Uwe Heemann

IgG4-related disease (IgG4-RD) is a rare immune-mediated, fibroinflammatory disease with heterogenous presentations and no standardized treatment recommendations. This study investigates long-term efficacy and safety of current therapeutic strategies with a focus on rituximab. A retrospective analysis was conducted on 24 patients diagnosed with IgG4-RD at a German tertiary center (2010–2020) using the 2020 revised comprehensive diagnostic criteria. Patients were recruited from Rheumatology and Nephrology. Data included organ involvement, laboratory results, histology, treatments, relapses, therapy-related damage, and comorbidities. The cohort included 12 males and 12 females, median age at diagnosis 53 (95%CI 37.0; 61.0) years. Males had more affected organs (2.4 vs. 1.6; p = 0.036) and higher IgG4 levels (>5× upper limit: 33.3% vs. 16.7%; p = 0.036). Immunosuppressive therapy was initiated in 87.5% of patients, with glucocorticoids (GC) universally included. Rituximab was administered to 71.4%, mainly as a 4 x 375 mg/m² regimen (77.3%), with a median follow-up post first rituximab of 51.0 months (95%CI 27.0; 63.0). Adverse events were not more frequent with rituximab compared to other regimens. At last visit, 47.6% were off immunosuppressives and 38.1% remained on GC. Active organ involvement declined, though 16.7% showed organ damage progression. Relapses were frequent (81.0%), but less common upon rituximab initiation (26.7%). This representative IgG4-RD cohort demonstrates that long-term treatment with rituximab as maintenance therapy is generally effective and safe regardless of therapeutic regimen. Despite this glucocorticoid use remains high, highlighting the need for guidelines to standardize the use of glucocorticoids and DMARDs like rituximab in both induction and maintenance therapy.

Background: Coagulation disorders, including both bleeding and thrombotic complications, are common in patients undergoing hemodialysis (HD). Here, we aimed to characterize platelet function in patients undergoing hemodialysis three times per week, compared to healthy controls. Methods: Platelet function was assessed using the Multiplate analyzer (Roche), which is based on multiple electrode impedance aggregometry. Platelet aggregation was induced using adenosine diphosphate (ADP), and the area under the curve (AUC) served as the primary endpoint. In addition, platelet counts and C-reactive protein (CRP) levels were measured. To further evaluate nitric oxide (NO)-mediated inhibition of platelet aggregation, blood samples were incubated with the NO donor, sodium nitroprusside (SNP), and the phosphodiesterase 5A (PDE5A) inhibitor, sildenafil. Results: A total of 60 patients undergoing HD and 67 healthy controls were included in the analysis. Patients receiving HD treatment had significantly lower platelet counts compared to healthy controls (226.9 ± 53.47 vs. 246.7 ± 47.21 G/L, p = 0.029). Platelet aggregation was markedly reduced in patients undergoing HD compared to controls (462.0 ± 266.54 vs. 644.5 ± 254.44 AU × min, p < 0.001) with a significant correlation for platelet count (r = 0.42, p = 0.001) and systemic inflammation as indicated by CRP levels (r = 0.28, p = 0.035). Following SNP and sildenafil administration, inhibition of platelet aggregation remained more pronounced in patients undergoing HD. However, the change in platelet aggregation after SNP/sildenafil treatment did not differ significantly between the groups. Conclusions: Patients undergoing HD exhibit altered platelet function, indicated by reduced aggregation and platelet counts, as well as an association with systemic inflammation. Multiple electrode impedance aggregometry appears to be a feasible method for detecting platelet function alterations in patients receiving HD treatment. Responsiveness to NO donors was preserved in patients undergoing HD. Further studies are needed to identify the underlying mechanisms, particularly the role of NO signaling in platelet dysfunction in patients undergoing HD.

Background Cardiac complications driven by microvascular changes are one of the primary reasons for mortality in patients with Fabry disease (FD). While enzyme replacement therapy (ERT) can effectively clear globotriaosylceramide (Gb3) deposits in the endothelium, it remains controversial whether ERT fully resolves microvascular dysfunction, particularly in advanced cases. Methods We conducted a cross-sectional observational study of 63 FD patients, of whom 60 had quality retinal vessel analysis (RVA) data and were age- and gender-matched to a healthy control group (HC, n=60, matched out of 204). Associations with disease severity, echocardiographic and laboratory parameters, and ERT were explored. Results FD patients exhibited significantly reduced venular flicker-induced dilation (vFID, 3.5% ± 1.6% vs. 4.6% ± 2.4%; p = 0.006), narrower central retinal arteriolar equivalents (CRAE, 165.2 µm [153.5 - 183.2] vs. 183.2 µm [174.7 - 191.4], p < 0.001), and lower arteriolar-venular ratio (AVR, 0.82 [0.74 - 0.87] vs. 0.86 [0.82 - 0.91]; p < 0.001) compared to HC, independent of cardiovascular risk factors. Despite ERT, retinal microvascular health remains incompletely recovered in severely affected FD patients. Narrower retinal arterioles are closely associated with echocardiographic parameters and laboratory markers of cardiac involvement. Additionally, CRAE demonstrated accuracy comparable to LysoGb3 levels in identifying GLA variants with a potential cardiac phenotype. FD patients exhibited elevated chronic inflammation and endothelial dysfunction markers, including Rantes, MCP1, CXCL10, ICAM-1, VCAM-1, and VEGF. In FD patients with cardiac variants, higher levels of inflammatory parameters were associated with impaired retinal microcirculation. Conclusion Our findings demonstrate that RVA can detect microvascular alterations in FD, offering a potential non-invasive approach for assessing disease severity and monitoring cardiovascular health. The persistence of retinal microvascular changes despite ERT may reflect the need for earlier interventions. Longitudinal studies are warranted to further explore the predictive value of RVA for Fabry-related cardiovascular outcomes. Registration https://clinicaltrials.gov/study/NCT06758648; Unique identifier: NCT06758648. Novelty and Significance What Is Known? Fabry disease (FD) is an X-linked lysosomal storage disorder characterized by the accumulation of globotriaosylceramide (Gb3), leading to microvascular dysfunction and cardiac complications. Enzyme replacement therapy (ERT) and pharmacological chaperone therapy (PCT) are available treatments, but their ability to fully reverse microvascular changes remains uncertain. Retinal vessel analysis (RVA) is a non-invasive tool previously used to monitor systemic microvascular health in cardiovascular diseases. What New Information Does This Article Contribute? Retinal microvascular abnormalities, including arteriolar narrowing and reduced venular dilation, are detectable in FD, even in patients receiving ERT. Retinal vessel parameters are strongly associated with systemic markers of cardiac involvement. RVA offers a non-invasive, cost-effective method to assess microvascular health and could serve as a valuable tool for disease monitoring and stratification in FD. Summary FD is a rare genetic disorder associated with significant microvascular and cardiac complications due to the progressive accumulation of Gb3. Although ERT is a cornerstone of FD management, we demonstrate that retinal microvascular abnormalities persist despite treatment, particularly in patients with advanced disease. By employing RVA, the study highlights the close association between retinal arteriolar narrowing, systemic markers of cardiac involvement and disease severity. These findings underscore the potential of RVA as a non-invasive, cost-effective method for assessing endothelial health, monitoring disease severity and cardiac involvment in FD. Additionally, the results suggest that earlier interventions and adjunctive therapies targeting endothelial dysfunction and inflammation may be necessary to improve outcomes in advanced cases. RVA could play a pivotal role in routine care by providing insights into systemic vascular health and optimizing Fabry-specific therapies.

Background SARS-CoV-2 infection may lead to Post-COVID Syndrome (PCS), characterized by debilitating symptoms like persistent fatigue, cardiovascular symptoms, and cognitive dysfunction. Persistent endothelial dysfunction (ED) is a potential driver of ongoing symptoms. Yet, the underlying biological mechanisms remain unclear. Methods In this prospective observational study, we characterized 41 PCS patients and 24 healthy controls (HC, matched out of n = 204, recruited before the pandemic) and investigated the effect of SARS-CoV-2 Spike protein 1 (S1) and plasma from PCS patients on human retinal endothelial cells (HREC). Results Plasma samples from PCS patients exhibited significantly elevated erythropoietin, VEGF and MCP-1 alongside decreased IL-6 levels compared to HC. Low Haemoglobin and Haematocrit were negatively associated with PCS severity. VEGF levels were positively correlated with Anti-S1 IgG levels in patients and upregulated on mRNA level in HREC exposed to S1. Additionally, S1 exposure promoted ROS production and transiently activated HIF-1α in HREC. Persistent activation of HIF-2α by S1 led to disrupted endothelial integrity. HREC exposed to plasma from severely affected PCS patients showed increased ROS and compromised barrier function. Treatment with Belzutifan, a HIF-2α inhibitor, restored barrier integrity in HREC exposed to S1 or PCS-plasma. Conclusion These findings suggest that HIF-2α-mediated ED in PCS might be a potential therapeutical target for Belzutifan. Trial registration URL: https://www.clinicaltrials.gov; Unique identifier: NCT05635552 What Is Known? Endothelial dysfunction (ED) is a consequence of acute SARS-CoV-2 infection and may lead to Post-COVID syndrome (PCS) symptoms. Patients with PCS show elevated inflammation and endothelial dysfunction markers. Spike proteins can persist for up to 12 months post-infection, driving ongoing inflammation and immune activation. What New Information Does This Article Contribute? Low haemoglobin (Hb) and high VEGF correlate with higher Anti-S1 IgG and low Hb is associated with higher C19-YRS severity score. PCS patients exhibit higher Erythropoietin (EPO) levels when compared to HC. Spike protein 1 (S1) alone and PCS patient’s plasma induce endothelial dysfunction primarily through HIF-2α activation. Both S1 and PCS plasma cause oxidative stress and disrupting endothelial integrity. Inhibition of HIF-2α effectively restores endothelial barrier integrity disrupted by S1 and PCS plasma. What New Information Does This Article Contribute?Persistent circulation of spike proteins can sustain chronic inflammation and immune activation in patients with PCS. Here we show that plasma from PCS patients exhibits significantly elevated levels of VEGF which positively correlates with Anti-S1 IgG. Low haemoglobin was associated with higher Anti-S1 IgG titres and correlated with a higher C19-YRS severity score. Levels of EPO were higher in PCS patients, with a more pronounced effect observed in patients with cardiovascular symptoms. In human retinal endothelial cells, both S1 and plasma from PCS patients primarily induce ED through HIF-2α activation, rather than NF-κB. Both factors lead to significant oxidative stress, evidenced by increased ROS production which in turn disrupts endothelial barrier integrity and function. Notably, Belzutifan, a HIF-2α inhibitor, can restore this compromised endothelial function, offering a potential therapeutic target for PCS.

Background: Hemodialysis patients have reduced serologic immunity after SARS-CoV-2 vaccination compared to the general population and an increased risk of morbidity and mortality when exposed to SARS-CoV-2. Methods: Sixty-six hemodialysis patients immunized four times with the original SARS-CoV-2 vaccines (BNT162b2, mRNA-1273) either received a booster with the adapted Comirnaty Original/Omicron BA.4-5 vaccine 8.3 months after the fourth vaccination and/or experienced a breakthrough infection. Two months before and four weeks after the fifth vaccination, the live-virus neutralization capacities of Omicron variants BA.5, BQ.1.1, and XBB.1.5 were determined, as well as neutralizing and quantitative anti-SARS-CoV-2 spike-specific IgG antibodies. Results: Four weeks after the fifth vaccination with the adapted vaccine, significantly increased neutralizing antibodies and the neutralization of Omicron variants BA.5, BQ.1.1, and XBB.1.5 were observed. The increase was significantly higher than after the fourth vaccination for variants BQ.1.1 and BA.5. Of all analyzed variants, BA.5 was neutralized best after the fifth vaccination. We did not see a difference in humoral immunity between the group with an infection and the group with a vaccination as a fifth spike exposure. Fivefold-vaccinated patients with a breakthrough infection showed a significantly higher neutralization capacity of XBB.1.5. Conclusion: A fifth SARS-CoV-2 vaccination with the adapted vaccine improves both wild-type specific antibody titers and the neutralizing capacity of the current Omicron variants BA.5, BQ.1.1, and XBB.1.5 in hemodialysis patients. Additional booster vaccinations with adapted vaccines will likely improve immunity towards current and original SARS-CoV-2 variants and are, therefore, recommended in hemodialysis patients. Further longitudinal studies must show the extent to which this booster vaccination avoids a breakthrough infection.

Background: Economic restrictions and workforce cuts have continually challenged conventional autopsies. Recently, the COVID-19 pandemic has added tissue quality and safety requirements to the investigation of this disease, thereby launching efforts to upgrade autopsy strategies. Methods: In this proof-of-concept study, we performed bedside ultrasound-guided minimally invasive autopsy (US-MIA) in the ICU of critically ill COVID-19 patients using a structured protocol to obtain non-autolyzed tissue. Biopsies were assessed for their quality (vitality) and length of biopsy (mm) and for diagnosis. The efficiency of the procedure was monitored in five cases by recording the time of each step and safety issues by swabbing personal protective equipment and devices for viral contamination. Findings: Ultrasound examination and tissue procurement required a mean time period of 13 min and 54 min, respectively. A total of 318 multiorgan biopsies were obtained from five patients. Quality and vitality standards were fulfilled, which not only allowed for specific histopathological diagnosis but also the reliable detection of SARS-CoV-2 virions in unexpected organs using electronic microscopy and RNA-expressing techniques. Interpretation: Bedside multidisciplinary US-MIA allows for the fast and efficient acquisition of autolytic-free tissue and offers unappreciated potential to overcome the limitations of research in postmortem studies.

Introduction. Due to chronic inflammation, maintenance hemodialysis (MHD) patients continue to show excess mortality. Acetate-free citrate-buffered A concentrates could be a way to improve the biocompatibility of the procedure, reduce chronic inflammation, and thus in the long term improve the prognosis of patients. Methods. Using a pre-post design (3 months of acetate followed by 3 months of citrate-acidified A concentrates in standard bicarbonate-based dialysate hemodialysis, CiaHD) and linear mixed model analysis in 61 stable HD patients, we assessed the impact of CiaHD on counts and phenotypes of peripheral T cells and monocytes by flow cytometry. Results. Switching to CiaHD left C-reactive protein (CRP) levels and leucocyte counts unaffected. However, CiaHD increased lymphocyte counts ex vivo. Furthermore, we found a decrease in total CD3+CD4+CD69+ ((10⁹/L), mean ± SD: acetate, 0.04 ± 1.0 versus citrate, 0.02 ± 0.01; = 0.02) activated cells, while the number of CD28+ T cells remained stable. No differences were noted regarding T-cell exhaustion marker expression, CD14+CD16+ monocyte counts, and PMN-MDSCs. Conclusion. Compared with acetate, CiaHD has a minor impact on lymphocyte counts and CD4+T-cell activation, which was independent of systemic CRP and ionized magnesium, calcium levels, and other dialysis prescription modalities.

Background: Kidney transplant recipients (KTRs) who have a highly impaired immune response are in need of intensified and safe vaccination strategies to achieve seroconversion and prevent severe disease. Methods: We searched the Web of Science Core Collection, the Cochrane COVID-19 Study Register and the WHO COVID-19 global literature on coronavirus disease from January 2020 to 22 July 2022 for prospective studies that assessed immunogenicity and efficacy after three or more SARS-CoV-2 vaccine doses. Results: In 37 studies on 3429 patients, de novo seroconversion after three and four vaccine doses ranged from 32 to 60% and 25 to 37%. Variant-specific neutralization was 59 to 70% for Delta and 12 to 52% for Omicron. Severe disease after infection was rarely reported but all concerned KTRs lacked immune responses after vaccination. Studies investigating the clinical course of COVID-19 found remarkably higher rates of severe disease than in the general population. Serious adverse events and acute graft rejections were very rare. Substantial heterogeneity between the studies limited their comparability and summary. Conclusion: Additional SARS-CoV-2 vaccine doses are potent and safe in general terms as well as regarding transplant-specific outcomes whilst the Omicron wave remains a significant threat to KTRs without adequate immune responses.