Microglia and macrophages appear to be the most common cells in the GBM microenvironment. In the present study we investigated the status of macrophages/microglia activation in surgical specimens from 41 patients diagnosed with grade IV GBM. For each patient we analyzed both the center of tumor and the parenchyma surrounding the tumor. The specimens were stained for: i) IBA1, a 17-kDa EF hand protein specifically expressed in microglia/macrophages ii) CD163, a cell surface antigen associated with M2 phenotype; iii) iNOS, taken as a functional marker of M1 phenotype, and iv) ARG-I, taken as a functional marker of M2 phenotype. Staining was scored in a double-blinded score on a scale from 0 to 5. Our results suggest that CD163 expression is higher within the tumor than in surrounding periphery in both male and female patients; while iNOS is higher within the tumor in males, no significant difference was found for ARG-1. In addition, analyzing the data in TGCA database, we found that CD163 expression was significantly and inversely correlated with mean survival times, with average survival times ranging from 448days in patients having low expression, to 319 in mid, and 353 in patients with high CD163 expressing tumors. In contrast, no significant association was found between survival time and ARG-1 or iNOS expression.

Background In critically ill patients, the use of high tigecycline dosages (HD TGC) (200 mg/day) has been recently increasing but few pharmacokinetic/pharmacodynamic (PK/PD) data are available. We designed a prospective observational study to describe the pharmacokinetic/pharmacodynamic (PK/PD) profile of HD TGC in a cohort of critically ill patients with severe infections. Results This was a single centre, prospective, observational study that was conducted in the 20-bed mixed ICU of a 1500-bed teaching hospital in Rome, Italy. In all patients admitted to the ICU between 2015 and 2018, who received TGC (200 mg loading dose, then 100 mg q12) for the treatment of documented infections, serial blood samples were collected to measure steady-state TGC concentrations. Moreover, epithelial lining fluid (ELF) concentrations were determined in patients with nosocomial pneumonia. Amongst the 32 non-obese patients included, 11 had a treatment failure, whilst the other 21 subjects successfully eradicated the infection. There were no between-group differences in terms of demographic aspects and main comorbidities. In nosocomial pneumonia, for a target AUC0-24/MIC of 4.5, 75% of the patients would be successfully treated in presence of 0.5 mcg/mL MIC value and all the patients obtained the PK target with MIC ≤ 0.12 mcg/mL. In intra-abdominal infections (IAI), for a target AUC0-24/MIC of 6.96, at least 50% of the patients would be adequately treated against bacteria with MIC ≤ 0.5 mcg/mL. Finally, in skin and soft-tissue infections (SSTI), for a target AUC0-24/MIC of 17.9 only 25% of the patients obtained the PK target at MIC values of 0.5 mcg/mL and less than 10% were adequately treated against germs with MIC value ≥ 1 mcg/mL. HD TGC showed a relevant pulmonary penetration with a median and IQR ELF/plasma ratio (%) of 152.9 [73.5–386.8]. Conclusions The use of HD TGC is associated with satisfactory plasmatic and pulmonary concentrations for the treatment of severe infections due to fully susceptible bacteria (MIC < 0.5 mcg/mL). Even higher dosages and combination strategies may be suggested in presence of difficult to treat pathogens, especially in case of SSTI and IAI.

The glioblastoma (GB) microenvironment includes cells of the innate immune system identified as glioma-associated microglia/macrophages (GAMs) that are still poorly characterized. A potential role on the mechanisms regulating GAM activity might be played by the endoplasmic reticulum protein ERp57/PDIA3 (protein disulfide-isomerase A3), the modulation of which has been reported in a variety of cancers. Moreover, by using The Cancer Genome Atlas database, we found that overexpression of PDIA3 correlated with about 55% reduction of overall survival of glioma patients. Therefore, we analyzed the expression of ERp57/PDIA3 using specimens obtained after surgery from 18 GB patients. Immunohistochemical analysis of tumor samples revealed ERp57/PDIA3 expression in GB cells as well as in GAMs. The ERp57/PDIA3 levels were higher in GAMs than in the microglia present in the surrounding parenchyma. Therefore, we studied the role of PDIA3 modulation in microglia–glioma interaction, based on the ability of conditioned media collected from human GB cells to induce the activation of microglial cells. The results indicated that reduced PDIA3 expression/activity in GB cells significantly limited the microglia pro-tumor polarization towards the M2 phenotype and the production of pro-inflammatory factors. Our data support a role of PDIA3 expression in GB-mediated protumor activation of microglia.

The characterization of human microglia has been hampered by poor availability of human cell sources. However, microglia is involved in the physiopathology of multiple sclerosis, Alzheimer’s disease, Parkinson’s disease, HIV dementia, retinal degenerative diseases, cancer, and many other conditions. Therefore, there is an important need to have experimental paradigms of human microglia characterized and usable to study the role of microglia in the different pathologies in which it is involved. In the present work, we carried out an extensive characterization of Immortalized Human Microglia—SV40 cell line (IMhu), marketed by Applied Biological Material. The functional response of IMhu to a large variety of stimuli was studied. In particular, we investigated morphology, mortality, and changes in the production of different cytokines and chemokines, both under basal conditions and after stimulation. Moreover, western blotting analysis was conducted on phospho-mTOR (Ser 2448) and downstream parameters, p-P70S6K and 4EBP1, in order to understand if IMhu can be used for evaluations of mTOR pathway. In conclusion, IMhu cells proved to be a useful experimental model to investigate the physiopathology of inflammatory disease that involved microglia cells, including pathological conditions that involved the mTOR pathway.

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(1) Background: Colistin-only susceptible (COS) Acinetobacter baumannii (AB) ventilator-associated pneumonia (VAP) represents a clinical challenge in the Intensive Care Unit (ICU) due to the negligible lung diffusion of this molecule and the low-grade evidence on efficacy of its nebulization. (2) Methods: We conducted a prospective observational study on 134 ICU patients with COS-AB VAP to describe the ‘real life’ clinical use of high-dose (5 MIU q8) aerosolized colistin, using a vibrating mesh nebulizer. Lung pharmacokinetics and microbiome features were investigated. (3) Results: Patients were enrolled during the COVID-19 pandemic with the ICU presenting a SAPS II of 42 [32–57]. At VAP diagnosis, the median PaO2/FiO2 was 120 [100–164], 40.3% were in septic shock, and 24.6% had secondary bacteremia. The twenty-eight day mortality was 50.7% with 60.4% and 40.3% rates of clinical cure and microbiological eradication, respectively. We did not observe any drug-related adverse events. Epithelial lining fluid colistin concentrations were far above the CRAB minimal-inhibitory concentration and the duration of nebulized therapy was an independent predictor of microbiological eradication (12 [9.75–14] vs. 7 [4–13] days, OR (95% CI): 1.069 (1.003–1.138), p = 0.039). (4) Conclusions: High-dose and prolonged colistin nebulization, using a vibrating mesh, was a safe adjunctive therapeutic strategy for COS-AB VAP. Its right place and efficacy in this setting warrant investigation in interventional studies.

The anti-vascular endothelial growth factor-A (VEGF-A) monoclonal antibody (mAb) bevacizumab is an FDA-approved monotherapy for the treatment of recurrent glioblastoma (GB), a highly angiogenic and infiltrative tumour. However, bevacizumab does not increase overall survival and blockade of VEGF-A/VEGF receptor (VEGFR)-2 signal transduction is associated with severe adverse effects due to inhibition of physiological angiogenesis. Conversely, VEGFR-1 does not play a relevant role in physiological angiogenesis in the adult. VEGFR-1 is activated by both VEGF-A and placenta growth factor (PlGF), a protein involved in tumour growth and progression. In previous studies, it was demonstrated that inhibition of VEGFR-1 using a specific mAb developed in our laboratories reduced angiogenesis and GB cell chemotaxis and increased the survival of tumour-bearing mice. Failure of treatments directed toward the VEGF-A/VEGFR-2 axis could in part be due to inefficient targeting of the tumour microenvironment. In the present study, VEGFR-1 expression was investigated in GB-associated microglia/macrophages (GAMs) by analysing surgical specimens collected from 42 patients with GB. Data obtained from The Cancer Genome Atlas (TCGA) database revealed that upregulation of the VEGFR-1 ligands VEGF-A and PlGF was associated with a significant reduction in overall survival for patients with GB, highlighting the potential relevance of this receptor in the aggressiveness of GB. Immunohistochemical analysis indicated that VEGFR-1 is expressed not only in GB tissue but also in GAMs. Furthermore, the percentage of VEGFR-1-positive GAMs was significantly higher in the tumour region compared with that noted in the surrounding parenchyma. Thus, VEGFR-1 represents a potential therapeutic target for the treatment of GB, being present not only in GB and endothelial cells, but also in GAMs that are involved in tumour progression.

Previous studies in the rat suggest that microglial cells represent a potential druggable target for nerve growth factor (NGF) in the brain. The painless human Nerve Growth Factor (hNGFp) is a recombinant mutated form of human nerve growth factor (hNGF) that shows identical neurotrophic and neuroprotective properties of wild-type NGF but displays at least 10-fold lower algogenic activity. From the pharmacological point of view, hNGFp is a biased tropomyosin receptor kinase A (TrkA) agonist and displays a significantly lower affinity for the p75 neurotrophin receptor (p75NTR). This study aimed to evaluate the expression of TrkA and p75NTR NGF receptors in two different human microglia cell lines, and to investigate the effects of hNGFp and wild-type NGF (NGF) on L-arginine metabolism, taken as a marker of microglia polarization. Both NGF receptors are expressed in human microglia cell lines and are effective in transducing signals triggered by NGF and hNGFp. The latter and, to a lesser extent, NGF inhibit cytokine-stimulated inducible nitric oxide synthase (iNOS) expression and nitric oxide (NO) production in these cells. Conversely NGF but not hNGFp stimulates arginase-mediated urea production.