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1.
Front Immunol ; 15: 1395684, 2024.
Artículo en Inglés | MEDLINE | ID: mdl-38868776

RESUMEN

Circulating follicular helper T cells (cTfh) can show phenotypic alterations in disease settings, including in the context of tissue-damaging autoimmune or anti-viral responses. Using severe COVID-19 as a paradigm of immune dysregulation, we have explored how cTfh phenotype relates to the titre and quality of antibody responses. Severe disease was associated with higher titres of neutralising S1 IgG and evidence of increased T cell activation. ICOS, CD38 and HLA-DR expressing cTfh correlated with serum S1 IgG titres and neutralising strength, and interestingly expression of TIGIT by cTfh showed a negative correlation. TIGIT+cTfh expressed increased IFNγ and decreased IL-17 compared to their TIGIT-cTfh counterparts, and showed reduced capacity to help B cells in vitro. Additionally, TIGIT+cTfh expressed lower levels of CD40L than TIGIT-cTfh, providing a potential explanation for their poor B-helper function. These data identify phenotypic changes in polyclonal cTfh that correlate with specific antibody responses and reveal TIGIT as a marker of cTfh with altered function.


Asunto(s)
Anticuerpos Antivirales , Linfocitos B , COVID-19 , Receptores Inmunológicos , SARS-CoV-2 , Células T Auxiliares Foliculares , Adulto , Anciano , Femenino , Humanos , Masculino , Persona de Mediana Edad , Anticuerpos Neutralizantes/inmunología , Anticuerpos Neutralizantes/sangre , Anticuerpos Antivirales/sangre , Anticuerpos Antivirales/inmunología , Linfocitos B/inmunología , COVID-19/inmunología , Inmunoglobulina G/sangre , Inmunoglobulina G/inmunología , Activación de Linfocitos/inmunología , Receptores Inmunológicos/inmunología , SARS-CoV-2/inmunología , Células T Auxiliares Foliculares/inmunología , Anciano de 80 o más Años
2.
Int Orthop ; 2024 Jun 14.
Artículo en Inglés | MEDLINE | ID: mdl-38874669

RESUMEN

PURPOSE: Currently no guidance exists within the literature regarding diagnostic criteria or the long-term outcomes for paediatric patients with acute compartment syndrome (ACS). We conducted a retrospective cohort study reviewing all cases of paediatric ACS managed at a single tertiary referral centre with the aim of characterising the factors responsible for the eventual outcomes. METHODS: The patient cohort was identified retrospectively by interrogating the hospital coding system for all paediatric patients between January 2014 and November 2022. The electronic emergency department, inpatient and operative notes as well as clinic letters for each patient were reviewed and data collected regarding presentation, associated injuries, management and subsequent complications plus length of follow-up. The data was analysed to determine if differences in presentation or management affected long term outcome. RESULTS: The final cohort consisted of 34 patients with a mean age of ten years at the time of presentation. The mean time from presentation to fasciotomy was 27.6 h (range 3.0 - 66.6). There was an overall complication rate of 37.5% with a mean follow-up period of 21 months. Patients who had direct closure of their fasciotomy wounds had a significantly lower complications rate and fewer operations compared to those who healed via other wound coverage methods or secondary intention (p < 0.05). CONCLUSIONS: Significantly higher complication rates were observed in patients who were unable to have direct wound closure following emergency fasciotomy. This information may be utilised to rationalise long term treatment plans and in counselling of patients and parents.

3.
Heart Lung ; 67: 152-157, 2024.
Artículo en Inglés | MEDLINE | ID: mdl-38762963

RESUMEN

BACKGROUND: Support groups for people with Implantable Cardioverter Defibrillators (ICDs) are widely used, however, it is not clear what people with ICDs gain from a support group or what format they should take. OBJECTIVES: The aim of the present study is to define the perceived benefit of ICD support groups and develop practical recommendations for group format. METHODS: 14 individuals with ICDs were interviewed using a semi-structured interview guide. Reflexive thematic analysis methods were utilised to code and analyse the transcripts before generating themes. RESULTS: Four themes were defined: confronting mortality, coping through sharing, coping through learning, and providing space. Making connections with other people with ICDs, reassurance, access to information, and advice from health care professionals were important perceived benefits of the support group. CONCLUSION: People with ICDs may have to confront their own mortality and adapt to considerable life changes after implant. The findings from the present study have improved understanding of how support groups are perceived and how ICD indication and group format influence the experience. A blended format of in-person community meetings, online forums, HCP-led education and space for person-person interaction is recommended. Importantly, provision of support should not be time-limited to allow people to access it when it most likely to be of benefit to them.


Asunto(s)
Adaptación Psicológica , Desfibriladores Implantables , Grupos de Autoayuda , Humanos , Desfibriladores Implantables/psicología , Masculino , Femenino , Persona de Mediana Edad , Anciano , Adulto , Apoyo Social , Investigación Cualitativa
4.
Int J Behav Med ; 2024 May 09.
Artículo en Inglés | MEDLINE | ID: mdl-38724879

RESUMEN

BACKGROUND: Research on age-progression facial morphing interventions for smoking cessation has not investigated the effect of different instructions for intervention delivery. The objective of this pilot study was to investigate the influence of two instruction types used to deliver the intervention on efficacy of the intervention. METHOD: Women were recruited and randomly allocated to an age-progression intervention session with (i) neutral instructions; (ii) instructions designed to reassure; or (iii) a condition that controlled for participant engagement ("control"). The conditions were delivered in a one-time procedure, after which primary (quitting intentions) and secondary (cigarettes/week, quit attempts) outcomes were measured immediately post-intervention, and at 1 and 3 months. RESULTS: Seventy-two women (M = 25.7; SD = 0.9) were recruited and randomly allocated to condition (Neutral n = 27, Reassuring n = 22, Control n = 23). Quitting intentions were higher in the Reassuring versus Control arm (3 months post-intervention, F = 4.37, p = 0.016, 95% CI [0.231, 2.539], eta2 = 0.11); quit attempts were greater in the two intervention arms (58%) versus Control (1-month post-intervention, 15%) (χ2 = 9.83, p < 0.05, OR 1.00 [0.28, 3.63]). CONCLUSIONS: Findings highlight the importance of optimising instructions to enhance intervention efficacy. TRIAL REGISTRATION: clinicaltrials.gov Record: NCT03749382.

5.
J Am Chem Soc ; 146(19): 13133-13141, 2024 May 15.
Artículo en Inglés | MEDLINE | ID: mdl-38695282

RESUMEN

Triphenylmethyl (trityl) radicals have shown potential for use in organic optoelectronic applications, but the design of practical trityl structures has been limited to donor/radical charge-transfer systems due to the poor luminescence of alternant symmetry hydrocarbons. Here, we circumvent the symmetry-forbidden transition of alternant hydrocarbons via excited-state symmetry breaking in a series of phenyl-substituted tris(2,4,6-trichlorophenyl)methyl (TTM) radicals. We show that 3-fold phenyl substitution enhances the emission of the TTM radical and that steric control modulates the optical properties in these systems. Simple ortho-methylphenyl substitution boosts the photoluminescence quantum efficiency from 1% (for TTM) to 65% at a peak wavelength of 612 nm (for 2-T3TTM) in solution. In the crystalline solid state, the neat 2-T3TTM radical shows a remarkably high photoluminescence quantum efficiency of 25% for emission peaking at 706 nm. This has implications in the design of aryl-substituted radical structures where the electronic coupling of the substituents influences variables such as emission, charge transfer, and spin interaction.

6.
J Hand Surg Eur Vol ; : 17531934241246479, 2024 Apr 20.
Artículo en Inglés | MEDLINE | ID: mdl-38641940

RESUMEN

We investigated whether ChatGPT was able to increase the Flesch reading ease and the Flesch-Kincaid reading level of elective clinic letters written by hand surgeons. ChatGPT could not reliably simplify the hand clinic letters any further.

7.
Dermatol Ther (Heidelb) ; 14(2): 489-504, 2024 Feb.
Artículo en Inglés | MEDLINE | ID: mdl-38372938

RESUMEN

INTRODUCTION: Receptor-interacting protein kinase 1 (RIPK1), a key mediator of inflammation through necroptosis and proinflammatory cytokine production, may play a role in the pathogenesis of immune-mediated inflammatory diseases such as chronic plaque psoriasis. An experimental medicine study of RIPK1 inhibition with GSK2982772 immediate-release formulation at doses up to 60 mg three times daily in mild to moderate plaque psoriasis indicated that efficacy may be improved with higher trough concentrations of GSK2982772. METHODS: This multicenter, randomized, double-blind, placebo-controlled, repeat-dose study (NCT04316585) assessed the efficacy, safety, pharmacokinetics, and pharmacodynamics of 960 mg GSK2982772 (once-daily modified-release formulation) in patients with moderate to severe plaque psoriasis. Twenty-nine patients were randomized 2:1 to GSK2982772 (N = 19) or placebo (N = 10) for 12 weeks. RESULTS: GSK2982772 was well tolerated with trough concentrations greater than tenfold higher than the previous phase 1 study with immediate release. Despite near complete RIPK1 target engagement in blood and modest reduction in circulating inflammatory cytokines, the proportion of patients achieving 75% improvement from baseline in Psoriasis Area Severity Index score at week 12 was similar between GSK2982772 and placebo (posterior median 1.8% vs 4.9%, respectively), with an estimated median treatment difference of - 2.3%. This analysis incorporated historical placebo data through the use of an informative prior distribution on the placebo arm. Week 4 changes in skin biopsy gene expression suggested sufficient local drug exposure to elicit a pharmacodynamic response. CONCLUSION: Administration of the RIPK1 inhibitor GSK2982772 to patients with moderate to severe plaque psoriasis did not translate into meaningful clinical improvements.


Psoriasis is thought to be caused by problems with the immune system, including possibly receptor-interacting protein kinase 1 (RIPK1), which plays an important role in the development of inflammation. A previous study suggested that the drug, GSK2982772, which interferes with RIPK1, might improve symptoms in patients with psoriasis. This study examined whether higher doses of GSK2982772 than previously studied would be beneficial for patients with psoriasis. The study found that the severity of psoriasis was similar in patients treated with GSK2982772 for 12 weeks as in those who did not receive the drug, indicating that GSK298772 did not improve psoriasis.

8.
Nat Rev Immunol ; 24(6): 435-451, 2024 Jun.
Artículo en Inglés | MEDLINE | ID: mdl-38308004

RESUMEN

Following the seminal discovery of insulin a century ago, treatment of individuals with type 1 diabetes (T1D) has been largely restricted to efforts to monitor and treat metabolic glucose dysregulation. The recent regulatory approval of the first immunotherapy that targets T cells as a means to delay the autoimmune destruction of pancreatic ß-cells highlights the critical role of the immune system in disease pathogenesis and tends to pave the way for other immune-targeted interventions for T1D. Improving the efficacy of such interventions across the natural history of the disease will probably require a more detailed understanding of the immunobiology of T1D, as well as technologies to monitor residual ß-cell mass and function. Here we provide an overview of the immune mechanisms that underpin the pathogenesis of T1D, with a particular emphasis on T cells.


Asunto(s)
Diabetes Mellitus Tipo 1 , Células Secretoras de Insulina , Diabetes Mellitus Tipo 1/inmunología , Diabetes Mellitus Tipo 1/terapia , Humanos , Células Secretoras de Insulina/inmunología , Animales , Linfocitos T/inmunología , Inmunoterapia/métodos , Autoinmunidad/inmunología
9.
Int Immunol ; 36(3): 89-98, 2024 Feb 21.
Artículo en Inglés | MEDLINE | ID: mdl-38164992

RESUMEN

Interleukin 21 (IL-21) is a pleiotropic cytokine that is overproduced in multiple autoimmune settings. Provision of IL-21 from follicular helper T cells is an important component of T-cell help within germinal centers (GC), and the last few years have seen a resurgence of interest in IL-21 biology in the context of the GC environment. While it has been more than a decade since T cell-derived IL-21 was found to upregulate B-cell expression of the GC master transcription factor B-cell lymphoma 6 (Bcl-6) and to promote GC expansion, several recent studies have collectively delivered significant new insights into how this cytokine shapes GC B-cell selection, proliferation, and fate choice. It is now clear that IL-21 plays an important role in GC zonal polarization by contributing to light zone GC B-cell positive selection for dark zone entry as well as by promoting cyclin D3-dependent dark zone inertial cycling. While it has been established that IL-21 can contribute to the modulation of GC output by aiding the generation of antibody-secreting cells (ASC), recent studies have now revealed how IL-21 signal strength shapes the fate choice between GC cycle re-entry and ASC differentiation in vivo. Both provision of IL-21 and sensitivity to this cytokine are finely tuned within the GC environment, and dysregulation of this pathway in autoimmune settings could alter the threshold for germinal center B-cell selection and differentiation, potentially promoting autoreactive B-cell responses.


Asunto(s)
Centro Germinal , Linfocitos T Colaboradores-Inductores , Interleucinas , Linfocitos B , Diferenciación Celular
10.
bioRxiv ; 2023 Dec 04.
Artículo en Inglés | MEDLINE | ID: mdl-38106196

RESUMEN

Interleukin-2 (IL-2) variants with increased CD25 dependence that selectively expand Foxp3+ regulatory T (TR) cells are in clinical trials for treating inflammatory diseases. Using an Fc-fused IL-2 mutein (Fc.IL-2 mutein) we developed that prevents diabetes in non-obese diabetic (NOD) mice, we show that Fc.IL-2 mutein induced an activated TR population with elevated proliferation, a transcriptional program associated with Stat5- and TCR-dependent gene modules, and high IL-10 and CTLA-4 expression. Increased IL-10 signaling limited surface MHC class II upregulation during conventional dendritic cell (cDC) maturation, while increased CTLA-4-dependent transendocytosis led to the transfer of CD80 and CD86 costimulatory ligands from maturing cDCs to TR cells. In NOD mice, Fc.IL-2 mutein treatment promoted the suppression of cDCs in the inflamed pancreas and pancreatic lymph nodes resulting in T cell anergy. Thus, IL-2 mutein-expanded TR cells have enhanced functional properties and restrict cDC function, offering promise for targeted immunotherapy use in autoimmune disease.

11.
Mil Psychol ; : 1-13, 2023 Nov 03.
Artículo en Inglés | MEDLINE | ID: mdl-37921638

RESUMEN

Defense and Security Personnel (DSP) often have to operate in the presence of stressful demands. Prior research has identified factors and processes associated with DSP being able to perform resiliently in demanding situations and settings. The aim of the present study was to develop a resilient performance training programme for UK defense and security operators. An intervention mapping (IM) method was used to guide the development of the programme. Typically, IM follows six sequential phases. In the present work, these phases were shaped by insights from prior research (e.g. systematic review and end user interviews), the input of a dedicated working group (N = 13) and from practitioner focus groups. During the IM process, the importance of programme flexibility was emphasized by practitioners. As such, the enAbling REsilieNt performAnce (ARENA) training programme was designed to be agile and include both face-to-face training and online learning modules. Theoretical behavior change principles, closely aligned to findings of earlier work on resilient defense and security performance, were used to underpin programme content and delivery. Future research should seek to gather data on the impact of the ARENA programme, in the targeted biological, psychological and social factors that previously been associated with resilient performances.

13.
Bone Jt Open ; 4(9): 720-727, 2023 Sep 21.
Artículo en Inglés | MEDLINE | ID: mdl-37730212

RESUMEN

Aims: Achievement of accurate microbiological diagnosis prior to revision is key to reducing the high rates of persistent infection after revision knee surgery. The effect of change in the microorganism between the first- and second-stage revision of total knee arthroplasty for periprosthetic joint infection (PJI) on the success of management is not clear. Methods: A two-centre retrospective cohort study was conducted to review the outcome of patients who have undergone two-stage revision for treatment of knee arthroplasty PJI, focusing specifically on isolated micro-organisms at both the first- and second-stage procedure. Patient demographics, medical, and orthopaedic history data, including postoperative outcomes and subsequent treatment, were obtained from the electronic records and medical notes. Results: The study cohort consisted of 84 patients, of whom 59.5% (n = 50) had successful eradication of their infection at a mean follow-up of 4.7 years. For the 34 patients who had recurrence of infection, 58.8% (n = 20) had a change in isolated organism, compared to 18% (n = 9) in the infection eradication group (p < 0.001). When adjusting for confound, there was no association when the growth on the second stage was the same as the first (odd ratio (OR) 2.50, 95% confidence interval (CI) 0.49 to 12.50; p = 0.269); however, when a different organism was identified at the second stage, this was independently associated with failure of treatment (OR 8.40, 95% CI 2.91 to 24.39; p < 0.001). There were no other significant differences between the two cohorts with regard to patient demographics or type of organisms isolated. Conclusion: Change in the identified microorganism between first- and second-stage revision for PJI was associated with failure of management. Identification of this change in the microorganism prior to commencement of the second stage may help target antibiotic management and could improve the success of surgery in these patients.

14.
J Exp Med ; 220(10)2023 10 02.
Artículo en Inglés | MEDLINE | ID: mdl-37466652

RESUMEN

Germinal center (GC) dysregulation has been widely reported in the context of autoimmunity. Here, we show that interleukin 21 (IL-21), the archetypal follicular helper T cell (Tfh) cytokine, shapes the scale and polarization of spontaneous chronic autoimmune as well as transient immunization-induced GC. We find that IL-21 receptor deficiency results in smaller GC that are profoundly skewed toward a light zone GC B cell phenotype and that IL-21 plays a key role in selection of light zone GC B cells for entry to the dark zone. Light zone skewing has been previously reported in mice lacking the cell cycle regulator cyclin D3. We demonstrate that IL-21 triggers cyclin D3 upregulation in GC B cells, thereby tuning dark zone inertial cell cycling. Lastly, we identify Foxo1 regulation as a link between IL-21 signaling and GC dark zone formation. These findings reveal new biological roles for IL-21 within GC and have implications for autoimmune settings where IL-21 is overproduced.


Asunto(s)
Centro Germinal , Linfocitos T Colaboradores-Inductores , Animales , Ratones , Ciclina D3 , Regulación hacia Arriba
15.
Int Arch Occup Environ Health ; 96(7): 1015-1027, 2023 09.
Artículo en Inglés | MEDLINE | ID: mdl-37269341

RESUMEN

OBJECTIVE: Taking regular rest breaks while working positively impacts productivity and wellbeing. While home and hybrid working styles have become a popular choice for employees, the impact of, and perceptions towards, taking breaks while working at home is poorly understood. The current research aimed to explore attitudes towards taking rest breaks while working from home and capture levels of breaks taken, wellbeing and productivity in a sample of UK white-collar workers. METHODS: A mixed method approach was applied where self-report data from an online survey were gathered from individuals (N = 140) from one organisation. Open-ended questions regarding attitudes and perceptions towards rest break behaviours were obtained. Further quantitative measures included the number of breaks taken while working from home, levels of productivity (measured by the Health and performance Presenteeism subscale) and mental wellbeing (measured by the Short Warwick-Edinburgh Mental wellbeing scale). Both quantitative and qualitative analysis approaches were applied. RESULTS: Qualitative responses indicated two overarching themes (1) Personal and (2) Organisational sat above four further themes including Movement outside, Structure of home working, Home environment and Digital presence. Additionally, quantitative findings indicated that the number of breaks taken outside was associated with positive changes in wellbeing. CONCLUSION: Employers could aim to support employees working from home in taking outside breaks through flexible working patterns, authentic leadership, and a change in company social norms around break behaviours. Such organisational changes could help to improve workforce productivity and wellbeing.


Asunto(s)
Actitud , Humanos , Encuestas y Cuestionarios , Autoinforme
16.
Lancet ; 401(10394): 2149-2162, 2023 06 24.
Artículo en Inglés | MEDLINE | ID: mdl-37030316

RESUMEN

Type 1 diabetes is a chronic disease caused by autoimmune destruction of pancreatic ß cells. Individuals with type 1 diabetes are reliant on insulin for survival. Despite enhanced knowledge related to the pathophysiology of the disease, including interactions between genetic, immune, and environmental contributions, and major strides in treatment and management, disease burden remains high. Studies aimed at blocking the immune attack on ß cells in people at risk or individuals with very early onset type 1 diabetes show promise in preserving endogenous insulin production. This Seminar will review the field of type 1 diabetes, highlighting recent progress within the past 5 years, challenges to clinical care, and future directions in research, including strategies to prevent, manage, and cure the disease.


Asunto(s)
Diabetes Mellitus Tipo 1 , Células Secretoras de Insulina , Humanos , Diabetes Mellitus Tipo 1/tratamiento farmacológico , Insulina/uso terapéutico
17.
J Wrist Surg ; 12(2): 121-127, 2023 Apr.
Artículo en Inglés | MEDLINE | ID: mdl-36926211

RESUMEN

Background In response to the coronavirus pandemic the British Orthopaedic Association Standards for Trauma and Orthopaedics (BOAST) guidelines advised treating distal radius fractures (DRFs) non-operatively where possible. Questions/Purpose The aim of this study was to assess whether the coronavirus disease 2019 (COVID-19) pandemic lockdown within the United Kingdom did alter the management of DRFs and whether there was any subsequent change in patient outcome or complication rate. Patients and Methods A retrospective cohort study was performed at a single orthopaedic center within the United Kingdom. The cohort of patients presenting with DRFs during the first lockdown was identified through the virtual fracture clinic database. The cohort of patients from the previous year was also identified for comparison. Data was collected on patient demographics, radiological features of the fractures, management, patient outcome and subsequent complications. Comparisons were then made between the cohorts for each year. Results The pre-COVID cohort had a significantly higher number of patients reviewed in face-to-face clinic appointments ( p = 0.0044) and the mean number of clinic appointments for those patients was significantly higher ( p = 0.0149). There was no significant difference between the cohorts regarding patient complications or any need for return to theater with a minimum 10 month follow-up period. Conclusion Despite comparative numbers and patterns of DRFs as well as no significant difference in the number of injuries requiring orthopaedic intervention, the burden on fracture clinic services was significantly reduced during the COVID pandemic. Encouragingly, this reduction in follow-up has not translated into an increased prevalence of complications or requirement for further surgery. Level of Evidence The level of evidence of the study is level III.

18.
Immunother Adv ; 3(1): ltad001, 2023.
Artículo en Inglés | MEDLINE | ID: mdl-36818683

RESUMEN

Efficacy of checkpoint inhibitor therapies in cancer varies greatly, with some patients showing complete responses while others do not respond and experience progressive disease. We aimed to identify correlates of response and progression following PD-1-directed therapy by immunophenotyping peripheral blood samples from 20 patients with advanced malignant melanoma before and after treatment with the PD-1 blocking antibody pembrolizumab. Our data reveal that individuals responding to PD-1 blockade were characterised by increased CD8 T cell proliferation following treatment, while progression was associated with an increase in CTLA-4-expressing Treg. Remarkably, unsupervised clustering analysis of pre-treatment T cell subsets revealed differences in individuals that went on to respond to PD-1 blockade compared to individuals that did not. These differences mapped to expression of the proliferation marker Ki67 and the costimulatory receptor CD28 as well as the inhibitory molecules 2B4 and KLRG1. While these results require validation in larger patient cohorts, they suggest that flow cytometric analysis of a relatively small number of T cell markers in peripheral blood could potentially allow stratification of PD-1 blockade treatment response prior to therapy initiation.

19.
J Perioper Pract ; 33(7-8): 239-247, 2023.
Artículo en Inglés | MEDLINE | ID: mdl-35652250

RESUMEN

BACKGROUND: Intraoperative cell salvage is an established method to reduce the requirement for and the volume of allogenic blood transfusion but adds to the financial cost of performing surgery. AIMS: The primary aim of this study was to determine which patients and what type of revision hip surgery benefit most from intraoperative cell salvage. METHODS: This observational study included patients who underwent revision hip surgery performed by the senior author at a single orthopaedic unit. The cohort was divided into single and two-component revision groups; then, the transfusion requirement combined with analysis of patient factors was used to create a decision-making protocol. FINDINGS: The two-component group had a significantly higher number of cases using cell salvage and a higher total transfusion volume. Patients who required postoperative allogenic blood transfusions had a higher mean age, were less likely to have received tranexamic acid and had a lower preoperative haemoglobin level. CONCLUSION: Based on these results, a decision-making protocol was developed for when to use cell salvage in revision hip surgery.


Asunto(s)
Artroplastia de Reemplazo de Cadera , Ácido Tranexámico , Humanos , Transfusión de Sangre Autóloga/métodos , Transfusión Sanguínea , Estudios Retrospectivos
20.
Blood Adv ; 7(1): 46-59, 2023 01 10.
Artículo en Inglés | MEDLINE | ID: mdl-36269841

RESUMEN

Mice lacking the immunoreceptor tyrosine-based inhibition motif-containing co-inhibitory receptor G6b-B (Mpig6b, G6b knockout, KO) are born with a complex megakaryocyte (MK) per platelet phenotype, characterized by severe macrothrombocytopenia, expansion of the MK population, and focal myelofibrosis in the bone marrow and spleen. Platelets are almost completely devoid of the glycoprotein VI (GPVI)-FcRγ-chain collagen receptor complex, have reduced collagen integrin α2ß1, elevated Syk tyrosine kinase activity, and a subset has increased surface immunoglobulins. A similar phenotype was recently reported in patients with null and loss-of-function mutations in MPIG6B. To better understand the cause and treatment of this pathology, we used pharmacological- and genetic-based approaches to rescue platelet counts and function in G6b KO mice. Intravenous immunoglobulin resulted in a transient partial recovery of platelet counts, whereas immune deficiency did not affect platelet counts or receptor expression in G6b KO mice. Syk loss-of-function (R41A) rescued macrothrombocytopenia, GPVI and α2ß1 expression in G6b KO mice, whereas treatment with the Syk kinase inhibitor BI1002494 partially rescued platelet count but had no effect on GPVI and α2ß1 expression or bleeding. The Src family kinase inhibitor dasatinib was not beneficial in G6b KO mice. In contrast, treatment with the thrombopoietin mimetic romiplostim rescued thrombocytopenia, GPVI expression, and platelet reactivity to collagen, suggesting that it may be a promising therapeutic option for patients lacking functional G6b-B. Intriguingly, GPVI and α2ß1 expression were significantly downregulated in romiplostim-treated wild-type mice, whereas GPVI was upregulated in romiplostim-treated G6b KO mice, suggesting a cell intrinsic feedback mechanism that autoregulates platelet reactivity depending on physiological needs.


Asunto(s)
Plaquetas , Trombocitopenia , Ratones , Animales , Plaquetas/metabolismo , Megacariocitos/metabolismo , Trombocitopenia/genética , Familia-src Quinasas/metabolismo , Colágeno/metabolismo
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