High-Density Lipoprotein Particles and Torque Teno Virus in Stable Outpatient Kidney Transplant Recipients

Torque teno virus (TTV) is emerging as a potential marker for monitoring immune status. In transplant recipients who are immunosuppressed, higher TTV DNA loads are observed than in healthy individuals. TTV load measurement may aid in optimizing immunosuppressive medication dosing in solid organ transplant recipients. Additionally, there is a growing interest in the role of HDL particles in immune function; therefore, assessment of both HDL concentrations and TTV load may be of interest in transplant recipients. The objective of this study was to analyze TTV loads and HDL parameters in serum samples collected at least one year post-transplantation from 656 stable outpatient kidney transplant recipients (KTRs), enrolled in the TransplantLines Food and Nutrition Cohort (Groningen, the Netherlands). Plasma HDL particles and subfractions were measured using nuclear magnetic resonance spectroscopy. Serum TTV load was measured using a quantitative real-time polymerase chain reaction. Associations between HDL parameters and TTV load were examined using univariable and multivariable linear regression. The median age was 54.6 [IQR: 44.6 to 63.1] years, 43.3% were female, the mean eGFR was 52.5 (±20.6) mL/min/1.73 m2 and the median allograft vintage was 5.4 [IQR: 2.0 to 12.0] years. A total of 539 participants (82.2%) had a detectable TTV load with a mean TTV load of 3.04 (±1.53) log10 copies/mL, the mean total HDL particle concentration was 19.7 (±3.4) μmol/L, and the mean HDL size was 9.1 (±0.5) nm. The univariable linear regression revealed a negative association between total HDL particle concentration and TTV load (st.β = -0.17, 95% CI st.β: -0.26 to -0.09, p < 0.001). An effect modification of smoking behavior influencing the association between HDL particle concentration and TTV load was observed (Pinteraction = 0.024). After adjustment for age, sex, alcohol intake, hemoglobin, eGFR, donor age, allograft vintage and the use of calcineurin inhibitors, the negative association between HDL particle concentration and TTV load remained statistically significant in the non-smoking population (st.β = -0.14, 95% CI st.β: -0.23 to -0.04, p = 0.006). Furthermore, an association between small HDL particle concentration and TTV load was found (st.β = -0.12, 95% CI st.β: -0.22 to -0.02, p = 0.017). Higher HDL particle concentrations were associated with a lower TTV load in kidney transplant recipients, potentially indicative of a higher immune function. Interventional studies are needed to provide causal evidence on the effects of HDL on the immune system.

Increasing Antibody Responses to Five Doses of SARS-CoV-2 mRNA Vaccine in Lung Transplant Patients

PURPOSE

COVID-19 causes high mortality in Lung Transplant (LTx) patients, therefore vaccination in this population is potentially life-saving. However, the antibody response is impaired after three vaccinations in LTx patients. We questioned whether this response might be increased, and therefore studied the serological IgG antibody response across up to five doses of the SARS-CoV-2 vaccine. In addition, risk factors for non-response were investigated.

METHODS

In this large retrospective cohort study, antibody responses were assessed after 1-5 mRNA-based SARS-CoV-2 vaccines in all LTx patients between February 2021 and September 2022. A positive vaccine response was defined as an IgG level ≥ 300 BAU/mL. Positive antibody responses due to COVID-19 infection were excluded from the analysis. Outcome and clinical parameters were compared between responders and non-responders, and multivariable logistic regression analysis was performed to determine the risk factors for vaccine-response failure.

RESULTS

The antibody responses of 292 LTx patients were analyzed. Positive antibody response to 1-5 SARS-CoV-2 vaccinations occurred in 0%, 15%, 36%, 46%, and 51%, respectively. During the study period, 146/292 (50%) of the vaccinated individuals tested positive for SARS-CoV-2 infection. The COVID-19-related mortality was 2.7% (4/146), and all four patients were non-responders. Risk factors associated with non-response to SARS-CoV-2 vaccines in univariable analyses were age (p = 0.004), chronic kidney disease (CKD) (p = 0.006), and shorter time since transplantation (p = 0.047). In the multivariable analysis, they were CKD (p = 0.043), and shorter time since transplantation (p = 0.028).

CONCLUSION

A two- to five-dose regime of SARS-CoV-2 vaccines in LTx patients increases the probability of vaccine response and results in a cumulative vaccine response in 51% of the LTx population. LTx patient antibody response to SARS-CoV-2 vaccinations is therefore impaired, especially in patients shortly after LTx, patients with CKD, and the elderly.

COVID or no COVID: Interpreting inconclusive SARS-CoV-2 qPCR results in different populations and platforms

Introduction

High cycle threshold values (Ct) value) results for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) may be true infections or false-positive results. Misinterpretation of results has negative consequences. Goal of this study was to evaluate quantitative real-time polymerase chain reaction (qPCR) results with high Ct-values, to reach a point where a correct interpretation can be given.

Methods

High Ct-value results of SARS-CoV-2 in respiratory samples taken between April 2020 and January 2021 were analysed. Three different SARS-CoV-2 qPCR assays (in-house, Alinity M and Xpert Xpress) were used for screening patients and healthcare workers (HCW). High Ct-value results were defined as "inconclusive". The Ct-value cut-off for the interpretation of the test as "positive" and "inconclusive" were based on quality assurance panel results and manufacturers' instructions.

Results

Out of totally 50.295 samples tested for SARS-CoV-2, the in-house and Alinity M qPCR together yielded 379 inconclusive results. A second sample existed for 217 samples, allowing dynamics of the PCR in time. Of these, 187 were negative (86%), 11 again inconclusive (5%) and 19 positive (9%). Sixteen out of 19 persons with a positive result were HCW, 14 (74%) had a link to a SARS-CoV-2 infected person. The majority of inconclusive results detected with the Xpert Xpress (n=45 of 3603), were related to individuals with a known history of SARS-CoV-2 infection (n=28, 62%).

Conclusion

This study shows the importance of re-testing inconclusive SARS-CoV-2 qPCR results. Only then, the correct (true or false) interpretation can be given, leading to the right measures.

Proton Pump Inhibitor Use, Fatigue, and Health-Related Quality of Life in Kidney Transplant Recipients: Results From the TransplantLines Biobank and Cohort Study

RATIONALE & OBJECTIVE

Prior studies report that the use of proton pump inhibitors (PPIs) can adversely affect gut microbiota and gastrointestinal uptake of micronutrients, in particular iron and magnesium, and are used frequently by kidney transplant recipients. Altered gut microbiota, iron deficiency, and magnesium deficiency have been implicated in the pathogenesis of chronic fatigue. Therefore, we hypothesized that PPI use may be an important and underappreciated cause of fatigue and reduced health-related quality of life (HRQoL) in this population.

STUDY DESIGN

Cross-sectional study.

SETTING & PARTICIPANTS

Kidney transplant recipients (≥1 year after transplantation) enrolled in the TransplantLines Biobank and Cohort Study.

EXPOSURE

PPI use, PPI type, PPI dosage, and duration of PPI use.

OUTCOME

Fatigue and HRQoL, assessed using the validated Checklist Individual Strength 20 Revised questionnaire and Short Form-36 questionnaire.

ANALYTICAL APPROACH

Logistic and linear regression.

RESULTS

We included 937 kidney transplant recipients (mean age 56±13 years, 39% female) at a median of 3 (1-10) years after transplantation. PPI use was associated with fatigue severity (regression coefficient 4.02, 95% CI, 2.18 to 5.85, P<0.001), a higher risk of severe fatigue (OR 2.05, 95% CI, 1.48 to 2.84, P<0.001), lower physical HRQoL (regression coefficient-8.54, 95% CI, -11.54 to-5.54, P<0.001), and lower mental HRQoL (regression coefficient-4.66, 95% CI, -7.15 to-2.17, P<0.001). These associations were independent of potential confounders including age, time since transplantation, history of upper gastrointestinal disease, antiplatelet therapy, and the total number of medications. They were present among all individually assessed PPI types and were dose dependent. Duration of PPI exposure was only associated with fatigue severity.

LIMITATIONS

Residual confounding and inability to assess causal relationships.

CONCLUSIONS

PPI use is independently associated with fatigue and lower HRQoL among kidney transplant recipients. PPI use might be an easily accessible target for alleviating fatigue and improving HRQoL among kidney transplant recipients. Further studies examining the effect of PPI exposure in this population are warranted.

OUP accepted manuscript

Chronic enterovirus infections can cause significant morbidity, particularly in immunocompromised patients. This study describes a fatal case associated with a chronic untypeable enterovirus infection in an immunocompromised patient admitted to a Dutch university hospital over nine months. We aimed to identify the enterovirus genotype responsible for the infection and to determine potential evolutionary changes. Long-read sequencing was performed using viral targeted sequence capture on four respiratory and one faecal sample. Phylogenetic analysis was performed using a maximum likelihood method, along with a root-to-tip regression and time-scaled phylogenetic analysis to estimate evolutionary changes between sample dates. Intra-host variant detection, using a Fixed Ploidy algorithm, and selection pressure, using a Fixed Effect Likelihood and a Mixed Effects Model of Evolution, were also used to explore the patient samples. Near-complete genomes of enterovirus C104 (EV-C104) were recovered in all respiratory samples but not in the faecal sample. The recovered genomes clustered with a recently reported EV-C104 from Belgium in August 2018. Phylodynamic analysis including ten available EV-C104 genomes, along with the patient sequences, estimated the most recent common ancestor to occur in the middle of 2005 with an overall estimated evolution rate of 2.97 × 10⁻³ substitutions per year. Although positive selection pressure was identified in the EV-C104 reference sequences, the genomes recovered from the patient samples alone showed an overall negative selection pressure in multiple codon sites along the genome. A chronic infection resulting in respiratory failure from a relatively rare enterovirus was observed in a transplant recipient. We observed an increase in single-nucleotide variations between sample dates from a rapidly declining patient, suggesting mutations are weakly deleterious and have not been purged during selection. This is further supported by the persistence of EV-C104 in the patient, despite the clearance of other viral infections. Next-generation sequencing with viral enrichment could be used to detect and characterise challenging samples when conventional workflows are insufficient.

Isotype-specific Antibody Responses to Mycobacterium avium paratuberculosis Antigens Are Associated With the Use of Biologic Therapy in Inflammatory Bowel Disease

BACKGROUND

The role of Mycobacterium avium paratuberculosis [MAP] in inflammatory bowel disease [IBD], especially Crohn's disease [CD] is controversial due conflicting results and lack of reproducibility and standardised tests. The current study focuses on the role of MAP in disease progression and genetic susceptibility, as MAP is likely one of many factors involved in the complex pathogenesis of IBD, potentially affecting a subgroup depending on genetic susceptibility.

METHODS

Serum from 812 patients was evaluated with seven immunoglobulin [Ig] isotype-specific serology tests assessing humoral response to three different MAP antigens. For each of these in total 21 tests, the intra-assay and inter-assay coefficients were used to evaluate test accuracy. Reliable assays were subsequently analysed in relation to disease characteristics and need for biologic therapy/surgery. Genome-wide genotyping was available for all participants. Genetic determinants of humoral response to MAP antigens were evaluated using genome-wide association analysis and polygenic risk scores [PRS].

RESULTS

High IgA or IgM response to MAP2609 was associated with increased use of biologic therapy in CD and ulcerative colitis [UC] [odds ratios 2.69; 95% confidence interval 1.44-5.01; and 2.60, 1.46-4.64, respectively]. No associations were seen for risk of surgery [p-values > 0.29]. We could not identify genetic determinants nor polygenic risk scores for MAP response with genome-wide significance.

CONCLUSIONS

Extensive assays for serological response to MAP were evaluated using stringent criteria for reliability. Increased IgA and IgM response to MAP antigens was seen in patients exposed to biologic therapy, but no genetic determinants underlying this humoral response were found.

Immune response to varicella-zoster virus before and after renal transplantation

BACKGROUND

Herpes zoster (HZ) risk is high in renal transplant recipients. Vaccination prior to transplantation may provide a useful strategy for the prevention of HZ in the posttranplantation period. However, it is not known whether immunity to varicella-zoster virus (VZV) is affected due to treatment surrounding transplantation.

METHODS

Both humoral and cellular immunity to VZV were determined prior to and 2-3 years after renal transplantation in 60 adult patients, and 62 matched healthy controls. VZV-specific cellular immunity was measured by an interferon gamma (IFNγ) enzyme-linked immunospot (ELISpot) assay and by analyzing T-cell functionality using flowcytometry. VZV-IgG levels were measured using an in-house glycoprotein enzyme-linked immunosorbent assay (gpELISA).

RESULTS

Using paired analysis, it was determined that numbers of IFNγ-producing cells did not change after transplantation, but were significantly lower in transplant recipients after transplantation than in controls (p = 0.028). Patients in whom the post-transplant period was complicated by rejection or any acute infection (excluding HZ) had a lower number of IFNγ-producing cells than patients who did not. VZV IgG levels did not differ from controls, but a significant decrease was observed after transplantation (p < 0.0001).

CONCLUSIONS

VZV-specific cellular immunity, which is essential in the prevention of HZ, did not markedly change in patients following renal transplantation. This suggests that preventive vaccination before transplantation may be beneficial. Our results extend knowledge on VZV immunity after transplantation, vital when considering strategies for the prevention of HZ in these patients.

Latent cytomegalovirus infection does not influence long-term disease outcomes in inflammatory bowel disease, but is associated with later onset of disease

OBJECTIVES

Cytomegalovirus (CMV) infection is common in the general population. CMV infection negatively affects disease course in transplant recipients and HIV patients. Whereas primary CMV infections may occur sporadically in seronegative patients, all seropositive patients with inflammatory bowel syndrome (IBD) are at risk for CMV reactivation due to the inflammatory mucosal and use of immunosuppressive medication. It is unclear whether latent CMV infection, and risk of reactivations, influences long-term disease outcomes. In this study, we aim to explore whether CMV infection affects disease outcomes in IBD patients.

METHODS

We performed a cross-sectional cohort study with 1404 patients with IBD from a single center. Clinical characteristics and disease outcomes were prospectively collected. We scrutinized CMV serology test results and performed additional CMV serology testing if serum was available.

RESULTS

Out of 699 IBD patients with CMV serology, 303 (43.3%) were seropositive, comparable to the general Dutch population. CMV seropositivity was associated with older age, longer IBD disease duration, non-Western origin, birth outside the Netherlands and a lower educational level (p-values ≤ .004). CMV seropositivity was not associated with more complicated long-term disease outcomes of IBD (p-values > .05). Seropositive patients presented with symptoms and were diagnosed at an older age compared to seronegative patients (p-values < .01).

CONCLUSIONS

CMV seropositivity does not influence disease outcomes of IBD patients and seems to be associated with a delay in IBD onset. Guidelines regarding CMV screening in patients with IBD are currently based on a low level of evidence. These data support the recommendation that routine CMV serology measurement is not necessary in the clinical care of IBD.

The emergence of enterovirus D68 in a Dutch University Medical Center and the necessity for routinely screening for respiratory viruses

BACKGROUND

Since August 2014, an increase in infections caused by enterovirus D68 (EV-D68) was reported in the USA and Canada, for the most part in children presenting with severe respiratory symptoms.

OBJECTIVES

To determine whether an increase in severe EV-D68 respiratory infections was observed in our region.

STUDY DESIGN

Samples from patients with respiratory symptoms were screened for viral pathogens, including rhinovirus and enterovirus. Subsequently, samples positive for rhinovirus and enterovirus were routinely sequenced for phylogenetic analysis. Furthermore, an additional method was used to detect EV-D68 specifically.

RESULTS

During the first three quarters of the year 2014, 1896 respiratory samples were analyzed; 39 (2%) of them tested positive for enterovirus. Eighteen samples tested positive for EV-D68, obtained from 16 different patients admitted to our hospital. Eleven were children below the age of 18, of whom five children needed intensive care treatment. The remaining five samples were from adults, who all had an underlying disease; three were transplant patients (heart, lung and renal transplantation), the other two had an underlying lung condition (COPD, asthma). Phylogenetic analysis showed a close relationship with the strains circulating currently in the USA, all belonging to the known EV-D68 genetic subtypes.

CONCLUSIONS

We observed an increase of EV-D68 infections in our population, both in children as well as in adult. In 2014 there have been 16 cases so far, compared to none in 2011 and 2013 and a single case in 2012. Phylogenetic analysis identified two similar clusters as shown in the USA and Canada.