Differential expansion of circulating human MDSC subsets in patients with cancer, infection and inflammation

Background

Myeloid-derived suppressor cells (MDSC) are a functional myeloid cell subset that includes myeloid cells with immune suppressive properties. The presence of MDSC has been reported in the peripheral blood of patients with several malignant and non-malignant diseases. So far, direct comparison of MDSC across different diseases and Centers is hindered by technical pitfalls and a lack of standardized methodology. To overcome this issue, we formed a network through the COST Action Mye-EUNITER (www.mye-euniter.eu) with the goal to standardize and facilitate the comparative analysis of human circulating MDSC in cancer, inflammation and infection. In this manuscript, we present the results of the multicenter study Mye-EUNITER MDSC Monitoring Initiative, that involved 13 laboratories and compared circulating MDSC subsets across multiple diseases, using a common protocol for the isolation, identification and characterization of these cells.

Methods

We developed, tested, executed and optimized a standard operating procedure for the isolation and immunophenotyping of MDSC using blood from healthy donors. We applied this procedure to the blood of almost 400 patients and controls with different solid tumors and non-malignant diseases. The latter included viral infections such as HIV and hepatitis B virus, but also psoriasis and cardiovascular disorders.

Results

We observed that the frequency of MDSC in healthy donors varied substantially between centers and was influenced by technical aspects such as the anticoagulant and separation method used. Expansion of polymorphonuclear (PMN)-MDSC exceeded the expansion of monocytic MDSC (M-MDSC) in five out of six solid tumors. PMN-MDSC expansion was more pronounced in cancer compared with infection and inflammation. Programmed death-ligand 1 was primarily expressed in M-MDSC and e-MDSC and was not upregulated as a consequence of disease. LOX-1 expression was confined to PMN-MDSC.

Conclusions

This study provides improved technical protocols and workflows for the multi-center analysis of circulating human MDSC subsets. Application of these workflows revealed a predominant expansion of PMN-MDSC in solid tumors that exceeds expansion in chronic infection and inflammation.

Changes in hypoxia level of CT26 tumors during various stages of development and comparing different methods of hypoxia determination

The aim of this study was to evaluate hypoxia level at various tumor developmental stages and to compare various methods of hypoxia evaluation in pre-clinical CT26 tumor model. Using three methods of hypoxia determination, we evaluated hypoxia levels during CT26 tumor development in BALB/c mice from day 4 till day 19, in 2-3 days intervals. Molecular method was based on the analysis of selected genes expression related to hypoxia (HIF1A, ANGPTL4, TGFB1, VEGFA, ERBB3, CA9) or specific for inflammation in hypoxic sites (CCL2, CCL5) at various time points after CT26 cancer cells inoculation. Imaging methods of hypoxia evaluation included: positron-emission tomography (PET) imaging using [18F]fluoromisonidazole ([18F]FMISO) and a fluorescence microscope imaging of pimonidazole (PIMO)-positive tumor areas at various time points. Our results showed that tumor hypoxia at molecular level was relatively high at early stage of tumor development as reflected by initially high HIF1A and VEGFA expression levels and their subsequent decrease. However, imaging methods (both PET and fluorescence microscopy) showed that hypoxia increased till day 14 of tumor development. Additionally, necrotic regions dominated the tumor tissue at later stages of development, decreasing the number of hypoxic areas and completely eliminating normoxic regions (observed by PET). These results showed that molecular methods of hypoxia determination are more sensitive to show changes undergoing at cellular level, however in order to measure and visualize hypoxia in the whole organ, especially at later stages of tumor development, PET is the preferred tool. Furthermore we concluded, that during development of tumor, two peaks of hypoxia occur.

[Novel multiplex real-time PCR assay for detection and differentiation of herpes simplex virus type 1 and 2 DNA]

INTRODUCTION

Herpes simplex viruses type 1 and 2 are the cause of world spread multiple infections with different course and severity. The aim of this work was to design and to optimize multiplex real-time PCR assay for simultaneous detection of HSV-1 and HSV-2. The second aim of the project was to check if the designed method is laboratory useful analyzing different clinical specimens.

MATERIALS AND METHODS

In this experiment primers and probes were designed to specific viral sequences: for HSV-1 to the gene of viral DNA polymerase; for HSV-2 to the UL5 sequence. For performing qPCR assay TaqMan chemistry was used. Reference strains HSV-I McIntyre and HSV-2 MS were used as a positive control. To test laboratory utility of the designed method 58 different clinical specimens were analyzed.

RESULTS

Developed multiplex real-time PCR gave positive result only in the samples containing genetic material of HSV-1/2. Of the 58 clinical samples tested, 27 proved to be positive for HSV-1 and 17 for HSV-2. The 7 samples showed the presence of both types of DNA herpes simplex virus, and 7 others were found for both HSV-1 and HSV-2 negative.

CONCLUSIONS

Obtained results show that the designed method is highly specific and can possibly be used to simultaneously detect and differentiate HHV-1/2. Both high specificity and very short time of analysis have great importance in diagnosing immunocompromised patients, which ought to be diagnosed quickly and effectively in order to provide appropriate treatment.