Leukocyte Adhesion deficiency-I Research Articles

Clinical and immunological characteristics of 69 leukocyte adhesion deficiency-I patients.

In order to support the comprehensive classification of Leukocyte Adhesion Deficiency-I (LAD-I) severity by simultaneous screening of CD11a/CD18, this study assessed clinical, laboratory, and genetic findings along with outcomes of 69 LAD-I patients during the last 15 years. Sixty-nine patients (40 females and 29 males) with a clinical phenotype suspected of LAD-I were referred to Immunology, Asthma, and Allergy research institute, Tehran, Iran between 2007 and 2022 for further advanced immunological screening and genetic evaluations as well as treatment, were enrolled in this study. The diagnosis median age of the patients was 6 months. Delayed umbilical cord separation was found in 25 patients (36.2%). The median diagnostic delay time was 4 months (min-max: 0-82 months). Forty-six patients (66.7%) were categorized as severe (CD18 and/or CD11a: below 2%); while 23 children (33.3%) were in moderate category (CD18 and/or CD11a: 2%-30%). During the follow-ups, 55.1% of children were alive with a mortality rate of 44.9%. Skin ulcers (75.4%), omphalitis (65.2%), and gingivitis (37.7%) were the most frequent complaints. Genetic analysis of the patients revealed 14 previously reported and three novel pathogenic mutations in the ITGB2 gene. The overall survival of patients with and without hematopoietic stem cell transplantation was 79.3% and 55.6%, respectively. Physicians' awareness of LAD-I considering delayed separation of umbilical cord marked neutrophilic leukocytosis, and variability in CD11 and CD18 expression levels, and genetic analysis leads to early diagnosis and defining disease severity. Moreover, the prenatal diagnosis would benefit families with a history of LAD-I.

Severe Leukocyte Adhesion Deficiency-I (LAD-I) Lentiviral-Mediated Ex-Vivo Gene Therapy: Ongoing Phase 1/2 Study Results

BackgroundSevere leukocyte adhesion deficiency-I (LAD-I) is an autosomal recessive inborn error of immunity due to mutations in the ITGB2 gene that encodes the common CD18 subunit of β2-integrins, essential for neutrophil adhesion to the inflamed endothelium and transmigration into tissues. Severe LAD-I, defined as <2% of normal CD18 polymorphonucleocyte [PMN] expression, is characterized by frequent and often refractory bacterial and fungal infections, impaired wound healing, and significant pediatric mortality in the absence of allogeneic hematopoietic stem cell transplant (HSCT). HSCT is potentially curative but limited by donor availability, graft-versus-host disease, and graft failure. The gene therapy RP-L201-0318 (NCT03812263) employs autologous CD34+ cells transduced with a lentiviral vector carrying ITGB2 to restore CD18 expression. MethodsPatients ≥3 months old with severe LAD-I were enrolled. Hematopoietic stem cells (HSCs) were collected via apheresis after mobilization with granulocyte-colony stimulating factor and plerixafor and transduced ex-vivo with Chim-CD18-WPRE-LV. Myeloablative therapeutic drug monitoring (TDM) busulfan conditioning preceded RP-L201 infusion. Patients were followed for safety and efficacy measures, including survival to age two and ≥1-year post-infusion, peripheral blood [PB] PMN CD18 expression, PB vector copy number [VCN], neutrophilia improvement, decrease in infections/hospitalizations, and resolution of skin/periodontal abnormalities. ResultsNine patients (age five months to nine years) received RP-L201; follow-up was 3 to 24 months. RP-L201 cell doses ranged from 2.8 × 106 to 10 × 106 CD34+ cells/kg with a drug product VCN of 1.8 to 3.8. All nine patients demonstrated PMN CD18 restoration (median expression of 56.3%) with sustained, stable genetic markings (median PB mononuclear cell VCN of 1.53). At one year, the overall survival (OS) rate was 100% per Kaplan-Meier estimate. Pre-treatment leukocytosis improved uniformly. Hospitalizations and severe infections were significantly reduced following therapy. No RP-L201-related serious adverse events (SAEs) were reported. Insertion site analyses indicate highly polyclonal integration patterns across the entire cohort. ConclusionRP-L201 has a favorable safety profile and confers durable correction of the severe LAD-I phenotype with improved clinical course in all nine pediatric patients treated as demonstrated via all laboratory and clinical parameters.

3 - Lentiviral-Mediated Ex-Vivo Gene Therapy for Pediatric Patients with Severe Leukocyte Adhesion Deficiency-I (LAD-I): Interim Results from an Ongoing Phase 1/2 Study

3 - Lentiviral-Mediated Ex-Vivo Gene Therapy for Pediatric Patients with Severe Leukocyte Adhesion Deficiency-I (LAD-I): Interim Results from an Ongoing Phase 1/2 Study

Interim Results from an Ongoing Phase 1/2 Study of Lentiviral-mediated Ex-vivo Gene Therapy for Pediatric Patients with Severe Leukocyte Adhesion Deficiency-I (LAD-I)

Background: Leukocyte adhesion deficiency-I (LAD-I) results from mutations in ITGB2 encoding the β2-integrin CD18. Severe LAD-I (<2% CD18+ polymorphonucleocytes [PMNs]) causes severe and often refractory infections, impaired wound healing, and frequent childhood mortality. Allogeneic hematopoietic stem cell transplant is potentially curative but limited by donor availability, graft-versus-host disease, and graft failure. RP-L201-0318 (NCT03812263) employs autologous CD34+ cells transduced with a lentiviral vector carrying ITGB2. Methods: Patients ≥3 months old with severe LAD-I were enrolled. Hematopoietic stem and progenitor cells (HSPCs) were collected via apheresis after mobilization with granulocyte-colony stimulating factor and plerixafor and transduced ex-vivo with Chim-CD18-WPRE-LV. Myeloablative therapeutic drug monitoring (TDM) busulfan conditioning preceded RP-L201 infusion. Patients are followed for safety and efficacy including survival to age 2 and ≥1-year post-infusion, peripheral blood [PB] PMN CD18 expression, PB vector copy number [VCN], neutrophilia improvement, decrease in infections/hospitalizations, and resolution of skin/periodontal abnormalities. Results: Nine patients (ages 5 months to 9 years) received RP-L201, all with follow-up of 3 to 24 months. RP-L201 cell doses ranged from 2.8x106 to 10x106 CD34+ cells/kg with a drug product VCN of 1.8 to 3.8. All 9 patients demonstrated PMN CD18 restoration with median expression of 56.3% and sustained, stable genetic markings with median peripheral blood mononuclear cell VCN of 1.53. At 1 year, the overall survival (OS) rate is 100% per Kaplan-Meier estimate. Neutrophilia resolved uniformly. Hospitalizations and severe infections were significantly reduced following therapy. The safety profile has been highly favorable with no RP-L201-related serious adverse events (SAEs); insertion site analyses indicate polyclonal integration patterns. Conclusion: RP-L201 confers durable reversal of the severe LAD-I phenotype with improved clinical course in 9 of 9 pediatric patients.

A Phase 1/2 Study of Lentiviral-Mediated Ex-Vivo Gene Therapy for Pediatric Patients with Severe Leukocyte Adhesion Deficiency-I (LAD-I): Interim Results

▪Background: Leukocyte Adhesion Deficiency-I (LAD-I) is a rare disorder of neutrophil adhesion resulting from ITGB2 mutations encoding for the β2-integrin component, CD18. Severe LAD-I (CD18 <2% of polymorphonuclear [PMN] cells) is characterized by severe infections, impaired wound healing, and childhood mortality. Allogeneic hematopoietic stem cell transplant (alloHSCT) is potentially curative; however, its efficacy is limited by donor availability and risk of graft-versus-host disease (GVHD) and graft failure. RP-L201-0318 (NCT03812263), a phase 1/2 open-label trial currently underway, employs autologous CD34+ cells transduced with a lentiviral vector (LV) carrying the ITGB2 gene (cDNA)Methods: Pediatric patients ≥ 3 months old with severe LAD-I are eligible. HSCs are collected via apheresis after mobilization with granulocyte-colony stimulating factor (G-CSF) and plerixafor and transduced with Chim-CD18-WPRE-LV. Myeloablative therapeutic drug monitoring (TDM) busulfan conditioning precedes RP-L201 infusion. Patients are followed for safety and efficacy (i.e., survival to age 2 and at least 1-year post-infusion, increase in PMN leukocyte CD18 expression to at least 10%, peripheral blood [PB] vector copy number [VCN], decrease in infections/hospitalizations, and resolution of skin or periodontal abnormalities).Results: Seven patients (ages 5mos-9yrs) have received RP-L201; all with follow-up ≥3 to 18 months. RP-L201 cell doses ranged from 2.8x106 to 6.5x106 CD34+ cells/kg with VCN from 1.8-3.8 copies/cell. No serious RP-L201 related treatment-emergent adverse events were reported. PB PMN CD18 expression in Patient 1 at 18-months post-treatment was 40% (vs. < 1% at baseline), with PB VCN of 1.44. Baseline skin lesions resolved with no new lesions reported. CD18 expression in the subsequent 6 patients has been 25-80% in neutrophils and stable for each patient from 3 to up to 18 months post-treatment. No new infections have been reported in patients post-infusion. The safety profile of RP-L102 remains highly favorable with no serious adverse events (SAEs) attributed to the investigational product (IP).Conclusion: RP-L201 leads to durable neutrophil CD18 expression and improved clinical course. Additional patient treatment is ongoing in 2021. DisclosuresKohn: UC Regents: Patents & Royalties; Pluto Immunotherapeutics: Membership on an entity's Board of Directors or advisory committees; Allogene: Membership on an entity's Board of Directors or advisory committees; ImmunoVec: Membership on an entity's Board of Directors or advisory committees; Lyrik Therapeutics: Membership on an entity's Board of Directors or advisory committees; MyoGene Bio: Membership on an entity's Board of Directors or advisory committees; Bluebird Bio: Membership on an entity's Board of Directors or advisory committees; Sangamo Biosciences: Membership on an entity's Board of Directors or advisory committees. Booth: GSK: Honoraria; Takeda: Honoraria; SOBI: Consultancy, Honoraria; Orchard Therapeutics: Consultancy, Honoraria; Rocket Pharmaceuticals, Inc.: Consultancy. Sevilla: Miltenyi: Consultancy; Novartis: Consultancy; Amgen: Consultancy; Rocket Pharmaceuticals, Inc.: Consultancy, Other: J.Sevilla is an inventor on patents on lentiviral vectors filed by CIEMAT, CIBERER and Fundación Jiménez Díaz, and may be entitled to receive financial benefits from the licensing of such patents.; SOBI: Consultancy. Rao: Rocket Pharmaceuticals, Inc.: Current Employment, Current equity holder in publicly-traded company. Almarza: Rocket Pharmaceuticals, Inc.: Current Employment, Current equity holder in publicly-traded company. Nicoletti: Rocket Pharmaceuticals, Inc.: Current Employment, Current equity holder in publicly-traded company. de Oliveira: Orchard Therapeutics: Research Funding; Bluebird Bio: Research Funding. Law: Rocket Pharmaceuticals, Inc.: Current Employment, Current equity holder in publicly-traded company. Beard: Rocket Pharmaceuticals, Inc.: Current Employment, Current equity holder in publicly-traded company. Choi: Rocket Pharmaceuticals, Inc.: Current Employment, Current equity holder in publicly-traded company. Zeini: Rocket Pharmaceuticals, Inc.: Current Employment, Current equity holder in publicly-traded company. Thrasher: Orchard Therapeutics: Consultancy, Current equity holder in publicly-traded company, Membership on an entity's Board of Directors or advisory committees; Generation bio: Consultancy, Current equity holder in publicly-traded company, Membership on an entity's Board of Directors or advisory committees; 4Bio Capital: Consultancy, Membership on an entity's Board of Directors or advisory committees; Rocket Pharmaceuticals: Consultancy, Membership on an entity's Board of Directors or advisory committees. Bueren: Rocket Pharmaceuticals, Inc.: Consultancy, Other: J.Bueren is an inventor on patents on lentiviral vectors filed by CIEMAT, CIBERER and Fundación Jiménez Díaz, may be entitled to receive financial benefits from the licensing of such patents and receives funding for research., Patents & Royalties, Research Funding. Schwartz: Rocket Pharmaceuticals, Inc.: Current Employment, Current equity holder in publicly-traded company.

Leukocyte Adhesion Deficiency-I (LAD-I): A Comprehensive Review of Published Cases

LAD-I is a rare disorder of leukocyte adhesion, resulting from ITGB2 gene mutations encoding for the Beta-2 Integrin component CD18. CD18 deficiencies prevent integrin dimerization and endothelial leukocyte adhesion, essential for extravasation and antimicrobial activity. LAD-I is characterized by delayed separation,of the umbilical cord, omphalitis, poor wound healing and leukocytosis. Severe LAD-I (<2% of normal neutrophil [PMN] CD18 levels) is characterized by recurrent serious infections and early mortality unless treated by allogeneic haematopoietic stem cell transplant (HSCT). Mortality for severe LAD-I was reported as 75% by age 2 in an initial 1988 multicenter retrospective study. Moderate LAD-I (2-30% of PMN CD18 levels) is more indolent; although most pts survive childhood with recurrent skin and mucosal surface infections, mortality by age 40 can exceed 50%.Reports regarding LAD-I have been published in recent decades but no recent comprehensive prognostic assessments are available. We sought an updated understanding of severe LAD-I with emphasis on prognosis in the absence of HSCT, HSCT outcomes and association of CD18 expression with clinical features. We created a database of all published LAD-I cases via Pubmed searches and review of available references.Three hundred thirty LAD-I cases were reported between 1975-2017 in 111 publications (89 case-reports; largest series n=36). The nations reporting the most cases were Iran (n=64), USA (n=52), and India (n=45); the highest number of publications were from US centers (26). 113 pts were considered to have severe LAD-I, 63 moderate and 154 were not classified. PMN CD18 expression levels was reported for 270 cases and was <2% in 138 patients (51%) and ≥2% in 132 pts. Four pts with CD18 >2% were considered to have severe LAD-I (CD18% range 2.4 - 17.3). Gender was noted for 289 pts; 153 (53%) were male. Age at presentation was reported for 152 cases. For 65 pts with CD18<2%, median presentation was age 1 m (range 0.03-18m); for 64 pts with CD18 ≥2%, median presentation was age 6m (range 0.03-192m).We sought to understand whether prognosis for severe LAD-I in the absence of HSCT is similar to the initially-reported 25% survival to age 2. There were 59 severe LAD-I cases (per investigator assessment or CD18 <2%) for whom survival to 2 years was reported, 38 of whom died prior to age 2 (64% mortality). Mortality was similar for the subset of 43 cases reported since 2000 (58%, 25 deaths). Early mortality was substantially lower in patients with CD18 ≥2% and the majority of pts with CD18 >4% survived to adulthood. Outcomes for 119 pts who received HSCT were consistent with recent series; phenotypic correction was reported in 85% of pts with HLA-matched sibling donors. Mortality was 15% overall (8% for HLA-matched sibling recipients). The 27 pts receiving haploidentical HSCT had frequent graft failure (33%) with 16 (59%) receiving ≥1 subsequent HSCT.Infection details and CD18% were available for 159 (48%) cases. The most frequent infections in pts with CD18 <2% were respiratory tract (39%), sepsis (28%) and otitis media (27%) and for pts with CD18 ≥2% they were periodontal (51%), otitis media (35%) and sepsis (25%). Perianal skin infections and necrotic skin ulcers were noted in >10%. Umbilical complications were more frequent in severe LAD-I (94 of 112 pts with CD18<2% [84%] and 49 of 83 with CD18 ≥2% [59%; p = 0.0001]). For severe LAD-I pts with ≥2 years of follow-up (or death prior to 2y), there was correlation between absence of umbilical complications and survival to 24 m (p < 0.001). WBCs were reported in 149 cases (median 45 x 109/L; range 10 - 150 x 109/L) (normal range 4.5 to 11 × 109/L).There were limited correlations between CD18 expression and WBC (r < 0.1) and between CD18 and CD11 expression (r < 0.5).Severe LAD-I remains a life-threatening condition with limited 2-year survival in the absence of allogeneic HSCT. Umbilical complications and granulocytosis occur in nearly all pts. Respiratory tract, ear, sepsis, oral and skin infections are common. HSCT is potentially curative; transplant-mortality and other complications are frequent, especially in haploidentical transplants. Rapid identification of pts with potential LAD-I (unusual or severe infections in infancy, granulocytosis and umbilical complications) is essential to enable referral to centers with disease expertise. DisclosuresThrasher:4bio Ventures Management Ltd: Other: Advisory Board; Orchard Therapeutics: Consultancy; Rocket Pharmaceuticals Ltd: Consultancy; Torus Therapeutics, Inc: Other: Advisory Board. Kohn:BioMarin Pharmaceutical: Research Funding; Orchard Therapeutics Ltd.: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Kite Pharma: Consultancy, Membership on an entity's Board of Directors or advisory committees; Biogen IDEC: Research Funding.

Gene Therapies for Primary Immune Deficiencies

Gene therapy is an innovative treatment for Primary Immune Deficiencies (PIDs) that uses autologous hematopoietic stem cell transplantation to deliver stem cells with added or edited versions of the missing or malfunctioning gene that causes the PID. Initial studies of gene therapy for PIDs in the 1990–2000's used integrating murine gamma-retroviral vectors. While these studies showed clinical efficacy in many cases, especially with the administration of marrow cytoreductive conditioning before cell re-infusion, these vectors caused genotoxicity and development of leukoproliferative disorders in several patients. More recent studies used lentiviral vectors in which the enhancer elements of the long terminal repeats self-inactivate during reverse transcription (“SIN” vectors). These SIN vectors have excellent safety profiles and have not been reported to cause any clinically significant genotoxicity. Gene therapy has successfully treated several PIDs including Adenosine Deaminase Severe Combined Immunodeficiency (SCID), X-linked SCID, Artemis SCID, Wiskott-Aldrich Syndrome, X-linked Chronic Granulomatous Disease and Leukocyte Adhesion Deficiency-I. In all, gene therapy for PIDs has progressed over the recent decades to be equal or better than allogeneic HSCT in terms of efficacy and safety. Further improvements in methods should lead to more consistent and reliable efficacy from gene therapy for a growing list of PIDs.

A Phase 1/2 Study of Lentiviral-Mediated Ex-Vivo Gene Therapy for Pediatric Patients with Severe Leukocyte Adhesion Deficiency-I (LAD-I): Results from Phase 1

Introduction: LAD-I is a rare inherited disorder of leukocyte (primarily neutrophil) adhesion to endothelial cell surfaces, migration, and chemotaxis resulting from ITGB2 gene mutations encoding for the β2-integrin component, CD18. Severe LAD-I (i.e., CD18 expression on &amp;lt;2% of PMNs) is characterized by recurrent severe infections, impaired wound healing, and childhood mortality. Although allogeneic hematopoietic stem cell transplant (alloHSCT) is potentially curative, its utilization and efficacy are limited by HLA-matched donor availability and risk of graft-versus-host disease (GVHD). RP-L201-0318 (clinical trials.gov # NCT03812263) is a phase 1/2 open-label clinical trial evaluating the safety and efficacy of autologous CD34+ cells transduced with a lentiviral vector (LV) carrying the ITGB2 gene encoding for CD18 (Chim-CD18-WPRE) in severe LAD-I. Methods: Pediatric patients ≥ 3 months old with severe LAD-I (demonstrated by CD18 expression on &amp;lt;2% PMNs and at least 1 prior significant bacterial or fungal infection) are eligible. Peripheral blood (PB) HSCs are collected via apheresis after mobilization with granulocyte-colony stimulating factor (G-CSF) and Plerixafor. CD34+ cells are selected, transduced with Chim-CD18-WPRE LV, and cryopreserved. Myeloablative conditioning with busulfan (with therapeutic drug monitoring (TDM) to adjust dosing to enable target area under the curve (AUC)) is administered, followed by infusion of the investigational drug product (RP-L201). Patients are followed for safety assessments (i.e., replication competent lentivirus (RCL) and insertion site analysis (ISA)), and efficacy -- survival to age 2 and at least 1-year post-infusion without alloHSCT, increase in neutrophil CD18 expression to at least 10%, PB vector copy number (VCN), decrease in infections and/or hospitalizations, and resolution of skin or periodontal abnormalities. Results: Two patients (ages 9 and 3) were treated in Phase 1. Both have a history of recurrent severe infections, documented ITGB2 mutations, and baseline CD18, CD11a, and CD11b expression &amp;lt; 1%. Mobilization and apheresis procedures were performed successfully and busulfan was administered at the target AUC. Investigational product comprised of 4.2x106 CD34+ cells/kg with VCN of 3.8 copies/cell (liquid culture) for Patient 1 and 2.8x106 CD34+ cells/kg with VCN of 2.5 for Patient 2 and were infused without complications. No serious treatment-emergent adverse events were reported. Neutrophil engraftment was observed in &amp;lt; 3 weeks in both patients. For Patient 1, PB PMN CD18 expression 6 months post-treatment was 47% (sustained from 45% at 3-months, vs. &amp;lt; 1% at baseline), with PB VCN of 1.3. Skin lesions present at baseline were resolving with no new lesions. Replication competent lentiviral (RCL) testing at 3 months and 6 months post-infusion were negative. Safety and efficacy data 12-months post-treatment for Patient 1 and 6-months post-treatment for Patient 2 will be available at the time of presentation. Conclusion: Initial results from Phase 1 demonstrate preliminary safety and efficacy of RP-L201 for reversal of severe LAD-I. Enrollment of patients in the Phase 2 study is underway. Disclosures Kohn: Allogene Therapeutics: Consultancy, Membership on an entity's Board of Directors or advisory committees; Orchard Therapeutics: Consultancy, Patents &amp; Royalties, Research Funding. Rao:Rocket Pharmaceuticals, Inc.: Current Employment, Current equity holder in publicly-traded company. Almarza:Rocket Pharmaceuticals, Inc.: Current Employment, Current equity holder in publicly-traded company. Nicoletti:Rocket Pharmaceuticals, Inc.: Current Employment, Current equity holder in publicly-traded company. Law:Rocket Pharmaceuticals, Inc.: Current Employment, Current equity holder in publicly-traded company. Beard:Rocket Pharmaceuticals, Inc.: Current Employment, Current equity holder in publicly-traded company. Sevilla:Novartis: Other: Advisory Board; Sobi: Other: Advisory Board; Rocket Pharma: Consultancy; Amgen: Other: Advisory Board. Bueren:Rocket Pharmaceuticals, Inc.: Consultancy, Current equity holder in publicly-traded company, Other: Consultant for Rocket Pharmaceuticals, Inc. and has licensed medicinal products and receives research funding and equity from this company., Patents &amp; Royalties, Research Funding. Schwartz:Rocket Pharmaceuticals, Inc.: Current Employment, Current equity holder in publicly-traded company.

Report of a Chinese Cohort with Leukocyte Adhesion Deficiency-I and Four Novel Mutations.

We aimed to report the characteristics of leukocyte adhesion deficiency-I (LAD-I) and four novel mutations in the ITGB2 gene in a Chinese cohort. Seven patients with LAD-I were reported in our study. Clinical manifestations and immunological phenotypes were reviewed. The expression of CD18 was detected by flow cytometry. Next-generation sequencing (NGS) and Sanger sequencing were performed to identify gene mutations. The mean onset age of all the patients was 1.3months. Recurrent bacterial infections of the skin and lungs were the most common symptoms. Most patients (6/7) had delayed cord separation. The number of white blood cells (WBC) was increased significantly, except that two patients had a mild increase in the number of WBC during infection-free periods. The expression of CD18 was very low in all patients. Homozygous or compound heterozygous mutations in the ITGB2 gene were identified in each patient. Four mutations were novel, including c.1794dupC (p.N599Qfs*93), c.1788C>A (p.C596X), c.841-849del9, and c.741+1delG. Two patients had large deletions of the ITGB2 gene. Five patients were cured by hematopoietic stem cell transplantation (HSCT). This study reported the clinical and molecular characteristics of a Chinese patient cohort. It is helpful in understanding the current status of the disease in China.

Primary immunodeficiencies reveal the essential role of tissue neutrophils in periodontitis.

Periodontitis is a common human inflammatory disease. In this condition, microbiota trigger excessive inflammation in oral mucosal tissues surrounding the dentition, resulting in destruction of tooth-supporting structures (connective tissue and bone). While susceptibility factors for common forms of periodontitis are not clearly understood, studies in patients with single genetic defects reveal a critical role for tissue neutrophils in disease susceptibility. Indeed, various genetic defects in the development, egress from the bone marrow, chemotaxis, and extravasation are clearly linked to aggressive/severe periodontitis at an early age. Here, we provide an overview of genetic defects in neutrophil biology that are linked to periodontitis. In particular, we focus on the mechanisms underlying Leukocyte Adhesion Deficiency-I, the prototypic Mendelian defect of impaired neutrophil extravasation and severe periodontitis.

Leukocyte adhesion deficiency-I caused by a novel mutation in ITGB2 presenting with pyoderma gangrenosum

Background: Leukocyte adhesion deficiency (LAD) syndromes are primary immunodeficiency disorders caused by defects in adhesion molecules on leukocytes resulting in impaired migration into tissues. Common cutaneous manifestations of LAD include bacterial infections, omphalitis with delayed separation of the umbilical cord, impaired pus formation and poor wound healing. LAD is associated with significant morbidity and mortality, making early diagnosis and management integral in the care of these patients. Methods: Molecular testing and flow cytometry for expression of CD18 were performed on 2 siblings presenting with cutaneous lesions including pyoderma gangrenosum (PG). Results: We describe 2 siblings with a novel homozygous mutation in ITGB2 (c.2070del, p.Asp690Glufs*25) resulting in an atypical presentation of LAD-I with PG. Conclusion: LAD should be considered in patients presenting with unexplained PG, even in the absence of significant infections or umbilical cord complications. Statement of novelty: To the best of our knowledge, we describe a novel homozygous mutation in ITGB2 (c.2070del, p.Asp690Glufs*25) resulting in LAD-I. Patients with LAD-I may present with unexplained PG and may lack classic symptoms including umbilical cord complications.

Leukocyte adhesion deficiency-I: A comprehensive review of all published cases

Leukocyte adhesion deficiency-I: A comprehensive review of all published cases

Leukocyte Adhesion Deficiency-I: Clinical and Molecular Characterization in an Indian Population.

To describe clinical and flow cytometric immunophenotyping details of 26 patients of Leukocyte adhesion deficiency-I (LAD-I) along with molecular characterization of 7 patients. Diagnosis of LAD-I was suspected on the basis of clinical features, white blood cell count and absolute neutrophil counts and flow cytometric assessment of expression of CD18 and CD11(a, b, c) on leukocytes. Mutation analysis was performed using DNA PCR and conformation sensitive gel electrophoresis (CSGE) technique followed by sequencing. All the patients were symptomatic by the age of 6mo, with history of recurrent bacterial infections involving skin, mucosa or umbilical cord (omphalitis) being the most frequent presenting symptoms. White blood cells (WBC) and absolute neutrophil counts (ANC) were markedly elevated, without any specific morphological findings. On flow cytometry, CD11a and CD11c showed moderate correlation with CD18 expression. Mutation analysis was performed in 7 patients and six different mutations (4 missense, 2 nonsense and 1 splice site) were identified, all of which were homozygous in nature. A presentation of repeated bacterial infections during infancy, especially omphalitis, with markedly elevated absolute neutrophil counts should trigger investigations for LAD-I including flow cytometric analysis of CD11/CD18 expression.

Subgingival microbial communities in Leukocyte Adhesion Deficiency and their relationship with local immunopathology.

Leukocyte Adhesion Deficiency I (LAD-I) is a primary immunodeficiency caused by single gene mutations in the CD18 subunit of β2 integrins which result in defective transmigration of neutrophils into the tissues. Affected patients suffer from recurrent life threatening infections and severe oral disease (periodontitis). Microbial communities in the local environment (subgingival plaque) are thought to be the triggers for inflammatory periodontitis, yet little is known regarding the microbial communities associated with LAD-I periodontitis. Here we present the first comprehensive characterization of the subgingival communities in LAD-I, using a 16S rRNA gene-based microarray, and investigate the relationship of this tooth adherent microbiome to the local immunopathology of periodontitis. We show that the LAD subgingival microbiome is distinct from that of health and Localized Aggressive Periodontitits. Select periodontitis-associated species in the LAD microbiome included Parvimonas micra, Porphyromonas endodontalis, Eubacterium brachy and Treponema species. Pseudomonas aeruginosa, a bacterium not typically found in subgingival plaque is detected in LAD-I. We suggest that microbial products from LAD-associated communities may have a role in stimulating the local inflammatory response. We demonstrate that bacterial LPS translocates into the lesions of LAD-periodontitis potentially triggering immunopathology. We also show in in vitro assays with human macrophages and in vivo in animal models that microbial products from LAD-associated subgingival plaque trigger IL-23-related immune responses, which have been shown to dominate in patient lesions. In conclusion, our current study characterizes the subgingival microbial communities in LAD-periodontitis and supports their role as triggers of disease pathogenesis.

Molecular characterization of leukocyte adhesion deficiency-I in Indian patients: identification of 9 novel mutations.

Leukocyte adhesion deficiency type-I (LAD-I) is caused by mutations in the ITGB2 gene, encoding the β2-subunit of β2-integrin (CD18) which leads to markedly reduced expression of CD18 on leukocytes resulting into recurrent life threatening infections. Here we aim to identify the molecular defects underlying LAD-I in Indian patients and correlate with the clinical presentation. Blood was collected from 30 patients and their parents for absolute neutrophil count, expression of CD18 and CD11 by flow cytometry and DNA extraction. PCR and DNA sequencing of the ITGB2 gene was done for mutation characterization. Phenotypically, 22 patients were LAD-I(0), 1 was LAD-I(-) and 7 were LAD-I(+) showing no expression and reduced expression of CD18 respectively. Nine novel mutations in 15 patients and 11 known mutations in 16 patients were detected. Prenatal diagnosis was performed for 5 families. In this study 30 patients were phenotypically and genotypically evaluated for a less known disease LAD-I. Unavailability of curative options to majority of the patients and high cost of supportive care emphasize the need to increase awareness about a suspicious case so that timely management can be given to the patient and prenatal diagnosis can be offered to their families.

Leukocyte adhesion deficiency‐I variant syndrome (LAD‐Iv, LAD‐III): Molecular characterization of the defect in an index family

Leukocyte adhesion deficiencies are rare clinical syndromes of impaired host defense that provide novel insights into regulation of immune and inflammatory responses. Leukocyte adhesion deficiency (LAD)-I variant (LAD-Iv), also called LAD-III, is a unique disorder in which inside-out signaling of β₁, β₂, and β₃ integrins on leukocytes and platelets is disrupted, leading to impaired cellular adhesion, recurrent infections, and bleeding. We originally reported the second patient with this disorder to be identified and characterized the adhesive deficiencies and functional phenotype of this subject's leukocytes. Here, we show that the molecular defect in this index subject is a new mutation in FERMT3 (KINDLIN-3) which encodes KINDLIN-3, a cytoskeletal protein that interacts with the cytoplasmic tails of β₁, β₂, and β₃ integrins and is required for inside-out and outside-in signaling of these heterodimers. We also report clinical features and previously unrecognized defects in cells from a new patient, a sibling of the original subject that we described who carries the same FERMT3 mutation. Mutations in FERMT3 have now been shown to be the basis for LAD-Iv/LAD-III in each of the four original patients or families that established this syndrome, including the family that we describe.

Neutrophil‐selective transgenic RNA interference in vivo

Tissue specific silencing of genes has applications for genetic engineering. Current strategies rely on Cre/Lox technology in mice requiring the generation of multiple transgenic lines and breeding strategies. Here we pursued a method to silence genes in neutrophils using an miRNA strategy. As proof of principle, we chose CD18 as the target gene since it is an abundantly expressed surface protein. CD18 specific miRNA hairpin driven by the myeloid specific MRP8 promoter resulted in a &gt;90% reduction in CD18 protein levels in neutrophils and monocytes with no observable decrease in T cells and only a partial diminution in macrophages. Neutrophil CD18 silencing resulted in mild neutrophilia, splenomegaly and significant defects in neutrophil trafficking in irritant dermatitis. Our data demonstrate the utility of using miRNA approaches to silence genes in neutrophils which are terminally differentiated cells with a short half life that largely precludes their genetic manipulation in vitro. Furthermore, the mouse model provides a valuable tool to examine the contribution of CD18 on neutrophils to Leukocyte Adhesion Deficiency I (LADI), a complex inherited disorder in which reduced or absent CD18 expression in multiple leukocyte subsets leads to impaired innate and adaptive immune responses.Note: XC, ML and NT contributed equally. Supported by: NIH KO1AR054984 (XC), HL065095 and AR050800 (T.N.M), and a Arthritis Foundation fellowship (NT).

Genetics, biology and clinical management of myeloid cell primary immune deficiencies: chronic granulomatous disease and leukocyte adhesion deficiency

Chronic granulomatous disease and leukocyte adhesion deficiency are the major primary immune deficiencies affecting phagocytic blood cells. Major advances in clinical diagnosis and development of novel treatments for these disorders merit review. Clinically beneficial gene therapy correction of X-linked chronic granulomatous disease in two adult patients was reported. Nonmyeloablative busulfan conditioning before administration of gene corrected autologous hematopoietic stem cells was likely an essential maneuver to achieve successful gene therapy. There is an increased association of autoimmune disorders with chronic granulomatous disease. Preimplantation genetic diagnosis of leukocyte adhesion deficiency-I led to the birth of a normal child. A canine model of leukocyte adhesion deficiency-I facilitated development of new nonmyeloablative hematopoietic stem cell transplant and gene therapy approaches to leukocyte adhesion deficiency. Nonmyeloablative transplantation may provide an effective, but less toxic approach for leukocyte adhesion deficiency in children. There have been advances in understanding the basis of leukocyte adhesion deficiency-II and III. The most important subjects reviewed in this chapter include new advances in development of gene therapy for chronic granulomatous disease and leukocyte adhesion deficiency-I; transplantation for leukocyte adhesion deficiency-I; prenatal diagnosis of leukocyte adhesion deficiency-I; and association of autoimmune diseases with chronic granulomatous disease.