Cell-specific Extracellular Vesicles and Their miRNA Cargo Released Into the Organ Preservation Solution During Cold Ischemia Storage as Biomarkers for Liver Transplant Outcomes.

BACKGROUND: Liver transplantation (LT) is crucial for end-stage liver disease patients, but organ shortages persist. Donation after circulatory death (DCD) aims to broaden the donor pool but presents challenges. Complications like acute rejection, hepatic artery thrombosis, and biliary issues still impact posttransplant prognosis. Biomarkers, including extracellular vesicles (EVs) and microRNAs (miRNAs), show promise in understanding and monitoring posttransplant events. This study explores the role of EVs and their miRNA cargo in LT, including their potential as diagnostic tools. METHODS: EVs from intrahepatic end-ischemic organ preservation solution (eiOPS) in 79 donated livers were detected using different techniques (nanosight tracking analysis, transmission electron microscopy, and flow cytometry). EV-derived miRNAs were identified by quantitative real time-polymerase chain reaction. Bioinformatics analysis was performed using the R platform. RESULTS: Different-sized and origin-specific EVs were found in eiOPS, with significantly higher concentrations in DCD compared with donation after brain death organs. Additionally, several EV-associated miRNAs, including let-7d-5p, miR-28-5p, miR-200a-3p, miR-200b-3p, miR-200c-3p, and miR-429, were overexpressed in DCD-derived eiOPS. These miRNAs also exhibited differential expression patterns in liver tissue biopsies. Pathway analysis revealed enrichment in signaling pathways involved in extracellular matrix organization and various cellular processes. Moreover, specific EVs and miRNAs correlated with clinical outcomes, including survival and early allograft dysfunction. A predictive model combining biomarkers and clinical variables showed promise in acute rejection detection after LT. CONCLUSIONS: These findings provide new insights into the use of EVs and miRNAs as biomarkers and their possible influence on posttransplantation outcomes, potentially contributing to improved diagnostic approaches and personalized treatment strategies in LT.

Operational tolerance research in liver transplantation: a bibliometric analysis using a new web resource.

Background: Operational tolerance in liver transplantation (OT-LT), defined as the graft survival with normal function in absence of immunosuppression, has been a field of intense research since the 1980s. Thereafter, tens of clinical trials and hundreds of articles have been published, making it challenging for researchers to assimilate all the information, more so outside of their disciplines. The aim of the present study was to analyze the research in OT-LT through a new web tool (https://tolerance.imib.es). Methods: We have developed a web resource that allowed the identification of the present trends and potential research avenues in OL-LT, an overview biomedical terms that were most often cited, including which journals published the most articles, and an advanced search engine that exploited all the information in these publications. Results: A total of 734 studies were analyzed until November 2023, with a mean of 15 articles published per year, a total sum of 3,751 impact factor points and a total of 26,542 citations. The analysis of citations allowed us to establish a ranking of the most prolific countries, authors, journals and institutions, in addition to the most influential publications in OT-LT. Likewise, keyword and co-occurrence analyses answered which themes involving OT-LT are the most popular, whereas cooperation analysis showed that principal authors in OT-LT form a network, although the lack of international cooperation, especially with regard to clinical trials, appears to be one of the main challenges. Conclusion: Despite its limitations, our web tool will allow both OT-LT expert and novel researchers to be able to draw a comprehensive picture of the past, present and future of OT-LT research.

Time since liver transplant and immunosuppression withdrawal outcomes: Systematic review and individual patient data meta-analysis.

BACKGROUND & AIMS: Successful immunosuppression withdrawal (ISW) is possible for a subfraction of liver transplant (LT) recipients but the factors that define the risk of ISW failure are largely unknown. One candidate prognostic factor for ISW success or operational tolerance (OT) is longer time between LT and ISW which we term "pre-withdrawal time". To clarify the impact of pre-withdrawal time span on subsequent ISW success or failure, we conducted a systematic review with meta-analysis. METHODS: We systematically interrogated the literature for LT recipient ISW studies reporting pre-withdrawal time. Eligible articles from Embase, Medline, and the Cochrane Central Register of Controlled Trials were used for backward and forward citation searching. Pre-withdrawal time individual patient data (IPD) was requested from authors. Pooled mean differences and time-response curves were calculated using random-effects meta-analyses. RESULTS: We included 17 studies with 691 patients, 15 of which (620 patients) with IPD. Study-level risk of bias was heterogeneous. Mean pre-withdrawal time was greater by 427 days [95% confidence interval (CI) 67-788] in OT compared to non-OT patients. This increase was potentiated to 799 days (95% CI 369-1229) or 1074 days (95% CI 685-1463) when restricting analysis to adult or European study participants. In time-response meta-analysis for adult or European ISW candidates, likelihood of OT increased by 7% (95% CI 4-10%) per year after LT (GRADE low- and moderate-certainty of evidence, respectively). CONCLUSIONS: Our data support the impact of pre-withdrawal time in ISW decision-making for adult and European LT recipients. PROSPERO REGISTRATION: CRD42021272995.

Purinergic P2X7 receptor expression increases in leukocytes from intra-abdominal septic patients.

Inflammation is a tightly coordinated response of the host immune system to bacterial and viral infections, triggered by the production of inflammatory cytokines. Sepsis is defined as a systemic inflammatory response followed by immunosuppression of the host and organ dysfunction. This imbalance of the immune response increases the risk of mortality of patients with sepsis, making it a major problem for critical care units worldwide. The P2X7 receptor plays a crucial role in activating the immune system by inducing the activation of peripheral blood mononuclear cells. In this study, we analyzed a cohort of abdominal origin septic patients and found that the expression of the P2X7 receptor in the plasma membrane is elevated in the different subsets of lymphocytes. We observed a direct relationship between the percentage of P2X7-expressing lymphocytes and the early inflammatory response in sepsis. Additionally, in patients whose lymphocytes presented a higher percentage of P2X7 surface expression, the total lymphocytes populations proportionally decreased. Furthermore, we found a correlation between elevated soluble P2X7 receptors in plasma and inflammasome-dependent cytokine IL-18. In summary, our work demonstrates that P2X7 expression is highly induced in lymphocytes during sepsis, and this correlates with IL-18, along with other inflammatory mediators such as IL-6, IL-8, and procalcitonin.

Endothelial cell activation mediated by cold ischemia-released mitochondria is partially inhibited by defibrotide and impacts on early allograft function following liver transplantation.

DAMPs (danger-associated molecular patterns) are self-molecules of the organism that appear after damage. The endothelium plays several roles in organ rejection, such as presenting alloantigens to T cells and contributing to the development of inflammation and thrombosis. This study aimed to assess whether DAMPs present in the organ preservation solution (OPS) after cold ischemic storage (CIS) contribute to exacerbating the endothelial response to an inflammatory challenge and whether defibrotide treatment could counteract this effect. The activation of cultured human umbilical vein endothelial cells (HUVECs) was analyzed after challenging with end-ischemic OPS (eiOPS) obtained after CIS. Additionally, transwell assays were performed to study the ability of eiOPS to attract lymphocytes across the endothelium. The study revealed that eiOPS upregulated the expression of MCP-1 and IL-6 in HUVECs. Moreover, eiOPS increased the membrane expression of ICAM-1and HLA-DR, which facilitated leukocyte migration toward a chemokine gradient. Furthermore, eiOPS demonstrated its chemoattractant ability. This activation was mediated by free mitochondria. Defibrotide was found to partially inhibit the eiOPS-mediated activation. Moreover, the eiOPS-mediated activation of endothelial cells (ECs) correlated with early allograft dysfunction in liver transplant patients. Our finding provide support for the hypothesis that mitochondria released during cold ischemia could trigger EC activation, leading to complications in graft outcomes. Therefore, the analysis and quantification of free mitochondria in the eiOPS samples obtained after CIS could provide a predictive value for monitoring the progression of transplantation. Moreover, defibrotide emerges as a promising therapeutic agent to mitigate the damage induced by ischemia in donated organs.

Selecting the Appropriate Downstaging and Bridging Therapies for Hepatocellular Carcinoma: What Is the Role of Transarterial Radioembolization? A Pooled Analysis.

BACKGROUND: Transarterial radioembolization in HCC for LT as downstaging/bridging has been increasing in recent years but some indication criteria are still unclear. METHODS: We conducted a systematic literature search of primary research publications conducted in PubMed, Scopus and ScienceDirect databases until November 2022. Relevant data about patient selection, HCC features and oncological outcomes after TARE for downstaging or bridging in LT were analyzed. RESULTS: A total of 14 studies were included (7 downstaging, 3 bridging and 4 mixed downstaging and bridging). The proportion of whole liver TARE was between 0 and 1.6%. Multiple TARE interventions were necessary for 16.7% up to 28% of the patients. A total of 55 of 204 patients across all included studies undergoing TARE for downstaging were finally transplanted. The only RCT included presents a higher tumor response with the downstaging rate for LT of TARE than TACE (9/32 vs. 4/34, respectively). Grade 3 or 4 adverse effects rate were detected between 15 and 30% of patients. CONCLUSIONS: TARE is a safe therapeutic option with potential advantages in its capacity to necrotize and reduce the size of the HCC for downstaging or bridging in LT.

Usefulness of PIVKA-II for monitoring after liver transplantation in patients with hepatocellular carcinoma.

The high morbidity and mortality of hepatocellular carcinoma (HCC) has encouraged the search for new biomarkers to be used alongside alpha-foetoprotein (AFP) and imaging tests. The aim of this study was to evaluate the clinical contribution of protein induced by vitamin K absence or antagonist-II (PIVKA-II) for HCC monitoring after liver transplantation (LT) and compare it with AFP, a routinely used tumour marker. A total of 46 HCC patients (Milan criteria) were enrolled in this study. Serum levels of PIVKA-II and AFP were measured before and after transplantation. Clinical features were determined for all the patients that were included. Significant correlations were found between PIVKA-II expression levels and some clinicopathological features, such as tumour size and number of pre-transplant transarterial chemoembolizations (TACEs). Serum levels of PIVKA-II and AFP decreased significantly after LT and increased in patients with tumour recurrence. Serum PIVKA-II levels may play an important role in predicting disease severity. Furthermore, monitoring PIVKA-II levels in HCC transplant recipients reflects the tumor early recurrence after transplantation and could be used, complementing AFP and imaging tests, as a novel biomarker of this pathology.

New challenges in cholangiocarcinoma candidates for elective surgery: harnessing the microbiome dysbiosis.

BACKGROUND: The gut microbiota, composed by several species of microorganisms, works to preserve the liver-gut homeostasis and plays an important role during digestion and absorption of nutrients, and in the immune response of the host. In this review, we analyzed the influence of microbiota in patients with cholangiocarcinoma (CCA) who were candidates for elective surgery. METHODS: A literature review was conducted to identify papers that provided empiric evidence to support that the altered microbiota composition (dysbiosis) is related also to CCA development. RESULTS: Bacteria such as Helicobacter pylori, Helicobacter hepaticus, and Opisthorchis viverrini increase the risk of CCA. The most abundant genera were Enterococcus, Streptococcus, Bacteroides, Klebsiella, and Pyramidobacter in CCA's biliary microbiota. Additionally, levels of Bacteroides, Geobacillus, Meiothermus, and Anoxybacillus genera were significantly higher. An enrichment of Bifidobacteriaceae, Enterobacteriaceae, and Enterococcaceae families has also been observed in CCA tumor tissue. Microbiota is related to postoperative outcomes in abdominal surgery. The combination of caloric restriction diets in liver cancer or CCA increases the effect of the chemotherapy treatment. CONCLUSION: The correct use of nutrition for microbiota modulation according to each patient's needs could be a therapeutic tool in combination with elective surgery and chemotherapy to diminish side effects and improve prognosis. Further investigations are needed to fully understand the mechanisms by which they are related.

Danger signals released during cold ischemia storage activate NLRP3 inflammasome in myeloid cells and influence early allograft function in liver transplantation.

BACKGROUND: Innate immunity plays a fundamental role in solid organ transplantation. Myeloid cells can sense danger signals or DAMPs released after tissue or cell damage, such as during ischemia processes. This study aimed to identify DAMPs released during cold ischemia storage of human liver and analyze their ability to activate the inflammasome in myeloid cells and the possible implications in terms of short-term outcomes of liver transplantation. METHODS: 79 samples of organ preservation solution (OPS) from 79 deceased donors were collected after cold static storage. We used different analytical methods to measure DAMPs in these end-ischemic OPS (eiOPS) samples. We also used eiOPS in the human macrophage THP-1 cell line and primary monocyte cultures to study inflammasome activation. FINDINGS: Different DAMPs were identified in eiOPS, several of which induced both priming and activation of the NLRP3 inflammasome in human myeloid cells. Cold ischemia time and donation after circulatory death negatively influenced the DAMP signature. Moreover, the presence of oligomeric inflammasomes and interleukin-18 in eiOPS correlated with early allograft dysfunction in liver transplant patients. INTERPRETATION: DAMPs released during cold ischemia storage prime and activate the NLRP3 inflammasome in liver macrophages after transplantation, inducing a pro-inflammatory environment that will complicate the outcome of the graft. The use of pharmacological blockers targeting DAMPs or the NLRP3 inflammasome in liver ischemia during static cold storage or through extracorporeal organ support could be a suitable strategy to increase the success of liver transplantation. FUNDING: Fundación Mutua Madrileña and Instituto de Salud Carlos III, Madrid, Spain.

P2X7 receptor activation impairs antitumour activity of natural killer cells.

BACKGROUND AND PURPOSE: A high number of intratumoural infiltrating natural killer (NK) cells is associated with better survival in several types of cancer, constituting an important first line of defence against tumours. Hypoxia in the core of solid tumours induces cellular stress and ATP release into the extracellular space where it triggers purinergic receptor activation on tumour-associated immune cells. The aim of this study was to assess whether activation of the purinergic receptor P2X7 by extracellular ATP plays a role in the NK cells antitumour activity. EXPERIMENTAL APPROACH: We carried out in vitro experiments using purified human NK cells triggered through P2X7 by extracellular ATP. NK cell killing activity against the tumour target cells K562 was studied by means of NK cytotoxicity assays. Likewise, we designed a subcutaneous solid tumour in vivo mouse model. KEY RESULTS: In this study we found that human NK cells, expressing a functional plasma membrane P2X7, acquired an anergic state after ATP treatment, which impaired their antitumour activity and decreased IFN-γ secretion. This effect was reversed by specific P2X7 antagonists and pretreatment with either IL-2 or IL-15. Furthermore, genetic P2rx7 knockdown resulted in improved control of tumour size by NK cells. In addition, IL-2 therapy restored the ability of NK cells to diminish the size of tumours. CONCLUSIONS AND IMPLICATIONS: Our results show that P2X7 activation represents a new mechanism whereby NK cells may lose antitumour effectiveness, opening the possibility of generating modified NK cells lacking P2X7 but with improved antitumour capacity.

Emerging Role of NLRP3 Inflammasome and Pyroptosis in Liver Transplantation.

The nucleotide-binding domain leucine-rich repeat-receptor, pyrin domain-containing-3 (NLRP3) inflammasome contributes to the inflammatory response by activating caspase-1, which in turn participates in the maturation of interleukin (IL)-1ß and IL-18, which are mainly secreted via pyroptosis. Pyroptosis is a lytic type of cell death that is controlled by caspase-1 processing gasdermin D. The amino-terminal fragment of gasdermin D inserts into the plasma membrane, creating stable pores and enabling the release of several proinflammatory factors. The activation of NLRP3 inflammasome and pyroptosis has been involved in the progression of liver fibrosis and its end-stage cirrhosis, which is among the main etiologies for liver transplantation (LT). Moreover, the NLRP3 inflammasome is involved in ischemia-reperfusion injury and early inflammation and rejection after LT. In this review, we summarize the recent literature addressing the role of the NLRP3 inflammasome and pyroptosis in all stages involved in LT and argue the potential targeting of this pathway as a future therapeutic strategy to improve LT outcomes. Likewise, we also discuss the impact of graft quality influenced by donation after circulatory death and the expected role of machine perfusion technology to modify the injury response related to inflammasome activation.

Characterization of P2X7 Receptors in Human Blood Cells.

P2X7 receptors are expressed in different circulating immune cells. Depending on the cell in which they are expressed, their function could vary from activation of the leucine-rich repeat receptor pyrin domain containing 3 (NLRP3) inflammasome or the shedding of different surface receptors. The P2X7 receptor has been involved in the evolution of several inflammatory diseases, and thus its characterization in blood samples is important to investigate its role in human diseases. In this chapter, we present different methods to detect the presence and the activation of P2X7 receptors in whole blood samples. These methods could be used to evaluate the degree of P2X7 receptor activation in blood samples from patients suffering different chronic inflammatory diseases.

Soluble P2X7 Receptor Is Elevated in the Plasma of COVID-19 Patients and Correlates With Disease Severity.

Inflammation is a tightly coordinated response against bacterial and viral infections, triggered by the production of pro-inflammatory cytokines. SARS-CoV-2 infection induces COVID-19 disease, characterized by an inflammatory response mediated through the activation of the NLRP3 inflammasome, which results in the production of IL-1ß and IL-18 along with pyroptotic cell death. The NLRP3 inflammasome could be also activated by sterile danger signals such as extracellular ATP triggering the purinergic P2X7 receptor. Severe inflammation in the lungs of SARS-CoV-2-infected individuals is associated with pneumonia, hypoxia and acute respiratory distress syndrome, these being the causes of death associated with COVID-19. Both the P2X7 receptor and NLRP3 have been considered as potential pharmacological targets for treating inflammation in COVID-19. However, there is no experimental evidence of the involvement of the P2X7 receptor during COVID-19 disease. In the present study, we determined the concentration of different cytokines and the P2X7 receptor in the plasma of COVID-19 patients and found that along with the increase in IL-6, IL-18 and the IL-1 receptor antagonist in the plasma of COVID-19 patients, there was also an increase in the purinergic P2X7 receptor. The increase in COVID-19 severity and C-reactive protein concentration positively correlated with increased concentration of the P2X7 receptor in the plasma, but not with the IL-18 cytokine. The P2X7 receptor was found in the supernatant of human peripheral blood mononuclear cells after inflammasome activation. Therefore, our data suggest that determining the levels of the P2X7 receptor in the plasma could be a novel biomarker of COVID-19 severity.

Characterization of Novel Pathogenic Variants Leading to Caspase-8 Cleavage-Resistant RIPK1-Induced Autoinflammatory Syndrome.

Pathogenic RIPK1 variants have been described as the cause of two different inborn errors of immunity. Biallelic loss-of-function variants cause the recessively inherited RIPK1 deficiency, while monoallelic variants impairing the caspase-8-mediated RIPK1 cleavage provoke a novel autoinflammatory disease (AID) called cleavage-resistant RIPK1-induced autoinflammatory (CRIA) syndrome. The aim of this study was to characterize the pathogenicity of two novel RIPK1 variants located at the cleavage site of caspase-8 detected in patients with dominantly-inherited, early-onset undefined AID. RIPK1 genotyping was performed by Sanger and next-generation sequencing. Clinical and analytical data were collected from medical charts, and in silico and in vitro assays were performed to evaluate the functional consequences. Genetic analyses identified two novel heterozygous RIPK1 variants at the caspase-8 cleavage site (p.Leu321Arg and p.Asp324Gly), which displayed a perfect intrafamilial phenotype-genotype segregation following a dominant inheritance pattern. Structural analyses suggested that these variants disrupt the normal RIPK1 structure, probably making it less accessible to and/or less cleavable by caspase-8. In vitro experiments confirmed that the p.Leu321Arg and p.Asp324Gly RIPK1 variants were resistant to caspase-8-mediated cleavage and induced a constitutive activation of necroptotic pathway in a similar manner that previously characterized RIPK1 variants causing CRIA syndrome. All these results strongly supported the pathogenicity of the two novel RIPK1 variants and the diagnosis of CRIA syndrome in all enrolled patients. Moreover, the evidences here collected expand the phenotypic and genetic diversity of this recently described AID, and provide interesting data about effectiveness of treatments that may benefit future patients.

NLRP3 Inflammasome and Pyroptosis in Liver Pathophysiology: The Emerging Relevance of Nrf2 Inducers.

Inflammasomes, particularly the nucleotide-binding oligomerization domain, leucine-rich repeat, and pyrin domain containing 3 (NLRP3) inflammasome, apparently serve as crucial regulators of the inflammatory response through the activation of Caspase-1 and induction of pro-inflammatory cytokines and pyroptotic cell death. Pyroptosis is a type of programmed cell death mediated by Caspase-1 cleavage of Gasdermin D and the insertion of its N-terminal fragment into the plasma membrane, where it forms pores, enabling the release of different pro-inflammatory mediators. Pyroptosis is considered not only a pro-inflammatory pathway involved in liver pathophysiology but also an important pro-fibrotic mediator. Diverse molecular mechanisms linking oxidative stress, inflammasome activation, pyroptosis, and the progression of liver pathologies have been documented. Numerous studies have indicated the protective effects of several antioxidants, with the ability to induce nuclear factor erythroid 2-related factor 2 (Nrf2) activity on liver inflammation and fibrosis. In this review, we have summarised recent studies addressing the role of the NLRP3 inflammasome and pyroptosis in the pathogenesis of various hepatic diseases, highlighting the potential application of Nrf2 inducers in the prevention of pyroptosis as liver protective compounds.

Assessment of ASC Oligomerization by Flow Cytometry.

Inflammasomes are multiprotein complexes that critically control different aspects of innate and adaptive immunity. Upon activation, inflammasome proteins oligomerize forming scaffolds to nucleate the apoptosis-associated speck-like protein containing a CARD (ASC) in filaments that will finally result in large ASC oligomers that are commonly named as ASC specks. In this chapter, we present a method to monitor NLRP3 or pyrin inflammasome activation in human monocytes upon extracellular ATP or Clostridium difficile toxin B treatment, respectively, by detecting intracellular oligomers of ASC by flow cytometry. This method could be used to evaluate the degree of inflammasome activation in blood samples from patients suffering from different chronic inflammatory diseases.

Proteomics in Liver Transplantation: A Systematic Review.

Background: Although proteomics has been employed in the study of several models of liver injury, proteomic methods have only recently been applied not only to biomarker discovery and validation but also to improve understanding of the molecular mechanisms involved in transplantation. Methods: The study was conducted following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) methodology and the guidelines for performing systematic literature reviews in bioinformatics (BiSLR). The PubMed, ScienceDirect, and Scopus databases were searched for publications through April 2020. Proteomics studies designed to understand liver transplant outcomes, including ischemia-reperfusion injury (IRI), rejection, or operational tolerance in human or rat samples that applied methodologies for differential expression analysis were considered. Results: The analysis included 22 studies after application of the inclusion and exclusion criteria. Among the 497 proteins annotated, 68 were shared between species and 10 were shared between sample sources. Among the types of studies analyzed, IRI and rejection shared a higher number of proteins. The most enriched pathway for liver biopsy samples, IRI, and rejection was metabolism, compared to cytokine-cytokine receptor interactions for tolerance. Conclusions: Proteomics is a promising technique to detect large numbers of proteins. However, our study shows that several technical issues such as the identification of proteoforms or the dynamic range of protein concentration in clinical samples hinder the successful identification of biomarkers in liver transplantation. In addition, there is a need to minimize the experimental variability between studies, increase the sample size and remove high-abundance plasma proteins.

Humanitarian Surgical Missions in Times of COVID-19: Recommendations to Safely Return to a Sub-Saharan Africa Low-Resource Setting.

BACKGROUND: Since the declaration of the pandemic, humanitarian medicine has been discontinued. Until now, there have been no general recommendations on how humanitarian surgical missions should be organized. METHODS: Based on our experience in the field of humanitarian surgical missions to Sub-Saharan Africa, a panel of recommendations in times of COVID-19 was developed. The fields under study were as follows: (1) Planning of a multidisciplinary project; (2) Organization of the infrastructure; (3) Screening, management and treatment of SARS-COV-2; (4) Diagnostic tests for SARS-COV-2; (5) Surgical priorization and (6) Context of patients during health-care assistance. We applied a risk bias measurement to obtain a consensus among humanitarian health-care providers with experience in this field. RESULTS: A total of 94.36% of agreement were reached for the approval of the recommendations. Emergency surgery must be a priority, and elective surgery adapted. For emergency surgery, we established a priority level 1a (< 24 h) and 1b (< 72 h). For an elective procedure, according our American College of Surgeon adaptation score, process with more than 60 points should be reconsidered. Due to the low life expectancy in many African countries, we consider 45-50 years as age of risk. In case of SARS-COV-2 active infection or high clinical suspicion, the screening, management and treatment should be following the international guidelines adapted to duration of the stay, available infrastructure, size of the cooperation team and medical resources. CONCLUSIONS: Humanitarian surgical mission in times of COVID-19 is a challenge that must extrapolate the established recommendations to the local cooperation environment.

Emerging Role of the Inflammasome and Pyroptosis in Hypertension.

Inflammasomes are components of the innate immune response that have recently emerged as crucial controllers of tissue homeostasis. In particular, the nucleotide-binding domain, leucine-rich-containing (NLR) family pyrin domain containing 3 (NLRP3) inflammasome is a complex platform involved in the activation of caspase-1 and the maturation of interleukin (IL)-1ß and IL-18, which are mainly released via pyroptosis. Pyroptosis is a caspase-1-dependent type of cell death that is mediated by the cleavage of gasdermin D and the subsequent formation of structurally stable pores in the cell membrane. Through these pores formed by gasdermin proteins cytosolic contents are released into the extracellular space and act as damage-associated molecular patterns, which are pro-inflammatory signals. Inflammation is a main contributor to the development of hypertension and it also is known to stimulate fibrosis and end-organ damage. Patients with essential hypertension and animal models of hypertension exhibit elevated levels of circulating IL-1ß. Downregulation of the expression of key components of the NLRP3 inflammasome delays the development of hypertension and pharmacological inhibition of this inflammasome leads to reduced blood pressure in animal models and humans. Although the relationship between pyroptosis and hypertension is not well established yet, pyroptosis has been associated with renal and cardiovascular diseases, instances where high blood pressure is a critical risk factor. In this review, we summarize the recent literature addressing the role of pyroptosis and the inflammasome in the development of hypertension and discuss the potential use of approaches targeting this pathway as future anti-hypertensive strategies.