Adriana Sumoza-Toledo

Chemotaxis of Mouse Bone Marrow Neutrophils and Dendritic Cells Is Controlled by ADP-Ribose, the Major Product Generated by the CD38 Enzyme Reaction

The ectoenzyme CD38 catalyzes the production of cyclic ADP-ribose (cADPR) and ADP-ribose (ADPR) from its substrate, NAD+. Both products of the CD38 enzyme reaction play important roles in signal transduction, as cADPR regulates calcium release from intracellular stores and ADPR controls cation entry through the plasma membrane channel TRPM2. We previously demonstrated that CD38 and the cADPR generated by CD38 regulate calcium signaling in leukocytes stimulated with some, but not all, chemokines and controls leukocyte migration to inflammatory sites. However, it is not known whether the other CD38 product, ADPR, also regulates leukocyte trafficking In this study we characterize 8-bromo (8Br)-ADPR, a novel compound that specifically inhibits ADPR-activated cation influx without affecting other key calcium release and entry pathways. Using 8Br-ADPR, we demonstrate that ADPR controls calcium influx and chemotaxis in mouse neutrophils and dendritic cells activated through chemokine receptors that rely on CD38 and cADPR for activity, including mouse FPR1, CXCR4, and CCR7. Furthermore, we show that the calcium and chemotactic responses of leukocytes are not dependent on poly-ADP-ribose polymerase 1 (PARP-1), another potential source of ADPR in some leukocytes. Finally, we demonstrate that NAD+ analogues specifically block calcium influx and migration of chemokine-stimulated neutrophils without affecting PARP-1-dependent calcium responses. Collectively, these data identify ADPR as a new and important second messenger of mouse neutrophil and dendritic cell migration, suggest that CD38, rather than PARP-1, may be an important source of ADPR in these cells, and indicate that inhibitors of ADPR-gated calcium entry, such as 8Br-ADPR, have the potential to be used as anti-inflammatory agents.

Dendritic cell maturation and chemotaxis is regulated by TRPM2-mediated lysosomal Ca2+ release

Chemokines induce calcium (Ca2+) signaling and chemotaxis in dendritic cells (DCs), but the molecular players involved in shaping intracellular Ca2+ changes remain to be characterized. Using siRNA and knockout mice, we show that in addition to inositol 1,4,5‐trisphosphate (IP3)‐mediated Ca2+ release and store‐operated Ca2+ entry (SOCE), the transient receptor potential melastatin 2 (TRPM2) channel contributes to Ca2+ release but not Ca2+ influx in mouse DCs. Consistent with these findings, TRPM2 expression in DCs is restricted to endolysosomal vesicles, whereas in neutrophils, the channel localizes to the plasma membrane. TRPM2‐deficient DCs show impaired maturation and severely compromised chemokine‐activated directional migration as well as bacterial‐induced DC trafficking to the draining lymph nodes. Defective DC chemotaxis is due to perturbed chemokine‐receptor‐initiated Ca2+ signaling mechanisms, which include suppression of TRPM2‐mediated Ca2+ release and secondary modification of SOCE. DCs deficient in both TRPM2 and IP3 receptor signaling lose their ability to perform chemotaxis entirely. These results highlight TRPM2 as a key player regulating DC chemotaxis through its function as Ca2+ release channel and confirm ADP‐ribose as a novel second messenger for intracellular Ca2+ mobilization.—Sumoza‐Toledo, A., Lange, I., Cortado, H., Bhagat, H., Mori, Y., Fleig, A., Penner, R., Partida‐Sánchez, S. Dendritic cell maturation and chemotaxis is regulated by TRPM2‐mediated lysosomal Ca2+ release. FASEB J. 25, 3529–3542 (2011). www.fasebj.org

The spreading of B lymphocytes induced by CD44 cross‐linking requires actin, tubulin, and vimentin rearrangements

CD44 is a polymorphic family of adhesion molecules widely distributed on cells and tissues. CD44 is up‐regulated on activated lymphocytes, and it can function as a receptor, mediating rolling and migration. Although it has been demonstrated that anti‐CD44 antibodies bound to tissue‐culture plates induce multidirectional emission of retractile dendrites (“spreading”) in activated murine B lymphocytes, the involvement of cytoskeleton elements in this phenomenon is largely unknown. In this work, it is shown that the generation of dendrites induced by CD44 cross‐linking in activated B cells depends on actin, microtubules, and vimentin reorganization. Immunofluorescence analysis showed that dendrite formation began with actin polymerization, and its extension was favored by microtubules and intermediate filaments of vimentin oriented to the polymerized actin. Pretreatment of activated B lymphocytes with cytochalasin E inhibited the dendrites formation; moreoer, when cells were treated with this drug at different time points during the dendrite formation process, the stability of the dendrites was affected. In contrast, although the treatment with colchicine and nocodazole (tubulin polymerization inhibitors) inhibited the dendrites formation, it did not inhibit the initial phase of actin polymerization. According to these results, B cell spreading and dendrite formation induced by anti‐CD44 antibodies require coordinated rearrangements of actin, microtubules, and vimentin, being the actin cytoskeleton, the most important element that confers stability and drives the morphological changes during B cell spreading, conceivably preparing B lymphocytes for locomotion.

Meeting report from the 2nd International Symposium on New Frontiers in Cardiovascular Research. Protecting the cardiovascular system from ischemia: between bench and bedside

Recent advances in basic cardiovascular research as well as their translation into the clinical situation were the focus at the last “New Frontiers in Cardiovascular Research meeting”. Major topics included the characterization of new targets and procedures in cardioprotection, deciphering new players and inflammatory mechanisms in ischemic heart disease as well as uncovering microRNAs and other biomarkers as versatile and possibly causal factors in cardiovascular pathogenesis. Although a number of pathological situations such as ischemia–reperfusion injury or atherosclerosis can be simulated and manipulated in diverse animal models, also to challenge new drugs for intervention, patient studies are the ultimate litmus test to obtain unequivocal information about the validity of biomedical concepts and their application in the clinics. Thus, the open and bidirectional exchange between bench and bedside is crucial to advance the field of ischemic heart disease with a particular emphasis of understanding long-lasting approaches in cardioprotection.

TRPM7 kinase activity regulates murine mast cell degranulation

The Mg2+ and Ca2+ conducting transient receptor potential melastatin 7 (TRPM7) channel–enzyme (chanzyme) has been implicated in immune cell function. Mice heterozygous for a TRPM7 kinase deletion are hyperallergic, while mice with a single point mutation at amino acid 1648, silencing kinase activity, are not. As mast cell mediators trigger allergic reactions, we here determine the function of TRPM7 in mast cell degranulation and histamine release. Our data establish that TRPM7 kinase activity regulates mast cell degranulation and release of histamine independently of TRPM7 channel function. Our findings suggest a regulatory role of TRPM7 kinase activity on intracellular Ca2+ and extracellular Mg2+ sensitivity of mast cell degranulation.

TRPM2 channels are not required for acute airway inflammation in OVA-induced severe allergic asthma in mice

BackgroundAirway inflammation and asthma have been linked to oxidative stress and the melastatin-related transient receptor potential cation channel, member 2 (TRPM2), which can be activated by reactive oxygen species (ROS), has emerged as a potential therapeutic target for inflammatory diseases.ObjectiveUsing TRPM2 deficient (TRPM2-/-) mice, we investigated whether the TRPM2 ion channel, which mediates calcium (Ca2+) influx and lysosomal Ca2+ release, plays a role in the pathophysiology of severe allergic asthma in mouse.MethodsSevere allergic asthma was initiated in wild type (WT) and TRPM2-/- mice by repeated sensitization with ovalbumin (OVA)/aluminum hydroxide on Days 0, 7 and 14, followed by intranasal challenge on Days 21, 22 and 23. Mice were investigated for the presence of airway responsiveness, airway inflammation, production of allergen-specific antibodies, cytokine response and lung pathology.ResultsThe absence of TRPM2 channels has no obvious effect on major etiologic markers of severe allergic asthma in this mouse model. Neither airway resistance nor mucus production are affected in TRPM2-/- mice. TRPM2 channel ablation also does not alter airway inflammation or immunocyte infiltration and does not affect antibody response or cytokine levels.ConclusionsTRPM2 is not required for airway inflammation in OVA-induced severe allergic asthma in mice. Accordingly, TRPM2 might not be a suitable therapeutic target for airway inflammation caused by allergens in humans.

Frecuencia de infección por virus del papiloma humano en pacientes con cáncer del aparato digestivo

INTRODUCTION AND AIM Cancer is the result of the interaction of genetic and environmental factors. It has recently been related to viral infections, one of which is human papillomavirus. The aim of the present study was to describe the frequency of human papillomavirus infection in patients with digestive system cancers. MATERIALS AND METHODS A prospective, multicenter, observational study was conducted on patients with gastrointestinal cancer at 2public healthcare institutes in Veracruz. Two tumor samples were taken, one for histologic study and the other for DNA determination of human papillomavirus and its genotypes. Anthropometric variables, risk factors, sexual habits, tumor location, and histologic type of the cancer were analyzed. Absolute and relative frequencies were determined using the SPSS version 24.0 program. RESULTS Fifty-three patients were studied. They had gastrointestinal cancer located in: the colon (62.26%), stomach (18.87%), esophagus (7.55%), rectum (7.55%), and small bowel (3.77%). Human papillomavirus was identified in 11.32% of the patients, 66.7% of which corresponded to squamous cell carcinoma and 33.3% to adenocarcinoma. Only genotype 18 was identified. Mean patient age was 61.8±15.2 years, 56.60% of the patients were men, and 43.40% were women. A total of 15.8% of the patients had a family history of cancer and 31.6% had a personal history of the disease, 38.6% were tobacco smokers, and 61.4% consumed alcohol. Regarding sex, 5.3% of the patients said they were homosexual, 3.5% were bisexual, 29.8% engaged in oral sex, and 24.6% in anal sex. CONCLUSIONS Our study showed that human papillomavirus infection was a risk factor for the development of gastrointestinal cancer, especially of squamous cell origin.