The invasive margin of early-stage human colon tumors is infiltrated with neutrophils of an antitumoral phenotype.

Neutrophils infiltrate several types of cancer; however, whether their presence is associated with disease progression remains controversial. Here, we show that colon tumors overexpress neutrophil chemoattractants compared to healthy tissues, leading to their recruitment to the invasive margin and the central part of colon tumors. Of note, tumor-associated neutrophils expressing tumor necrosis factor α, which usually represents an antitumoral phenotype, were predominantly located in the invasive margin. Tumor-associated neutrophils from the invasive margin displayed an antitumoral phenotype with higher ICAM-1 and CD95 expression than neutrophils from healthy adjacent tissues. A higher neutrophil/lymphocyte ratio was found at later stages compared to the early phases of colon cancer. A neutrophil/lymphocyte ratio ≤3.5 predicted tumor samples had significantly more neutrophils at the invasive margin and the central part. Moreover, tumor-associated neutrophils at the invasive margin of early-stage tumors showed higher ICAM-1 and CD95 expression. Coculture of colon cancer cell lines with primary neutrophils induced ICAM-1 and CD95 expression, confirming our in situ findings. Thus, our data demonstrate that tumor-associated neutrophils with an antitumoral phenotype characterized by high ICAM-1 and CD95 expression infiltrate the invasive margin of early-stage colon tumors, suggesting that these cells can combat the disease at its early courses. The presence of tumor-associated neutrophils with antitumoral phenotype could help predict outcomes of patients with colon cancer.

Fas/FasL Signaling Regulates CD8 Expression During Exposure to Self-Antigens.

Activation of self-reactive CD8+ T cells induces a peripheral tolerance mechanism that involves loss of CD8 expression. Because genetic deficiency of Fas and Fasl causes the accumulation of double-negative (DN; CD3+ TCR-αß+ CD4- CD8-) T cells that have been proposed to derive from CD8+ cells, we decided to explore the role of Fas and FasL in self-antigen-induced CD8 downregulation. To this end, we quantified Fas and FasL induction by different stimuli and analyzed the effects of Fas/FasL deficiency during a protective immune response and after exposure to self-antigens. Our data describes how Fas and FasL upregulation differs depending on the setting of CD8 T cell activation and demonstrates that Fas/FasL signaling maintains CD8 expression during repetitive antigen stimulation and following self-antigen encounter. Together, our results reveal an unexpected role of Fas/FasL signaling and offer a new insight into the role of these molecules in the regulation of immune tolerance.

Coarse Grained Molecular Dynamic Simulations for the Study of TNF Receptor Family Members' Transmembrane Organization.

The Tumor Necrosis Factor (TNF) and the TNF receptor (TNFR) superfamilies are composed of 19 ligands and 30 receptors, respectively. The oligomeric properties of ligands, both membrane bound and soluble, has been studied most. However, less is known about the oligomeric properties of TNFRs. Earlier reports identified the extracellular, membrane-distal, cysteine-rich domain as a pre-ligand assembly domain which stabilizes receptor dimers and/or trimers in the absence of ligand. Nevertheless, recent reports based on structural nuclear magnetic resonance (NMR) highlight the intrinsic role of the transmembrane domains to form dimers (p75NTR), trimers (Fas), or dimers of trimers (DR5). Thus, understanding the structural basis of transmembrane oligomerization may shed light on the mechanism for signal transduction and the impact of disease-associated mutations in this region. To this end, here we used an in silico coarse grained molecular dynamics approach with Martini force field to study TNFR transmembrane homotypic interactions. We have first validated this approach studying the three TNFR described by NMR (p75NTR, Fas, and DR5). We have simulated membrane patches composed of 36 helices of the same receptor equidistantly distributed in order to get unbiassed information on spontaneous proteins assemblies. Good agreement was found in the specific residues involved in homotypic interactions and we were able to observe dimers, trimers, and higher-order oligomers corresponding to those reported in NMR experiments. We have, applied this approach to study the assembly of disease-related mutations being able to assess their impact on oligomerization stability. In conclusion, our results showed the usefulness of coarse grained simulations with Martini force field to study in an unbiased manner higher order transmembrane oligomerization.

Genetic Switches between Cancer and Emphysema Resolution of Cigarette-Smoke Induced Inflammation.

Cigarette smoke initiates an inflammatory response that has aftermath long after quitting. We segregated former smokers, according to their lung function and their co-founding diseases, in 3 groups: Cancer, Emphysema and COPD. Then we searched for outlier genes in intersections of Venn diagrams where we identified 6 subsets and 23 genes that may be responsible for disease outcome. Genes expressed in the cancer patients with or without emphysema (PPA subset) were BHLH, FPRL2, CD49D, DEADH, NRs4A3, MBLL, GNS, BE675435, ISGF-3, and FLJ23462. Patients with emphysema as co-founding disease, with or without cancer (APP), had only ANXA2 in common. Genes expressed only in non-cancer patients (AAP subset) of COPD group were IL-1A, SOX13, RPP38; TBXA2R, NPEPL1, CFLAR, TFEB, PRKCBP1, IGF1R, DDX11, and KCNAB1. HIV-1Rev was the gene expressed in cancer patients with emphysema (APA subset). Then, we also looked at out-layers genes significantly expressed in all patients (PPP subset with 5066 genes), the down-regulated in Emphysema were MMP9, PLUNC, CEACAM5, and NR4A1 while the up-regulated were F2R, COL15A1, PDE4C, and BGN. We chose genes and checked them at the protein level on immune cells, this showed that neutrophils from Cancer group had increased expression of CD49d, and their total number was also increased in bronchial-alveolar lavage (154%). Macrophages in the lung of patients with emphysema were associated with a significant increase of adhesion molecule CD58 and to significant CD95 decrease, indicating they do not die. Besides, macrophages downregulated MMP9 in the lung compared to blood macrophages. Overall, we find that cancer progression requires a stickier and greater number of neutrophils in the lung while emphysema requires stickier and longevous macrophages to lead matrix destruction, and together with higher expression of SOX13 and RPP38, may promote autoimmunity. We also identified two genes, ANXA2 and HIV1-rev, that may be a pivot between cancer and emphysema outcome of inflammation.

Early activation of CD95 is limited and localized to the cytotoxic synapse.

The cytotoxic synapse formed between cytotoxic T lymphocytes or natural killer cells expressing CD95L and target cells with CD95 on their surface is a key pathway for apoptosis induction by the immune system. Despite similarities with the immune synapse in antigen presenting cells, little is known about the role of the spatiotemporal organization of agonistic proteins/receptor interactions for CD95 signaling. Here, we have developed an artificial cytotoxic synapse to examine how mobility and geometry of an anti-CD95 agonistic antibody affect receptor aggregation and mobility, ie the first step of receptor activation. By measuring the distribution, diffusion coefficient, and fraction of immobile CD95 receptor in living cells, we show that at short times, the initial activation of CD95 occurs locally and is limited to the contact region of the cytotoxic synapse. This anisotropic activation of apoptotic signaling supports a role for confined interactions on the efficiency of signal transduction that may have implications for biomedical applications of extrinsic apoptosis induction.

The FAS-670 AA genotype is associated with high proviral load in peruvian HAM/TSP patients.

Human T-lymphotropic virus 1 (HTLV-1) is the etiologic agent of the HTLV-1-associated myelopathy/tropical spastic paraparesis (HAM/TSP). Apoptosis is a mechanism of defense elicited by many triggers, including cross-linking of the FAS receptor expressed in viruses-infected cells, and the ligand FASL presented by T-cytotoxic cells. As HAM/TSP has been associated with high levels of proviral load (PVL), we hypothesized that certain genotypes of single-nucleotide polymorphisms (SNPs) associated with a decreased protein expression of FAS and FASL could be risk factors for this disease. Three SNPs: FAS-670A/G (rs1800682), FAS-1377G/A (rs2234767), and FASL-844C/T (rs763110) were analyzed in 73 HAM/TSP patients and 143 HTLV-1 asymptomatic carriers. Ancestry informative markers were used to adjust for ethnicity through a principal component analysis. Gender, age, PVL, and the first three principal components were used as covariates. The FAS/FASL genotype distribution was not associated with HAM/TSP presence (P-> 0.05). The FAS-670 AA genotype was associated with high PVL in comparison to FAS-670 GG in HAM/TSP patients (P = 0.015), while in asymptomatic carriers low levels of PVL were observed (P > 0.05). Our findings suggest that rs1800682, rs2234767, and rs763110 genotypes are not associated with the presence of HAM/TSP, but that the FAS-670 AA genotype can promote higher PVL values in HAM/TSP patients. J. Med. Virol. 89:726-731, 2017. © 2016 Wiley Periodicals, Inc.

P2X7 receptor-induced death of motor neurons by a peroxynitrite/FAS-dependent pathway.

The P2X7 receptor/channel responds to extracellular ATP and is associated with neuronal death and neuroinflammation in spinal cord injury and amyotrophic lateral sclerosis. Whether activation of P2X7 directly causes motor neuron death is unknown. We found that cultured motor neurons isolated from embryonic rat spinal cord express P2X7 and underwent caspase-dependent apoptosis when exposed to exceptionally low concentrations of the P2X7 agonist 2'(3')-O-(4-Benzoylbenzoyl)-ATP. The P2X7 inhibitors BBG, oATP, and KN-62 prevented 2'(3')-O-(4-Benzoylbenzoyl)-ATP-induced motor neuron death. The endogenous P2X7 agonist ATP induced motor neuron death at low concentrations (1-100 µM). High concentrations of ATP (1 mM) paradoxically became protective due to degradation in the culture media to produce adenosine and activate adenosine receptors. P2X7-induced motor neuron death was dependent on neuronal nitric oxide synthase-mediated production of peroxynitrite, p38 activation, and autocrine FAS signaling. Taken together, our results indicate that motor neurons are highly sensitive to P2X7 activation, which triggers apoptosis by activation of the well-established peroxynitrite/FAS death pathway in motor neurons.

Expression of death cellular receptors FAS/CD95 and DR4 during porcine placentation / Expresión de los receptores de muerte celular FAS/CD95 y DR4 durante la placentación porcina

Apoptosis is a permanent and dynamic physiological process by which an organism eliminates the undesirable cells without causing an inflammatory response. The objective of this work was to study the expression of FAS, DR4 and other members of the TNF-R1 superfamily extrinsic route apoptotic receptors the DNA fragmentation and the cellular apoptosis in placental samples at the early, mid and late pregnancy on +/- 30, +/- 55 and +/- 114 gestational days, respectively. We used placental histological sections of samples fixed in buffered saline formaldehyde. Immunohistochemical techniques were performed to detect the apoptotic receptors, whereas the DNA fragmentation was detected by TUNEL reaction and apoptotic cellular ultrastructure was detected by TEM conventional techniques. Apoptosis related receptors were immunolocalized in the early pig gestation and correlated with apoptosis, suggesting a role in the cellular remodelling of the placenta. At gestation day 55, apoptosis might be correlated to FAS route, but not by DR4-mediating pathway. At the end of gestation, increased apoptosis and both receptors markers were detected showing cellular death due to the extrinsic route through FAS and DR4 receptors. In conclusion, the immunolocalization of FAS and TNF R-1 receptors along the pig placental development correlates with TUNEL reaction and with apoptotic ultrastructure observed by TEM and seems to occur through different pathways along gestation.

La apoptosis es un proceso fisiológico, dinámico y permanente a través del cual un organismo elimina células indeseables sin provocar una respuesta inflamatoria. El objetivo del presente trabajo fue estudiar la expresión de los receptores de la vía extrínseca de apoptosis, FAS, DR4 y otros miembros de la superfamilia TNF-R1, la fragmentación del ADN y la apoptosis celular a través de TEM, en muestras placentarias del inicio, la mitad y el final de la gestación, hacia el día +/- 30, +/- 55 y +/- 114 de preñez, respectivamente. Se realizaron cortes histológicos de las muestras placentarias fijadas en formol tamponado. Para la detección de los receptores de apoptosis se realizaron técnicas inmunohistoquímicas, para el estudio de la fragmentación del ADN se utilizó el ensayo TUNEL y para el análisis de la ultraestructura celular apoptótica la técnica convencional de TEM. La inmunolocalización de los receptores de muerte celular al inicio de la preñez porcina sugiere el rol de la apoptosis en la remodelación celular placentaria. Hacia el día 55 de preñez, la apoptosis detectada ocurriría únicamente a través de la vía del receptor FAS, no del receptor DR4. Al final de la gestación, se detectó un incremento de la apoptosis y la expresión de ambos receptores, indicando que la muerte celular a través de la vía de señalización extrínseca estaría inducida por los receptores FAS y DR4. En conclusión, la inmunolocalización de los receptores FAS y otros miembros del TNF-R1, los resultados de TUNEL y la ultraestructura celular apoptótica observada en la placentación porcina, indican que la apoptosis detectada ocurre por diferentes vías de inducción a lo largo de la gestación.