Abstract Adaptive immune receptor repertoires (AIRRs) are rich with information that can be mined for insights into the workings of the immune system. Gene usage, CDR3 properties, clonal lineage structure, and sequence diversity are all capable of revealing the dynamic immune response to perturbation by disease, vaccination, or other interventions. Here we focus on a conceptual introduction to the many aspects of repertoire analysis and orient the reader toward the uses and advantages of each. Along the way, we note some of the many software tools that have been developed for these investigations and link the ideas discussed to chapters on methods provided elsewhere in this volume.
Preventing the progression to acute respiratory distress syndrome (ARDS) in COVID-19 is an unsolved challenge. The involvement of T cell immunity in this exacerbation remains unclear. To identify predictive markers of COVID-19 progress and outcome, we analyzed peripheral blood of 10 COVID-19-associated ARDS patients and 35 mild/moderate COVID-19 patients, not requiring intensive care. Using multi-parametric flow cytometry, we compared quantitative, phenotypic, and functional characteristics of circulating bulk immune cells, as well as SARS-CoV-2 S-protein-reactive T cells between the two groups. ARDS patients demonstrated significantly higher S-protein-reactive CD4+ and CD8+ T cells compared to non-ARDS patients. Of interest, comparison of circulating bulk T cells in ARDS patients to non-ARDS patients demonstrated decreased frequencies of CD4+ and CD8+ T cell subsets, with activated memory/effector T cells expressing tissue migration molecule CD11a++. Importantly, survival from ARDS (4/10) was accompanied by a recovery of the CD11a++ T cell subsets in peripheral blood. Conclusively, data on S-protein-reactive polyfunctional T cells indicate the ability of ARDS patients to generate antiviral protection. Furthermore, decreased frequencies of activated memory/effector T cells expressing tissue migratory molecule CD11a++ observed in circulation of ARDS patients might suggest their involvement in ARDS development and propose the CD11a-based immune signature as a possible prognostic marker.
Background: The inhibition of sodium-glucose co-transporter 2 (SGLT-2) has been shown to be beneficial in the treatment of diabetic and non-diabetic patients with heart failure. The underlying mechanisms are incompletely understood. The present prospective study investigates for the first time the effect of empagliflozin on various soluble markers of inflammation in patients with reduced ejection fraction (HFrEF). Methods: We included 50 inpatients with HFrEF and diabetes mellitus type 2. A total of 25 patients received a therapy with the SGLT-2-inhibitor empagliflozin in addition to standard medication; the other 25 patients did not receive empagliflozin and were considered the control group. Quality of life, functional status and soluble immunological parameters in serum were assessed at baseline and after 3 months. Results: The baseline characteristics of both groups revealed no significant differences. Patients on empagliflozin demonstrated a significant improvement in the Minnesota living with heart failure questionnaire (baseline 44.2 ± 20.2 vs. 24 ± 17.7; p < 0.001), in distance in the 6-min walk test (baseline 343 ± 145 m vs. 450 ± 115 m; p < 0.001) and in soluble interleukin-6 level (baseline 21.7 ± 21.8 pg/mL vs. 13.7 ± 15.8 pg/mL; p = 0.008). There was no significant change of these or other parameters in the control group (p > 0.05 each). Conclusions: The empagliflozin-induced improvement of quality of life and functional capacity in patients with HFrEF and type 2 diabetes mellitus is accompanied by a substantial reduction of interleukin-6 levels. Thus, anti-inflammatory effects may contribute to the benefits of SGLT-2-inhibitors in heart failure.
Abstract SARS-CoV-2 is characterized by a multiorgan tropism including the kidneys. Recent autopsy series indicated that SARS-CoV-2 can infect both tubular and glomerular cells. Whereas tubular cell infiltration may contribute to acute kidney injury, data on a potential clinical correlative to glomerular affection is rare. We describe the first case of nephrotic syndrome in the context of COVID-19 in a renal transplant recipient. A 35 year old male patient received a kidney allograft for primary focal segmental glomerulosclerosis (FSGS). Three months posttransplant a recurrence of podocytopathy was successfully managed by plasma exchange, ivIG, and a conversion from tacrolimus to belatacept (initial proteinuria > 6 g/l decreased to 169 mg/l). Six weeks later he was tested positive for SARS-CoV-2 and developed a second increase of proteinuria (5.6 g/l). Renal allograft biopsy revealed diffuse podocyte effacement and was positive for SARS-CoV-2 in RNA in-situ hybridation indicating a SARS-CoV-2 associated recurrence of podocytopathy. Noteworthy, nephrotic proteinuria resolved spontaneously after recovering from COVID-19. The present case expands the spectrum of renal involvement in COVID-19 from acute tubular injury to podocytopathy in renal transplant recipients. Thus, it may be wise to test for SARS-CoV-2 prior to initiation of immunosuppression in new onset glomerulopathy during the pandemic.
Abstract Background Recent data demonstrate potentially protective pre-existing T cells reactive against the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) in samples of healthy blood donors, collected before the SARS-CoV-2 pandemic. Whether pre-existing immunity is also detectable in immunosuppressed patients is currently not known. Methods Fifty-seven patients were included in this case–control study. We compared the frequency of SARS-CoV-2-reactive T cells in the samples of 20 renal transplant (RTx) patients to 20 age/gender matched non-immunosuppressed/immune competent healthy individuals collected before the onset of the SARS-CoV-2 pandemic. Seventeen coronavirus disease 2019 (COVID-19) patients were used as positive controls. T cell reactivity against Spike-, Nucleocapsid-, and Membrane- SARS-CoV-2 proteins were analyzed by multi-parameter flow cytometry. Antibodies were analyzed by neutralization assay. Results Pre-existing SARS-CoV-2-reactive T cells were detected in the majority of unexposed patients and healthy individuals. In RTx patients, 13/20 showed CD4 + T cells reactive against at least one SARS-CoV-2 protein. CD8 + T cells reactive against at least one SARS-CoV-2 protein were demonstrated in 12/20 of RTx patients. The frequency and Th1 cytokine expression pattern of pre-formed SARS-CoV-2 reactive T cells did not differ between RTx and non-immunosuppressed healthy individuals. Conclusions This study shows that the magnitude and functionality of pre-existing SARS-CoV-2 reactive T cell in transplant patients is non-inferior compared to the immune competent cohort. Although several pro-inflammatory cytokines were produced by the detected T cells, further studies are required to prove their antiviral protection. Graphic abstract
Objective: BACKGROUND: Blood pressure has been traditionally measured at peripheral arteries. In the past decade evidence has grown, that central aortic blood pressure may be a more powerful predictor for cardiovascular events, but data on its regulation are rare. The present works examines the impact of microgravity on central blood pressure for the first time. Methods: We performed seven parabolic flights with 22 seconds of weightlessness in each parabola. Hemodynamic parameters including central systolic blood pressure were measured non-invasively in a free-floating position in 20 healthy subjects (19–43 years of age). Results: Arterial elasticity at rest was normal in all participants (augmentation index 14% [interquartile range IQR 10–22], pulse wave velocity 5.2 m/s [IQR 5.0–5.4]). Transition of 1 g to 0 g led to a significant increase of central systolic blood pressure from 124 (IQR 118–133) to 127 (IQR 119–133) mmHg (p = 0.017). Cardiac index propelled significantly from 2.5 (IQR 2.2–2.8) to 2.7 (IQR 2.3–3.0) l/min/m2 (p < 0.001), whilst peripheral vascular resistance showed a decrease from 1.30 (IQR 1.14–1.48) to 1.25 (IQR 1.15–1.40) s*mmHg/ml (p = 0.037). Peripheral systolic blood pressure did not change significantly (p > 0.05). Conclusion: Whereas there is a multitude of studies on the effects of microgravity on peripheral blood pressure, this study provides first data on central aortic blood pressure. An acute loss of gravity leads to a central blood volume shift with an augmentation of cardiac output. In healthy subjects with normal arterial stiffness the compensatory decrease of peripheral resistance does not outweigh this effect resulting in an increase of central blood pressure.
Abstract The current pandemic is caused by the SARS-CoV-2 virus and large progress in understanding the pathology of the virus has been made since its emergence in late 2019. Several reports indicate short lasting immunity against endemic coronaviruses, which contrasts repeated reports that biobanked venous blood contains SARS-CoV-2 reactive T cells even before the outbreak in Wuhan. This suggests there exists a preformed T cell memory in individuals not exposed to the pandemic virus. Given the similarity of SARS-CoV-2 to other members of the Coronaviridae family, the endemic coronaviruses appear likely candidates to generate this T cell memory. However, given the apparent poor immunological memory created by the endemic coronaviruses, other immunity against other common pathogens might offer an alternative explanation. Here, we utilize a combination of epitope prediction and similarity to common human pathogens to identify potential sources of the SARS-CoV-2 T cell memory. We find that no common human virus, other than beta-coronaviruses, can explain the pre-existing SARS-CoV-2 reactive T cells in uninfected individuals. Our study suggests OC43 and HKU1 are the most likely pathogens giving rise to SARS-CoV-2 preformed immunity.
Dear Editor, The post-COVID syndrome (post-COVID) constitutes a major physical and psychological problem for many subjects after recovery from coronavirus disease 2019 (COVID-19) [1]. Symptoms include fatigue, shortness of breath, myalgia and cognitive dysfunction. They frequently have a deleterious effect on everyday functioning. To date, there is no evidence-based therapy. Since autoimmunity is supposed to contribute to post-COVID, we administered intravenous immunoglobulins (IVIg) as an immunomodulatory approach to patients with severe post-COVID refractory to supportive therapeutic measures. We performed a retrospective case–control study comparing 10 patients who received 3–4 monthly courses of IVIg (0.5 g/kg PrivigenR, CSL Behring, Austria; Group 1) in addition to supportive treatment, 10 patients who were treated with inhaled glucocorticoids (budesonide 2 × 0.2 mg/day, Group 2) and 10 patients who were treated by supportive measures in a specialized post-COVID outpatient clinic (Group 3). Matching of controls was based on severity of symptoms, time since COVID-19 and age. Post-COVID symptoms at baseline and follow-up were retrospectively quantified using a 19-item questionnaire based on the ISARIC COVID-19 follow-up study protocol [2]. Comparison of intraindividual changes in the modified ISARIC score from baseline to follow-up was analyzed using the Kruskal–Wallis test. A detailed description of protocol and statistics is presented in the Supporting Information. The study was approved by the local ethics committee of the Ruhr-University Bochum (reg. number 22–7546). The study population was homogeneous for age, comorbidities and time since SARS-CoV-2 infection. Baseline symptoms were not significantly different except insomnia (more frequent in Group 1). A clinical and epidemiological characterization is presented in Table S1. Median baseline modified ISARIC score was 8 (interquartile range [IQR] 6.5–8.5) in Group 1, 8 (IQR 4.75–10.0) in Groups 2 and 7 (IQR 5.5–7.5) in Group 3. At follow-up, the ISARIC score significantly dropped to 3 (IQR 1.0–3.0, p = 0.021) in Group 1, 7 (IQR 4.75–9.25, p = 0.02) in Group 2 and 6 (IQR 4.0–7.0, p = 0.001) in Group 3 (Fig. 1). The change of score (Δ) was significantly higher in Group 1 (−5.44 ± 2.35; p < 0.001) than in Groups 2 (−0.3 ± 0.82; p < 0.05) and 3 (−0.89 ± 0.93; p < 0.05, Table S1). In addition, a strong effect size (r = 0.825) could be demonstrated for Group 1. All patients from Group 1 reported relief of symptoms, whereas only four patients (40%) of Group 2 and six patients (60%) in Group 3 did so. As presented in Fig. S1, the most prominent improvements after administration of IVIg were observed for listlessness, brain fog and fatigue. A screening for autoantibodies including ANA, ANCA, dsDNA-ab and ENA-6-profile was negative before and after administration of IVIg. Moreover, the treatment with IVIg was not associated with a significant change in the concentration of the following cytokines in a subset of patients: IL-1β, IFN-α2, IFN-γ, TNF-α, MCP-1, IL-6, IL-8, IL-10, IL-12p70, IL-17A, IL-18, IL-23 and IL-33. The present study identifies IVIg as a promising candidate for the treatment of severe post-COVID refractory to supportive measures. Patients receiving IVIg and supportive measures reported a substantially greater relief of symptoms than patients receiving supportive therapy alone. Interestingly, especially the most restrictive symptoms of fatigue, listlessness and brain fog responded well to this approach. With regard to the high physical and psychological stress, the subsequent impairment of daily functioning and the lack of any specific treatment so far, these results are promising. The most probable pathophysiologic mechanisms of post-COVID include virus-specific pathophysiologic changes, sequelae of post-critical illness and immunologic aberrations in response to the acute infection leading to autoimmunity-mediated damage [3]. Thus, several autoantibodies have been identified in acute COVID-19 [4]. IVIg contain a broad spectrum of anti-idiotypic antibodies, which neutralize the deleterious autoimmune antibodies. This mechanism is very attractive in the context of post-COVID because it remediates antibody-mediated autoimmunity without the side effect of systemic immunosuppression. Although this is the first report on the use of IVIg in post-COVID, some data indicate a positive effect of IVIg administration in acute COVID-19. However, data on this issue are sparse and controversial [5]. Notably, IVIg therapy ameliorates symptoms in patients with myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS) as well, especially if it was triggered by a viral infection [6]. In this context, post-COVID may be regarded as a SARS-CoV-2-induced CFS. This matched case–control study is limited by its size and its retrospective character. Thus, it is hypothesis-building but does not prove the efficacy of IVIg in post-COVID. The substantial difference between the three groups nevertheless suggests that IVIg might be a candidate approach for post-COVID that requires further evaluation in randomized controlled trials. Open Access funding enabled and organized by Projekt DEAL. The authors received no specific funding for this study. The authors have declared no conflicts of interest. Supplementary Table 1: Clinical characterization of study population. Supplementary Table 2: Individual symptoms at baseline according to the modified ISARIC-Score. Please note: The publisher is not responsible for the content or functionality of any supporting information supplied by the authors. Any queries (other than missing content) should be directed to the corresponding author for the article.
