Toll-like receptor 4 (TLR4) is known to contribute to the modulation of insulin resistance and systemic inflammation seen in obesity and the metabolic syndrome. The present study was performed to investigate the fertility competence of TLR4 knock out male mice (TLR4 mice) on a high-fat diet (HFD), compared to a normal-chow diet (NCD). The controls included wildtype (WT) mice fed on a HFD or NCD. Six-week-old male mice were fed with either a NCD or HFD for 20 weeks. Body and organ weights, serum levels of glucose, triglycerides and hepatoxicity, sperm quality and spermatogenesis were observed after the sacrifice. Also, randomly selected male mice were mated with virgin female mice after feeding of 19 weeks. The weight of the body and organs increased in WT and TLR4 mice on a HFD compared to those of mice on a NCD. The weights of the reproductive organs did not vary among the treatment groups. The motility and concentration of the epididymal spermatozoa decreased in both WT and TLR4 mice fed a HFD. The pregnancy rate and litter size declined in the HFD-fed WT mice compared to the HFD-fed TLR4 mice. In conclusion, the HFD alters energy and steroid metabolism in mice, which may lead to male reproductive disorders. However, fertility competence was somewhat restored in HFD-fed TLR4 male mice, suggesting that the TLR4 is involved in testis dysfunction due to metabolic imbalance.

The GroEL heat-shock protein from Fusobacterium nucleatum, a periodontopathogen, activates risk factors for atherosclerosis in human microvascular endothelial cells (HMEC-1) and ApoE-/- mice. In this study, we analyzed the signaling pathways by which F. nucleatum GroEL induces the proinflammatory factors in HMEC-1 cells known to be risk factors associated with the development of atherosclerosis and identified the cellular receptor used by GroEL. The MAPK and NF-κB signaling pathways were found to be activated by GroEL to induce the expression of interleukin- 8 (IL-8), monocyte chemoattractant protein 1 (MCP- 1), intercellular adhesion molecule 1 (ICAM-1), vascular cell adhesion molecule 1 (VCAM-1), E-selectin, and tissue factor (TF). These effects were inhibited by a TLR4 knockdown. Our results thus indicate that TLR4 is a key receptor that mediates the interaction of F. nucleatum GroEL with HMEC-1 cells and subsequently induces an inflammatory response via the MAPK and NF-κB pathways.

The primary cause of periodontitis is plaque-associated anaerobic gram-negative bacteria. As shown in the patients with defects in the number or function of neutrophils, innate immunity plays an important role in resistance to bacterial infection and periodontitis. Toll-like receptor 4(TLR4) is one of the key receptors that recognize the molecular patterns of microbes and initiate innate immune response. To understand the role of TLR4 in the pathogenesis of periodontitis, we investigated whether Asp299Gly of TLR4 mutation is associated with periodontitis in Korean population. Subjects for this study included 90 healthy subjects and 98 periodontitis patients. The Asp299Gly mutation was screened by PCR-Restriction Fragment Length Polymorphism(RFLP) of genomic DNA from blood cells using a primer that creates a NcoI restriction site only in the mutant allele. The Asp299Gly mutation was not found in all subjects tested. Our results suggest that the Asp299Gly mutation of TLR4 is very rare in a Korean population. Further mutation screening may be required to determine the role of TLR4 in the pathogenesis of periodontitis.

본 연구는 EA에 의한 대식세포의 활성화를 매개로 한 항암효과와 항암작용과 관련된 대식세포의 면역조절효과를 확인하였다. 연구 결과 EA에 의해 RAW264.7세포 및 peritoneal macrophage 모두에서 항암효과가 증가하였으며, 증가된 대식세포의 항암효과는 TLR4 signaling을 blocking하는 CLI-095을 함께 처리하였을 때 일부 감소되었다. 이는 EA에 의한 항암 효과가 부분적으로 TLR4를 경유하는 기전으로 나타나는 것을 의미한다. 또한, EA에 대한 대식세포의 NO 분비조절효과를 측정하였으며, EA는 대식세포의 NO 생성을 증가시켰으나, 인위적으로 염증을 유발시켜 NO를 과도하게 분비한 상태에서는 NO 분비를 오히려 억제시키는 결과를 나타내었다. 이와 같이 EA에 의한 NO조절에 대한 이중 효과는 인체에 면역증강과 항염증 효과라는 긍정적인 효과를 나타내는 방향으로 조절하고 있으므로 EA를 이용한 항암요법의 보조제 및 면역보조제로써의 활용에 유익할 것으로 사료된다. 향후 EA에 대한 항암 작용 및 NO 조절에서 세포내 신호전달 작용기전에 대한 심도 있는 연구가 진행되어야 할 것으로 보인다.