-
1.
Mechanistic understanding of the combined immunodeficiency in complete human CARD11 deficiency.
Lu, HY, Sharma, M, Sharma, AA, Lacson, A, Szpurko, A, Luider, J, Dharmani-Khan, P, Shameli, A, Bell, PA, Guilcher, GMT, et al
The Journal of allergy and clinical immunology. 2021;(6):1559-1574.e13
Abstract
BACKGROUND Germline pathogenic variants impairing the caspase recruitment domain family member 11 (CARD11)-B cell chronic lymphocytic leukemia/lymphoma 10 (BCL10)-MALT1 paracaspase (MALT1) (CBM) complex are associated with diverse human diseases including combined immunodeficiency (CID), atopy, and lymphoproliferation. However, the impact of CARD11 deficiency on human B-cell development, signaling, and function is incompletely understood. OBJECTIVES This study sought to determine the cellular, immunological, and biochemical basis of disease for 2 unrelated patients who presented with profound CID associated with viral and fungal respiratory infections, interstitial lung disease, and severe colitis. METHODS Patients underwent next-generation sequencing, immunophenotyping by flow cytometry, signaling assays by immunoblot, and transcriptome profiling by RNA-sequencing. RESULTS Both patients carried identical novel pathogenic biallelic loss-of-function variants in CARD11 (c.2509C>T; p.Arg837∗) leading to undetectable protein expression. This variant prevented CBM complex formation, severely impairing the activation of nuclear factor-κB, c-Jun N-terminal kinase, and MALT1 paracaspase activity in B and T cells. This functional defect resulted in a developmental block in B cells at the naive and type 1 transitional B-cell stage and impaired circulating T follicular helper cell (cTFH) development, which was associated with impaired antibody responses and absent germinal center structures on lymph node histology. Transcriptomics indicated that CARD11-dependent signaling is essential for immune signaling pathways involved in the development of these cells. Both patients underwent hematopoietic stem cell transplantations, which led to functional normalization. CONCLUSIONS Complete human CARD11 deficiency causes profound CID by impairing naive/type 1 B-cell and cTFH cell development and abolishing activation of MALT1 paracaspase, NF-κB, and JNK activity. Hematopoietic stem cell transplantation functionally restores impaired signaling pathways.
-
2.
Beyond cholesterol metabolism: The pleiotropic effects of proprotein convertase subtilisin/kexin type 9 (PCSK9). Genetics, mutations, expression, and perspective for long-term inhibition.
Cesaro, A, Bianconi, V, Gragnano, F, Moscarella, E, Fimiani, F, Monda, E, Scudiero, O, Limongelli, G, Pirro, M, Calabrò, P
BioFactors (Oxford, England). 2020;(3):367-380
Abstract
Proprotein convertase subtilisin/kexin type 9 (PCSK9) has a crucial role in lipid metabolism, particularly due to its function in low-density lipoprotein receptor degradation. Gain-of-function genetic mutations of PCSK9 result in autosomal dominant familial hypercholesterolemia, characterized by high levels of low-density lipoprotein cholesterol (LDL-C) and clinical signs of early atherosclerosis. In recent years, PCSK9 has become an important therapeutic target for cholesterol-lowering therapy. Particularly, its inhibition with monoclonal antibodies has shown excellent efficacy in decreasing LDL-C and reducing cardiovascular events. However, PCSK9, first identified in the brain, seems to be a ubiquitous protein with different tissue-specific functions also independent of cholesterol metabolism. Accordingly, it appears to be involved in the immune response, haemostasis, glucose metabolism, neuronal survival, and several other biological functions. This review provides a comprehensive overview of the genetics, biochemical structure, expression, and function of PCSK9 and discusses the potential implications of its long-term pharmacological inhibition.
-
3.
R516Q mutation in Melanoma differentiation-associated protein 5 (MDA5) and its pathogenic role towards rare Singleton-Merten syndrome; a signature associated molecular dynamics study.
Raghuraman, P, Sudandiradoss, C
Journal of biomolecular structure & dynamics. 2019;(3):750-765
Abstract
Singleton-Merten syndrome, a critical and rare multifactorial disorder that is closely linked to R516Q mutation in MDA5 protein associated with an enhanced interferon response in the affected individual. In the present study, we provide conclusive key evidence on R516Q mutation and their connectivity towards sequence-structural basis dysfunction of MDA5 protein. Among the various mutations, we found R516Q is the most pathogenic mutation based on mutational signature Q-A-[RE]-G-R-[GA]-R-A-[ED]-[DE]-S-[ST]-Y-[TSAV]-L-V designed from our work. Further, we derived a distant ortholog for this mutational signature from which we identified 343 intra-residue interactions that fall communally in the position required to maintain the structural and functional integration of protein architecture. This identification served us to understand the critical role of hot spots in residual aggregation that holds a native form of folding conformation in the functional region. In addition, the long-range molecular dynamics simulation demarcated the residual dependencies of conformational transition in distinct regions (L29360-370α18, α19380-410L31, α21430-480L33-α22-L35 and α24510-520L38) occurring upon R516Q mutation. Together, our results emphasise that the dislocation of functional hot spots Pro229, Arg414, Val498, Met510, Ala513, Gly515 and Arg516 in MDA5 protein which is important for interior structural packing and fold arrangements. In a nutshell, our findings are perfectly conceded with other experimental reports and will have potential implications in immune therapeutical advancement for rare singleton-merten syndrome.
-
4.
HCMV UL97 phosphotransferase gene mutations may be associated with antiviral resistance in immunocompromised patients in Belém, PA, Northern Brazil.
Silva, DFLD, Cardoso, JF, Silva, SPD, Arruda, LMF, Medeiros, RLF, Moraes, MM, Sousa, RCM
Revista da Sociedade Brasileira de Medicina Tropical. 2018;(2):141-145
Abstract
INTRODUCTION Human cytomegalovirus is one of the causes of opportunist infections in immunocompromised patients, and is triggered by factors such as state of viral latency, weakened immune responses, and development of antiviral resistance to ganciclovir, the only drug offered by the public health system in Brazil to treat the infection. The goal of this study was to identify mutations that may be associated with antiviral resistance in immunocompromised patients. METHODS Molecular analysis was performed in 82 blood samples and subjected to genomic DNA extraction by a silica-based method. Three sequences of the HCMV UL97 gene, which encodes a phosphotransferase protein required for activation of ganciclovir, were amplified by polymerase chain reaction. Pyrosequencing methods were applied to one external 2096-bp segment DNA and two internal sequences between nucleotides 1087 to 1828 to detect mutations in this gene. RESULTS Approximately 10% of sequences contained mutations between nucleotides 377 and 594, in conserved regions of the UL97 gene, leading to amino acid changes. Eleven coding mutations were identified, including changes leading to amino acid substitutions, E596K and S604F, which were observed in 100% of samples and are described for the first time in Brazil. In addition, one mutation (A594V) that is associated with ganciclovir resistance was detected in a kidney transplant patient. CONCLUSIONS Further studies to detect mutations associated with HCMV resistance to antiviral drugs are required to demonstrate the need to increase the variety and availability of drugs used to treat viral infections in the public health care system in Brazil.
-
5.
The genetic landscape of Alzheimer disease.
Carmona, S, Hardy, J, Guerreiro, R
Handbook of clinical neurology. 2018;:395-408
Abstract
Alzheimer disease (AD), a progressive and neurodegenerative disease, is the most common form of dementia with high incidence in elderly people. Neuropathologically the disease is defined by the combined presence of extracellular amyloid-beta (Aβ) plaques and intracellular neurofibrillary tangles of phosphorylated tau protein. Genetically, the first clues were provided by genetic linkage studies that led to the identification of APP, PSEN1, and PSEN2 mutations as the main causes of autosomal-dominant early-onset AD. Another important hallmark was the identification of the APOE ɛ4 allele as a risk factor for late-onset AD. Over the last 20 years the development and implementation of new genetic and genomic technologies have allowed the identification of other genetic players in this disease. Genome-wide association studies identified more than 20 loci with common variability having small contributions to the susceptibility of AD. The majority of the genes mapped in these loci are known to be involved in specific biologic pathways: cholesterol metabolism, immune response, and endocytosis. More recently, the application of next-generation sequencing (mainly whole-exome sequencing) has begun to reveal the contribution of rarer variants with medium effects on risk for AD. This area of research has come a long way with many and important results allowing a better understanding of the disease. More efforts are still needed, however, to fully understand the etiology of this disease in order to establish reliable individual predictive models and put us closer to the development of a curative, preventive, or modulator drug.
-
6.
MECHANISMS IN ENDOCRINOLOGY: The multiple facets of GHRH/GH/IGF-I axis: lessons from lifetime, untreated, isolated GH deficiency due to a GHRH receptor gene mutation.
Aguiar-Oliveira, MH, Souza, AHO, Oliveira, CRP, Campos, VC, Oliveira-Neto, LA, Salvatori, R
European journal of endocrinology. 2017;(2):R85-R97
Abstract
Twenty years ago, we described kindred of 105 individuals with isolated GH deficiency (IGHD) in Itabaianinha County, in northeast Brazil, carrying a homozygous mutation in the GH-releasing hormone receptor gene. These subjects exhibit markedly reduced GH responsiveness to stimulatory tests, and anterior pituitary hypoplasia. Serum concentrations of IGF-I, IGF binding protein type 3 and the acid-labile subunit are markedly reduced, with a lesser reduction of IGF-II. The most striking physical findings of these IGHD individuals are the proportionate short stature, doll facies, high-pitched voice and visceral obesity with reduced fat-free mass. There is neither microphallus, nor neonatal hypoglycemia. Puberty is delayed, menopause anticipated, but fertility is preserved in both genders. The reduction in bone sizes is not even, with mean standard deviation scores for height of -7.2, total maxillary length of -6.5, total facial height of -4.3 and cephalic perimeter of -2.7. In addition, the non-osseous growth is not uniform, preserving some organs, like pancreas, liver, kidney, brain and eyes, and compromising others such as thyroid, heart, uterus and spleen. These subjects present higher prevalence of dizziness, mild high-tones sensorineural hearing loss, reduction of vascular retinal branching points, increase of optic disk, genu valgum and increased systolic blood pressure. Biochemically, they have high low density lipoprotein cholesterol and C-reactive protein levels, but maintain increased insulin sensitivity, and do not show premature atherosclerosis. Finally, they have normal immune function, and normal longevity. This review details the findings and summarizes 20 years of clinical research carried out in this unique population.
-
7.
A clinical update on inflammasomopathies.
Sönmez, HE, Özen, S
International immunology. 2017;(9):393-400
Abstract
Inflammasomes are important elements of the innate immune defense. The most common autoinflammatory syndromes, as well a number of rare ones, are due to hereditary defects in the inflammasomes, hence are called inflammasomopathies. The recent clinical advances in these diseases will be reviewed, with special emphasis on reflecting the international collaborative work in the field. Recent recommendations for familial Mediterranean fever, cryopyrin-associated periodic syndromes and hyper-IgD syndrome/mevalonate kinase deficiency will be presented and diagnostics tests, treatment alternatives and follow-up recommendations will be summarized. The other rare inflammasomopathies will be briefly discussed based on clinical features; these diseases are pyogenic arthritis, pyoderma gangrenosum and acne, NLRC4-related macrophage-activation syndrome of enterocolitis, mutations in NLRP12 that cause hereditary periodic fever syndromes (familial cold inflammatory syndrome 2) and NLRP1-associated autoinflammation with arthritis and dyskeratosis.
-
8.
Key mutations stabilize antigen-binding conformation during affinity maturation of a broadly neutralizing influenza antibody lineage.
Xu, H, Schmidt, AG, O'Donnell, T, Therkelsen, MD, Kepler, TB, Moody, MA, Haynes, BF, Liao, HX, Harrison, SC, Shaw, DE
Proteins. 2015;(4):771-80
-
-
Free full text
-
Abstract
Affinity maturation, the process in which somatic hypermutation and positive selection generate antibodies with increasing affinity for an antigen, is pivotal in acquired humoral immunity. We have studied the mechanism of affinity gain in a human B-cell lineage in which two main maturation pathways, diverging from a common ancestor, lead to three mature antibodies that neutralize a broad range of H1 influenza viruses. Previous work showed that increased affinity in the mature antibodies derives primarily from stabilization of the CDR H3 loop in the antigen-binding conformation. We have now used molecular dynamics simulations and existing crystal structures to identify potentially key maturation mutations, and we have characterized their effects on the CDR H3 loop and on antigen binding using further simulations and experimental affinity measurements, respectively. In the two maturation pathways, different contacts between light and heavy chains stabilize the CDR H3 loop. As few as two single-site mutations in each pathway can confer substantial loop stability, but none of them confers experimentally detectable stability on its own. Our results support models of the germinal center reaction in which two or more mutations can occur without concomitant selection and show how divergent pathways have yielded functionally equivalent antibodies.
-
9.
Receptor conformation and constitutive activity in CCR5 chemokine receptor function and HIV infection.
Flanagan, CA
Advances in pharmacology (San Diego, Calif.). 2014;:215-63
Abstract
The CCR5 chemokine receptor mediates the effects of proinflammatory β-chemokines that stimulate chemotaxis, activation, and proliferation of macrophages and T cells. CCR5 is also the major coreceptor that mediates HIV infection in combination with CD4. Chemokine agonists of CCR5 stimulate the activation of cellular calcium and protein kinase signaling pathways that depend on the activation of Gαi and probably also Gαq in some cells. Chemokines also stimulate the recruitment of β-arrestin, which is required for clathrin-dependent receptor internalization and acts as a scaffold protein for the chemotaxis signaling complex that mobilizes the actin cytoskeleton. CCR5 is partially constitutively active for the activation of Gαi, but the physiological significance has not been studied. HIV binding to CCR5 also activates G protein and protein kinase signaling but, in addition, stimulates the production of proinflammatory cytokines, including TNF-α, and mobilizes the actin cytoskeleton to form the fusion pore that allows viral entry and subsequently supports viral replication in the cell. The CCR5 conformation that mediates the fusion of the viral and cell membranes is unknown, but it is probably distinct from the conformation that mediates G protein signaling. Nonpeptide CCR5 blockers are allosteric inverse agonists that increase dissociation of both chemokines and HIV envelope proteins, but this does not correlate with their ability to inhibit HIV infection. Nevertheless, the inverse agonist activity may ameliorate the immune activation that exacerbates AIDS pathogenesis. Inverse agonists of CCR5 have established efficacy for the treatment of AIDS, but may also be useful in preventing HIV infection.
-
10.
Common variants of the vitamin D binding protein gene and adverse health outcomes.
Malik, S, Fu, L, Juras, DJ, Karmali, M, Wong, BY, Gozdzik, A, Cole, DE
Critical reviews in clinical laboratory sciences. 2013;(1):1-22
-
-
Free full text
-
Abstract
The vitamin D binding protein (DBP) is the major plasma carrier for vitamin D and its metabolites, but it is also an actin scavenger, and is the precursor to the immunomodulatory protein, Gc-MAF. Two missense variants of the DBP gene - rs7041 encoding Asp432Glu and rs4588 encoding Thr436Lys - change the amino acid sequence and alter the protein function. They are common enough to generate population-wide constitutive differences in vitamin D status, based on assay of the serum metabolite, 25-hydroxyvitamin D (25OHD). Whether these variants also influence the role of vitamin D in an immunologic milieu is not known. However, the issue is relevant, given the immunomodulatory effects of DBP and the role of protracted innate immune-related inflammation in response to tissue injury or repeated infection. Indeed, DBP and vitamin D may jointly or independently contribute to a variety of adverse health outcomes unrelated to classical notions of their function in bone and mineral metabolism. This review summarizes the reports to date of associations between DBP variants, and various chronic and infectious diseases. The available information leads us to conclude that DBP variants are a significant and common genetic factor in some common disorders, and therefore, are worthy of closer attention. In view of the heightened interest in vitamin D as a public health target, well-designed studies that look simultaneously at vitamin D and its carrier in relation to genotypes and adverse health outcome should be encouraged.