Machine Learning Identifies Key Proteins in Primary Sclerosing Cholangitis Progression and Links High CCL24 to Cirrhosis.

Primary sclerosing cholangitis (PSC) is a rare, progressive disease, characterized by inflammation and fibrosis of the bile ducts, lacking reliable prognostic biomarkers for disease activity. Machine learning applied to broad proteomic profiling of sera allowed for the discovery of markers of disease presence, severity, and cirrhosis and the exploration of the involvement of CCL24, a chemokine with fibro-inflammatory activity. Sera from 30 healthy controls and 45 PSC patients were profiled with proximity extension assay, quantifying the expression of 2870 proteins, and used to train an elastic net model. Proteins that contributed most to the model were tested for correlation to enhanced liver fibrosis (ELF) score and used to perform pathway analysis. Statistical modeling for the presence of cirrhosis was performed with principal component analysis (PCA), and receiver operating characteristics (ROC) curves were used to assess the useability of potential biomarkers. The model successfully predicted the presence of PSC, where the top-ranked proteins were associated with cell adhesion, immune response, and inflammation, and each had an area under receiver operator characteristic (AUROC) curve greater than 0.9 for disease presence and greater than 0.8 for ELF score. Pathway analysis showed enrichment for functions associated with PSC, overlapping with pathways enriched in patients with high levels of CCL24. Patients with cirrhosis showed higher levels of CCL24. This data-driven approach to characterize PSC and its severity highlights potential serum protein biomarkers and the importance of CCL24 in the disease, implying its therapeutic potential in PSC.

Targeting CCL24 in Inflammatory and Fibrotic Diseases: Rationale and Results from Three CM-101 Phase 1 Studies.

BACKGROUND: Overexpression of C-C motif chemokine ligand 24 (CCL24) is associated with inflammatory and fibrotic diseases, including primary sclerosing cholangitis (PSC), systemic sclerosis, metabolic dysfunction-associated steatotic liver disease (MASLD) and metabolic dysfunction-associated steatohepatitis (MASH). CM-101 is a humanized monoclonal antibody that neutralizes CCL24 to attenuate inflammation and fibrosis in preclinical models. Here we report the results from two Phase 1a studies investigating the safety and tolerability of intravenous (IV) and subcutaneous (SC) CM-101 in healthy participants, and in one Phase 1b study of IV and SC CM-101 in patients with MASLD without evidence of MASH. METHODS: In each dose group (0.75 mg/kg, 2.5 mg/kg, 5.0 mg/kg, and 10.0 mg/kg) of the single-center, double-blind, placebo-controlled Phase 1a IV study, healthy volunteers were randomized 3:1 to receive a single IV infusion of CM-101 or placebo. In another Phase 1a, single-center, double-blind placebo-controlled study, healthy volunteers were randomized 3:1 to receive a single SC injection of CM-101 5.0 mg/kg or placebo. In the multicenter, double-blind, placebo-controlled Phase 1b MASLD study, patients with MASLD without evidence of MASH were randomized 3:1 to receive the following: cohort 1, IV CM-101 2.5 mg/kg or placebo, and cohort 2, SC CM-101 5.0 mg/kg or placebo every three weeks for 12 weeks. The primary endpoints (for all these studies) were safety, tolerability, and serum pharmacokinetic parameters of CM-101. RESULTS: In each study, adverse events were rare and mild to moderate. The CM-101 pharmacokinetics profile was typical of a monoclonal antibody, with a terminal half-life of approximately 19 days when given IV and approximately 17 days when given as SC injection. In patients with MASLD without evidence of MASH, CM-101 was associated with decreased serum levels of inflammatory, fibrotic, and collagen turnover biomarkers. CONCLUSIONS: In healthy volunteers and patients with MASLD without evidence of MASH, IV and SC CM-101 was well tolerated at doses ranging from 0.75 mg/kg to10.0 mg/kg and engaged its target (i.e., CCL24), indicating therapeutic potential in treating inflammatory and fibrotic diseases. CLINICAL TRIAL RETROSPECTIVELY REGISTRATION: NCT06025851, NCT06037577, and NCT06044467. Date of registration: September 2023.

The Role of CCL24 in Primary Sclerosing Cholangitis: Bridging Patient Serum Proteomics to Preclinical Data.

Primary sclerosing cholangitis (PSC) is an inflammatory and fibrotic biliary disease lacking approved treatment. We studied CCL24, a chemokine shown to be overexpressed in damaged bile ducts, and its involvement in key disease-related mechanisms. Serum proteomics of PSC patients and healthy controls (HC) were analyzed using the Olink® proximity extension assay and compared based on disease presence, fibrosis severity, and CCL24 levels. Disease-related canonical pathways, upstream regulators, and toxicity functions were elevated in PSC patients compared to HC and further elevated in patients with high CCL24 levels. In vitro, a protein signature in CCL24-treated hepatic stellate cells (HSCs) differentiated patients by disease severity. In mice, CCL24 intraperitoneal injection selectively recruited neutrophils and monocytes. Treatment with CM-101, a CCL24-neutralizing antibody, in an α-naphthylisothiocyanate (ANIT)-induced cholestasis mouse model effectively inhibited accumulation of peribiliary neutrophils and macrophages while reducing biliary hyperplasia and fibrosis. Furthermore, in PSC patients, CCL24 levels were correlated with upregulation of monocyte and neutrophil chemotaxis pathways. Collectively, these findings highlight the distinct role of CCL24 in PSC, influencing disease-related mechanisms, affecting immune cells trafficking and HSC activation. Its blockade with CM-101 reduces inflammation and fibrosis and positions CCL24 as a promising therapeutic target in PSC.

Chronic Human Pegivirus 2 without Hepatitis C Virus Co-infection.

Most human pegivirus 2 (HPgV-2) infections are associated with past or current hepatitis C virus (HCV) infection. HPgV-2 is thought to be a bloodborne virus: higher prevalence of active infection has been found in populations with a history of parenteral exposure to viruses. We evaluated longitudinally collected blood samples obtained from injection drug users (IDUs) for active and resolved HPgV-2 infections using a combination of HPgV-2-specific molecular and serologic tests. We found evidence of HPgV-2 infection in 11.2% (22/197) of past or current HCV-infected IDUs, compared with 1.9% (4/205) of an HCV-negative IDU population. Testing of available longitudinal blood samples from HPgV-2-positive participants identified 5 with chronic infection (>6 months viremia in >3 timepoints); 2 were identified among the HCV-positive IDUs and 3 among the HCV-negative IDUs. Our findings indicate that HPgV-2 can establish chronic infection and replicate in the absence of HCV.

Recovery of the Gut Microbiota after Antibiotics Depends on Host Diet, Community Context, and Environmental Reservoirs.

Antibiotics alter microbiota composition and increase infection susceptibility. However, the generalizable effects of antibiotics on and the contribution of environmental variables to gut commensals remain unclear. To address this, we tracked microbiota dynamics with high temporal and taxonomic resolution during antibiotic treatment in a controlled murine system by isolating variables such as diet, treatment history, and housing co-inhabitants. Human microbiotas were remarkably resilient and recovered during antibiotic treatment, with transient dominance of resistant Bacteroides and taxa-asymmetric diversity reduction. In certain cases, in vitro sensitivities were not predictive of in vivo responses, underscoring the significance of host and community context. A fiber-deficient diet exacerbated microbiota collapse and delayed recovery. Species replacement through cross housing after ciprofloxacin treatment established resilience to a second treatment. Single housing drastically disrupted recovery, highlighting the importance of environmental reservoirs. Our findings highlight deterministic microbiota adaptations to perturbations and the translational potential for modulating diet, sanitation, and microbiota composition during antibiotics.

Hepatitis C virus surveillance and identification of human pegivirus 2 in a large Cameroonian cohort.

The prevalence of chronic hepatitis C virus (HCV) and the presence of human pegivirus 2 (HPgV-2) have not been examined in Cameroon, although HCV has been associated with HPgV-2 infections previously. Herein we aimed to characterize the burden and genetic diversity of HCV and the presence of HPgV-2 in Cameroon. Retrospective plasma specimens collected from N = 12 369 consenting subjects in South Cameroon from 2013 to 2016 were included in the study. The majority (97.1%) of participants were patients seeking health care. All specimens were screened for HCV using the Abbott RealTime HCV viral load assay and positive specimens with remaining volume were also screened for HPgV-2 antibodies on the Abbott ARCHITECT instrument, followed by molecular characterization. Overall, HCV RNA was detected in 305 (2.47%; 95% CI: 2.21%-2.75%) specimens. Notably, the prevalence of HCV RNA was 9.09% amongst participants over age 40 and 3.81% amongst males. Phylogenetic classification of N = 103 HCV sequences identified genotypes 1 (19.4%), 2 (15.5%) and 4 (65.1%) within the study cohort. Amongst HCV RNA-positive specimens, N = 28 (10.6%; 95% CI: 7.44%-14.90%) specimens also had detectable HPgV-2 antibodies. Of these, N = 2 viremic HPgV-2 infections were confirmed by sequencing and shared 93-94 median % identity with strains found on other continents. This is the first study to determine the prevalence of chronic HCV in Cameroon, and the discovery of HPgV-2 in this study cohort expands the geography of HPgV-2 to the African continent, indicating a widespread distribution exists.

Development of the Abbott RealTime ZIKA assay for the qualitative detection of Zika virus RNA from serum, plasma, urine, and whole blood specimens using the m2000 system.

Zika virus is an arthropod-borne flavivirus that has rapidly developed into a world-wide concern. Discovered in 1947, the virus was relatively obscure until an outbreak occurred in 2007 in the Yap islands and spread eventually to the Americas in 2015. Only 20% of patients infected with Zika virus develop symptoms. However, there can be serious consequences of infection including birth defects in developing fetuses and links to Guillain-Barré syndrome. The swift rise in infections has necessitated the development of diagnostic tests for both the detection of viral RNA and the presence of virus-specific antibodies. Abbott has developed a dual target RT-PCR assay for the detection of Zika virus RNA within serum, plasma, whole blood, and urine using the automated m2000 system for sample extraction to result reporting. The Abbott RealTime ZIKA assay has a limit of detection of 30 copies per mL in serum, 40 copies per mL in plasma and urine, and 120 copies per mL in whole blood and demonstrates high specificity against challenges from closely related infectious agents.

Development of a high-throughput multiplexed real time RT-PCR assay for detection of human pegivirus 1 and 2.

Human Pegivirus 2 (HPgV-2) was recently identified in the bloodstream of HCV-infected and multiply transfused individuals. Initial reports show HPgV-2 circulates at a low prevalence in HCV co-infected individuals, necessitating testing of large cohorts of samples to identify infected persons. The identification of additional HPgV-2 cases was facilitated by the development of a high throughput and reliable molecular reverse transcription polymerase chain reaction (RT-PCR) assay intended for use on the automated Abbott m2000 system with a capability of extracting and testing 96 samples at once. A dual target approach was taken to reduce the risk of a false-negative result, amplifying sequences within the 5' UTR and NS2/3 coding regions of HPgV-2. The assay was expanded to multiplex detection of the other human Pegivirus, HPgV-1 (formerly GBV-C), to allow simultaneous prevalence comparison. The limit of detection (LOD; 95% detection) for HPgV-2 was experimentally determined to be 126 copies/mL. Through use of the newly developed multiplex assay, 21 strains of HPgV-2 circulating in HCV past or present infections were identified, with all strains confirmed by next generation sequencing. The multiplexed assay has high specificity and showed no cross-reactivity of HPgV-2 with HPgV-1 or other Flaviviruses. This automated assay will be instrumental in future studies addressing HPgV-2 pathogenicity, prevalence, and sequence diversity.

Antibodies to the Novel Human Pegivirus 2 Are Associated with Active and Resolved Infections.

A novel blood-borne human pegivirus (HPgV), HPgV-2, was recently identified in hepatitis C virus (HCV)-infected individuals and individuals who had received multiple transfusions. Robust serological assays capable of detecting antibodies in HPgV-2-infected individuals are needed to establish global seroprevalence rates and potential disease associations. The two objectives of this study were to determine the utility of mammalian cell-expressed HPgV-2 E2 glycoprotein or bacterium-expressed nonstructural protein 4AB (NS4AB) in detecting past or present infections and to compare the total prevalence (antibody and RNA positive) of HPgV-2 with that of the other human pegivirus, HPgV-1 (GB virus C [GBV-C]). HPgV-2 E2 antibodies were detected in 13 (92.86%) of 14 HPgV-2-viremic cases, and NS4AB antibodies were detected in 8 (57.14%) of 14 cases. The HPgV-2 seroprevalence was significantly higher (P < 0.0001) among HCV-infected individuals (3.31% [24 of 726 samples]) than among non-HCV-infected individuals (0.30% [4 of 1,348 samples]). Of 31 anti-E2-positive samples, 22 had supplemental supporting data; 12 samples were HPgV-2 RNA positive and 10 nonviremic samples were antibody positive for peptides or NS4AB. The total prevalence of HPgV-1 (35.00%) was significantly higher than that of HPgV-2 (1.33%) in all populations tested (P < 0.0001). For HPgV-1, codetection of antibodies to E2 and RNA was infrequent (5.88%). In contrast, antibodies to E2 were detected in most HPgV-2-viremic individuals (92.86%), as is observed among individuals chronically infected with HCV, most of whom are antibody positive for HCV E2. Our studies indicate that HPgV-2 circulates with HCV and displays a profile similar to the serological profile of HCV-infected persons, although the pathogenicity of this virus has yet to be established.

SagB Glucosaminidase Is a Determinant of Staphylococcus aureus Glycan Chain Length, Antibiotic Susceptibility, and Protein Secretion.

UNLABELLED: The envelope of Staphylococcus aureus is comprised of peptidoglycan and its attached secondary polymers, teichoic acid, capsular polysaccharide, and protein. Peptidoglycan synthesis involves polymerization of lipid II precursors into glycan strands that are cross-linked at wall peptides. It is not clear whether peptidoglycan structure is principally determined during polymerization or whether processive enzymes affect cell wall structure and function, for example, by generating conduits for protein secretion. We show here that S. aureus lacking SagB, a membrane-associated N-acetylglucosaminidase, displays growth and cell-morphological defects caused by the exaggerated length of peptidoglycan strands. SagB cleaves polymerized glycan strands to their physiological length and modulates antibiotic resistance in methicillin-resistant S. aureus (MRSA). Deletion of sagB perturbs protein trafficking into and across the envelope, conferring defects in cell wall anchoring and secretion, as well as aberrant excretion of cytoplasmic proteins. IMPORTANCE: Staphylococcus aureus is thought to secrete proteins across the plasma membrane via the Sec pathway; however, protein transport across the cell wall envelope has heretofore not been studied. We report that S. aureus sagB mutants generate elongated peptidoglycan strands and display defects in protein secretion as well as aberrant excretion of cytoplasmic proteins. These results suggest that the thick peptidoglycan layer of staphylococci presents a barrier for protein secretion and that SagB appears to extend the Sec pathway across the cell wall envelope.

Discovery of a Novel Human Pegivirus in Blood Associated with Hepatitis C Virus Co-Infection.

Hepatitis C virus (HCV) and human pegivirus (HPgV), formerly GBV-C, are the only known human viruses in the Hepacivirus and Pegivirus genera, respectively, of the family Flaviviridae. We present the discovery of a second pegivirus, provisionally designated human pegivirus 2 (HPgV-2), by next-generation sequencing of plasma from an HCV-infected patient with multiple bloodborne exposures who died from sepsis of unknown etiology. HPgV-2 is highly divergent, situated on a deep phylogenetic branch in a clade that includes rodent and bat pegiviruses, with which it shares <32% amino acid identity. Molecular and serological tools were developed and validated for high-throughput screening of plasma samples, and a panel of 3 independent serological markers strongly correlated antibody responses with viral RNA positivity (99.9% negative predictive value). Discovery of 11 additional RNA-positive samples from a total of 2440 screened (0.45%) revealed 93-94% nucleotide identity between HPgV-2 strains. All 12 HPgV-2 RNA-positive cases were identified in individuals also testing positive for HCV RNA (12 of 983; 1.22%), including 2 samples co-infected with HIV, but HPgV-2 RNA was not detected in non-HCV-infected individuals (p<0.0001), including those singly infected by HIV (p = 0.0075) or HBV (p = 0.0077), nor in volunteer blood donors (p = 0.0082). Nine of the 12 (75%) HPgV-2 RNA positive samples were reactive for antibodies to viral serologic markers, whereas only 28 of 2,429 (1.15%) HPgV-2 RNA negative samples were seropositive. Longitudinal sampling in two individuals revealed that active HPgV-2 infection can persist in blood for at least 7 weeks, despite the presence of virus-specific antibodies. One individual harboring both HPgV-2 and HCV RNA was found to be seronegative for both viruses, suggesting a high likelihood of simultaneous acquisition of HCV and HPgV-2 infection from an acute co-transmission event. Taken together, our results indicate that HPgV-2 is a novel bloodborne infectious virus of humans and likely transmitted via the parenteral route.

Switching to Omnitrope(®) from Other Recombinant Human Growth Hormone Therapies: A Retrospective Study in an Integrated Healthcare System.

INTRODUCTION: This study was conducted using an integrated retrospective database to evaluate the effectiveness of Omnitrope(®) (Sandoz) on children with growth hormone deficiency (GHD), idiopathic short stature (ISS), and Turner Syndrome (TS) who switched from a non-Omnitrope recombinant human growth hormone (rhGH) preparation during routine clinical care. METHODS: This was a retrospective study which identified patients with GHD, ISS, and TS during the study time period of January 1, 2006 and July 31, 2011. Patients were included if they switched to Omnitrope from another non-Omnitrope rhGH therapy during the study time period, were <18 years of age at time of switch, and on a prior rhGH therapy for at least 15 months pre-switch and on Omnitrope for 15 months post-switch. Auxological parameters (height, height standard deviation score [HSDS], height velocity [HV], and height velocity standard deviation score [HVSDS]) were evaluated during post-switch. RESULTS: One hundred and three patients were identified: GHD (n = 57), ISS (n = 26), and TS (n = 20). There was continuous growth in height for all 103 patients with an average rate of 6.52 cm over the 15-month post-switch period. Patients with GHD grew an average rate of 6.30 cm, patients with ISS grew an average rate of 6.58 cm, and patients with TS grew an average rate of 6.52 cm over the 15-month post-switch period. The average rate of HSDS was increased by 0.04 for all patients. The HV and HVSDS demonstrated the expected decline with advancing age and prolonged duration of treatment. CONCLUSIONS: The growth trajectories of rhGH-treated patients were not negatively impacted by switching to Omnitrope and growth rates remained as expected prior to the switch.

Release of protein A from the cell wall of Staphylococcus aureus.

Staphylococcal protein A (SpA) is anchored to the cell wall envelope of Staphylococcus aureus by sortase A, which links the threonyl (T) of its C-terminal LPXTG motif to peptidoglycan cross-bridges (i.e., Gly5). SpA binds the Fcγ domains of IgG and protects staphylococci from opsonophagocytic clearance. Moreover, SpA cross-links B-cell receptors to modify host adaptive immune responses. The mechanisms whereby SpA is released from the bacterial surface to access the host's immune system are not known. Here we demonstrate that SpA is released with murein tetrapeptide-tetraglycyl [L-Ala-D-iGln-(SpA-Gly5)L-Lys-D-Ala-Gly4] linked to its C-terminal threonyl. LytN, a cross-wall murein hydrolase, contributes to the release of SpA by removing amino sugars [i.e., N-acetylmuramic acid-N-acetylglucosamine (MurNAc-GlcNAc)] from attached peptidoglycan, whereas LytM, a pentaglycyl-endopeptidase, triggers polypeptide release from the bacterial envelope. A model is proposed whereby murein hydrolases cleave the anchor structure of released SpA to modify host immune responses.

Staphylococcus aureus mutants lacking the LytR-CpsA-Psr family of enzymes release cell wall teichoic acids into the extracellular medium.

The LytR-CpsA-Psr (LCP) proteins are thought to transfer bactoprenol-linked biosynthetic intermediates of wall teichoic acid (WTA) to the peptidoglycan of Gram-positive bacteria. In Bacillus subtilis, mutants lacking all three LCP enzymes do not deposit WTA in the envelope, while Staphylococcus aureus Δlcp mutants display impaired growth and reduced levels of envelope phosphate. We show here that the S. aureus Δlcp mutant synthesized WTA yet released ribitol phosphate polymers into the extracellular medium. Further, Δlcp mutant staphylococci no longer restricted the deposition of LysM-type murein hydrolases to cell division sites, which was associated with defects in cell shape and increased autolysis. Mutations in S. aureus WTA synthesis genes (tagB, tarF, or tarJ2) inhibit growth, which is attributed to the depletion of bactoprenol, an essential component of peptidoglycan synthesis (lipid II). The growth defect of S. aureus tagB and tarFJ mutants was alleviated by inhibition of WTA synthesis with tunicamycin, whereas the growth defect of the Δlcp mutant was not relieved by tunicamycin treatment or by mutation of tagO, whose product catalyzes the first committed step of WTA synthesis. Further, sortase A-mediated anchoring of proteins to peptidoglycan, which also involves bactoprenol and lipid II, was not impaired in the Δlcp mutant. We propose a model whereby the S. aureus Δlcp mutant, defective in tethering WTA to the cell wall, cleaves WTA synthesis intermediates, releasing ribitol phosphate into the medium and recycling bactoprenol for peptidoglycan synthesis.

Determinants of murein hydrolase targeting to cross-wall of Staphylococcus aureus peptidoglycan.

Cells of eukaryotic or prokaryotic origin express proteins with LysM domains that associate with the cell wall envelope of bacteria. The molecular properties that enable LysM domains to interact with microbial cell walls are not yet established. Staphylococcus aureus, a spherical microbe, secretes two murein hydrolases with LysM domains, Sle1 and LytN. We show here that the LysM domains of Sle1 and LytN direct murein hydrolases to the staphylococcal envelope in the vicinity of the cross-wall, the mid-cell compartment for peptidoglycan synthesis. LysM domains associate with the repeating disaccharide ß-N-acetylmuramic acid, (1→4)-ß-N-acetylglucosamine of staphylococcal peptidoglycan. Modification of N-acetylmuramic acid with wall teichoic acid, a ribitol-phosphate polymer tethered to murein linkage units, prevents the LysM domain from binding to peptidoglycan. The localization of LytN and Sle1 to the cross-wall is abolished in staphylococcal tagO mutants, which are defective for wall teichoic acid synthesis. We propose a model whereby the LysM domain ensures septal localization of LytN and Sle1 followed by processive cleavage of peptidoglycan, thereby exposing new LysM binding sites in the cross-wall and separating bacterial cells.

LytN, a murein hydrolase in the cross-wall compartment of Staphylococcus aureus, is involved in proper bacterial growth and envelope assembly.

Cell cycle progression for the spherical microbe Staphylococcus aureus requires the coordinated synthesis and remodeling of peptidoglycan. The majority of these rearrangements takes place at the mid-cell, in a compartment designated the cross-wall. Secreted polypeptides endowed with a YSIRK-G/S signal peptide are directly delivered to the cross-wall compartment. One such YSIRK-containing protein is the murein hydrolase LytN. lytN mutations precipitate structural damage to the cross-wall and interfere with staphylococcal growth. Overexpression of lytN also affects growth and triggers rupture of the cross-wall. The lytN phenotype can be reversed by the controlled expression of lytN but not by adding purified LytN to staphylococcal cultures. LytN harbors LysM and CHAP domains, the latter of which functions as both an N-acetylmuramoyl-L-alanine amidase and D-alanyl-glycine endopeptidase. Thus, LytN secretion into the cross-wall promotes peptidoglycan separation and completion of the staphylococcal cell cycle.

Anti-CD3 antibody visilizumab is not effective in patients with intravenous corticosteroid-refractory ulcerative colitis.

BACKGROUND AND AIMS: Pilot studies with visilizumab, a humanised monoclonal antibody to CD3, suggest efficacy for corticosteroid-refractory ulcerative colitis (UC). A placebo-controlled trial was warranted. METHODS: A randomised, double-blind, placebo-controlled study evaluated the efficacy of visilizumab induction treatment in 127 patients with severely active UC despite treatment with ≥5 days of intravenous corticosteroids. Patients received placebo or visilizumab 5µg/kg intravenously on days 1 and 2. Corticosteroids were tapered according to disease activity. Patients were followed up for 90 days. The primary end point was induction of response at day 45. Secondary end points included remission and mucosal healing at day 45, symptomatic response at day 15 and colectomy. RESULTS: Response at day 45 occurred in 55% of patients receiving visilizumab compared with 47% of those who received placebo (p=0.475). Remission at day 45 occurred in 8% of patients receiving visilizumab compared with 9% of those who received placebo (p=0.704). Mucosal healing at day 45 occurred in 29% of patients receiving visilizumab compared with 26% of those who received placebo (p=0.799). Symptomatic response at day 15 occurred in 82% of patients receiving visilizumab compared with 74% of those who received placebo (p=0.244). Colectomy was performed in 18% of patients receiving visilizumab compared with 7% of those who received placebo (p=0.130). Cardiac disorders and vascular disorders occurred more frequently in the patients who received visilizumab. CONCLUSION: Visilizumab at a dose of 5µg/kg for two consecutive days was not effective for severe, corticosteroid-refractory UC and was associated with increased cardiac and vascular adverse events. (Registered at http://www.clinicaltrials.govNCT00279422/).