AXL inhibition suppresses early allograft monocyte-to-macrophage differentiation and prolongs allograft survival

Innate immune cells are important in the initiation and potentiation of alloimmunity in transplantation. Immediately upon organ anastomosis and reperfusion, recipient monocytes enter the graft from circulation and differentiate to inflammatory macrophages to promote allograft inflammation. However, factors that drive their differentiation to inflammatory macrophages are not understood. Here, we show that the receptor tyrosine kinase AXL was a key driver of early intragraft differentiation of recipient infiltrating monocytes to inflammatory macrophages in the presence of allogeneic stimulation and cell-to-cell contact. In this context, the differentiated inflammatory macrophages were capable of efficient alloantigen presentation and allostimulation of T cells of the indirect pathway. Consequently, early and transient AXL inhibition with the pharmacological inhibitor bemcentinib resulted in a profound reduction of initial allograft inflammation and a significant prolongation of allograft survival in a murine heart transplant model. Our results support further investigation of AXL inhibition as part of an induction regimen for transplantation.

Effects of transfusing older red blood cells and platelets on obstetric patient outcomes: A retrospective cohort study

OBJECTIVE

To investigate associations between transfusion of blood products close to the end of shelf-life and clinical outcomes in obstetric inpatients.

METHODS

Mortality and morbidity were compared in patients transfused exclusively with red blood cells (RBC) stored for less than 21 days (fresh) versus RBC stored for 35 days or longer (old), and platelets (PLT) stored for 3 days or fewer (fresh) versus 4 days or longer (old) in Queensland, Australia from 2007 to 2013. Multivariable models were used to examine associations between these groups of blood products and clinical end points.

RESULTS

There were 3371 patients who received RBC and 280 patients who received PLT of the eligible storage durations. Patients transfused with old RBC received fewer transfusions (2.7 ± 1.8 vs. 2.3 ± 1.0 units; P < 0.001). However, a higher rate of single-unit transfusions was also seen in those patients who exclusively received old RBC (252 [9.3%] vs. 92 [13.7%]; P = 0.003). Comparison of fresh vs. old blood products revealed no differences in the quantities of transfused RBC (9.5 ± 5.9 vs. 9.1 ± 5.2 units; P = 0.680) or PLT (1.5 ± 0.8 vs. 1.4 ± 1.1 units; P = 0.301) as well as the length of hospital stay for RBC (3 [2-5] vs. 3 [2-5] days; P = 0.124) or PLT (5 [4-8] vs. 6 [4-9] days; P = 0.120).

CONCLUSION

Transfusing exclusively older RBC or PLT was not associated with increased morbidity or mortality.

Examining the Characteristics of Colchicine-Induced Myelosuppression in Clinical Cases: A Systematic Review

OBJECTIVE

The use of colchicine has been associated with varying degrees of myelosuppression. Despite expanded use in cardiovascular and inflammatory conditions, there remains clinician concern because of potential myelosuppressive side effects. A systematic review was conducted to explore the reported myelosuppressive events of colchicine.

METHODS

A systematic review was conducted using the MeSH terms ("colchicine") AND ("myelosuppression," "bone*," "marrow," "suppression," "aplasia," "leukopenia/leucopenia," "lymphopenia," "neutropenia") on September 1, 2020, and was updated on November 30, 2021. The search was conducted in PubMed, ScienceDirect, Scopus, Embase, and Cochrane Library. The search included references published from 1978 to 2020 and was limited to English-language observational studies (ie, case reports, case series, case control studies, and cohort studies) or trial data.

RESULTS

In total, 3233 articles were screened, with 30 studies of 47 patients with myelosuppression from colchicine identified. Most patients with myelosuppression had comorbidities, including renal impairment (21/47, 44.7%). Out of 47 patients, 15 (31.9%) and 13 (27.7%) were reported to be concurrently taking cytochrome P450 3A4 (CYP3A4) inhibitors and P-glycoprotein (P-gp) efflux transporter inhibitors, respectively. Patients with renal impairment accounted for the majority of overall patients taking these CYP3A4 and P-gp inhibitors (8/15, 53.3%, and 8/13, 61.5%, respectively). Out of 21 patients with renal impairment, 13 had worsening cytopenia during colchicine use. The presentations ranged from moderate anemia (grade 2) to severe thrombocytopenia, neutropenia, and leukopenia (grade 4).

CONCLUSION

Colchicine has few reports of myelosuppression. The majority of patients with myelosuppression had preexisting renal impairment or concomitant CYP3A4 or P-gp inhibitor use. Caution should be taken in this subset of patients with increased monitoring.

Rapamycin and inulin for third-dose vaccine response stimulation (RIVASTIM): Inulin - study protocol for a pilot, multicentre, randomised, double-blinded, controlled trial of dietary inulin to improve SARS-CoV-2 vaccine response in kidney transplant recipients

INTRODUCTION

Kidney transplant recipients (KTRs) are at an increased risk of hospitalisation and death from COVID-19. Vaccination against SARS-CoV-2 is our primary risk mitigation strategy, yet vaccine effectiveness in KTRs is suboptimal. Strategies to enhance vaccine efficacy are therefore required. Current evidence supports the role of the gut microbiota in shaping the immune response to vaccination. Gut dysbiosis is common in KTRs and is a potential contributor to impaired COVID-19 vaccine responses. We hypothesise that dietary fibre supplementation will attenuate gut dysbiosis and promote vaccine responsiveness in KTRs.

METHODS AND ANALYSIS

Rapamycin and inulin for third-dose vaccine response stimulation-inulin is a multicentre, randomised, prospective, double-blinded, placebo-controlled pilot trial examining the effect of dietary inulin supplementation prior to a third dose of COVID-19 vaccine in KTRs who have failed to develop protective immunity following a 2-dose COVID-19 vaccine schedule. Participants will be randomised 1:1 to inulin (active) or maltodextrin (placebo control), administered as 20 g/day of powdered supplement dissolved in water, for 4 weeks prior to and following vaccination. The primary outcome is the proportion of participants in each trial arm that achieve in vitro neutralisation of live SARS-CoV-2 virus at 4 weeks following a third dose of COVID-19 vaccine. Secondary outcomes include the safety and tolerability of dietary inulin, the diversity and differential abundance of gut microbiota, and vaccine-specific immune cell populations and responses.

ETHICS AND DISSEMINATION

Ethics approval was obtained from the Central Adelaide Local Health Network (CALHN) Human Research Ethics Committee (HREC) (approval number: 2021/HRE00354) and the Sydney Local Health District (SHLD) HREC (approval numbers: X21-0411 and 2021/STE04280). Results of this trial will be published following peer-review and presented at scientific meetings and congresses.

TRIAL REGISTRATION NUMBER

ACTRN12621001465842.

Rapamycin and inulin for booster vaccine response stimulation (RIVASTIM)—rapamycin: study protocol for a randomised, controlled trial of immunosuppression modification with rapamycin to improve SARS-CoV-2 vaccine response in kidney transplant recipients

Kidney transplant recipients are at an increased risk of severe COVID-19-associated hospitalisation and death. Vaccination has been a key public health strategy to reduce disease severity and infectivity, but the effectiveness of COVID vaccines is markedly reduced in kidney transplant recipients. Urgent strategies to enhance vaccine efficacy are needed.

Methods: RIVASTIM-rapamycin is a multicentre, randomised, controlled trial examining the effect of immunosuppression modification prior to a third dose of COVID-19 vaccine in kidney transplant recipients who have failed to develop protective immunity to a 2-dose COVID-19 vaccine schedule. Participants will be randomised 1:1 to either remain on standard of care immunosuppression with tacrolimus, mycophenolate, and prednisolone (control) or cease mycophenolate and commence sirolimus (intervention) for 4 weeks prior to and following vaccination. The primary outcome is the proportion of participants in each trial arm who develop protective serological neutralisation of live SARS-CoV-2 virus at 4–6 weeks following a third COVID-19 vaccination. Secondary outcomes include SARS-CoV-receptor binding domain IgG, vaccine-specific immune cell populations and responses, and the safety and tolerability of sirolimus switch.

Discussion: Immunosuppression modification strategies may improve immunological vaccine response. We hypothesise that substituting the mTOR inhibitor sirolimus for mycophenolate in a triple drug regimen will enhance humoral and cell-mediated responses to COVID vaccination for kidney transplant recipients.

Trial registration: Australia New Zealand Clinical Trials Registry ACTRN12621001412820. Registered on 20 October 2021; https://www.anzctr.org.au/Trial/Registration/TrialReview.aspx?id=382891&isReview=true

COVID vaccination can be completed in subjects with a history of allergic reactions to the vaccines or their components - experience from a specialist clinic in South Australia

The development of vaccines against SARS-CoV2 has been a key public health response to the COVID-19 pandemic. However, since their introduction there have been reports of anaphylactic reactions in vaccinees with history of allergy. We developed an allergy testing protocol allowing vaccination with available COVID-19 vaccines in Australia. Patients referred to a state-wide COVID-19 vaccine allergy clinic between March and August 2021 with a history of allergy underwent skin prick testing and intradermal testing to both available vaccine formulations (BNT162b2, ChAdOx1-S), excipients (polyethylene glycol, polysorbate 80), excipient-containing medications, and controls. Where available, basophil activation testing was conducted. 53 patients underwent testing for possible excipient allergy (n = 19), previous non-COVID vaccine reaction (n = 13), or previous reaction to dose 1 of COVID-19 vaccine (n = 21). Patients were predominantly female (n = 43, 81%), aged 18-83 (median 54) years. 44 patients tested negative and 42 of these received at least their first dose of a COVID-19 vaccine. 9 patients tested positive to excipients or excipient-containing medication only (n = 3), or vaccines (n = 6). 5 patients were positive to just BNT162b2, 3/5 have been vaccinated with ChAdOx1-S. 1 who was skin test positive to both vaccines, but negative BAT to ChAdOx1-S was successfully vaccinated with ChAdOx1-S. Even in a high-risk population, most patients can be vaccinated with available COVID-19 vaccines. This paper reports local experiences using a combined allergy testing protocol with skin testing and BAT during the pandemic. This article is protected by copyright. All rights reserved.

AstraZeneca ChAdOx1-S COVID-19 vaccine can be safely administered in patients with EDTA allergy

BACKGROUND

Immediate hypersensitivity reactions to COVID-19 vaccines have been postulated to be linked to their excipients, such as polyethylene glycol (PEG) in Pfizer Comirnaty, or polysorbate 80 and ethylenediaminetetracetic acid (EDTA) in AstraZeneca ChAdOx1-S [recombinant] (Vaxzevria). These excipients are found in a range of other products, including injectable and oral medications as well as intravenous radiocontrast media (RCM) and various cosmetic products. Patients with proven excipient allergy may be advised to avoid a COVID-19 vaccine containing that excipient and/or potentially cross-reactive excipients. This may result in individual patients not receiving vaccines, especially if an alternate option is not available, and on a broader level contribute to vaccine hesitancy. We present two cases of previously confirmed EDTA anaphylaxis with positive intradermal testing, who had negative Vaxzevria vaccine in-vivo testing and subsequently tolerated the vaccine. CASE 1: A patient with history of anaphylaxis to RCM and local anaesthetics (LA) had positive intradermal test (IDT) to EDTA nine years earlier. Skin testing to Vaxzeria vaccine (up to 1:10 IDT), Comirnaty vaccine (up to 1:10 IDT) and EDTA 0.3 mg/mL IDT were negative. However, following EDTA 3 mg/ml IDT, he developed immediate generalised urticaria without anaphylaxis. Basophil activation testing was negative to disodium EDTA, Vaxzevria and Cominarty vaccines. Given the negative in-vitro and in-vivo testing to Vaxzevria vaccine, he proceeded to Vaxzevria immunisation and tolerated both doses. CASE 2: A patient with history of anaphylaxis to RCM had positive skin testing to EDTA and RCM containing EDTA six years earlier. Following referral to COVID19 vaccine clinic, Vaxzevria vaccine (1:10 IDT) and Cominarty vaccine (1:10 IDT) were negative whilst EDTA was positive at 0.3 mg/mL IDT. He subsequently tolerated both Vaxzevria vaccinations.

CONCLUSION

Excipient allergy does not necessarily preclude a patient from receiving a vaccine containing that excipient. Allergy testing can help identify excipient-allergic patients who may still tolerate vaccination, which is important in situations where COVID-19 vaccination options are limited.

Feasibility of perflutren microsphere contrast transthoracic echocardiography in the visualization of ventricular endocardium during venovenous extracorporeal membrane oxygenation in a validated ovine model

BACKGROUND

Transthoracic echocardiography (TTE) during extra corporeal membrane oxygenation (ECMO) is important but can be technically challenging. Contrast-specific TTE can improve imaging in suboptimal studies. These contrast microspheres are hydrodynamically labile structures. This study assessed the feasibility of contrast echocardiography (CE) during venovenous (VV) ECMO in a validated ovine model.

METHOD

Twenty-four sheep were commenced on VV ECMO. Parasternal long-axis (Plax) and short-axis (Psax) views were obtained pre- and postcontrast while on VV ECMO. Endocardial definition scores (EDS) per segment were graded: 1 = good, 2 = suboptimal 3 = not seen. Endocardial border definition score index (EBDSI) was calculated for each view. Endocardial length (EL) in the Plax view for the left ventricle (LV) and right ventricle (RV) was measured.

RESULTS

Summation EDS data for the LV and RV for unenhanced TTE (UE) versus CE TTE imaging: EDS 1 = 289 versus 346, EDS 2 = 38 versus 10, EDS 3 = 33 versus 4, respectively. Wilcoxon matched-pairs rank-sign tests showed a significant ranking difference (improvement) pre- and postcontrast for the LV (P < 0.0001), RV (P < 0.0001) and combined ventricular data (P < 0.0001). EBDSI for CE TTE was significantly lower than UE TTE for the LV (1.05 ± 0.17 vs. 1.22 ± 0.38, P = 0.0004) and RV (1.06 ± 0.22 vs. 1.42 ± 0.47, P = 0.0.0006) respectively. Visualized EL was significantly longer in CE versus UE for both the LV (58.6 ± 11.0 mm vs. 47.4 ± 11.7 mm, P < 0.0001) and the RV (52.3 ± 8.6 mm vs. 36.0 ± 13.1 mm, P < 0.0001), respectively.

CONCLUSIONS

Despite exposure to destructive hydrodynamic forces, CE is a feasible technique in an ovine ECMO model. CE results in significantly improved EDS and increased EL.

A novel echocardiographic imaging technique, intracatheter echocardiography, to guide veno-venous extracorporeal membrane oxygenation cannulae placement in a validated ovine model

Background

Echocardiography plays a fundamental role in cannulae insertion and positioning for extracorporeal membrane oxygenation (ECMO). Optimal access and return cannulae orientation is required to prevent recirculation. The aim of this study was to compare a novel imaging technique, intracatheter echocardiography (iCATHe), with conventional intracardiac echocardiography (ICE) to guide placement of ECMO access and return venous cannulae.

Methods

Twenty sheep were commenced on veno-venous ECMO (VV ECMO). Access and return ECMO cannulae were positioned using an ICE-guided technique. Following the assessment of cannulae position, the ICE probe was then introduced inside the cannulae, noting location of the tip. After 24 h, the sheep were euthanized and cannulae position was determined at post mortem. The two-tailed McNemar test was used to compare iCATHe with ICE cannulae positioning.

Results

ICE and iCATHe imaging was possible in all 20 sheep commenced on ECMO. There was no significant difference between the two methods in assessing access cannula position (proportion correct for each 90%, incorrect 10%). However, there was a significant difference between ICE and iCATHe success rates for the return cannula (p = 0.001). Proportion correct for iCATHe and ICE was 80% and 15% respectively. iCATHe was 65% more successful (95% CI 27% to 75%) at predicting the placement of the return cannula. There were no complications related to the ICE or iCATHe imaging.

Conclusion

iCATHe is a safe and feasible imaging technique to guide real-time VV ECMO cannulae placement and improves accuracy of return cannula positioning compared to ICE.

Electronic supplementary material

The online version of this article (doi:10.1186/2197-425X-2-2) contains supplementary material, which is available to authorized users.

Training in general (internal) medicine alone

A freestanding training programme for general (internal) medicine (G(I)M) alone was established in the Oxford deanery four years ago. The programme was designed to provide three years' training post-MRCP for specialist registrars, selected in open competition, and covers all aspects of acute medical care including four months in intensive care. The first four to complete training have achieved consultant level appointments. The programme also attracted a number of trainees who wished to obtain appropriate qualifications in high dependency and critical care medicine. The programme offers the opportunity to create specialists properly trained in G(I)M who will be able to continue to provide an important service as specialists or practising as consultants in G(I)M alone.

Staff grades and associate specialists: their continuing professional development and aspirations

A survey of staff grades and associate specialists in the Oxford deanery showed that there were slightly more females (53%). There were 44% who had on-call commitments, a third of these were first on call. Thirty-eight per cent of the staff grades and 55% of the associate specialists had membership or fellowship of their relevant Royal College. The majority undertake continuing professional development and a majority would like promotion but only a small minority is prepared to relocate to further their training.

Outcome of diabetic pregnancy and glucose intolerance in pregnancy: an audit of fetal loss in Newcastle General Hospital 1977-1990

The outcome of pregnancy complicated by established diabetes or gestational glucose intolerance (diabetes mellitus or impaired glucose tolerance) is compared with the outcome of non-diabetic pregnancy. Between 1977 and 1990, 169 pregnancies in women with established diabetes and 61 pregnancies in women with gestational glucose intolerance were referred to the Newcastle General Hospital. The perinatal mortality (PNM) in women with established diabetes was 8.2/1000 and the viable fetal loss (sum of PNM, neonatal and infant loss) was 41/1000. The PNM in women with gestational glucose intolerance was 49.2/1000 and the viable fetal loss was 82/1000. The PNM in the background population was 11.6/1000. The fetal malformation rate was 17.3% for established diabetes, 9.8% in gestational glucose intolerance and 2.2% in the background population. Fetal abnormality remains the major cause of viable fetal loss in both established diabetes and gestational glucose intolerance.