Yoshihiko Soga

Macrophage-Adipocyte Interaction: Marked Interleukin-6 Production by Lipopolysaccharide

Objective: Recent studies suggested macrophages were integrated in adipose tissues, interacting with adipocytes, thereby exacerbating inflammatory responses. Persistent low‐grade infection by gram‐negative bacteria appears to promote atherogenesis. We hypothesized a ligand for toll‐like receptor 4 (TLR4), bacterial lipopolysaccharide (LPS), would further exaggerate macrophage‐adipocyte interaction.

DNA microarray analyses of genes expressed differentially in 3T3-L1 adipocytes co-cultured with murine macrophage cell line RAW264.7 in the presence of the toll-like receptor 4 ligand bacterial endotoxin

Recent studies have suggested that macrophages were integrated into adipose tissues to interact with adipocytes, thereby exacerbating inflammatory responses. Furthermore, both adipocytes and macrophages appear to express toll-like receptor-4 (TLR-4), and free fatty acids may stimulate cells through TLR-4. Herein, we analyzed genes differentially expressed in adipocytes when co-cultured with macrophages in the presence of a ligand for TLR-4, bacterial lipopolysaccharide (LPS). RAW264.7, a murine macrophage cell line and differentiated 3T3-L1 adipocytes were co-cultured using a transwell system. Genes differentially expressed in adipocytes were analyzed by the DNA microarray method following 4, 8, 12 and 24 h stimulation with 1 ng ml−1 of Escherichia coli LPS. Randomly selected genes with high expressions were confirmed by quantitative methods at both the gene and the protein level. Co-culture of macrophages and adipocytes with a low LPS concentration (1 ng ml−1) markedly upregulated gene expressions associated with inflammation and/or angiogenesis, such as those of interleukin-6 (IL-6), MCP-1, RANTES and CXCL1/KC, in adipocytes. Furthermore, several genes associated with insulin resistance were differentially expressed. Upregulations of genes encoding MCP-1, RANTES and CXC/KC were confirmed by quantitative methods. These results suggest that ligands for TLR-4 stimulate both adipocytes and macrophages to upregulate the expressions of many genes associated with inflammation and/or angiogenesis.

Adipocyte-macrophage interaction may mediate LPS-induced low-grade inflammation: potential link with metabolic complications

Chronic low-grade infection has been suggested to be associated with metabolic disorder such as diabetes. However, the molecular mechanism underlying this important association is largely unknown. The only clue established so far is that many subjects exhibit elevated levels of C-reactive protein as measured by highly sensitive assay. Here, we hypothesized that adipocyte–macrophage interaction plays a key role in amplifying such low grade infection to the level of influencing metabolic disorders. The presence of macrophages in abdominal adipose tissues was investigated by immunohistochemistry. To see whether molecules associated with acute phase protein, LPS signaling, and persistent recruitment of monocytes, are produced at higher amounts in adipocytes co-cultured with macrophages stimulated with low concentration of LPS (1 ng/ml), we measured serum amyloid A (SAA), LPS binding protein (LBP), soluble CD14 (sCD14), and RANTES levels in culture supernatant of co-cultures. Lastly, we investigated in vivo effect of low-grade LPS infusion on the production of these molecules using obese model mice. The macrophages were certainly identified in abdominal adipose tissues. Investigated molecules, especially LBP, SAA, and RANTES were produced at higher amounts in co-cultures stimulated with LPS compared with the cells without LPS. The ob/ob, and high-fat diet-induced obesity mice produced higher amounts of LBP, SAA, and RANTES one day after LPS infusion (1 ng/ml/g body weight) compared with ob/– and normal-fat fed control mice. Thus, adipocytes and infiltrated macrophages, and their interaction with low endotoxin stimulation appear to play an important role in amplifying and maintaining LPS-induced low-grade inflammation.

Oral mucositis in patients receiving reduced-intensity regimens for allogeneic hematopoietic cell transplantation: Comparison with conventional regimen

Goals of workSevere oral mucositis induced by allogeneic hematopoietic cell transplantation (HCT) is associated with intolerable pain and risk of systemic bacteremia infection. Differences between conventional HCT and reduced-intensity regimens for allogeneic HCT (RIST) may influence the occurrence and severity of oral mucositis. Here, we evaluated oral mucositis in patients undergoing RIST and compared the results with those in conventional allogeneic HCT patients to facilitate predictive measures for mucositis.Patients and methodsA total of 127 consecutive patients undergoing HCT (conventional, 63; RIST, 64) were included in this study. Severity of oral mucositis during HCT period was evaluated daily. Differences in severity of mucositis among HCT types were analyzed. Use of morphine to control pain due to oral mucositis was evaluated in each HCT method.Main resultsThe severity of oral mucositis was reduced in patients undergoing RIST. Worsening of oral mucositis was delayed in patients receiving RIST. Use of morphine to control pain due to oral mucositis was significantly decreased in patients undergoing RIST compared with those receiving conventional allogeneic HCT.ConclusionsThe severity of oral mucositis was reduced and the peak day of oral mucositis was delayed in RIST patients compared with those receiving conventional HCT.

Antimicrobial effects of the saliva substitute, Oralbalance, against microorganisms from oral mucosa in the hematopoietic cell transplantation period.

GoalsThe commercially available saliva substitute Oralbalance® has been reported to alleviate symptoms of post-radiotherapy xerostomia in head and neck cancer patients. Oralbalance® may also be effective for xerostomia in patients undergoing hematopoietic cell transplantation (HCT) with high-dose chemotherapy and total-body irradiation. However, HCT patients are severely compromised, and saliva substitute must therefore not promote infection. This study was performed to determine the effects of Oralbalance® on microbial species identified during HCT.Patients and methodsMicrobial identification of oral mucosa was performed in 28 patients undergoing HCT. The antimicrobial effects of Oralbalance® against bacteria and fungi detected in the HCT period were examined in vitro. Briefly, bacteria and fungi were spread on agar plates, and 0.1g of Oralbalance® gel was applied (about φ1cm). After incubation at 37°C for 24h, the presence of a transparent zone of inhibition around Oralbalance® was observed.Main resultsNot only bacterial species constituting normal flora of the oral mucosa but also those not usually constituting normal flora, e.g., coagulase-negative Staphylococcus, were detected. A transparent zone was observed around Oralbalance® in all bacterial species examined. No transparent zone was observed for Candida albicans, but growth was inhibited in the area where Oralbalance® was applied.ConclusionsOralbalance® does not facilitate increases in microorganisms in the HCT period. Oral care with Oralbalance® does not promote infection in patients undergoing HCT.

Progress of oral care and reduction of oral mucositis—a pilot study in a hematopoietic stem cell transplantation ward

PurposeOral mucositis is a common symptomatic complication associated with hematopoietic stem cell transplantation (HCT). We use simple strategies aimed to reduce oral mucositis by keeping the oral cavity clean and moist. Here, we report on the progress of oral care and the changes in the degree of oral mucositis. The purpose of this pilot study is to evaluate the effects of our strategies on the prevalence and the severity of oral mucositis.MethodsFifty-three consecutive patients from 2003 to 2006 administered with conventional allogeneic HCT were enrolled in this study. The degree of oral mucositis was evaluated daily in all patients. Our oral care program was divided into two periods: “examination and trial period (2003 and 2004)” and “intensive oral care period (2005 and 2006).” In the latter, an oral care regimen was carried out systematically by a multidisciplinary team.ResultsUsing our oral care strategies, the prevalence of ulcerative oral mucositis was decreased significantly. The rate was reduced from 76% (10 of 13) of patients with ulcerative oral mucositis in 2003 to only 20% (3 of 15) in 2006.ConclusionsOur pilot study suggests that oral mucositis in HCT patients can be alleviated by simple strategies aimed at keeping the oral cavity clean and moist.

High glucose up-regulates lipopolysaccharide-stimulated inflammatory cytokine production via c-jun N-terminal kinase in the monocytic cell line THP-1

Diabetic subjects are susceptible to atherosclerosis. It has been postulated that inflammation plays a crucial role in atherogenesis. Since previous studies suggested persistent low-grade infection by Gram-negative bacteria such as Chlamydia spp. and/or periodontal infection is associated with increased atherogenesis among diabetic subjects, we hypothesized that macrophages under hyperglycemia respond to lipopolysaccharide (LPS) challenge in a more exaggerated manner than under normal glucose conditions. Therefore, we examined cytokine productivity and associated signal transduction molecules in LPS-stimulated the monocytic cell line THP-1, under conditions of hyperglycemia. Differentiated THP-1 cells were cultured under normal and high glucose conditions without fetal bovine serum, and were stimulated with Escherichia coli LPS in the presence of LPS binding protein. Following stimulation, activated signal transduction molecules were detected by protein microarray and confirmed thereafter. Results indicated that c-jun N-terminal kinase (JNK) was highly-phosphorylated at high glucose concentrations, and this was confirmed by Western-immunoblotting. Tumor necrosis factor-α and monocyte chemo-attractant protein-1 production were significantly enhanced under these conditions. SP600125, a selective inhibitor of JNK, dose-dependently suppressed the production of these cytokine. Therefore, we suggest that this may be one of the mechanisms by which sub-clinical infection by Gram-negative bacteria promotes atherosclerosis in diabetic subjects.

Incidence and Risk Factors of Osteonecrosis of the Jaw in Advanced Cancer Patients after Treatment with Zoledronic Acid or Denosumab: A Retrospective Cohort Study

Zoledronic acid and denosumab are two antiresorptive drugs currently in use for treating osteoporosis. They have different mechanisms of action, but both have been shown to delay the onset of skeletal-related events in patients with advanced cancer. However, medication-related osteonecrosis of the jaw (MRONJ) has been reported in cancer patients treated with zoledronic acid or denosumab. We studied 155 patients with several types of advanced cancer who were treated with zoledronic acid or denosumab in our hospital during the period from April 2010 through March 2013. Thirteen of these 155 patients (8.4%) developed MRONJ. MRONJ development was significantly associated with the number of zoledronic acid or denosumab infusions (p<0.001) and the duration of zoledronic acid or denosumab therapy (p<0.001). Logistic regression analysis showed that diabetes [odds ratio (OR)=6.699, 95% confidence interval (CI), 1.435-31.277, p=0.016], anemia [OR=14.559, 95% CI, 2.161-98.069, p=0.006], and pus discharge [OR=6.491, 95% CI, 1.514-27.835, p=0.012] significantly increased the risk of developing MRONJ. However, the risk of MRONJ was significantly lower [OR=0.137, 95% CI, 0.020-0.944, p=0.043] when patients received periodical dentistry maintenance. Diabetes, anemia, and pus discharge may also play roles in its development. These findings suggest that the active inclusion of dentistry maintenance in bisphosphonate or denosumab treatment of cancer patients can reduce MRONJ development.

Assessment of Chromosome 19 for Genetic Association in Severe Chronic Periodontitis

BACKGROUND A genome-association study is a powerful tool for analyzing small gene effects in complex diseases such as chronic periodontitis (CP), although the cost of analysis is prohibitive. We designed a study using the DNA pooling method, which could be a breakthrough in lowering such costs. This study was conducted to assess the genetic association in severe CP in a Japanese population. METHODS We adopted a DNA pooling method by genotyping 454 densely spaced microsatellite (MS) markers in chromosome 19 as a pilot study, with the possibility of future use in a whole-genome study. This can reduce the high cost and technical burden, which is generally unavoidable in a genomic association study. Pooled DNA samples from 300 case subjects, 300 control subjects, and 200 systemically healthy subjects were screened by genotyping MS markers. The case-control association in the candidate region was analyzed by individual typing of MS and single nucleotide polymorphisms (SNPs). RESULTS The single MS marker allele 17 of 1902G31 was isolated in association with severe CP (P = 0.0012 for 2 x 2; P <0.046 for 2 x m, where m refers to the number of polymorphic alleles observed in a population). No other SNP or MS polymorphism hypothesized to affect biologic functions in the critical region was found in the linkage disequilibrium block analysis. CONCLUSIONS We efficiently isolated the susceptible locus for severe CP in chromosome 19 and identified a useful marker to evaluate the risk for disease. This approach can be applied to a whole-genome study in severe CP.

Thiazolidinedione (Pioglitazone) Blocks P. gingivalis- and F. nucleatum, but not E. coli, Lipopolysaccharide (LPS)-induced Interleukin-6 (IL-6) Production in Adipocytes

An elevated level of C-reactive protein (CRP) predicts the future development of coronary heart disease. Periodontitis appears to up-regulate CRP. CRP is produced by hepatocytes in response to interleukin-6 (IL-6). A major source of IL-6 in obese subjects is adipocytes. We hypothesized that lipopolysaccharide (LPS) from periodontal pathogens stimulated adipocytes to produce IL-6, and that the production was suppressed by the drugs targeted against insulin resistance, thiazolidinedione (pioglitazone), since this agent potentially showed an anti-inflammatory effect. Mouse 3T3-L1 adipocytes were stimulated with E. coli, P. gingivalis, and F. nucleatum LPS. The IL-6 concentration in culture supernatants was measured. All LPS stimulated adipocytes to produce IL-6. Although pioglitazone changed adipocyte appearance from large to small, and completely suppressed P. gingivalis and F. nucleatum LPS-induced IL-6 production, E. coli LPS-induced IL-6 production was not efficiently blocked. Thus, pioglitazone completely blocked periodontal-bacteria-derived LPS-induced IL-6 production in adipocytes, a major inducer of CRP.