Immune Landscape in Tumor Microenvironment: Implications for Biomarker Development and Immunotherapy.

Integration of the tumor microenvironment as a fundamental part of the tumorigenic process has undoubtedly revolutionized our understanding of cancer biology. Increasing evidence indicates that neoplastic cells establish a dependency relationship with normal resident cells in the affected tissue and, furthermore, develop the ability to recruit new accessory cells that aid tumor development. In addition to normal stromal and tumor cells, this tumor ecosystem includes an infiltrated immune component that establishes complex interactions that have a critical effect during the natural history of the tumor. The process by which immune cells modulate tumor progression is known as immunoediting, a dynamic process that creates a selective pressure that finally leads to the generation of immune-resistant cells and the inability of the immune system to eradicate the tumor. In this context, the cellular and functional characterization of the immune compartment within the tumor microenvironment will help to understand tumor progression and, ultimately, will serve to create novel prognostic tools and improve patient stratification for cancer treatment. Here we review the impact of the immune system on tumor development, focusing particularly on its clinical implications and the current technologies used to analyze immune cell diversity within the tumor.

Confirmation of sub-cellular resolution using oversampling imaging mass spectrometry.

The use of oversampling in MALDI (matrix-assisted laser desorption/ionization) imaging mass spectrometry (IMS) to improve lateral resolution is a common practice. However, its application is still controversial and recent studies reported a spot size-dependent change in the relative intensity of the spectra. Previously, using oversampling, we described the lipidome of the human colon epithelium, a 20-30 µm wide cell monolayer; even assessing the changes occurring within this monolayer associated with complex biological processes. Interestingly, the K-means analysis of those experiments unveiled the presence of a third epithelial cluster that anatomically matched the nuclei position. Taking into account the nucleus size (9-12 µm of diameter) and its distinctive lipidome, we decided to test whether this cluster was really of nuclear origin. Hence, the spectra obtained directly from tissue sections were compared with those recorded from the nuclei isolated from colon biopsies. The highest correlation coefficient was obtained when comparing the spectrum of the isolated nuclei with that of the tissue nuclear cluster, demonstrating the successful identification of the nuclear lipidome in the MALDI-IMS experiments run using oversampling and a lateral resolution of 10 µm/pixel. Importantly, it was established that phosphatidylinositol 38:4 nuclear levels remained stable along the colon crypt. That is, it mimicked neither the regular decrease observed in the epithelium nor the regular increase observed in the stroma, eliminating the chance of inter-pixel contamination. Altogether, besides confirming the usefulness of the oversampling technique, these results strongly reinforce the pivotal role IMS may have in promising fields such as single-cell analysis. Graphical abstract.

Tissue-selective alteration of ethanolamine plasmalogen metabolism in dedifferentiated colon mucosa.

Human colon lipid analysis by imaging mass spectrometry (IMS) demonstrates that the lipid fingerprint is highly sensitive to a cell's pathophysiological state. Along the colon crypt axis, and concomitant to the differentiation process, certain lipid species tightly linked to signaling (phosphatidylinositols and arachidonic acid (AA)-containing diacylglycerophospholipids), change following a rather simple mathematical expression. We extend here our observations to ethanolamine plasmalogens (PlsEtn), a unique type of glycerophospholipid presenting a vinyl ether linkage at sn-1 position. PlsEtn distribution was studied in healthy, adenomatous, and carcinomatous colon mucosa sections by IMS. In epithelium, 75% of PlsEtn changed in a highly regular manner along the crypt axis, in clear contrast with diacyl species (67% of which remained constant). Consistently, AA-containing PlsEtn species were more abundant at the base, where stem cells reside, and decreased while ascending the crypt. In turn, mono-/diunsaturated species experienced the opposite change. These gradients were accompanied by a gradual expression of ether lipid synthesis enzymes. In lamina propria, 90% of stromal PlsEtn remained unchanged despite the high content of AA and the gradient in AA-containing diacylglycerophospholipids. Finally, both lipid and protein gradients were severely affected in polyps and carcinoma. These results link PlsEtn species regulation to cell differentiation for the first time and confirm that diacyl and ether species are differently regulated. Furthermore, they reaffirm the observations on cell lipid fingerprint image sensitivity to predict cell pathophysiological status, reinforcing the translational impact both lipidome and IMS might have in clinical research.

First-Ever Stroke and Transient Ischemic Attack Incidence and 30-Day Case-Fatality Rates in a Population-Based Study in Argentina.

BACKGROUND AND PURPOSE: Epidemiological data about stroke are scarce in low- and middle-income Latin-American countries. We investigated annual incidence of first-ever stroke and transient ischemic attack (TIA) and 30-day case-fatality rates in a population-based setting in Tandil, Argentina. METHODS: We prospectively identified all first-ever stroke and TIA cases from overlapping sources between January 5, 2013, and April 30, 2015, in Tandil, Argentina. We calculated crude and standardized incidence rates. We estimated 30-day case-fatality rates. RESULTS: We identified 334 first-ever strokes and 108 TIAs. Age-standardized incidence rate per 100 000 for Segi's World population was 76.5 (95% confidence interval [CI], 67.8-85.9) for first-ever stroke and 25.1 (95% CI, 20.2-30.7) for first-ever TIA, 56.1 (95% CI, 48.8-64.2) for ischemic stroke, 13.5 (95% CI, 9.9-17.9) for intracerebral hemorrhage, and 4.9 (95% CI, 2.7-8.1) for subarachnoid hemorrhage. Stroke incidence was slightly higher for men (87.8; 95% CI, 74.6-102.6) than for women (73.2; 95% CI, 61.7-86.1) when standardized for the Argentinean population. Thirty-day case-fatality rate was 14.7% (95% CI, 10.8-19.5) for ischemic stroke, 24.1% (95% CI, 14.2-36.6) for intracerebral hemorrhage, and 1.9% (95% CI, 0.4-5.8) for TIA. CONCLUSIONS: This study provides the first prospective population-based stroke and TIA incidence and case-fatality estimate in Argentina. First-ever stroke incidence was lower than that reported in previous Latin-American studies, but first-ever TIA incidence was higher. Thirty-day case-fatality rates were similar to those of other population-based Latin-American studies.

Optimized Protocol To Analyze Changes in the Lipidome of Xenografts after Treatment with 2-Hydroxyoleic Acid.

Xenografts are a popular model for the study of the action of new antitumor drugs. However, xenografts are highly heterogeneous structures, and therefore it is sometimes difficult to evaluate the effects of the compounds on tumor metabolism. In this context, imaging mass spectrometry (IMS) may yield the required information, due to its inherent characteristics of sensitivity and spatial resolution. To the best of our knowledge, there is still no clear analysis protocol to properly evaluate the changes between samples due to the treatment. Here we present a protocol for the evaluation of the effect of 2-hydroxyoleic acid (2-OHOA), an antitumor compound, on xenografts lipidome based on IMS. Direct treated/control comparison did not show conclusive results. As we will demonstrate, a more sophisticated protocol was required to evaluate these changes including the following: (1) identification of different areas in the xenograft, (2) classification of these areas (necrotic/viable) to compare similar types of tissues, (3) suppression of the effect of the variation of adduct formation between samples, and (4) normalization of the variables using the standard deviation to eliminate the excessive impact of the stronger peaks in the statistical analysis. In this way, the 36 lipid species that experienced the largest changes between treated and control were identified. Furthermore, incorporation of 2-hydroxyoleic acid to a sphinganine base was also confirmed by MS/MS. Comparison of the changes observed here with previous results obtained with different techniques demonstrates the validity of the protocol.

Imaging mass spectrometry increased resolution using 2-mercaptobenzothiazole and 2,5-diaminonaphtalene matrices: application to lipid distribution in human colon.

Imaging mass spectrometry is becoming a reference technique in the field of lipidomics, due to its ability to map the distribution of hundreds of species in a single run, along a tissue section. The next frontier is now achieving increasing resolution powers to offer cellular (or even sub-cellular) resolution. Thus, the new spectrometers are equipped with sophisticated optical systems to decrease the laser spot to <30 µm. Here, we demonstrate that by using the correct matrix (i.e., a matrix that maximizes ion detection and forms small crystals) and a careful preparation, it is possible to achieve resolutions of ∼5-10 µm, even with spectrometers equipped with non-optimal optics, which produces laser spots of 50 µm or even larger. As a proof of concept, we present images of distributions of lipids, both in positive and negative ion mode, over human colon endoscopic sections, recorded using 2-mercaptobenzothiazole for positive ion mode and 2,5-diaminonaphtalene for negative ion mode and an LTQ-Orbitrap XL, equipped with a matrix-assisted laser desorption ionization (MALDI) source that produces astigmatic laser spots. Graphical Abstract Imaging mass spectrometry is becoming an invaluable technique to complement traditional histology, but still higher resolutions are required. Here we deal with such issue.

Sustained activation of sphingomyelin synthase by 2-hydroxyoleic acid induces sphingolipidosis in tumor cells.

The mechanism of action of 2-hydroxyoleic acid (2OHOA), a potent antitumor drug, involves the rapid and specific activation of sphingomyelin synthase (SMS), leading to a 4-fold increase in SM mass in tumor cells. In the present study, we investigated the source of the ceramides required to sustain this dramatic increase in SM. Through radioactive and fluorescent labeling, we demonstrated that sphingolipid metabolism was altered by a 24 h exposure to 2OHOA, and we observed a consistent increase in the number of lysosomes and the presence of unidentified storage materials in treated cells. Mass spectroscopy revealed that different sphingolipid classes accumulated in human glioma U118 cells after exposure to 2OHOA, demonstrating a specific effect on C16-, C20-, and C22-containing sphingolipids. Based on these findings, we propose that the demand for ceramides required to sustain the SMS activation (ca. 200-fold higher than the basal level) profoundly modifies both sphingolipid and phospholipid metabolism. As the treatment is prolonged, tumor cells fail to adequately metabolize sphingolipids, leading to a situation resembling sphingolipidosis, whereby cell viability is compromised.

A Drastic Shift in Lipid Adducts in Colon Cancer Detected by MALDI-IMS Exposes Alterations in Specific K+ Channels.

Even though colorectal cancer (CRC) is one of the most preventable cancers, it is one of the deadliest, and recent data show that the incidence in people <50 years has unexpectedly increased. While new techniques for CRC molecular classification are emerging, no molecular feature is as yet firmly associated with prognosis. Imaging mass spectrometry (IMS) lipidomic analyses have demonstrated the specificity of the lipid fingerprint in differentiating pathological from healthy tissues. During IMS lipidomic analysis, the formation of ionic adducts is common. Of particular interest is the [Na+]/[K+] adduct ratio, which already functions as a biomarker for homeostatic alterations. Herein, we show a drastic shift of the [Na+]/[K+] adduct ratio in adenomatous colon mucosa compared to healthy mucosa, suggesting a robust increase in K+ levels. Interrogating public databases, a strong association was found between poor diagnosis and voltage-gated potassium channel subunit beta-2 (KCNAB2) overexpression. We found this overexpression in three CRC molecular subtypes defined by the CRC Subtyping Consortium, making KCNAB2 an interesting pharmacological target. Consistently, its pharmacological inhibition resulted in a dramatic halt in commercial CRC cell proliferation. Identification of potential pharmacologic targets using lipid adduct information emphasizes the great potential of IMS lipidomic techniques in the clinical field.

Common and Differential Traits of the Membrane Lipidome of Colon Cancer Cell Lines and their Secreted Vesicles: Impact on Studies Using Cell Lines.

Colorectal cancer (CRC) is the fourth leading cause of cancer death in the world. Despite the screening programs, its incidence in the population below the 50s is increasing. Therefore, new stratification protocols based on multiparametric approaches are highly needed. In this scenario, the lipidome is emerging as a powerful tool to classify tumors, including CRC, wherein it has proven to be highly sensitive to cell malignization. Hence, the possibility to describe the lipidome at the level of lipid species has renewed the interest to investigate the role of specific lipid species in pathologic mechanisms, being commercial cell lines, a model still heavily used for this purpose. Herein, we characterize the membrane lipidome of five commercial colon cell lines and their extracellular vesicles (EVs). The results demonstrate that both cell and EVs lipidome was able to segregate cells according to their malignancy. Furthermore, all CRC lines shared a specific and strikingly homogenous impact on ether lipid species. Finally, this study also cautions about the need of being aware of the singularities of each cell line at the level of lipid species. Altogether, this study firmly lays the groundwork of using the lipidome as a solid source of tumor biomarkers.

Ins and Outs of Interpreting Lipidomic Results.

Membrane lipids are essential for life; however, research on how cells regulate cell lipid composition has been falling behind for quite some time. One reason was the difficulty in establishing analytical methods able to cope with the cell lipid repertoire. Development of a diversity of mass spectrometry-based technologies, including imaging mass spectrometry, has helped to demonstrate beyond doubt that the cell lipidome is not only greatly cell type dependent but also highly sensitive to any pathophysiological alteration such as differentiation or tumorigenesis. Interestingly, the current popularization of metabolomic studies among numerous disciplines has led many researchers to rediscover lipids. Hence, it is important to underscore the peculiarities of these metabolites and their metabolism, which are both radically different from protein and nucleic acid metabolism. Once differences in lipid composition have been established, researchers face a rather complex scenario, to investigate the signaling pathways and molecular mechanisms accounting for their results. Thus, a detail often overlooked, but of crucial relevance, is the complex networks of enzymes involved in controlling the level of each one of the lipid species present in the cell. In most cases, these enzymes are redundant and promiscuous, complicating any study on lipid metabolism, since the modification of one particular lipid enzyme impacts simultaneously on many species. Altogether, this review aims to describe the difficulties in delving into the regulatory mechanisms tailoring the lipidome at the activity, genetic, and epigenetic level, while conveying the numerous, stimulating, and sometimes unexpected research opportunities afforded by this type of studies.

Identification of Biomarkers of Necrosis in Xenografts Using Imaging Mass Spectrometry.

Xenografts are commonly used to test the effect of new drugs on human cancer. However, because of their heterogeneity, analysis of the results is often controversial. Part of the problem originates in the existence of tumor cells at different metabolic stages: from metastatic to necrotic cells, as it happens in real tumors. Imaging mass spectrometry is an excellent solution for the analysis of the results as it yields detailed information not only on the composition of the tissue but also on the distribution of the biomolecules within the tissue. Here, we use imaging mass spectrometry to determine the distribution of phosphatidylcholine (PC), phosphatidylethanolamine (PE), and their plasmanyl- and plasmenylether derivatives (PC-P/O and PE-P/O) in xenografts of five different tumor cell lines: A-549, NCI-H1975, BX-PC3, HT29, and U-87 MG. The results demonstrate that the necrotic areas showed a higher abundance of Na(+) adducts and of PC-P/O species, whereas a large abundance of PE-P/O species was found in all the xenografts. Thus, the PC/PC-ether and Na(+)/K(+) ratios may highlight the necrotic areas while an increase on the number of PE-ether species may be pointing to the existence of viable tumor tissues. Furthermore, the existence of important changes in the concentration of Na(+) and K(+) adducts between different tissues has to be taken into account while interpreting the imaging mass spectrometry results. Graphical Abstract ᅟ.

Analysis of the lipidome of xenografts using MALDI-IMS and UHPLC-ESI-QTOF.

Human tumor xenografts in immunodeficient mice are a very popular model to study the development of cancer and to test new drug candidates. Among the parameters analyzed are the variations in the lipid composition, as they are good indicators of changes in the cellular metabolism. Here, we present a study on the distribution of lipids in xenografts of NCI-H1975 human lung cancer cells, using MALDI imaging mass spectrometry and UHPLC-ESI-QTOF. The identification of lipids directly from the tissue by MALDI was aided by the comparison with identification using ESI ionization in lipid extracts from the same xenografts. Lipids belonging to PCs, PIs, SMs, DAG, TAG, PS, PA, and PG classes were identified and their distribution over the xenograft was determined. Three areas were identified in the xenograft, corresponding to cells in different metabolic stages and to a layer of adipose tissue that covers the xenograft.

2-hydroxy arachidonic acid: a new non-steroidal anti-inflammatory drug.

BACKGROUND: Nonsteroidal anti-inflammatory drugs (NSAIDs) are a family of COX1 and COX2 inhibitors used to reduce the synthesis of pro-inflammatory mediators. In addition, inflammation often leads to a harmful generation of nitric oxide. Efforts are being done in discovering safer NSAIDs molecules capable of inhibiting the synthesis of pro-inflammatory lipid mediators and nitric oxide to reduce the side effects associated with long term therapies. METHODOLOGY/PRINCIPAL FINDINGS: The analogue of arachidonic acid (AA), 2-hydroxy-arachidonic acid (2OAA), was designed to inhibit the activities of COX1 and COX2 and it was predicted to have similar binding energies as AA for the catalytic sites of COX1 and COX2. The interaction of AA and 2OAA with COX1 and COX2 was investigated calculating the free energy of binding and the Fukui function. Toxicity was determined in mouse microglial BV-2 cells. COX1 and COX2 (PGH2 production) activities were measured in vitro. COX1 and COX2 expression in human macrophage-like U937 cells were carried out by Western blot, immunocytochemistry and RT-PCR analysis. NO production (Griess method) and iNOS (Western blot) were determined in mouse microglial BV-2 cells. The comparative efficacy of 2OAA, ibuprofen and cortisone in lowering TNF-α serum levels was determined in C57BL6/J mice challenged with LPS. We show that the presence of the -OH group reduces the likelihood of 2OAA being subjected to H* abstraction in COX, without altering significantly the free energy of binding. The 2OAA inhibited COX1 and COX2 activities and the expression of COX2 in human U937 derived macrophages challenged with LPS. In addition, 2OAA inhibited iNOS expression and the production of NO in BV-2 microglial cells. Finally, oral administration of 2OAA decreased the plasma TNF-α levels in vivo. CONCLUSION/SIGNIFICANCE: These findings demonstrate the potential of 2OAA as a NSAID.

Program for the epidemiological evaluation of stroke in Tandil, Argentina (PREVISTA) study: rationale and design.

The availability of population-based epidemiological data on the incident risk of stroke is very scarce in Argentina and other Latin American countries. In response to the priorities established by the World Health Organization and the United Nations, PREVISTA was envisaged as a population-based program to determine the risk of first-ever and recurrent stroke and transient ischemic attack incidence and mortality in Tandil, Buenos Aires, Argentina. The study will be conducted according to Standardized Tools for Stroke Surveillance (STEPS Stroke) methodology and will enroll all new (incident) and recurrent consecutive cases of stroke and transient ischemic attack in the City of Tandil between May 1st, 2013 and April 30, 2015. The study will include patients with ischemic stroke, non-traumatic primary intracerebral hemorrhage, subarachnoid hemorrhage, and transient ischemic attack. To ensure the inclusion of every cerebrovascular event during an observation period of two years, we will instrument an 'intensive screening program', consisting of a comprehensive daily tracking of every potential event of stroke or transient ischemic attack using multiple overlapping sources. Mortality would be determined during follow-up for every enrolled patient. Also, fatal community events would be screened daily through revision of death certificates at funeral homes and local offices of vital statistics. All causes of death will be adjudicated by an ad-hoc committee. The close population of Tandil is representative of a large proportion of Latin-American countries with low- and middle-income economies. The findings and conclusions of PREVISTA may provide data that could support future health policy decision-making in the region.

Incidencia de fisuras labiopalatinas en recién nacidos y su manejo inicial / Initial treatment of cleft lips and palate in newborn

Las fisuras labiopalatinas son defectos anatomofuncionales que disminuyen las posibilidades de vida del recién nacido que las padece. Son una de las malformaciones congénitas más frecuentes en los seres humanos.Los niños que presentan estas anomalías necesitan mucha asistencia médica interdisciplinaria durante sus primeros años.De acuerdo al total de nacimientos vivos en el Hospital Central Militar, del 1§ de diciembre de 1997 al 31 de diciembre de 1998, que fue de 5,188, se presentaron 11 casos con algún tipo de fisura labiopalatina, siendo su incidencia entonces de 1:472.Nueve afectaron al sexo masculino y dos el femenino. El labio y paladar fisurado en cualquiera de sus variantes, se presentó con mayor frecuencia (7 casos). Predominó la fisura unilateral izquierda completa o incompleta (9 casos). Ocho fueron embarazos deseados y tres no deseados.La mayoría de casos se manejaron con obturador palatino de acrílico, para mejorar su alimentación principalmente y 5 de éstos, se manejaron además, con reposicionador elástico de premaxila o ®bigotera¼ (gorro de tela y resorte elástico) como tratamiento prequirúrgico.