Donor Atheromatous Disease is a Risk Factor for Hepatic Artery Thrombosis After Liver Transplantation.

The increasing age of liver donors and transplant candidates, together with the growing prevalence of metabolic comorbidities, could impact the risk of vascular complications after liver transplantation. We enrolled a consecutive cohort of adult patients undergoing liver transplantation from 2012 to 2021 who had a blinded pathological assessment of atherosclerosis in the donor and recipient hepatic arteries (HA). Patients receiving partial or reduced grafts, retransplantation, or combined organ transplantation were excluded. The relationship between HA atherosclerosis and HA thrombosis after liver transplantation was evaluated using logistic regression in the whole study cohort and in a propensity score-matched subpopulation. Among 443 eligible patients, 272 had a full pathological evaluation of the donor and recipient HA and were included in the study. HA atheroma was present in 51.5% of donors and in 11.4% of recipients. HA thrombosis occurred in 16 patients (5.9%), being more likely in patients who received a donor with HA atherosclerosis than in those without (10.7% vs. 0.8%; p < 0.001). Donor HA atherosclerosis was an independent risk factor of HA thrombosis (OR = 17.79; p = 0.008), and this finding was consistent in the propensity score-matched analysis according to age, sex, complex arterial anastomosis, and alcoholic liver disease (OR = 19.29; p = 0.007). Atheromatous disease in the recipient had no influence on the risk of HA thrombosis (OR = 1.70; p = 0.55). In conclusion, patients receiving donors with HA atherosclerosis are at increased risk for HA thrombosis after liver transplantation. The evaluation of the donor graft vasculature could guide antiplatelet therapy in the postoperative period.

SLAMF7 selectively favors degranulation to promote cytotoxicity in human NK cells.

NK cells play an important role in immunity by recognizing and eliminating cells undergoing infection or malignant transformation. This role is dependent on the ability of NK cells to lyse targets cells in a perforin-dependent mechanism and by secreting inflammatory cytokines. Both effector functions are controlled by several cell surface receptors. The Signaling Lymphocyte Activation Molecule (SLAM) family of receptors plays an essential role in regulating NK cell activation. Several studies have demonstrated that SLAMF7 regulates NK cell activation. However, the molecular and cellular mechanisms by which SLAMF7 influences NK effector functions are unknown. Here, we present evidence that physiological ligation of SLAMF7 in human NK cells enhances the lysis of target cells expressing SLAMF7. This effect was dependent on the ability of SLAMF7 to promote NK cell degranulation rather than cytotoxic granule polarization or cell adhesion. Moreover, SLAMF7-dependent NK cell degranulation was predominantly dependent on PLC-γ when compared to PI3K. These data provide novel information on the cellular mechanism by which SLAMF7 regulates human NK cell activation. Finally, this study supports a model for NK cell activation where activated receptors contribute by regulating specific discrete cellular events rather than multiple cellular processes.

Severity of SARS-CoV-2 infection is linked to double-negative (CD27- IgD-) B cell subset numbers.

OBJECTIVES: The role of B cells in COVID-19, beyond the production of specific antibodies against SARS-CoV-2, is still not well understood. Here, we describe the novel landscape of circulating double-negative (DN) CD27- IgD- B cells in COVID-19 patients, representing a group of atypical and neglected subpopulations of this cell lineage. METHODS: Using multiparametric flow cytometry, we determined DN B cell subset amounts from 91 COVID-19 patients, correlated those with cytokines, clinical and laboratory parameters, and segregated them by principal components analysis. RESULTS: We detected significant increments in the DN2 and DN3 B cell subsets, while we found a relevant decrease in the DN1 B cell subpopulation, according to disease severity and patient outcomes. These DN cell numbers also appeared to correlate with pro- or anti-inflammatory signatures, respectively, and contributed to the segregation of the patients into disease severity groups. CONCLUSION: This study provides insights into DN B cell subsets' potential role in immune responses against SARS-CoV-2, particularly linked to the severity of COVID-19.

Update on Novel Blood-Based Biomarkers for Lupus Nephritis Beyond Diagnostic Approaches.

Abstract: Systemic lupus erythematosus (SLE) is a chronic inflammatory autoimmune disease with a wide range of clinical presentations. Lupus nephritis (LN) is a frequent complication of SLE, representing a significant cause of morbidity and mortality in these patients. In addition, LN diagnosis remains suboptimal in most clinical contexts. The current gold standard for LN clinical diagnosis is a renal biopsy. Still, the invasiveness of this technique is an obstacle to the early detection of renal involvement and further monitoring of treatment results. Consequently, there are different areas for improvement in the field of LN, such as the search for novel non-invasive clinical biomarkers with an adequate correlation between clinical manifestations and actual histological damage. Although urine component-related studies are promising, the more robust blood/serum biomarkers may still be helpful in developing point-of-care systems that can be adapted to most clinical scenarios. Therefore, this brief review aims to highlight and summarize some of the most recently reported non-classical serum/blood potential LN biomarkers. (Rev Invest Clin. 2022;74(5):227-31).

SWATH-MS proteomics of PANC-1 and MIA PaCa-2 pancreatic cancer cells allows identification of drug targets alternative to MEK and PI3K inhibition.

Pancreatic cancer remains one of the most lethal diseases with dismal five-year survival rates. Although mutant KRas protein-driven activation of downstream MAPK Raf/MEK/ERK and PI3K/Akt signaling pathways represent major oncogenic alterations, signaling blockade with MEK and PI3K inhibitors has shown that intrinsic resistance may hamper the effectiveness of this targeted approach. However, there have been no mass spectrometry-based proteomic studies for in-depth comparison of protein expression differences between pancreatic cancer cells with sensitivity and resistance to MEK and PI3K kinase inhibitors. In this work, we compared PANC-1 and MIA PaCa-2 pancreatic cancer cells which are, respectively, resistant and sensitive to MEK- and PI3K-targeted therapy. We conducted a label-free data-independent acquisition mass spectrometry (SWATH-MS) study with extensive peptide fractionation to quantitate 4808 proteins and analyze differential expression of 743 proteins between resistant and sensitive cells. This allowed identification of the tumor suppressor protein phosphatase 2A (PP2A) and proteins from mitochondrial respiratory complex I implicated in oxidative phosphorylation as alternative candidate drug targets for cells resistant to MEK and PI3K inhibition. PP2A activator DT-061 decreased viability of PANC-1 cells and this was accompanied by reduced expression of c-Myc. PANC-1 cells also showed response to metformin and the novel complex I inhibitor IACS-010759. These findings provide insights into the distinct cellular proteomes and point out alternative pharmacological targets for MEK and PI3K inhibition-resistant pancreatic cancer cells.

mTOR Expression in Liver Transplant Candidates with Hepatocellular Carcinoma: Impact on Histological Features and Tumour Recurrence.

(1) Background: The mammalian target of rapamycin (mTOR) pathway activation is critical for hepatocellular carcinoma (HCC) progression. We aimed to evaluate the mTOR tissue expression in liver transplant (LT) patients and to analyse its influence on post-LT outcomes. (2) Methods: Prospective study including a cohort of HCC patients who underwent LT (2012⁻2015). MTOR pathway expression was evaluated in the explanted liver by using the "PathScan Intracellular Signalling Array Kit" (Cell Signalling). Kaplan-Meier and Cox regression analyses were performed to evaluate post-LT HCC recurrence. (3) Results: Forty-nine patients were included (average age 56.4 ± 6, 14.3% females). Phospho-mTOR (Ser2448) was over-expressed in peritumoral tissue as compared with tumoral tissue (ΔSignal 22.2%; p < 0.001). The mTOR activators were also increased in peritumoral tissue (phospho-Akt (Thr308) ΔSignal 18.2%, p = 0.004; phospho-AMPKa (Thr172) ΔSignal 56.3%, p < 0.001), as they were the downstream effectors responsible for cell growth/survival (phospho-p70S6K (Thr389) ΔSignal 33.3%, p < 0.001 and phospho-S6RP (Ser235/236) ΔSignal 54.6%, p < 0.001). MTOR expression was increased in patients with multinodular HCC (tumoral p = 0.01; peritumoral p = 0.001). Increased phospho-mTOR in tumoral tissue was associated with higher HCC recurrence rates after LT (23.8% vs. 5.9% at 24 months, p = 0.04). (4) Conclusion: mTOR pathway is over-expressed in patients with multinodular HCC and is it associated with increased post-LT tumour recurrence rates.

CLINICAL AND BIOMEDICAL APPLICATIONS OF SURFACE PLASMON RESONANCE SYSTEMS.

Surface plasmon resonance (SPR)-based biosensors offer superior analytical features such as simplicity, sensitivity, and specificity when compared to conventional methods in clinical analyses. In addition, they deliver real-time monitoring of label-free analytes with high-throughput approaches requiring little sample pretreatment that allows the analysis of virtually every clinical sample type to determine the amount and/or activity of any molecule of interest. Accordingly, SPR emerges as a novel, efficient, powerful, and relatively low-cost alternative tool for routine clinical analysis, opening also new horizons for developments in personalized medicine applied to diagnostics or therapeutics' monitoring.

High efficacy of Sofosbuvir plus Simeprevir in a large cohort of Spanish cirrhotic patients infected with genotypes 1 and 4.

BACKGROUND AND AIMS: Hepatitis C (HCV) therapy with Sofosbuvir (SOF)/Simeprevir (SMV) in clinical trials and real-world clinical practice, showed high rates of sustained virological response (SVR) in non-cirrhotic genotype (GT)-1 and GT-4 patients. These results were slightly lower in cirrhotic patients. We investigated real-life effectiveness and safety of SOF/SMV with or without ribavirin (RBV) in a large cohort of cirrhotic patients. METHODS: This collaborative multicentre study included data from 968 patients with cirrhosis infected with HCV-GT1 or 4, treated with SOF/SMV±RBV in 30 centres across Spain between January-2014 and December-2015. Demographic, clinical, virological and safety data were analysed. RESULTS: Overall SVR was 92.3%; the majority of patients were treated with RBV (62%) for 12 weeks (92.4%). No significant differences in SVR were observed between genotypes (GT1a:94.3%; GT1b:91.7%; GT4:91.1%). Those patients with more advanced liver disease (Child B/C, MELD≥10) or portal hypertension (platelet count≤100×109 /L, transient elastography≥21 Kpa) showed significantly lower SVR rates (84.4%-91.9%) than patients with less advanced liver disease (93.8%-95.9%, P<.01 in all cases). In the multivariate analysis, the use of RBV, female gender, baseline albumin≥35 g/L, MELD<10 and lack of exposure to a triple therapy regimen were independent predictors of SVR (P<.05). Serious adverse events (SAEs) and SAE-associated discontinuation events occurred in 5.9% and 2.6%. CONCLUSIONS: In this large cohort of cirrhotic patients managed in the real-world setting in Spain, SOF/SMV±RBV yielded to excellent SVR rates, especially in patients with compensated liver cirrhosis. In addition, this combination showed to be safe, with low rates of SAEs and early discontinuations.

Cutting edge: GPR35/CXCR8 is the receptor of the mucosal chemokine CXCL17.

Chemokines are chemotactic cytokines that direct the traffic of leukocytes and other cells in the body. Chemokines bind to G protein-coupled receptors expressed on target cells to initiate signaling cascades and induce chemotaxis. Although the cognate receptors of most chemokines have been identified, the receptor for the mucosal chemokine CXCL17 is undefined. In this article, we show that GPR35 is the receptor of CXCL17. GPR35 is expressed in mucosal tissues, in CXCL17-responsive monocytes, and in the THP-1 monocytoid cell line. Transfection of GPR35 into Ba/F3 cells rendered them responsive to CXCL17, as measured by calcium-mobilization assays. Furthermore, GPR35 expression is downregulated in the lungs of Cxcl17(-/-) mice, which exhibit defects in macrophage recruitment to the lungs. We conclude that GPR35 is a novel chemokine receptor and suggest that it should be named CXCR8.

Human B Regulatory Cells: The New Players in Autoimmune Disease.

Although the production of antigen-specific antibodies has been the originally accepted function of B-cells during immune responses, specific subsets that can negatively regulate inflammation, designated regulatory B-cells (Bregs), have been identified recently. These immunosuppressive cells support tolerance, mainly through the production of interleukin 10 and other unconventional factors. There have been emerging data suggesting their importance in diverse normal and pathologic processes. Novel and in development B-cell targeted therapies seem to be ideal treatments for different types of diseasessuch as cancer and allergy. Here, we discuss the current knowledge on the implication of Bregs in autoimmunity- elated diseases, highlighting the importance of these cells for the development of novel strategies in the treatment of these pathologies.

CXCL17 is a major chemotactic factor for lung macrophages.

Chemokines are a superfamily of chemotactic cytokines that direct the movement of cells throughout the body under homeostatic and inflammatory conditions. The mucosal chemokine CXCL17 was the last ligand of this superfamily to be characterized. Several recent studies have provided greater insight into the basic biology of this chemokine and have implicated CXCL17 in several human diseases. We sought to better characterize CXCL17's activity in vivo. To this end, we analyzed its chemoattractant properties in vivo and characterized a Cxcl17 (-/-) mouse. This mouse has a significantly reduced number of macrophages in its lungs compared with wild-type mice. In addition, we observed a concurrent increase in a new population of macrophage-like cells that are F4/80(+)CDllc(mid). These results indicate that CXCL17 is a novel macrophage chemoattractant that operates in mucosal tissues. Given the importance of macrophages in inflammation, these observations strongly suggest that CXCL17 is a major regulator of mucosal inflammatory responses.

Myosin 1g regulates cytoskeleton plasticity, cell migration, exocytosis, and endocytosis in B lymphocytes.

Myosin 1g (Myo1g) is a hematopoietic-specific myosin expressed mainly by lymphocytes. Here, we report the localization of Myo1g in B-cell membrane compartments such as lipid rafts, microvilli, and membrane extensions formed during spreading. By using Myo1g-deficient mouse B cells, we detected abnormalities in the adhesion ability and chemokine-induced directed migration of these lymphocytes. We also assessed a role for Myo1g in phagocytosis and exocytosis processes, as these were also irregular in Myo1g-deficient B cells. Taken together, our results show that Myo1g acts as a main regulator of different membrane/cytoskeleton-dependent processes in B lymphocytes.

Portable platform for leukocyte extraction from blood using sheath-free microfluidic DLD.

Leukocyte count is routinely performed for diagnostic purposes and is rapidly emerging as a significant biomarker for a wide array of diseases. Additionally, leukocytes have demonstrated considerable promise in novel cell-based immunotherapies. However, the direct retrieval of leukocytes from whole blood is a significant challenge due to their low abundance compared to erythrocytes. Here, we introduce a microfluidic-based platform that isolates and recovers leukocytes from diluted whole blood in a single step. Our platform utilizes a novel, sheathless method to initially sediment and focus blood cells into a dense stream while flowing through a tubing before entering the microfluidic device. A hexagonal-shaped structure, patterned at the device's inlet, directs all the blood cells against the channel's outer walls. The focused cells are then separated based on their size using the deterministic lateral displacement (DLD) microfluidic technique. We evaluated various parameters that could influence leukocyte separation, including different focusing structures (assessed both computationally and experimentally), the orientation of the tubing-chip interface, the effects of blood sample hematocrit (dilution), and flow rate. Our device demonstrated the ability to isolate leukocytes from diluted blood with a separation efficiency of 100%, a recovery rate of 76%, and a purity of 80%, while maintaining a cell viability of 98%. The device operates for over 30 min at a flow rate of 2 µL min-1. Furthermore, we developed a handheld pressure controller to drive fluid flow, enhancing the operability of our platform outside of central laboratories and enabling near-patient testing. Our platform can be integrated with downstream cell-based assays and analytical methods that require high leukocyte purity (80%), ranging from cell counting to diagnostics and cell culture applications.

Novel B-cell subsets as potential biomarkers in idiopathic inflammatory myopathies: insights into disease pathogenesis and disease activity.

Idiopathic inflammatory myopathies are a heterogeneous group of rare autoimmune disorders characterized by progressive muscle weakness and the histopathologic findings of inflammatory infiltrates in muscle tissue. Although their pathogenesis remains indefinite, the association of autoantibodies with clinical manifestations and the evidence of high effectiveness of depleting therapies suggest that B cells could be implicated. Therefore, we explored the landscape of peripheral B cells in this disease by multiparametric flow cytometry, finding significant numerical decreases in memory and double-negative subsets, as well as an expansion of the naive compartment relative to healthy controls, that contribute to defining disease-associated B-cell subset signatures and correlating with different clinical features of patients. Additionally, we determined the potential value of these subsets as diagnostic biomarkers, thus positioning B cells as neglected key elements possibly participating in idiopathic inflammatory myopathy onset or development.

CCL28 modulates neutrophil responses during infection with mucosal pathogens.

The chemokine CCL28 is highly expressed in mucosal tissues, but its role during infection is not well understood. Here we show that CCL28 promotes neutrophil accumulation in the gut of mice infected with Salmonella and in the lung of mice infected with Acinetobacter. Neutrophils isolated from the infected mucosa expressed the CCL28 receptors CCR3 and, to a lesser extent, CCR10, on their surface. The functional consequences of CCL28 deficiency varied between the two infections: Ccl28-/- mice were highly susceptible to Salmonella gut infection but highly resistant to otherwise lethal Acinetobacter lung infection. In vitro, unstimulated neutrophils harbored pre-formed intracellular CCR3 that was rapidly mobilized to the cell surface following phagocytosis or inflammatory stimuli. Moreover, CCL28 stimulation enhanced neutrophil antimicrobial activity, production of reactive oxygen species, and formation of extracellular traps, all processes largely dependent on CCR3. Consistent with the different outcomes in the two infection models, neutrophil stimulation with CCL28 boosted the killing of Salmonella but not Acinetobacter. CCL28 thus plays a critical role in the immune response to mucosal pathogens by increasing neutrophil accumulation and activation, which can enhance pathogen clearance but also exacerbate disease depending on the mucosal site and the infectious agent.

Myosin 1c participates in B cell cytoskeleton rearrangements, is recruited to the immunologic synapse, and contributes to antigen presentation.

Myosin 1c (Myo1c) is a member of the unconventional class I myosins of vertebrates, which directly link the plasma membrane with the microfilament cortical web. Although this molecular motor has been implicated in cell functions such as cytoskeleton organization, cell motility, nuclear transcription, and endocytosis, its role in hematopoietic cells is largely unknown. In this study, we show that Myo1c is abundantly expressed in murine B lymphocytes and is preferentially located at the plasma membrane, especially in peripheral processes such as microvilli. We observed that this motor concentrates at the growing membrane protrusions generated during B cell spreading and that it is actively recruited to the immune synapse. Interestingly, Myo1c was detected in lipid rafts of B cells and showed strong colocalization with MHC-II, particularly after cross-linking of these molecules. By transfection of a dominant negative form of Myo1c or specific siRNA, we also detected alterations in the spreading and Ag-presenting ability of these cells. The data suggest that Myo1c is involved in the cytoskeleton dynamics and membrane protein anchoring or sorting in B lymphocytes.

On-Chip Analysis of Protein Secretion from Single Cells Using Microbead Biosensors.

The profiling of the effector functions of single immune cells─including cytokine secretion─can lead to a deeper understanding of how the immune system operates and to potential diagnostics and therapeutical applications. Here, we report a microfluidic device that pairs single cells and antibody-functionalized microbeads in hydrodynamic traps to quantitate cytokine secretion. The device contains 1008 microchambers, each with a volume of ∼500 pL, divided into six different sections individually addressed to deliver an equal number of chemical stimuli. Integrating microvalves allowed us to isolate cell/bead pairs, preventing cross-contamination with factors secreted by adjacent cells. We implemented a fluorescence sandwich immunoassay on the biosensing microbeads with a limit of detection of 9 pg/mL and were able to detect interleukin-8 (IL-8) secreted by single blood-derived human monocytes in response to different concentrations of LPS. Finally, our platform allowed us to observe a significant decrease in the number of IL-8-secreting monocytes when paracrine signaling becomes disrupted. Overall, our platform could have a variety of applications for which the analysis of cellular function heterogeneity is necessary, such as cancer research, antibody discovery, or rare cell screening.

Salivary IgA subtypes as novel disease biomarkers in systemic lupus erythematosus.

Introduction: Immunoglobulin A (IgA) is the main antibody isotype in body fluids such as tears, intestinal mucous, colostrum, and saliva. There are two subtypes of IgA in humans: IgA1, mainly present in blood and mucosal sites, and IgA2, preferentially expressed in mucosal sites like the colon. In clinical practice, immunoglobulins are typically measured in venous or capillary blood; however, alternative samples, including saliva, are now being considered, given their non-invasive and easy collection nature. Several autoimmune diseases have been related to diverse abnormalities in oral mucosal immunity, such as rheumatoid arthritis, Sjogren's syndrome, and systemic lupus erythematosus (SLE). Methods: We decided to evaluate the levels of both IgA subtypes in the saliva of SLE patients. A light chain capture-based ELISA measured specific IgA1 and IgA2 levels in a cohort of SLE patients compared with age and gender-matched healthy volunteers. Results: Surprisingly, our results indicated that in the saliva of SLE patients, total IgA and IgA1 subtype were significantly elevated; we also found that salivary IgA levels, particularly IgA2, positively correlate with anti-dsDNA IgG antibody titers. Strikingly, we also detected the presence of salivary anti-nucleosome IgA antibodies in SLE patients, a feature not previously reported elsewhere. Conclusions: According to our results and upon necessary validation, IgA characterization in saliva could represent a potentially helpful tool in the clinical care of SLE patients with the advantage of being a more straightforward, faster, and safer method than manipulating blood samples.

Consequences of two naturally occurring missense mutations in the structure and function of Bruton agammaglobulinemia tyrosine kinase.

Bruton agammaglobulinemia tyrosine kinase (BTK) is a key protein in the B-cell receptor (BCR) signaling pathway and plays an essential role in the differentiation of B lymphocytes. X-linked agammaglobulinemia (XLA) is a primary humoral immunodeficiency caused by mutations in the gene encoding BTK. Previously, we identified two novel variations, L111P and E605G, in BTK; these are localized within the pleckstrin homology and Src homology 1 domains, respectively. In the present study, we evaluated the potential effects of these variations on the structural conformation and the function of BTK. Using in silico methods, we found that the L111P and E650G variations are not located directly in protein-protein interfaces but close to them. They distorted the native structural conformation of the BTK protein, affecting not only its geometry and stability but also its ability for protein recognition and in consequence its functionality. To confirm the results of the in silico assays, WT BTK, L111P, and E650G variants were expressed in the BTK-deficient DT40 cell line. The mutant proteins exhibited an absence of catalytic activity, aberrant redistribution after BCR-crosslinking, and deficient intracellular calcium mobilization. This work demonstrates that L111 and E605 residues are fundamental for the activation and function of BTK.

Metabolomics analysis identifies glutamic acid and cystine imbalances in COVID-19 patients without comorbid conditions. Implications on redox homeostasis and COVID-19 pathophysiology.

It is well known that the presence of comorbidities and age-related health issues may hide biochemical and metabolic features triggered by SARS-CoV-2 infection and other diseases associated to hypoxia, as they are by themselves chronic inflammatory conditions that may potentially disturb metabolic homeostasis and thereby negatively impact on COVID-19 progression. To unveil the metabolic abnormalities inherent to hypoxemia caused by COVID-19, we here applied gas chromatography coupled to mass spectrometry to analyze the main metabolic changes exhibited by a population of male patients less than 50 years of age with mild/moderate and severe COVID-19 without pre-existing comorbidities known to predispose to life-threatening complications from this infection. Several differences in serum levels of particular metabolites between normal controls and patients with COVID-19 as well as between mild/moderate and severe COVID-19 were identified. These included increased glutamic acid and reduced glutamine, cystine, threonic acid, and proline levels. In particular, using the entire metabolomic fingerprint obtained, we observed that glutamine/glutamate metabolism was associated with disease severity as patients in the severe COVID-19 group presented the lowest and higher serum levels of these amino acids, respectively. These data highlight the hypoxia-derived metabolic alterations provoked by SARS-CoV-2 infection in the absence of pre-existing co-morbidities as well as the value of amino acid metabolism in determining reactive oxygen species recycling pathways, which when impaired may lead to increased oxidation of proteins and cell damage. They also provide insights on new supportive therapies for COVID-19 and other disorders that involve altered redox homeostasis and lower oxygen levels that may lead to better outcomes of disease severity.