Human cell-based anti-inflammatory effects of rosiglitazone

PURPOSE

The C-X-C motif chemokine ligand 10 (CXCL10) participates in diabetes and diabetic cardiomyopathy development from the early stages. Rosiglitazone (RGZ) exhibits anti-inflammatory properties and can target cardiomyocytes secreting CXCL10, under interferon (IFN)γ and tumor necrosis factor (TNF)α challenge. Cardiomyocyte remodeling, CD4 + T cells and dendritic cells (DCs) significantly contribute to the inflammatory milieu underlying and promoting disease development. We aimed to study the effect of RGZ onto inflammation-induced secretion of CXCL10, IFNγ, TNFα, interleukin (IL)-6 and IL-8 by human CD4 + T and DCs, and onto IFNγ/TNFα-dependent signaling in human cardiomyocytes associated with chemokine release.

METHODS

Cells maintained within an inflammatory-like microenvironment were exposed to RGZ at near therapy dose (5 µM). ELISA quantified cytokine secretion; qPCR measured mRNA expression; Western blot analyzed protein expression and activation; immunofluorescent analysis detected intracellular IFNγ/TNFα-dependent trafficking.

RESULTS

In human CD4 + T cells and DCs, RGZ inhibited CXCL10 release likely with a transcriptional mechanism, and reduced TNFα only in CD4 + T cells. In human cardiomyocytes, RGZ impaired IFNγ/TNFα signal transduction, blocking the phosphorylation/nuclear translocation of signal transducer and activator of transcription 1 (Stat1) and nuclear factor-kB (NF-kB), in association with a significant decrease in CXCL10 expression, IL-6 and IL-8 release.

CONCLUSION

As the combination of Th1 biomarkers like CXCL10, IL-8, IL-6 with classical cardiovascular risk factors seems to improve the accuracy in predicting T2D and coronary events, future studies might be desirable to further investigate the anti-Th1 effect of RGZ.

Humanized mice efficiently engrafted with fetal hepatoblasts and syngeneic immune cells develop human monocytes and NK cells

BACKGROUND & AIMS

Human liver chimeric mice are useful models of human hepatitis virus infection, including hepatitis B and C virus infections. Independently, immunodeficient mice reconstituted with CD34(+) hematopoietic stem cells (HSC) derived from fetal liver reliably develop human T and B lymphocytes. Combining these systems has long been hampered by inefficient liver reconstitution of human fetal hepatoblasts. Our study aimed to enhance hepatoblast engraftment in order to create a mouse model with syngeneic human liver and immune cells.

METHODS

The effects of human oncostatin-M administration on fetal hepatoblast engraftment into immunodeficient fah(-/-) mice was tested. Mice were then transplanted with syngeneic human hepatoblasts and HSC after which human leukocyte chimerism and functionality were analyzed by flow cytometry, and mice were challenged with HBV.

RESULTS

Addition of human oncostatin-M enhanced human hepatoblast engraftment in immunodeficient fah(-/-) mice by 5-100 fold. In contrast to mice singly engrafted with HSC, which predominantly developed human T and B lymphocytes, mice co-transplanted with syngeneic hepatoblasts also contained physiological levels of human monocytes and natural killer cells. Upon infection with HBV, these mice displayed rapid and sustained viremia.

CONCLUSIONS

Our study provides a new mouse model with improved human fetal hepatoblast engraftment and an expanded human immune cell repertoire. With further improvements, this model may become useful for studying human immunity against viral hepatitis.

LAY SUMMARY

Important human pathogens such as hepatitis B virus, hepatitis C virus and human immunodeficiency virus only infect human cells which complicates the development of mouse models for the study of these pathogens. One way to make mice permissive for human pathogens is the transplantation of human cells into immune-compromised mice. For instance, the transplantation of human liver cells will allow the infection of these so-called "liver chimeric mice" with hepatitis B virus and hepatitis C virus. The co-transplantation of human immune cells into liver chimeric mice will further allow the study of human immune responses to hepatitis B virus or hepatitis C virus. However, for immunological studies it will be crucial that the transplanted human liver and immune cells are derived from the same human donor. In our study we describe the efficient engraftment of human fetal liver cells and immune cells derived from the same donor into mice. We show that liver co-engraftment resulted in an expanded human immune cell repertoire, including monocytes and natural killer cells in the liver. We further demonstrate that these mice could be infected with hepatitis B virus, which lead to an expansion of natural killer cells. In conclusion we have developed a new mouse model that could be useful to study human immune responses to human liver pathogens.