Metformin Suppresses MHC-Restricted Antigen Presentation by Inhibiting Co-Stimulatory Factors and MHC Molecules in APCs

Metformin is widely used for T2D therapy but its cellular mechanism of action is undefined. Recent studies on the mechanism of metformin in T2D have demonstrated involvement of the immune system. Current immunotherapies focus on the potential of immunomodulatory strategies for the treatment of T2D. In this study, we examined the effects of metformin on the antigen-presenting function of antigen-presenting cells (APCs). Metformin decreased both MHC class I and class II-restricted presentation of OVA and suppressed the expression of both MHC molecules and co-stimulatory factors such as CD54, CD80, and CD86 in DCs, but did not affect the phagocytic activity toward exogenous OVA. The class II-restricted OVA presentation-regulating activity of metformin was also confirmed using mice that had been injected with metformin followed by soluble OVA. These results provide an understanding of the mechanisms of the T cell response-regulating activity of metformin through the inhibition of MHC-restricted antigen presentation in relation to its actions on APCs.

Metformin Down-regulates TNF-alpha Secretion via Suppression of Scavenger Receptors in Macrophages

Obesity is consistently increasing in prevalence and can trigger insulin resistance and type 2 diabetes. Many lines of evidence have shown that macrophages play a major role in inflammation associated with obesity. This study was conducted to determine metformin, a widely prescribed drug for type 2 diabetes, would regulate inflammation through down-regulation of scavenger receptors in macrophages from obesity-induced type 2 diabetes. RAW 264.7 cells and peritoneal macrophages were stimulated with LPS to induce inflammation, and C57BL/6N mice were fed a high-fat diet to generate obesity-induced type 2 diabetes mice. Metformin reduced the production of NO, PGE2 and pro-inflammatory cytokines (IL-1beta, IL-6 and TNF-alpha) through down-regulation of NF-kappaB translocation in macrophages in a dose-dependent manner. On the other hand, the protein expressions of anti-inflammatory cytokines, IL-4 and IL-10, were enhanced or maintained by metformin. Also, metformin suppressed secretion of TNF-alpha and reduced the protein and mRNA expression of TNF-alpha in obese mice as well as in macrophages. The expression of scavenger receptors, CD36 and SR-A, were attenuated by metformin in macrophages and obese mice. These results suggest that metformin may attenuate inflammatory responses by suppressing the production of TNF-alpha and the expressions of scavenger receptors.

Phenotypic and genotypic characterization of Bifidobacterium isolates from healthy adult Koreans

A total of twenty-two strict anaerobic and Gram-positive Bifidobacteria, identified as B. adolescentis, B. pseudocatenulatum, or B. longum, were isolated from healthy adult Koreans. We here investigated the cell morphology, antimicrobial resistance patterns to novel antibiotics and genotypic differentiation of Bifidobacteria assessing repetitive DNA element PCR [rep-PCR] fingerprinting using the BOXA1R primer at the species level. All Bifidobacterium spp., except B. adolescentis SPM1005 and B. longum SPM1205, formed round and convex colonies. All B. adolescentis, B. pseudocatenulatum, and B. longum were opaque white glossy in colony color, and short, long, and irregular rods in morphological shape. In addition, all B. adolescentis, B. pseudocatenulatum, and B. longum formed a variety of shapes ranging from rods to Vshaped, Y-shaped, clubbed rods, or irregular. All Bifidobacterium spp., except B. adolescentis SPM0214, were sensitive to daptomycin [DAP], linezolid [LIN], and tigecycline [TIG]. B. adolescentis SPM0214 was resistant to DAP. Genomic fingerprinting patterns of B. adolescentis, B. pseudocatenulatum, and B. longum were diverse and different from those of the KCTC strain. The band size of B. adolescentis, B. pseududocatenulatum, and B. longum varied from 3.0 kb to 300 bp, 2.0 kb to 200 bp, and 2.0 kb to 500 bp, respectively. In conclusion, twenty-two strains of B. adolescentis, B. pseudocatenulatum, and B. longum isolated from healthy adult Koreans were very diverse in both phenotype and genotype. Moreover, this diversity of phenotype and genotype may support that health promoting effects of individual strain of Bifidobacterium spp. human isolates could be different and specific even within same species

Enteropathogenic Bacteria Contamination of Unchlorinated Drinking Water in Korea, 2010

OBJECTIVES: The purpose of this study was to assess the microbiological quality of unchlorinated drinking water in Korea, 2010. One hundred and eighty unchlorinated drinking water samples were collected from various sites in Seoul and Gyeonggi province. METHODS: To investigate bacterial presence, the pour plate method was used with cultures grown on selective media for total bacteria, total coliforms, and Staphylococcus spp., respectively. RESULTS: In the 180 total bacteria investigation, 72 samples from Seoul and 33 samples from Gyeonggi province were of an unacceptable quality (>10(2) CFU/mL). Of all the samples tested, total coliforms were detected in 28 samples (15.6%) and Staphylococcus spp. in 12 samples (6.7%). Most of the coliform isolates exhibited high-level resistance to cefazolin (88.2%), cefonicid (64.7%) and ceftazidime (20.6%). In addition, Staphylococcus spp. isolates exhibited high-level resistance to mupirocin (42%). Species of Pseudomonas, Acinetobacter, Cupriavidus, Hafnia, Rahnella, Serratia, and Yersinia were isolated from the water samples. CONCLUSIONS: The results of this study suggest that consumption of unchlorinated drinking water could represent a notable risk to the health of consumers. As such, there is need for continuous monitoring of these water sources and to establish standards.

Immunostimulatory Effects of Cordyceps militaris on Macrophages through the Enhanced Production of Cytokines via the Activation of NF-kappaB

BACKGROUND: Cordyceps militaris has been used in traditional medicine to treat numerous diseases and has been reported to possess both antitumor and immunomodulatory activities in vitro and in vivo. However, the pharmacological and biochemical mechanisms of Cordyceps militaris extract (CME) on macrophages have not been clearly elucidated. In the present study, we examined how CME induces the production of proinflammatory cytokines, transcription factor, and the expression of co-stimulatory molecules. METHODS: We confirmed the mRNA and protein levels of proinflammatory cytokines through RT-PCR and western blot analysis, followed by a FACS analysis for surface molecules. RESULTS: CME dose dependently increased the production of NO and proinflammatory cytokines such as IL-1beta, IL-6, TNF-alpha, and PGE(2), and it induced the protein levels of iNOS, COX-2, and proinflammatory cytokines in a concentration-dependent manner, as determined by western blot and RT-PCR analysis, respectively. The expression of co-stimulatory molecules such as ICAM-1, B7-1, and B7-2 was also enhanced by CME. Furthermore, the activation of the nuclear transcription factor, NF-kappaB in macrophages was stimulated by CME. CONCLUSION: Based on these observations, CME increased proinflammatory cytokines through the activation of NF-kappaB, further suggesting that CME may prove useful as an immune-enhancing agent in the treatment of immunological disease.

Cordycepin Suppresses Expression of Diabetes Regulating Genes by Inhibition of Lipopolysaccharide-induced Inflammation in Macrophages

BACKGROUND: It has been recently noticed that type 2 diabetes (T2D), one of the most common metabolic diseases, causes a chronic low-grade inflammation and activation of the innate immune system that are closely involved in the pathogenesis of T2D. Cordyceps militaris, a traditional medicinal mushroom, produces a component compound, cordycepin (3'-deoxyadenosine). Cordycepin has been known to have many pharmacological activities including immunological stimulating, anti-cancer, and anti-infection activities. The molecular mechanisms of cordycepin in T2D are not clear. In the present study, we tested the role of cordycepin on the anti-diabetic effect and anti-inflammatory cascades in LPS-stimulated RAW 264.7 cells. METHODS: We confirmed the levels of diabetes regulating genes mRNA and protein of cytokines through RT-PCR and western blot analysis and followed by FACS analysis for the surface molecules. RESULTS: Cordycepin inhibited the production of NO and pro-inflammatory cytokines such as IL-1beta, IL-6, and TNF-alpha in LPS-activated macrophages via suppressing protein expression of pro-inflammatory mediators. T2D regulating genes such as 11beta-HSD1 and PPARgamma were decreased as well as expression of co-stimulatory molecules such as ICAM-1 and B7-1/-2 were also decreased with the increment of its concentration. In accordance with suppressed pro-inflammatory cytokine production lead to inhibition of diabetic regulating genes in activated macrophages. Cordycepin suppressed NF-kappaB activation in LPS-activated macrophages. CONCLUSION: Based on these observations, cordycepin suppressed T2D regulating genes through the inactivation of NF-kappaB dependent inflammatory responses and suggesting that cordycepin will provide potential use as an immunomodulatory agent for treating immunological diseases.

Role of Cordycepin and Adenosine on the Phenotypic Switch of Macrophages via Induced Anti-inflammatory Cytokines

BACKGROUND: Chronic low grade inflammation is closely linked to type II diabetes, obesity, and atherosclerosis. Macrophages play a key role in the regulation of pro- or anti-inflammatory actions at the lesion sites of disease. Components of cordyceps militaris, cordycepin and adenosine, have been used for the modulation of inflammatory diseases. The effects of cordycepin in the modulation of macrophages have yet to be elucidated. We investigated the effects of cordycepin and adenosine on the morphological changes of macrophages under the inflammatory condition of LPS and an anti-inflammatory condition involving high concentrations of adenosine. METHODS: We confirmed the mRNA levels of the M1/M2 cytokine genes through RT-PCR and morphological change. RESULTS: LPS-activated macrophages returned to their inactivated original shape, i.e., they looked like naive macrophages, through the treatment with high concentrations of cordycepin (40 microgram/ml). LPS and adenosine activated macrophages also returned to their original inactivated shapes after cordycepin treatment; however, at relatively higher levels of cordycepin than adenosine. This change did not occur with relatively low concentrations of cordycepin. Adenosine down-regulated the gene expression of M1 cytokines (IL-1beta, TNF-alpha) and chemokines (CX3CR1, RANTES), as well as cordycepin. Additionally, M2 cytokines (IL-10, IL-1ra, TGF-beta) were up-regulated by both cordycepin and adenosine. CONCLUSION: Based on these observations, both cordycepin and adenosine regulated the phenotypic switch on macrophages and suggested that cordycepin and adenosine may potentially be used as immunomodulatory agents in the treatment of inflammatory disease.