Role of Platelets in Inflammation and Cancer: Novel Therapeutic Strategies

Platelets play a central role in inflammation through their direct interaction with other cell types, such as leucocytes and endothelial cells, and by the release of many factors, that is, lipids [such as thromboxane (TX)A₂] and proteins (a wide number of angiogenic and growth factors) stored in α‐granules, and adenosine diphosphate (ADP), stored in dense granules. These platelet actions trigger autocrine and paracrine activation processes that lead to leucocyte recruitment into different tissues and phenotypic changes in stromal cells which contribute to the development of different disease states, such as atherosclerosis and atherothrombosis, intestinal inflammation and cancer. The signals induced by platelets may cause pro‐inflammatory and malignant phenotypes in other cells through the persistent induction of aberrant expression of cyclooxygenase (COX)‐2 and increased generation of prostanoids, mainly prostaglandin (PG)E₂. In addition to cardiovascular disease, enhanced platelet activation has been detected in inflammatory disease and intestinal tumourigenesis. Moreover, the results of clinical studies have shown that the antiplatelet drug aspirin reduces the incidence of vascular events and colorectal cancer. All these pieces of evidence support the notion that colorectal cancer and atherothrombosis may share a common mechanism of disease, that is, platelet activation in response to epithelial (in tumourigenesis) and endothelial (in tumourigenesis and atherothrombosis) injury. Extensive translational medicine research is necessary to obtain a definitive mechanistic demonstration of the platelet‐mediated hypothesis of colon tumourigenesis. The results of these studies will be fundamental to support the clinical decision to recommend the use of low‐dose aspirin, and possibly other antiplatelet agents, in primary prevention, that is, even for individuals at low cardiovascular risk.     

The Decrease of Serum Levels of Human Neutrophil Alpha-Defensins Parallels with the Surgery-Induced Amelioration of NASH in Obesity

Background  

Innate immune system participates actively into inflammatory processes, with immune cells and liver secreting a number of immune peptides. Among them, both soluble CD14 receptor (sCD14) and human neutrophil alpha-defensins (HNDs) may represent serum markers of necro-inflammation in obese patients with non-alcoholic fatty liver disease.     

Inflammatory colonic carcinogenesis: A review on pathogenesis and immunosurveillance mechanisms in ulcerative colitis

Ulcerative colitis(UC)is characterized by repeated flare-ups of inflammation that can lead to oncogenic insults to the colonic epithelial.UC-associated carcinogenesis presents a different sequence of tumorigenic events compared to those that contribute to the development of sporadic colorectal cancer.In fact,in UC,the early events are represented by oxidative DNA damage and DNA methylation that can produce an inhibition of oncosuppressor genes,mutation of p53,aneuploidy,and microsatellite instability.Hypermethylation of tumor suppressor and DNA mismatch repair gene promoter regions is an epigenetic mechanism of gene silencing that contribute to tumorigenesis and may represent the first step in inflammatory carcinogenesis.Moreover,p53 is frequently mutated in the early stages of UC-associated cancer.Aneuploidy is an independentrisk factor for forthcoming carcinogenesis in UC.Epithelial cell-T-cell cross-talk mediated by CD80 is a key factor in controlling the progression from low to high grade dysplasia in UC-associated carcinogenesis.     

Inhibition of oxidative metabolism leads to p53 genetic inactivation and transformation in neural stem cells

Alterations of mitochondrial metabolism and genomic instability have been implicated in tumorigenesis in multiple tissues. High-grade glioma (HGG), one of the most lethal human neoplasms, displays genetic modifications of Krebs cycle components as well as electron transport chain (ETC) alterations. Furthermore, the p53 tumor suppressor, which has emerged as a key regulator of mitochondrial respiration at the expense of glycolysis, is genetically inactivated in a large proportion of HGG cases. Therefore, it is becoming evident that genetic modifications can affect cell metabolism in HGG; however, it is currently unclear whether mitochondrial metabolism alterations could vice versa promote genomic instability as a mechanism for neoplastic transformation. Here, we show that, in neural progenitor/stem cells (NPCs), which can act as HGG cell of origin, inhibition of mitochondrial metabolism leads to p53 genetic inactivation. Impairment of respiration via inhibition of complex I or decreased mitochondrial DNA copy number leads to p53 genetic loss and a glycolytic switch. p53 genetic inactivation in ETC-impaired neural stem cells is caused by increased reactive oxygen species and associated oxidative DNA damage. ETC-impaired cells display a marked growth advantage in the presence or absence of oncogenic RAS, and form undifferentiated tumors when transplanted into the mouse brain. Finally, p53 mutations correlated with alterations in ETC subunit composition and activity in primary glioma-initiating neural stem cells. Together, these findings provide previously unidentified insights into the relationship between mitochondria, genomic stability, and tumor suppressive control, with implications for our understanding of brain cancer pathogenesis.Alterations of mitochondrial metabolism are found in several cancers (1). This can occur through inactivation of components of the tricarboxylic acid (TCA) cycle and electron transport chain (ETC) (1–5). In particular, high-grade gliomas (HGGs) display mutations in the TCA enzymes isocitrate dehydrogenase IDH1 and IDH2 (5). Notably, gliomas also present mutations in mitochondrial DNA (mtDNA) and alterations of the ETC, but whether these are early or late events in cancer pathogenesis remains to be determined (6–14). Finally, p53, which has emerged as an important regulator of mitochondrial metabolism and cellular redox control (15–17), is often found mutated or functionally inactivated in HGG. Its inactivation in neural progenitor/stem cells (NPCs), which act as HGG cells of origin, contributes to gliomagenesis (18–22). In particular, deletion of a significant portion of the p53 DNA binding domain induces the accumulation of cooperative oncogenic events, thus leading to HGG (21). However, it remains to be determined whether p53 metabolic functions contribute to suppression of neoplastic transformation in the nervous system. Although these studies suggest an involvement of altered mitochondria metabolism in brain tumorigenesis, direct evidence of its role as a driver or contributing factor in pathogenesis of HGG and other human cancers is missing. More generally, the role of mitochondrial dysfunction in regulation of tumor suppressive control remains only partially investigated.Here, we studied the effect of oxidative metabolism inhibition in normal NPCs. Our findings show that inhibition of respiration via knockdown (KD) of the complex I subunit NDUFA10 or by reducing mtDNA copy number results in p53 genetic loss, via a mechanism involving generation of reactive oxygen species (ROS) and ROS-mediated oxidative damage. In turn, this causes a glycolytic switch, a marked growth advantage, and tumor formation upon transplantation in the mouse brain. Overall, this study reveals that, in NPCs, the relationship between p53 and mitochondrial metabolism is bidirectional, with p53 being activator of mitochondrial metabolism as well as target for genetic inactivation upon inhibition of respiratory chain activity.     

Evaluation of the “AMR Direct Flow Chip Kit” DNA microarray for detecting antimicrobial resistance genes directly from rectal and nasopharyngeal clinical samples upon ICU admission

IntroductionPrompt detection of antibiotic resistance genes in healthcare institutions is of utmost importance in tackling the spread of multi-drug resistant micro-organisms. We evaluated the Antimicrobial Resistance (AMR) Direct Flow Chip Kit versus phenotypic screening assays for rectal and nasopharyngeal specimens upon ICU admission.MethodsA total of 184 dual specimens (92 rectal and 92 nasopharyngeal swabs) from 92 patients were collected from 11/2017 to 8/2018. All swabs were subjected to both AMR and phenotypic tests according to their origin. The degree of agreement of the two methods was assessed by the kappa coefficient.ResultsThe kappa coefficient showed perfect agreement for MRSA, ESBLs, oxacillinases and vancomycin resistance genes (1.000, p < 0.01) and very good agreement for mecA-positive CoNS, KPC-carbapenemases and metallo-beta-lactamases (0.870, p < 0.01; 0.864, p < 0.01; and 0.912, p < 0.01, respectively).ConclusionThe AMR Direct Flow Chip Kit is a useful alternative to phenotypic testing for rapid detection of resistance markers.     

Hematopoietic stem cell quiescence and function are controlled by the CYLD–TRAF2–p38MAPK pathway

The status of long-term quiescence and dormancy guarantees the integrity of hematopoietic stem cells (HSCs) during adult homeostasis. However the molecular mechanisms regulating HSC dormancy remain poorly understood. Here we show that cylindromatosis (CYLD), a tumor suppressor gene and negative regulator of NF-κB signaling with deubiquitinase activity, is highly expressed in label-retaining dormant HSCs (dHSCs). Moreover, Cre-mediated conditional elimination of the catalytic domain of CYLD induced dHSCs to exit quiescence and abrogated their repopulation and self-renewal potential. This phenotype is dependent on the interactions between CYLD and its substrate TRAF2 (tumor necrosis factor–associated factor 2). HSCs expressing a mutant CYLD with an intact catalytic domain, but unable to bind TRAF2, showed the same HSC phenotype. Unexpectedly, the robust cycling of HSCs lacking functional CYLD–TRAF2 interactions was not elicited by increased NF-κB signaling, but instead by increased activation of the p38MAPK pathway. Pharmacological inhibition of p38MAPK rescued the phenotype of CYLD loss, identifying the CYLD–TRAF2–p38MAPK pathway as a novel important regulator of HSC function restricting HSC cycling and promoting dormancy.Hematopoietic stem cells (HSCs) are defined by their ability to both life-long self-renew and give rise to all mature blood cell lineages. A tight balance between self-renewal and differentiation is crucial to maintain the integrity of the entire hematopoietic tissue, preventing exhaustion of the stem cell pool or development of hematopoietic malignancies such as leukemia. In the healthy murine BM, the highest self-renewal capacity has been attributed to dormant HSCs (dHSCs; Wilson et al., 2008; Foudi et al., 2009; Takizawa et al., 2011). These cells are long-term label retaining and are characterized by a deep long-term quiescent state, as in the absence of stress they divide only five times per lifetime. Although during homeostasis dHSCs constitute a silent stem cell reservoir, during stress situations such as infection or chemotherapy, they enter the cell cycle and start to proliferate, thereby replenishing the hematopoietic system of the cells that have been damaged or lost during injury (Wilson et al., 2008). Despite their important role at the helm of the hematopoietic hierarchy, very limited knowledge is available with respect to the molecular mechanism of the complex function of dHSCs (Trumpp et al., 2010).Ubiquitination is a posttranslational process whereby the highly conserved protein ubiquitin is covalently attached to target proteins through a multistep process involving ubiquitin-activating or -conjugating enzymes and ubiquitin ligases. The ubiquitin coupling to substrate proteins occurs on seven different lysine residues (K6, K11, K27, K29, K33, K48, or K63) and may involve a single ubiquitin molecule or a chain of them (Peng et al., 2003). Among the seven linkage types, K48, K11, and K63 are the most abundant ones. Lys11-linked polyubiquitin chains play important roles in the control of the cell cycle (Bremm and Komander, 2011), whereas lysine-48–linked polyubiquitin chains affect the stability of the substrate proteins, marking them for proteasomal degradation. Lysine-63–linked polyubiquitin chains have signaling functions instead, and they have been implicated in the control of DNA repair (Hofmann and Pickart, 1999), activation of the IκB kinase complex IKK (Deng et al., 2000), the IL-1/Toll-like receptor, and the NF-κB pathways (Chen, 2005; Conze et al., 2008).Ubiquitination is a reversible process and is antagonized by deubiquitinases (DUBs), enzymes hydrolyzing polyubiquitin chains. One the most studied DUBs, both in human patients and in mouse models, is cylindromatosis (CYLD; Bignell et al., 2000). The C-terminal catalytic domain of this protein possesses unique structural features that confer the enzyme specificity for Lys63-linked ubiquitin chains (Komander et al., 2008). This specific DUB activity is strictly linked to a tumor suppressor function. Mutations inactivating the C-terminal deubiquitination domain have been originally identified in patients affected by familial cylindromatosis, an autosomal-dominant disease which predisposes for the development of tumors of skin appendages (Bignell et al., 2000). Recently, the loss of CYLD expression and/or deubiquitination function has been described in multiple human tumors such as melanoma (Massoumi et al., 2006), hepatocellular carcinoma (Pannem et al., 2014), breast (Hutti et al., 2009), and adenoid cystic carcinoma (Stephens et al., 2013).CYLD inhibits tumor development mostly by preventing the activation of the NF-κB pathway. By removing lysine-63–linked polyubiquitin chains from Bcl-3, NF-κB essential modulator (NEMO), and TNF receptor–associated factors (TRAFs) such as TRAF2, CYLD interferes with TNF-induced activation of the classical NF-κB signaling cascade, thereby inhibiting cell proliferation and survival (Brummelkamp et al., 2003; Kovalenko et al., 2003; Trompouki et al., 2003; Massoumi et al., 2006). However, the biological role of CLYD is not limited to its tumor-suppressive function. By negatively regulating NF-κB activation, CYLD limits the inflammatory response during infections, thus minimizing tissue damage (Zhang et al., 2011). Furthermore, in vivo studies demonstrated that CYLD plays multiple roles during immune cell development and homeostasis (Sun, 2008).In this study, we use genetics to demonstrate that HSC dormancy is controlled by the DUB CYLD at the posttranslational level. The conditional inactivation of the CYLD DUB domain abolishes HSC quiescence, dormancy, and repopulation potential. Mechanistically, our data show that the CYLD–TRAF2 interaction is crucial to maintain dHSCs as it precludes p38MAPK activation, down-regulation of dormancy-associated genes, and entry of dHSCs into the cell cycle, ultimately preventing HSC exhaustion.     

Physiopathologic and clinical aspects of Krukenberg tumors

Although described for the first time for more than one hundred years ago, Krukenberg tumors still retain some controversial aspects. The lack of consensus and consistency in using a single definition, the difficulty to admit the existence of a primitive form of the tumor, the lack of knowledge concerning the precise mechanisms of metastases and the absence of a distinctive and characteristic clinical symptoms which often contrasts the usually large dimensions of the tumor are some of the aspects which need further elucidation.