccines; levels of natural antibodies binding lipopolysaccharide, lipoteichoic acid, and keyhole limpet hemocyanin; and classical and alternative complement activity. The most pronounced dietary-induced effects were found in the low line birds of the first generation: specific antibody titers to Newcastle disease vaccine were significantly elevated by 1 of the 2 diets. In the second generation, significant differences were found in lipoteichoic acid natural antibodies of the control and low line hens. At the end of the observation period of egg parameters, a significant difference in egg weight was found in birds of the high line. Our results suggest that nutritional differences have immunomodulatory effects on innate and adaptive humoral immune parameters in birds with high HPA axis reactivity and affect egg production in birds with low HPA axis reactivity.

Toxicological assessment of a particulate yeast (1,3/1,6)-β-d-glucan in rats

This study investigates the toxicity of WGP 3-6, a yeast-derived beta-glucan ingredient, during single-dose acute and sub-chronic toxicity studies in rats. For the acute study, Fisher-344 rats were administered WGP 3-6 via gavage at a dose of 2000 mg/kg body weight, and any evidence of toxicity was monitored over a 14-day period. WGP 3-6 was well tolerated, indicating that the LD(50) value is greater than 2000 mg/kg body weight. For the sub-chronic study, Fisher-344 rats (10/sex/group) were randomly allocated to receive daily gavage treatment with WGP 3-6 at doses of 0, 2, 33.3, or 100 mg/kg body weight. Control and high-dose satellite recovery groups of each sex also were included. Full toxicological monitoring and endpoint investigations were performed throughout and upon completion of the study. No negative effects on animal weights or food consumption attributable to WGP 3-6 were evident at any dose. In addition, no mortality, clinical pathology, functional/behavioral, microscopic, or gross observations indicating toxicity were observed. Sporadic changes in some biochemical and hematological parameters were observed; however, since the effects were within the physiological ranges in historical controls, were not dose-responsive, or were not observed in both sexes, they were determined to be of no toxicological significance. In conclusion, no adverse or toxic effects were observed after subchronic oral administration of 2, 33.3, or 100mg/kg body weight/day of WGP 3-6 in Fisher-344 rats, and therefore, a no observed adverse effect level (NOAEL) of 100 mg/kg body weight/day, the highest dose tested, was determined.

Technique for screening immune-enhancing polysaccharides in food using 1,25-dihydroxyvitamin D3-differentiated HL60 cells

A technique for screening immune-enhancing polysaccharides in food using the phagocytotic activity of 1,25-dihydroxyvitamin D3 (VD3)-differentiated HL60 cells is presented. HL60 cells, a human acute promyelocytic cell line, can differentiate along the monocytic lineage following exposure to VD3 or phorbol-12-myristate-13-acetate (PMA). For differentiated cells along the monocytic pathway, HL60 cells were maintained in RPMI 1640 medium supplemented with 10% FBS and 120 nM VD3 for more than 1 week. VD3-differentiated HL60 cells were seeded into 48-well plates, YG-labeled microspheres and polysaccharides were added and mixed using a plate shaker at 1100 rpm for 30 s, and then the mixture was incubated overnight at 37 degrees C in 5% CO2. The cells were fixed with 2% formaldehyde and resuspended in phosphate-buffered saline. The rate of phagocytosis was measured with a flow cytometer. VD3-differentiated cells but not non- and PMA-differentiated cells resulted in an elevation of phagocytic activity by various immune-enhancing polysaccharides in foods.

Carboxymethyl β-glucan Binds to Corneal Epithelial Cells and Increases Cell Adhesion to Laminin and Resistance to Oxidative Stress

PURPOSE

Polysaccharides are frequently used as viscoelastic agents to improve pharmacokinetics of ophthalmic preparations. Recently, polysaccharides from yeast cell walls such as beta-glucans have emerged as bioactive molecules endowed with immunomodulatory and cytoprotective properties. In this study, we investigated the effects of carboxymethyl beta-glucan (CMG), a water-soluble derivative of yeast beta-glucan, on cultured rabbit corneal epithelial cells.

METHODS

We developed a fluorescein-labeled CMG to visualize its binding to corneal cells by means of digital microscopy and image deconvolution. The effects of CMG on adhesion and survival of corneal epithelial cells exposed to noxious stimuli were also studied.

RESULTS

CMG binds defined regions scattered throughout the body of corneal cells, suggesting binding specificity. Tridimensional reconstruction of fluorescence shows that binding is localized mainly at the plasma and nuclear membranes. Interestingly, CMG binding is highly represented at the level of focal adhesion of cells spreading onto laminin. Accordingly, CMG promotes adhesion of corneal epithelial cells to laminin without affecting their proliferation rate. CMG also protects cells from oxidative stress-dependent cell death, being ineffective in preventing ultraviolet B cytotoxicity.

CONCLUSIONS

Data show that CMG dynamically binds to corneal epithelial cells, promoting cell adhesion and resistance to oxidative stress.

Enhanced susceptibility to periodontitis in an animal model of depression: reversed by chronic treatment with the anti-depressant tianeptine

OBJECTIVE

To test the hypothesis that the olfactory bulbectomy model of depression in rats could influence susceptibility to ligature-induced periodontitis, and that chronic treatment with the anti-depressant drug tianeptine could attenuate this effect.

MATERIAL AND METHODS

Tianeptine was given twice daily (10 mg/kg, i.p.) during the entire experiment, starting 29 days before induction of olfactory bulbectomy and periodontitis. Olfactory bulbectomized (OB) rats and sham-operated rats were given saline in a similar manner. Periodontal disease was assessed when the ligatures had been in place for 21 days. Two hours before decapitation, rats were injected with lipopolysaccharide (LPS;100 microg/kg, i.p.) to induce a robust immune and stress response.

RESULTS

Compared with sham-operated controls, OB rats developed significantly more periodontal bone loss, exhibited characteristic behavioural responses in a novel open field test, and showed a decreased expression of glucocorticoid receptors (GRs) in the hippocampus. LPS provoked a significantly larger increase in circulating levels of the stress hormone corticosterone and the cytokine transformation growth factor (TGF)-1beta but smaller tumour necrosis factor (TNF)-alpha levels. Tianeptine treatment of OB rats significantly inhibited peridodontal bone loss, normalized behavioural responses, enhanced TGF-1beta levels, and abolished TNF-alpha decrease, but did not attenuate the increased corticosterone response and the decreased hippocampal GR expression.

CONCLUSIONS

These experimental results are consistent with an emerging literature showing that life stress, anxiety, depression, pathological grief, and poor coping behaviour may dysregulate regulatory mechanisms within the brain involved in immune regulation, and thereby alter immune responses and influence the susceptibility/resistance to inflammatory disorders.

Neonatal dexamethasone and chronic tianeptine treatment inhibit ligature-induced periodontitis in adult rats

OBJECTIVE

The responsiveness of the hypothalamic-pituitary-adrenal (HPA) axis has been found to play a significant role for susceptibility and resistance to periodontal disease. In the present study we have investigated the effects of two different treatment strategies, which have been found to down-regulate the HPA axis, on ligature-induced periodontitis.

METHODS

In experiment 1, newborn rats were treated with the synthetic glucocorticoid hormone dexamethasone-21-phosphate, which permanently down-regulates HPA axis responsiveness. In experiment 2, adult rats were treated with the novel antidepressant drug tianeptine, which opposes the action of stress. Periodontitis was inflicted upon all rats. Just before decapitation the animals received gram-negative bacterial lipopolysaccharide (LPS) to induce a robust immune and HPA axis response.

RESULTS

Compared to the saline-treated control rats, dexamethasone-treated rats had significantly less periodontal bone loss (p < 0.01), reduced expression of glucocorticoid receptors in the hippocampus (p < 0.001), lower corticosterone (p=0.01) and higher plasma levels of the cytokine tumor necrosis factor (TNF)-alpha (p < 0.05) after LPS challenge. Also the tianeptine-treated rats showed significantly reduced periodontal bone loss (p=0.01), enhanced plasma levels of TNF-alpha (p < 0.05), and transforming growth factor-1beta (p < 0.01), whereas no significant difference was found in corticosterone levels.

CONCLUSION

An individual's responsiveness to danger signals, whether they are of immunological, chemical, or psychological origin, may be an important factor for explaining variability in susceptibility to periodontal disease. The results may provide new insight into the mechanisms of periodontal disease development, and open new vistas for disease prevention.