Elevated methylglyoxal (MGO) levels and altered immune cell responses are observed in diabetes. MGO is thought to modulate immune cell activation. The current study investigated whether fasting or post-glucose-load plasma MGO concentrations are associated with circulating immune cell counts and activation in a large cohort study.
696 participants of The Maastricht Study (age 60.3 ± 8.4 years, 51.9% women) underwent an oral glucose tolerance test (OGTT). Fasting and post-OGTT plasma MGO concentrations were measured using mass spectrometry. Numbers and activation of circulating immune cells at fasting state were quantified using flow cytometry. Activation scores were calculated by averaging individual marker z-scores for neutrophils (CD11b, CD11c, CD16) and classical, intermediate, and non-classical monocytes (CD11b, CD11c, CX3XR1, HLA-DR). Associations were analysed using multiple linear regression adjusted for potential confounders. Stratified analyses were performed for glucose metabolism status for associations between plasma MGO levels and immune cell counts.
Higher fasting plasma MGO concentrations were significantly associated with higher numbers of intermediate (β = 0.09 [95%CI 0.02; 0.17]) and non-classical monocytes (0.08 [0.002; 0.15]), but with lower activation scores for the intermediate monocytes (-0.14 [-0.22; -0.06]). Stratified analyses showed that positive associations between fasting plasma MGO levels and numbers of intermediate and non-classical monocytes appear only in participants with type 2 diabetes. Post-OGTT plasma MGO concentrations were not consistently associated with immune cells counts or activation.
Higher fasting plasma MGO concentrations are associated with higher intermediate and non-classical monocyte counts but with lower activation of intermediate monocytes.
© 2025. The Author(s).

The immune component of the tumor microenvironment is essential for the regulation of cancer progression. In breast cancer (BC), a patient's tumor mass is frequently infiltrated by neutrophils (tumor-associated neutrophils, TANs). Our study addressed the role of TANs and their mechanism of action in BC. Using quantitative IHC, ROC, and Cox analysis, we demonstrated that a high density of TANs infiltrating the tumor parenchyma was predictive of poor prognosis and of decreased progression-free survival of patients with BC, who underwent surgical tumor removal without previous neoadjuvant chemotherapy, in 3 different cohorts: training, validation, and independent cohorts. Conditioned medium from human BC cell lines prolonged the lifespan of healthy donor neutrophils ex vivo. Neutrophils activated by the supernatants of BC lines demonstrated an increased ability to stimulate proliferation, migration, and invasive activity of BC cells. Cytokines involved in this process were identified using antibody arrays. The relationship between these cytokines and the density of TANs was validated by ELISA and IHC in fresh BC surgical samples. It was determined that tumor-derived G-CSF significantly extended the lifespan and increased the metastasis-promoting activities of neutrophils via the PI3K-AKT and NF-κB pathways. Simultaneously, TAN-derived RLN2 promoted the migratory abilities of MCF7 cells via PI3K-AKT-MMP-9. Analysis of tumor tissues from 20 patients with BC identified a positive correlation between the density of TANs and the activation of the G-CSF-RLN2-MMP-9 axis. Finally, our data demonstrated that TANs in human BC have detrimental effects, supporting malignant cell invasion and migration.
© The Author(s) 2023. Published by Oxford University Press on behalf of Society for Leukocyte Biology.

Myeloid-derived suppressor cells (MDSC) are a subset of immature myeloid cells with suppressive activity well described in the context of cancer. They inhibit anti-tumour immunity, promote metastasis formation and can lead to immune therapy resistance. In a retrospective study, blood probes of 46 advanced melanoma patients were analysed before the first administration of anti-PD-1 immunotherapy and in the third month of treatment for MDSC, immature monocytic (ImMC), monocytic MDSC (MoMDSC) and granulocytic MDSC (GrMDSC) by multi-channel flow cytometry. Cell frequencies were correlated with response to immunotherapy, progression-free survival (PFS) and lactate dehydrogenase (LDH) serum level. Responders to anti-PD-1 therapy had higher MoMDSC levels (4.1 ± 1.2%) compared to non-responders (3.0 ± 1.2%) (p = 0.0333) before the first administration of anti-PD-1. No significant changes in MDSCs frequencies were observed in the groups of patients before and in the third month of therapy. The cut-off values of MDSCs, MoMDSCs, GrMDSCs and ImMCs for favourable 2- and 3-year PFS were established. Elevated LDH level is a negative prognostic factor of response to the treatment and is related to an elevated ratio of GrMDSCs and ImMCs level compared to patients' LDH level below the cut-off. Our data may provide a new perspective for more careful consideration of MDSCs, and specially MoMDSCs, as a tool for monitoring the immune status of melanoma patients. Changes in MDSC levels may have a potential prognostic value, however a correlation with other parameters must be established.

Highly heterogeneous cell populations require multiple flow cytometric markers for appropriate phenotypic characterization. This exponentially increases the complexity of 2D scatter plot analyses and exacerbates human errors due to variations in manual gating of flow data. We describe a semi-automated workflow, based entirely on the Flowjo Graphical User Interface (GUI), that involves the stepwise integration of several, newly available machine learning tools for the analysis of myeloid-derived suppressor cells (MDSCs) in septic and non-septic critical illness. Supervised clustering of flow cytometric data showed correlation with, but significantly different numbers of, MDSCs as compared with the cell numbers obtained by manual gating. Neither quantification method predicted 30-day clinical outcomes in a cohort of 16 critically ill and septic patients and 5 critically ill and non-septic patients. Machine learning identified a significant decrease in the proportion of PMN-MDSC in critically ill and septic patients as compared with healthy controls. There was no difference between the proportion of these MDSCs in septic and non-septic critical illness.
Copyright © 2022 Bonavia, Samuelsen, Luthy and Halstead.

Prolyl carboxypeptidase (PRCP) is involved in metabolic disorders by hydrolyzing anorexigenic peptides. A link between serum PRCP activity and obesity has been reported, but its origin/source is still unclear. Previously proven correlations between human serum PRCP activity and the amount of adipose tissue may suggest that adipose tissue is an important source of circulating PRCP. We investigated PRCP activity in visceral, subcutaneous adipose tissue (VAT and SCAT), skeletal muscle tissue and serum of lean and obese men with or without type 2 diabetes (T2D). Correlations between PRCP activity, metabolic and biochemical parameters and immune cell populations were assessed. PRCP activity was the highest in VAT, compared to SCAT, and was very low in skeletal muscle tissue in the overall group. Serum PRCP activity was significantly higher in T2-diabetic obese men, compared to lean and obese non-diabetic men, and was positively correlated with glycemic control. A positive correlation was observed between serum PRCP activity and VAT immune cell populations, which might indicate that circulating PRCP activity is deriving rather from the immune fraction than from adipocytes. In conclusion, PRCP activity was observed in human adipose tissue for the first time and serum PRCP activity is correlated with T2D in obese men.