Structure and function of the ecto-nucleotide pyrophosphatase/phosphodiesterase (ENPP) family: Tidying up diversity.

Ecto-nucleotide pyrophosphatase/phosphodiesterase (ENPP) family members (ENPP1-7) have been implicated in key biological and pathophysiological processes, including nucleotide and phospholipid signaling, bone mineralization, fibrotic diseases, and tumor-associated immune cell infiltration. ENPPs are single-pass transmembrane ecto-enzymes, with notable exceptions of ENPP2 (Autotaxin) and ENNP6, which are secreted and glycosylphosphatidylinositol (GPI)-anchored, respectively. ENNP1 and ENNP2 are the best characterized and functionally the most interesting members. Here, we review the structural features of ENPP1-7 to understand how they evolved to accommodate specific substrates and mediate different biological activities. ENPPs are defined by a conserved phosphodiesterase (PDE) domain. In ENPP1-3, the PDE domain is flanked by two N-terminal somatomedin B-like domains and a C-terminal inactive nuclease domain that confers structural stability, whereas ENPP4-7 only possess the PDE domain. Structural differences in the substrate-binding site endow each protein with unique characteristics. Thus, ENPP1, ENPP3, ENPP4, and ENPP5 hydrolyze nucleotides, whereas ENPP2, ENPP6, and ENNP7 evolved as phospholipases through adaptions in the catalytic domain. These adaptations explain the different biological and pathophysiological functions of individual members. Understanding the ENPP members as a whole advances our insights into common mechanisms, highlights their functional diversity, and helps to explore new biological roles.

Sequence-dependent trafficking and activity of GDE2, a GPI-specific phospholipase promoting neuronal differentiation.

GDE2 (also known as GDPD5) is a multispanning membrane phosphodiesterase with phospholipase D-like activity that cleaves select glycosylphosphatidylinositol (GPI)-anchored proteins and thereby promotes neuronal differentiation both in vitro and in vivo GDE2 is a prognostic marker in neuroblastoma, while loss of GDE2 leads to progressive neurodegeneration in mice; however, its regulation remains unclear. Here, we report that, in immature neuronal cells, GDE2 undergoes constitutive endocytosis and travels back along both fast and slow recycling routes. GDE2 trafficking is directed by C-terminal tail sequences that determine the ability of GDE2 to cleave GPI-anchored glypican-6 (GPC6) and induce a neuronal differentiation program. Specifically, we define a GDE2 truncation mutant that shows aberrant recycling and is dysfunctional, whereas a consecutive deletion results in cell-surface retention and gain of GDE2 function, thus uncovering distinctive regulatory sequences. Moreover, we identify a C-terminal leucine residue in a unique motif that is essential for GDE2 internalization. These findings establish a mechanistic link between GDE2 neuronal function and sequence-dependent trafficking, a crucial process gone awry in neurodegenerative diseases.This article has an associated First Person interview with the first author of the paper.

Autoimmune and autoinflammatory conditions after COVID-19 vaccination. New case reports and updated literature review.

Autoimmunity linked to COVID-19 immunization has been recorded throughout the pandemic. Herein we present six new patients who experienced relapses of previous autoimmune disease (AD) or developed a new autoimmune or autoinflammatory condition following vaccination. In addition, we documented additional cases through a systematic review of the literature up to August 1st, 2022, in which 464 studies (928 cases) were included. The majority of patients (53.6%) were women, with a median age of 48 years (IQR: 34 to 66). The median period between immunization and the start of symptoms was eight days (IQR: 3 to 14). New-onset conditions were observed in 81.5% (n: 756) of the cases. The most common diseases associated with new-onset events following vaccination were immune thrombocytopenia, myocarditis, and Guillain-Barré syndrome. In contrast, immune thrombocytopenia, psoriasis, IgA nephropathy, and systemic lupus erythematosus were the most common illnesses associated with relapsing episodes (18.5%, n: 172). The first dosage was linked with new-onset events (69.8% vs. 59.3%, P = 0.0100), whereas the second dose was related to relapsing disease (29.5% vs. 59.3%, P = 0.0159). New-onset conditions and relapsing diseases were more common in women (51.5% and 62.9%, respectively; P = 0.0081). The groups were evenly balanced in age. No deaths were recorded after the disease relapsed, while 4.7% of patients with new-onset conditions died (P = 0.0013). In conclusion, there may be an association between COVID-19 vaccination and autoimmune and inflammatory diseases. Some ADs seem to be more common than others. Vaccines and SARS-CoV-2 may induce autoimmunity through similar mechanisms. Large, well-controlled studies are warranted to validate this relationship and assess additional variables such as genetic and other environmental factors.

Lysophosphatidic acid produced by autotaxin acts as an allosteric modulator of its catalytic efficiency.

Autotaxin (ATX) is a secreted glycoprotein and the only member of the ectonucleotide pyrophosphatase/phosphodiesterase family that converts lysophosphatidylcholine (LPC) into lysophosphatidic acid (LPA). LPA controls key responses, such as cell migration, proliferation, and survival, implicating ATX-LPA signaling in various (patho)physiological processes and establishing it as a drug target. ATX structural and functional studies have revealed an orthosteric and an allosteric site, called the "pocket" and the "tunnel," respectively. However, the mechanisms in allosteric modulation of ATX's activity as a lysophospholipase D are unclear. Here, using the physiological LPC substrate, a new fluorescent substrate, and diverse ATX inhibitors, we revisited the kinetics and allosteric regulation of the ATX catalytic cycle, dissecting the different steps and pathways leading to LPC hydrolysis. We found that ATX activity is stimulated by LPA and that LPA activates ATX lysophospholipase D activity by binding to the ATX tunnel. A consolidation of all experimental kinetics data yielded a comprehensive catalytic model supported by molecular modeling simulations and suggested a positive feedback mechanism that is regulated by the abundance of the LPA products activating hydrolysis of different LPC species. Our results complement and extend the current understanding of ATX hydrolysis in light of the allosteric regulation by ATX-produced LPA species and have implications for the design and application of both orthosteric and allosteric ATX inhibitors.

Autotaxin facilitates selective LPA receptor signaling.

Autotaxin (ATX; ENPP2) produces the lipid mediator lysophosphatidic acid (LPA) that signals through disparate EDG (LPA1-3) and P2Y (LPA4-6) G protein-coupled receptors. ATX/LPA promotes several (patho)physiological processes, including in pulmonary fibrosis, thus serving as an attractive drug target. However, it remains unclear if clinical outcome depends on how different types of ATX inhibitors modulate the ATX/LPA signaling axis. Here, we show that the ATX "tunnel" is crucial for conferring key aspects of ATX/LPA signaling and dictates cellular responses independent of ATX catalytic activity, with a preference for activation of P2Y LPA receptors. The efficacy of the ATX/LPA signaling responses are abrogated more efficiently by tunnel-binding inhibitors, such as ziritaxestat (GLPG1690), compared with inhibitors that exclusively target the active site, as shown in primary lung fibroblasts and a murine model of radiation-induced pulmonary fibrosis. Our results uncover a receptor-selective signaling mechanism for ATX, implying clinical benefit for tunnel-targeting ATX inhibitors.

[Acute renal failure and chronic diarrhea: McKittrick-Wheelock syndrome]. / Insuficiencia renal aguda y diarrea crónica: síndrome de McKittrick-Wheelock.

In 1954, McKittrick and Wheelock described for the first time a syndrome presenting chronic lost of fluid and electrolytes secondary to chronic diarrhea, associated to large rectal villous adenomas. We report a case of a 75-year-old female who presented chronic diarrhea (3 to 4 depositions per day in the last year), accompanied by acute renal failure. In the rectal tact, we objective the presence of a mass of soft consistency with an irregular surface, occupying approximately two thirds of the circumference, at about 3 cm from the anal margin. It was confirmed by the colonoscopy and the patology was informed as villous adenoma, producing chronic diarrhea or McKittrick-Wheelock syndrome. We decide the surgical approach after the normalization of patient's general status and a proctectomy with coloanal anastomosis was performed. We conclude that we must think about this syndrome in aged patients with chronic diarrhea, alterations of the electrolyte balance and presence of renal failure. Surgery treatment after the replacement of water and electrolytes is the unique curative treatment. The absence of this can cause the death of these patients.

COVID-19 vaccine and autoimmunity. A new case of autoimmune hepatitis and review of the literature.

Autoimmunity following COVID-19 vaccination has been reported. Herein, a 79-year-old man with clinical and immunological features of autoimmune hepatitis type 1 after ChAdOx1 nCoV-19 vaccination is presented. Clinical manifestations rapidly remitted after the instauration of immunomodulatory management. This case, together with a comprehensive review of the literature, illustrates the association between COVID-19 vaccines and the development of autoimmune conditions.

A type IV Autotaxin inhibitor ameliorates acute liver injury and nonalcoholic steatohepatitis.

The lysophosphatidic acid (LPA) signaling axis is an important but rather underexplored pathway in liver disease. LPA is predominantly produced by Autotaxin (ATX) that has gained significant attention with an impressive number of ATX inhibitors (type I-IV) reported. Here, we evaluated the therapeutic potential of a (yet unexplored) type IV inhibitor, Cpd17, in liver injury. We first confirmed the involvement of the ATX-LPA signaling axis in human and murine diseased livers. Then, we evaluated the effects of Cpd17, in comparison with the classic type I inhibitor PF8380, in vitro, where Cpd17 showed higher efficacy. Thereafter, we characterized the mechanism-of-action of both inhibitors and found that Cpd17 was more potent in inhibiting RhoA-mediated cytoskeletal remodeling, and phosphorylation of MAPK/ERK and AKT/PKB. Finally, the therapeutic potential of Cpd17 was investigated in CCl4 -induced acute liver injury and diet-induced nonalcoholic steatohepatitis, demonstrating an excellent potential of Cpd17 in reducing liver injury in both disease models in vivo. We conclude that ATX inhibition, by type IV inhibitor in particular, has an excellent potential for clinical application in liver diseases.

Structure-Based Design of a Novel Class of Autotaxin Inhibitors Based on Endogenous Allosteric Modulators.

Autotaxin (ATX) facilitates the hydrolysis of lysophosphatidylcholine to lysophosphatidic acid (LPA), a bioactive phospholipid, which facilitates a diverse range of cellular effects in multiple tissue types. Abnormal LPA expression can lead to the progression of diseases such as cancer and fibrosis. Previously, we identified a potent ATX steroid-derived hybrid (partially orthosteric and allosteric) inhibitor which did not form interactions with the catalytic site. Herein, we describe the design, synthesis, and biological evaluation of a focused library of novel steroid-derived analogues targeting the bimetallic catalytic site, representing an entirely unique class of ATX inhibitors of type V designation, which demonstrate significant pathway-relevant biochemical and phenotypic biological effects. The current compounds modulated LPA-mediated ATX allostery and achieved indirect blockage of LPA1 internalization, in line with the observed reduction in downstream signaling cascades and chemotaxis induction. These novel type V ATX inhibitors represent a promising tool to inactivate the ATX-LPA signaling axis.

LAHMA: structure analysis through local annotation of homology-matched amino acids.

Comparison of homologous structure models is a key step in analyzing protein structure. With a wealth of homologous structures, comparison becomes a tedious process, and often only a small (user-biased) selection of data is used. A multitude of structural superposition algorithms are then typically used to visualize the structures together in 3D and to compare them. Here, the Local Annotation of Homology-Matched Amino acids (LAHMA) website (https://lahma.pdb-redo.eu) is presented, which compares any structure model with all of its close homologs from the PDB-REDO databank. LAHMA displays structural features in sequence space, allowing users to uncover differences between homologous structure models that can be analyzed for their relevance to chemistry or biology. LAHMA visualizes numerous structural features, also allowing one-click comparison of structure-quality plots (for example the Ramachandran plot) and `in-browser' structural visualization of 3D models.

Imaging Autotaxin In Vivo with 18F-Labeled Positron Emission Tomography Ligands.

Autotaxin (ATX) is a secreted phosphodiesterase that has been implicated in a remarkably wide array of pathologies, especially in fibrosis and cancer. While ATX inhibitors have entered the clinical arena, a validated probe for positron emission tomography (PET) is currently lacking. With the aim to develop a suitable ATX-targeted PET radioligand, we have synthesized a focused library of fluorinated imidazo[1,2-a]pyridine derivatives, determined their inhibition constants, and confirmed their binding mode by crystallographic analysis. Based on their promising in vitro properties, compounds 9c, 9f, 9h, and 9j were radiofluorinated. Also, a deuterated analog of [18F]9j, designated as [18F]ATX-1905 ([18F]20), was designed and proved to be highly stable against in vivo radiodefluorination compared with [18F]9c, [18F]9f, [18F]9h, and [18F]9j. These results along with in vitro and in vivo studies toward ATX in a mouse model of LPS-induced liver injury suggest that [18F]ATX-1905 is a suitable PET probe for the non-invasive quantification of ATX.

Autotaxin impedes anti-tumor immunity by suppressing chemotaxis and tumor infiltration of CD8+ T cells.

Autotaxin (ATX; ENPP2) produces lysophosphatidic acid (LPA) that regulates multiple biological functions via cognate G protein-coupled receptors LPAR1-6. ATX/LPA promotes tumor cell migration and metastasis via LPAR1 and T cell motility via LPAR2, yet its actions in the tumor immune microenvironment remain unclear. Here, we show that ATX secreted by melanoma cells is chemorepulsive for tumor-infiltrating lymphocytes (TILs) and circulating CD8+ T cells ex vivo, with ATX functioning as an LPA-producing chaperone. Mechanistically, T cell repulsion predominantly involves Gα12/13-coupled LPAR6. Upon anti-cancer vaccination of tumor-bearing mice, ATX does not affect the induction of systemic T cell responses but, importantly, suppresses tumor infiltration of cytotoxic CD8+ T cells and thereby impairs tumor regression. Moreover, single-cell data from melanoma tumors are consistent with intratumoral ATX acting as a T cell repellent. These findings highlight an unexpected role for the pro-metastatic ATX-LPAR axis in suppressing CD8+ T cell infiltration to impede anti-tumor immunity, suggesting new therapeutic opportunities.

The Structural Binding Mode of the Four Autotaxin Inhibitor Types that Differentially Affect Catalytic and Non-Catalytic Functions.

Autotaxin (ATX) is a secreted lysophospholipase D, catalysing the conversion of lysophosphatidylcholine (LPC) to bioactive lysophosphatidic acid (LPA). LPA acts through two families of G protein-coupled receptors (GPCRs) controlling key cellular responses, and it is implicated in many physiological processes and pathologies. ATX, therefore, has been established as an important drug target in the pharmaceutical industry. Structural and biochemical studies of ATX have shown that it has a bimetallic nucleophilic catalytic site, a substrate-binding (orthosteric) hydrophobic pocket that accommodates the lipid alkyl chain, and an allosteric tunnel that can accommodate various steroids and LPA. In this review, first, we revisit what is known about ATX-mediated catalysis, crucially in light of allosteric regulation. Then, we present the known ATX catalysis-independent functions, including binding to cell surface integrins and proteoglycans. Next, we analyse all crystal structures of ATX bound to inhibitors and present them based on the four inhibitor types that are established based on the binding to the orthosteric and/or the allosteric site. Finally, in light of these data we discuss how mechanistic differences might differentially modulate the activity of the ATX-LPA signalling axis, and clinical applications including cancer.

Rational Design of Autotaxin Inhibitors by Structural Evolution of Endogenous Modulators.

Autotaxin produces the bioactive lipid lysophosphatidic acid (LPA) and is a drug target of considerable interest for numerous pathologies. We report the expedient, structure-guided evolution of weak physiological allosteric inhibitors (bile salts) into potent competitive Autotaxin inhibitors that do not interact with the catalytic site. Functional data confirms that our lead compound attenuates LPA mediated signaling in cells and reduces LPA synthesis in vivo, providing a promising natural product derived scaffold for drug discovery.

Structure-Activity Relationships of Small Molecule Autotaxin Inhibitors with a Discrete Binding Mode.

Autotaxin (ATX) is a secreted enzyme responsible for the hydrolysis of lysophosphatidylcholine (LPC) to the bioactive lysophosphatidic acid (LPA) and choline. The ATX-LPA signaling pathway is implicated in cell survival, migration, and proliferation; thus, the inhibition of ATX is a recognized therapeutic target for a number of diseases including fibrotic diseases, cancer, and inflammation, among others. Many of the developed synthetic inhibitors for ATX have resembled the lipid chemotype of the native ligand; however, a small number of inhibitors have been described that deviate from this common scaffold. Herein, we report the structure-activity relationships (SAR) of a previously reported small molecule ATX inhibitor. We show through enzyme kinetics studies that analogues of this chemotype are noncompetitive inhibitors, and by using a crystal structure with ATX we confirm the discrete binding mode.

Carcinosarcoma with Choriocarcinomatous and Osteosarcomatous Differentiation in a Patient with Juvenile Polyposis Syndrome.

Juvenile polyposis syndrome (JPS) is an infrequent autosomal dominant hereditary predisposition to the occurrence of hamartomatous polyps in the colon and rectum. We describe the case of a 12-year-old boy with JPS associated with an abdominal tumor. Histological sections of the abdominal tumor showed components of adenocarcinoma, osteosarcoma, and choriocarcinoma. Immunohistochemistry was AE1/AE3, CK7, HCG and SALL4 positive. Juvenile polyposis syndrome patients are at increased risk of colorectal adenocarcinoma. However, we present a case of an adenocarcinoma associated with other unusual components. This association has not been reported before.

Manifestaciones radiológicas de malformaciones pulmonares congénitas. Experiencia de tres hospitales en Bogotá / Radiological Manifestations of Congenital Lung Malformations. Experience of three Hospitals in Bogotá

Objective: To describe the radiological characteristics of congenital pulmonary and airway malformations which are frequently found in pediatric patients, from three hospitals in Bogotá between the years 2010 - 2016. Materials and methods: Retrospective, observational and descriptive study with a sample of 27 patients, with an average age of 5 months, who met inclusion criteria: patients between 0 months and 17 years of age, with a confirmed diagnosis of congenital malformation of the lung, who underwent surgery for lung or airway lesion and whose histopathological study was compatible with congenital malformation of the lung. Results: The prevalence of congenital malformations is higher in females. 80% of cases had prenatal diagnosis, with cystic adenomatoid malformation being the most common and the main radiological feature being the cyst. Conclusion: Computed tomography allows detailed studies of these malformations, achieving greater accuracy compared to conventional techniques such as chest radiography and ultrasound.

Strongyloides stercolaris en lavado broncoalveolar / Strongyloides stercoralis in bronchoalveolar lavage specimen

Las estrongiloidiosis es una infección parasitaria frecuente en zonas tropicales y subtropicales. Suele ser asintomática y limitarse al intestino. Sin embargo, pueden darse casos de infección extraintestinal diseminada y potencialmente fatales en pacientes inmunocomprometidos. Se presenta el caso de una paciente diagnosticada con estrongiloidiosis mediante una muestra de lavado broncoalveolar procesada con los métodos de cytospin y citología convencional...

Strongyloidiasis is a parasitic infection found especially in tropical and subtropical regions. It is usually an asymptomatic and limited disease of the gut. However, potentially fatal cases of disseminated hyperinfection in immunosuppressed patients can occur. We present the case of a female patient with strongyloidiasis in bronchoalveolar lavage specimen processed as cytospin preparations and conventional cytology...

Hemoneumotórax espontáneo: presentación de caso / Spontaneous Hemopneumothorax: A Case Report

El hemoneumotórax espontáneo es una condición inusual, caracterizada por la acumulación de aire y sangre en la cavidad pleural, no precedida por trauma. La radiografía de tórax es la herramienta principal en el diagnóstico de esta entidad. Se presenta el caso de un hombre de 22 años con hemoneumotórax espontáneo. El paciente se recuperó sin complicaciones luego de la cirugía.

Spontaneous hemopneumothorax is an unusual condition, characterized by the accumulation of air and blood in the pleural cavity, not preceded by trauma. Chest radiography is the main tool in the diagnosis of this entity. We present, a case of a 22-year-old male with spontaneous hemopneumothorax. The patient recovered after surgery with no complications.