Improvement of immune dysregulation in individuals with long COVID at 24-months following SARS-CoV-2 infection

This study investigates the humoral and cellular immune responses and health-related quality of life measures in individuals with mild to moderate long COVID (LC) compared to age and gender matched recovered COVID-19 controls (MC) over 24 months. LC participants show elevated nucleocapsid IgG levels at 3 months, and higher neutralizing capacity up to 8 months post-infection. Increased spike-specific and nucleocapsid-specific CD4+ T cells, PD-1, and TIM-3 expression on CD4+ and CD8+ T cells were observed at 3 and 8 months, but these differences do not persist at 24 months. Some LC participants had detectable IFN-γ and IFN-β, that was attributed to reinfection and antigen re-exposure. Single-cell RNA sequencing at the 24 month timepoint shows similar immune cell proportions and reconstitution of naïve T and B cell subsets in LC and MC. No significant differences in exhaustion scores or antigen-specific T cell clones are observed. These findings suggest resolution of immune activation in LC and return to comparable immune responses between LC and MC over time. Improvement in self-reported health-related quality of life at 24 months was also evident in the majority of LC (62%). PTX3, CRP levels and platelet count are associated with improvements in health-related quality of life.

Oscillometry in Stable Single and Double Lung Allograft Recipients Transplanted for Interstitial Lung Disease: Results of a Multi-Center Australian Study

Peak spirometry after single lung transplantation (SLTx) for interstitial lung disease (ILD) is lower than after double lung transplantation (DLTx), however the pathophysiologic mechanisms are unclear. We aim to assess respiratory mechanics in SLTx and DLTx for ILD using oscillometry. Spirometry and oscillometry (tremoflo® C-100) were performed in stable SLTx and DLTx recipients in a multi-center study. Resistance (R5, R5-19) and reactance (X5) were compared between LTx recipient groups, matched by age and gender. A model of respiratory impedance using ILD and DLTx data was performed. In total, 45 stable LTx recipients were recruited (SLTx n = 23, DLTx n = 22; males: 87.0% vs. 77.3%; median age 63.0 vs. 63.0 years). Spirometry was significantly lower after SLTx compared with DLTx: %-predicted mean (SD) FEV1 [70.0 (14.5) vs. 93.5 (26.0)%]; FVC [70.5 (16.8) vs. 90.7 (12.8)%], p < 0.01. R5 and R5-19 were similar between groups (p = 0.94 and p = 0.11, respectively) yet X5 was significantly worse after SLTx: median (IQR) X5 [-1.88 (-2.89 to -1.39) vs. -1.22 (-1.87 to -0.86)] cmH2O.s/L], p < 0.01. R5 and X5 measurements from the model were congruent with measurements in SLTx recipients. The similarities in resistance, yet differences in spirometry and reactance between both transplant groups suggest the important contribution of elastic properties to the pathophysiology. Oscillometry may provide further insight into the physiological changes occurring post-LTx.

Psychiatric sequelae after SARS-Cov-2 infection: trajectory, predictors and associations in a longitudinal Australian cohort

A relationship between SARS-CoV-2 infection and psychiatric symptoms has been identified but is still being fully investigated. Neuropsychiatric sequalae have been reported for several infectious agents and are not unexpected for SARS-CoV-2 infection. This study follows for 12 months a sample (N = 144) of people who have had a confirmed infection of SARS-CoV-2. Medical and neuropsychiatric data and biological specimens are collected at 6 study visits. The 34-item SPHERE questionnaire, the Depression in the Medically Ill instrument, the EQ-5D-5L quality of life instrument and the visual analogue scale of fatigue were administered at multiple timepoints and associations with measures of illness and inflammatory biomarkers were investigated using the generalised estimating equation. Associations between inflammatory biomarkers and mental health measures of various effect sizes were identified. A robust inverse association was found between mental health outcomes and long covid status, but not between mental health outcomes and covid illness severity. This study suggests that long covid may be the strongest predictor of neuropsychiatric symptoms amongst people who have been infected with SARS-CoV-2.

The kynurenine pathway relates to post-acute COVID-19 objective cognitive impairment and PASC

OBJECTIVE

To determine the prevalence and natural history of post-acute COVID-19 objective cognitive impairment and function, and their relationship to demographic, clinical factors, post-acute sequelae of COVID-19 (PASC), and biomarkers.

METHODS

A total of 128 post-acute COVID-19 patients (age = 46 ± 15; 42% women, acute disease severity: not hospitalized: 38.6% mild: 0-1 symptoms, 52% 2+ symptoms; 9.4% hospitalized) completed standard cognition, olfaction, and mental health examinations 2-, 4-, and 12-month post diagnosis. Over the same time frame, WHO-defined PASC was determined. Blood cytokines, peripheral neurobiomarkers, and kynurenine pathway (KP) metabolites were measured. Objective cognitive function was demographically/practice corrected, and impairment prevalence was determined using the evidence-based Global Deficit Score method to detect at least mild cognitive impairment (GDS > 0.5). Linear mixed effect regression models with time effect (month post diagnosis) evaluated the relationships to cognition.

RESULTS

Across the 12-month study period, mild to moderate cognitive impairment ranged from 16% to 26%, and 46.5% were impaired at least once. Impairment associated with poorer work capacity (p < 0.05), and 2-month objectively tested anosmia (p < 0.05). PASC with (p = 0.01) and without disability (p < 0.03) associated with acute COVID-19 severity. KP measures showed prolonged activation (2 to 8 months) (p < 0.0001) linked to IFN-beta in those with PASC. Of the blood analytes, only the KP metabolites (elevated quinolinic acid, 3-hydroxyanthranilic acid, kynurenine, the kynurenine/tryptophan ratio) associated (p < 0.001) with poorer cognitive performance and greater likelihood of impairment. PASC, independent of disability associated with abnormal kynurenine/tryptophan (p < 0.03).

INTERPRETATION

The kynurenine pathway relates to post-acute COVID-19 objective cognitive impairment and PASC, thereby enabling biomarker and therapeutic possibilities.

Multispecies Outbreak of Nocardia Infections in Heart Transplant Recipients and Association with Climate Conditions, Australia

Extreme weather conditions, coupled with greater susceptibility to opportunistic infection, could explain this outbreak.

A multispecies outbreak of Nocardia occurred among heart transplant recipients (HTR), but not lung transplant recipients (LTR), in Sydney, New South Wales, Australia, during 2018–2019. We performed a retrospective review of 23 HTR and LTR who had Nocardia spp. infections during June 2015–March 2021, compared risk factors for Nocardia infection, and evaluated climate conditions before, during, and after the period of the 2018–2019 outbreak. Compared with LTR, HTR had a shorter median time from transplant to Nocardia diagnosis, higher prevalence of diabetes, greater use of induction immunosuppression with basiliximab, and increased rates of cellular rejection before Nocardia diagnosis. During the outbreak, Sydney experienced the lowest monthly precipitation and driest surface levels compared with time periods directly before and after the outbreak. Increased immunosuppression of HTR compared with LTR, coupled with extreme weather conditions during 2018–2019, may explain this outbreak of Nocardia infections in HTR.

Immunological dysfunction persists for 8 months following initial mild-to-moderate SARS-CoV-2 infection

A proportion of patients surviving acute coronavirus disease 2019 (COVID-19) infection develop post-acute COVID syndrome (long COVID (LC)) lasting longer than 12 weeks. Here, we studied individuals with LC compared to age- and gender-matched recovered individuals without LC, unexposed donors and individuals infected with other coronaviruses. Patients with LC had highly activated innate immune cells, lacked naive T and B cells and showed elevated expression of type I IFN (IFN-β) and type III IFN (IFN-λ1) that remained persistently high at 8 months after infection. Using a log-linear classification model, we defined an optimal set of analytes that had the strongest association with LC among the 28 analytes measured. Combinations of the inflammatory mediators IFN-β, PTX3, IFN-γ, IFN-λ2/3 and IL-6 associated with LC with 78.5-81.6% accuracy. This work defines immunological parameters associated with LC and suggests future opportunities for prevention and treatment.

Identifying the association between tacrolimus exposure and toxicity in heart and lung transplant recipients: A systematic review

AIMS

Tacrolimus is the cornerstone of immunosuppression management in heart and lung transplant recipients, improving overall survival. However, tacrolimus-associated toxicities, including nephrotoxicity, neurotoxicity, new-onset diabetes mellitus after transplant (NODAT), and gastrointestinal toxicity, are known contributors to increased post-transplant morbidity outcomes and reduced graft and recipient survival rates. The aim of this systematic review was to identify correlations between pharmacokinetic measures of tacrolimus exposure in heart and lung recipients and tacrolimus toxicities.

METHODS

MEDLINE, Embase, the Cochrane Library, CENTRAL and WHO Clinical Trial Registries were searched for published studies evaluating tacrolimus toxicities and their correlation to pharmacokinetic monitoring parameters in thoracic transplant recipients. Studies were reviewed by two authors, with data extracted for evaluation. Risk of bias was assessed using the PEDro scale for randomised control trials and the Newcastle Ottawa Scale for non-randomised cohort studies.

RESULTS

Eighteen studies were eligible; a randomised control trial, 11 observational cohort studies, and 6 case series or studies. Of these, 9 studies were in heart transplant recipients alone and 5 in lung transplant recipients alone, 2 studies were in heart and lung transplant recipients and 2 were heart, lung, liver or renal transplant recipients. Studies used variable criteria to define toxicities. Tacrolimus trough concentration (C₀) was the marker of tacrolimus exposure most commonly used. Ten studies reported on nephrotoxicity. Elevated tacrolimus C₀ was associated with acute kidney injury occurrence and severity in three observational studies. Increasing C₀ was a predictor of renal impairment in 6 studies. One study found that for each 5 ng/mL per year of tacrolimus exposure, defined by consecutive AUC, eGFR declined by 1.3 mL/min/1.73m² (p < 0.001). Comparatively, 2 studies failed to find a significant association between nephrotoxicity and tacrolimus exposure. Seven studies reported on neurotoxicity, including neuro-encephalopathies, polyneuropathies and symptomatic change in neurological status. Neurotoxicity occurred both with tacrolimus C₀ within therapeutic range and with supratherapeutic C₀. No significant association was found between NODAT and tacrolimus C₀ in two studies. One study reported on gastrointestinal toxicity, with supratherapeutic C₀ and elevated peak concentration in one lung transplant recipient three days prior to symptom development.

CONCLUSION

No clearly defined relationship between tacrolimus exposure and toxicities is described in the literature. Studies with clear toxicity criteria and pharmacokinetic markers of tacrolimus exposure are required to provide valuable information that may optimise tacrolimus therapy, helping to reduce toxicities in heart and lung transplant recipients.

Eosinophils in transbronchial biopsies: a predictor of chronic lung allograft dysfunction and reduced survival after lung transplantation - a retrospective single-center cohort study

Long-term outcomes after lung transplantation remain inferior to those of other solid organ groups. The significance of eosinophils detected on transbronchial biopsies (TBBx) after lung transplantation and their relationship to long-term outcomes remain unknown. A retrospective single-center cohort study was performed of patients transplanted between January 01, 2001, and July 31, 2018, who had at least 1 TBBx with evaluable parenchymal tissue. Multivariable Cox proportional hazard models were used to assess the associations between eosinophil detection and: all-cause mortality and Chronic Lung Allograft Dysfunction (CLAD). 8887 TBBx reports from 1440 patients were reviewed for the mention of eosinophils in the pathology report. 112 (7.8%) patients were identified with eosinophils on at least one TBBx. The median (95% CI) survival time for all patients was 8.28 (7.32-9.31) years. Multivariable analysis, adjusted for clinical variables known to affect post-transplant outcomes, showed that the detection of eosinophils was independently associated with an increased risk of death (HR 1.51, 95% CI 1.24-1.85, p < 0.01) and CLAD (HR 1.35, 95% CI 1.07-1.70, P = 0.01). Eosinophils detected in TBBx are associated with an increased risk of CLAD and death. There may be benefit in specifically reporting the presence of eosinophils in TBBx reports and incorporating their presence in clinical decision-making.

Tacrolimus exposure early after lung transplantation and exploratory associations with acute cellular rejection

AIMS

To (i) describe tacrolimus (TAC) pre-dose concentrations (C₀), (ii) calculate apparent oral TAC clearance (CL/F_HCT) adjusted for measured haematocrit (HCTi) and standardised to a HCT of 45%, across three observation time points and (iii) explore if low TAC C₀ or high mean CL/F_HCT are associated with an increased risk of rejection episodes early after lung transplantation.

METHODS

TAC whole blood concentration-time profiles and transbronchial biopsies were performed prospectively at weeks 3, 6 and 12 after lung transplantation. The TAC pre-dose concentration (C₀) was measured, and CL/F_HCT was determined using non-compartmental analysis. The associations between TAC C₀ and CL/F_HCT and rejection status were explored using repeated measures logistic regression.

RESULTS

Eighteen patients provided 377 TAC whole blood concentrations. Considerable variability around the median (IQR) CL/F_HCT 6.8 (4.2-15.9) L h^-1, and the median C₀ 12.7 (9.9-16.6) μg L^-1 was noted. Despite adjustment for haematocrit, a significant decrease was observed in CL/F_HCT in all patients over time: CL/F_HCT 14 (5.4-23) at week 3, CL/F_HCT 7.7 (4.5-12) at week 6 and CL/F_HCT 3.9 (2.4-11) L h^-1 at week 12 (p < 0.01). Seven (38.9%) patients experienced a single grade 2 rejection, whilst 11 (61.1%) patients experienced no rejection. Higher TAC C₀ were associated with a reduced risk of rejection OR 0.68 (95% CI 0.51-0.91, p = 0.02), and greater mean CL/F_HCT was associated with an increased risk of rejection OR 1.34 (95% CI 1.01-1.81 p = 0.04).

CONCLUSION

Monitoring TAC C₀, HCT and CL/F_HCT in patients after lung transplantation may assist clinicians in detecting patients at risk of acute rejection and may guide future research into TAC and HCT monitoring after lung transplantation.

Chest pain and recurrent chylothorax: an unusual presentation of malignant pleural mesothelioma

Malignant mesothelioma presenting with recurrent chylous effusion is rare. We describe the case of a 34‐year‐old female Macedonian immigrant who presented with central chest pain and subsequently a left‐sided chylous pleural effusion. The diagnosis was made on pleural biopsy via video‐assisted thoracoscopic surgery (VATS). Our case demonstrates the utility of thoracic magnetic resonance imaging (MRI) and the difficulties associated with pleural cytology and cervical lymph node biopsy in the establishment of a diagnosis of mesothelioma. It is a reminder that mesothelioma can metastasize to mediastinal and cervical lymph nodes, can occur in young people, and may present as a chylothorax.