Your browser doesn't support javascript.
Show: 20 | 50 | 100
Results 1 - 3 de 3
Filter
1.
Clin Rev Allergy Immunol ; 63(1): 22-35, 2022 Aug.
Article in English | MEDLINE | ID: covidwho-1971834

ABSTRACT

Interruptions or alterations in the B cell development pathway can lead to primary B cell immunodeficiency with resultant absence or diminished immunoglobulin production. While the most common cause of congenital agammaglobulinemia is X-linked agammaglobulinemia (XLA), accounting for approximately 85% of cases, other genetic forms of agammaglobulinemia have been identified. Early recognition and diagnosis of these conditions are pivotal for improved outcomes and prevention of sequelae and complications. The diagnosis of XLA is often delayed, and can be missed if patient has a mild phenotype. The lack of correlation between phenotype and genotype in this condition makes management and predicting outcomes quite difficult. In contrast, while less common, autosomal recessive forms of agammaglobulinemia present at younger ages and with typically more severe clinical features resulting in an earlier diagnosis. Some diagnostic innovations, such as KREC level measurements and serum BCMA measurements, may aid in facilitating an earlier identification of agammaglobulinemia leading to prompt treatment. Earlier diagnosis may improve the overall health of patients with XLA.


Subject(s)
Agammaglobulinemia , Agammaglobulinaemia Tyrosine Kinase/genetics , Agammaglobulinemia/diagnosis , Agammaglobulinemia/genetics , Genetic Diseases, X-Linked , Humans , Mutation , Protein-Tyrosine Kinases/genetics
2.
Curr Opin Allergy Clin Immunol ; 21(6): 525-534, 2021 12 01.
Article in English | MEDLINE | ID: covidwho-1447630

ABSTRACT

PURPOSE OF REVIEW: The clinical outcomes from COVID-19 in monogenic causes of predominant antibody deficiency have pivotal implications for our understanding of the antiviral contribution of humoral immunity. This review summarizes the lessons learned from COVID-19 infection in X-linked agammaglobulinemia (XLA) due to genetic defects in Bruton's tyrosine kinase (BTK). RECENT FINDINGS: Key molecular pathways underlying the development of severe COVID-19 are emerging, highlighting the possible contribution of BTK to hyperinflammation. SARS-CoV-2 specific T-cell responses and complement activation appear insufficient to achieve viral clearance in some B-cell deficient individuals. Whilst appearing efficacious in this group, use of convalescent plasma has been recently associated with the evolution of viral escape variants. Early data suggests individuals with XLA can mount a viral-specific T-cell vaccine response, however, the clinical significance of this is still emerging. SUMMARY: In contrast to reports made early in the pandemic, we show XLA patients remain susceptible to severe disease. Persistent infection was common and is likely to carry a significant symptom burden and risk of novel variant evolution. COVID-19 infection in this vulnerable, antibody deficient group due to genetic, therapeutic or disease causes may require prompt and specific intervention for both patient and societal benefit.


Subject(s)
Agammaglobulinaemia Tyrosine Kinase/genetics , Agammaglobulinemia/complications , COVID-19/immunology , Genetic Diseases, X-Linked/complications , SARS-CoV-2/immunology , Agammaglobulinemia/genetics , Agammaglobulinemia/immunology , COVID-19/diagnosis , COVID-19/virology , Evolution, Molecular , Genetic Diseases, X-Linked/genetics , Genetic Diseases, X-Linked/immunology , Humans , SARS-CoV-2/genetics , SARS-CoV-2/pathogenicity , Severity of Illness Index
3.
Elife ; 92020 11 23.
Article in English | MEDLINE | ID: covidwho-940328

ABSTRACT

Bruton's tyrosine kinase (BTK) is targeted in the treatment of B-cell disorders including leukemias and lymphomas. Currently approved BTK inhibitors, including Ibrutinib, a first-in-class covalent inhibitor of BTK, bind directly to the kinase active site. While effective at blocking the catalytic activity of BTK, consequences of drug binding on the global conformation of full-length BTK are unknown. Here, we uncover a range of conformational effects in full-length BTK induced by a panel of active site inhibitors, including large-scale shifts in the conformational equilibria of the regulatory domains. Additionally, we find that a remote Ibrutinib resistance mutation, T316A in the BTK SH2 domain, drives spurious BTK activity by destabilizing the compact autoinhibitory conformation of full-length BTK, shifting the conformational ensemble away from the autoinhibited form. Future development of BTK inhibitors will need to consider long-range allosteric consequences of inhibitor binding, including the emerging application of these BTK inhibitors in treating COVID-19.


Treatments for blood cancers, such as leukemia and lymphoma, rely heavily on chemotherapy, using drugs that target a vulnerable aspect of the cancer cells. B-cells, a type of white blood cell that produces antibodies, require a protein called Bruton's tyrosine kinase, or BTK for short, to survive. The drug ibrutinib (Imbruvica) is used to treat B-cell cancers by blocking BTK. The BTK protein consists of several regions. One of them, known as the kinase domain, is responsible for its activity as an enzyme (which allows it to modify other proteins by adding a 'tag' known as a phosphate group). The other regions of BTK, known as regulatory modules, control this activity. In BTK's inactive form, the regulatory modules attach to the kinase domain, blocking the regulatory modules from interacting with other proteins. When BTK is activated, it changes its conformation so the regulatory regions detach and become available for interactions with other proteins, at the same time exposing the active kinase domain. Ibrutinib and other BTK drugs in development bind to the kinase domain to block its activity. However, it is not known how this binding affects the regulatory modules. Previous efforts to study how drugs bind to BTK have used a version of the protein that only had the kinase domain, instead of the full-length protein. Now, Joseph et al. have studied full-length BTK and how it binds to five different drugs. The results reveal that ibrutinib and another drug called dasatinib both indirectly disrupt the normal position of the regulatory domains pushing BTK toward a conformation that resembles the activated state. By contrast, the three other compounds studied do not affect the inactive structure. Joseph et al. also examined a mutation in BTK that confers resistance against ibrutinib. This mutation increases the activity of BTK by disrupting the inactive structure, leading to B cells surviving better. Understanding how drug resistance mechanisms can work will lead to better drug treatment strategies for cancer. BTK is also a target in other diseases such as allergies or asthma and even COVID-19. If interactions between partner proteins and the regulatory domain are important in these diseases, then they may be better treated with drugs that maintain the regulatory modules in their inactive state. This research will help to design drugs that are better able to control BTK activity.


Subject(s)
Agammaglobulinaemia Tyrosine Kinase/antagonists & inhibitors , Catalytic Domain , Protein Conformation/drug effects , Protein Kinase Inhibitors/pharmacology , Adenine/analogs & derivatives , Adenine/chemistry , Adenine/metabolism , Adenine/pharmacology , Agammaglobulinaemia Tyrosine Kinase/chemistry , Agammaglobulinaemia Tyrosine Kinase/genetics , COVID-19/metabolism , COVID-19/prevention & control , COVID-19/virology , Dasatinib/chemistry , Dasatinib/metabolism , Dasatinib/pharmacology , Humans , Leukemia, Lymphocytic, Chronic, B-Cell/genetics , Leukemia, Lymphocytic, Chronic, B-Cell/prevention & control , Models, Molecular , Molecular Structure , Mutation , Piperidines/chemistry , Piperidines/metabolism , Piperidines/pharmacology , Protein Kinase Inhibitors/chemistry , Protein Kinase Inhibitors/metabolism , SARS-CoV-2/physiology , src Homology Domains/genetics
SELECTION OF CITATIONS
SEARCH DETAIL