Age-dependent cellular reactions of the human immune system of humanized NOD scid gamma mice on LPS stimulus

Inhibition of LPS-mediated TLR4 activation abrogates gastric adenocarcinoma-associated peritoneal metastasis

Surgical resection, the cornerstone of curative intent treatment for gastric adenocarcinoma, is associated with a high rate of infection-related post-operative complications, leading to an increased incidence of metastasis to the peritoneum. However, the mechanisms underlying this process are poorly understood. Lipopolysaccharide (LPS), an antigen from Gram-negative bacteria, represents a potential mechanism via induction of local and systemic inflammation through activation of Toll-like receptor (TLR). Here, we use both a novel ex vivo model of peritoneal metastasis and in vivo animal models to assess gastric cancer cell adhesion to peritoneum both before and after inhibition of the TLR4 pathway. We demonstrate that activation of TLR4 by either LPS or Gram-negative bacteria (E. coli) significantly increases the adherence of gastric cancer cells to human peritoneal mesothelial cells, and that this increased adherence is abrogated by inhibition of the TLR4 signal cascade and downstream TAK1 and MEK1/2 pathways. We also demonstrate that the influence of LPS on adherence extends to peritoneal tissue and metastatic spread. Furthermore, we show that loss of TLR4 at the site of metastasis reduces tumor cell adhesion, implicating the TLR4 signaling cascade in potentiating metastatic adhesion and peritoneal spread. These results identify potential therapeutic targets for the clinical management of patients undergoing resection for gastric cancer.

Humanized Mice as a Tool to Study Sepsis-More Than Meets the Eye

(1) Background. Repetitive animal studies that have disappointed upon translation into clinical therapies have led to an increased appreciation of humanized mice as a remedy to the shortcomings of rodent-based models. However, their limitations have to be understood in depth. (2) Methods. This is a narrative, comprehensive review of humanized mice and sepsis literature to understand the model's benefits and shortcomings. (3) Results: Studies involving humanized models of sepsis include bacterial, viral, and protozoan etiology. Humanized mice provided several unique insights into the etiology and natural history of sepsis and are particularly useful in studying Ebola, and certain viral and protozoan infections. However, studies are relatively sparse and based on several different models of sepsis and humanized animals. (4) Conclusions. The utilization of humanized mice as a model for sepsis presents complex limitations that, once surpassed, hold some potential for the advancement of sepsis etiology and treatment.

Perspectives on long pentraxin 3 and rheumatoid arthritis: several potential breakthrough points relying on study foundation of the past

Rheumatoid arthritis (RA) is a systemic chronic autoimmune inflammatory disease which is mainly characterized by synovitis and results in a severe burden for both the individual and society. To date, the underlying mechanisms of RA are still poorly understood. Pentraxin 3 (PTX3) is a typical long pentraxin protein which has been highly conserved during evolution. Meanwhile, functions as well as properties of PTX3 have been extensively studied. Several studies identified that PTX3 plays a predominate role in infection, inflammation, immunity and tumor. Interestingly, PTX3 has also been verified to be closely associated with development of RA. We therefore accomplished an elaboration of the relationships between PTX3 and RA. Herein, we mainly focus on the associated cell types and cognate cytokines involved in RA, in combination with PTX3. This review infers the insight into the interaction of PTX3 in RA and aims to provide novel clues for potential therapeutic target of RA in clinic.

Human immune cells infiltrate the spinal cord and impair recovery after spinal cord injury in humanized mice

Humanized mice can be used to better understand how the human immune system responds to central nervous system (CNS) injury and inflammation. The optimal parameters for using humanized mice in preclinical CNS injury models need to be established for appropriate use and interpretation. Here, we show that the developmental age of the human immune system significantly affects anatomical and functional outcome measures in a preclinical model of traumatic spinal cord injury (SCI). Specifically, it takes approximately 3-4 months for a stable and functionally competent human immune system to develop in neonatal immune compromised mice after they are engrafted with human umbilical cord blood stem cells. Humanized mice receiving a SCI before or after stable engraftment exhibit significantly different neuroinflammatory profiles. Importantly, the development of a mature human immune system was associated with worse lesion pathology and neurological recovery after SCI. In these mice, human T cells infiltrate the spinal cord lesion and directly contact human macrophages. Together, data in this report establish an optimal experimental framework for using humanized mice to help translate promising preclinical therapies for CNS injury.

A facile approach for development of a vaccine made of bacterial double-layered membrane vesicles (DMVs)

Bacterial infections cause acute and chronic diseases. Antimicrobial resistance and aging-related immune weakness remain challenging in therapy of infectious diseases. Vaccines are however an alternative to prevent bacterial infections. Here we report a facile method to rapidly generate bacterium-membrane-formed nanovesicles as a vaccine using nitrogen cavitation. The vaccine is comprised of double-layered membrane vesicles (DMVs) characterized by cryo-TEM, biochemistry and proteomics, showing DMVs possess the integrity of bacterial membrane and contain a wide range of membrane proteins required for vaccination. In the mouse sepsis model induced by Pseudomonas aeruginosa, we found that DMVs can improve mouse survival after mice were immunized with DMVs. The increased adaptive immunity and unique biodistribution of DMVs were responsible for enhanced protection of bacterial infection. Our studies demonstrate that this simple and innovative approach using nitrogen cavitation would be a promising technology for vaccine developments.

Potential Pitfalls of the Humanized Mice in Modeling Sepsis

Humanized mice are a state-of-the-art tool used to study several diseases, helping to close the gap between mice and human immunology. This review focuses on the potential obstacles in the analysis of immune system performance between humans and humanized mice in the context of severe acute inflammation as seen in sepsis or other critical care illnesses. The extent to which the reconstituted human immune system in mice adequately compares to the performance of the human immune system in human hosts is still an evolving question. Although certain viral and protozoan infections can be replicated in humanized mice, whether a highly complex and dynamic systemic inflammation like sepsis can be accurately represented by current humanized mouse models in a clinically translatable manner is unclear. Humanized mice are xenotransplant animals in the most general terms. Several organs (e.g., bone marrow mesenchymal cells, endothelium) cannot interact with the grafted human leukocytes effectively due to species specificity. Also the interaction between mice gut flora and the human immune system may be paradoxical. Often, grafting is performed utilizing an identical batch of stem cells in highly inbred animals which fails to account for human heterogeneity. Limiting factors include the substantial cost and restricting supply of animals. Finally, humanized mice offer an opportunity to gain knowledge of human-like conditions, requiring careful data interpretation just as in nonhumanized animals.