Standard vs. carbone dioxide adapted kidney replacement therapy in hypercapnic ARDS patients: a randomized controlled pilot trial (BigBIC).

BACKGROUND: Current continuous kidney replacement therapy (CKRT) protocols ignore physiological renal compensation for hypercapnia. This study aimed to explore feasibility, safety, and clinical benefits of pCO2-adapted CKRT for hypercapnic acute respiratory distress syndrome (ARDS) patients with indication for CKRT. METHODS: We enrolled mechanically ventilated hypercapnic ARDS patients (pCO2 > 7.33 kPa) receiving regional citrate anticoagulation (RCA) based CKRT in a prospective, randomized-controlled pilot-study across five intensive care units at the Charité-Universitätsmedizin Berlin, Germany. Patients were randomly assigned 1:1 to the control group with bicarbonate targeted to 24 mmol/l or pCO2-adapted-CKRT with target bicarbonate corresponding to physiological renal compensation. Study duration was six days. Primary outcome was bicarbonate after 72 h. Secondary endpoints included safety and clinical endpoints. Endpoints were assessed in all patients receiving treatment. RESULTS: From September 2021 to May 2023 40 patients (80% male) were enrolled. 19 patients were randomized to the control group, 21 patients were randomized to pCO2-adapted-CKRT. Five patients were excluded before receiving treatment: three in the control group (consent withdrawal, lack of inclusion criteria fulfillment (n = 2)) and two in the intervention group (lack of inclusion criteria fulfillment, sudden unexpected death) and were therefore not included in the analysis. Median plasma bicarbonate 72 h after randomization was significantly higher in the intervention group (30.70 mmol/l (IQR 29.48; 31.93)) than in the control group (26.40 mmol/l (IQR 25.63; 26.88); p < 0.0001). More patients in the intervention group received lung protective ventilation defined as tidal volume < 8 ml/kg predicted body weight. Thirty-day mortality was 10/16 (63%) in the control group vs. 8/19 (42%) in the intervention group (p = 0.26). CONCLUSION: Tailoring CKRT to physiological renal compensation of respiratory acidosis appears feasible and safe with the potential to improve patient care in hypercapnic ARDS. TRIAL REGISTRATION: The trial was registered in the German Clinical Trials Register (DRKS00026177) on September 9, 2021 and is now closed.

The early cellular signatures of protective immunity induced by live viral vaccination.

Here, we have used primary vaccination of healthy donors with attenuated live yellow fever virus 17D (YFV-17D) as a model to study the generation of protective immunity. In short intervals after vaccination, we analyzed the induction of YFV-17D specific T- and B-cell immunity, bystander activation, dendritic cell subsets, changes in serum cytokine levels, and YFV-17D-specific antibodies. We show activation of innate immunity and a concomitant decline of numbers of peripheral blood T and B cells. An early peak of antigen-specific T cells at day 2, followed by mobilization of innate immune cells, preceded the development of maximal adaptive immunity against YFV-17D at day 14 after vaccination. Interestingly, potent adaptive immunity as measured by high titers of neutralizing YFV-17D-specific antibodies, correlated with early activation and recruitment of YFV-17D-specific CD4(+) T cells and higher levels of sIL-6R. Thus our data might provide new insights into the interplay of innate and adaptive immunity for the induction of protective immunity.

Clonotype analysis of cytomegalovirus-specific cytotoxic T lymphocytes.

Cytotoxic T lymphocytes (CTL) control the replication of human cytomegalovirus (CMV). Previous studies assessed the clonotypic composition of CTL specific for individual immunodominant peptides within a certain HLA context. Such an approach has inherent limitations and may not assess the true clonal CTL response in vivo. Here, the clonotypic composition of CMV-specific CTL was determined in HLA-A2, CMV-seropositive kidney transplant recipients and healthy blood donors after stimulation of peripheral blood mononuclear cells with either a pp65 whole-peptide pool or a single immunodominant peptide. Even after stimulation with the whole peptide pool, CMV-specific CTL remained monoclonal or oligoclonal. Regarding intraindividual variation, the CDR3 motifs of the dominant clones were identical to those observed in CTL generated by the single immunodominant peptide. Sequencing of the CDR3 regions demonstrated significant interindividual variation; however, structural homology was observed for immunodominant clonotypes in three individuals. In conclusion, the highly focused T cell receptor repertoire found after stimulation with either a single immunodominant peptide or a peptide pool demonstrates a pivotal role for immunodominant epitopes in the generation of a clonal repertoire. These results provide new insights into the regulation of CMV clonal dominance and may contribute to the design and monitoring of adoptive immunotherapy.

Comparative characterization of decellularized renal scaffolds for tissue engineering.

Native extracellular matrix (ECM) provides scaffolds for tissue engineering with natural architecture and biochemical composition. Maintaining the native ECM in decellularized tissues provides cues for cells, which promote their tissue specific arrangement and function. Several approaches have been used to decellularize ECM from the kidney in order to reestablish renal tissue but their comparability is hampered because methods for decellularization and assessment of ECM vary widely. Therefore, we applied a standardized immersion protocol to decellularize porcine kidney tissue with three detergents Triton X-100, SDS and sodium deoxycholate (SDC) at variable temperatures. For comparative analysis decellularization efficacies, structural preservation, composition and cell attachment and viability were analyzed. Structural ECM-conservation is strongly dependent on decellularization temperature, while preservation of glycosaminoglycans (GAG), collagens and cytokines was affected by the detergents used. GAG and collagens were best maintained by 1% SDS at 4 °C, whereas cytokines were best maintained in 1% SDC at 4 °C. Viability and attachment of human induced pluripotent stem cell derived renal precursor cells were best in SDC-ECM and thus not associated with the degree of GAG and collagen maintenance but the cytokine preservation. Based on structural and functional characteristics, we developed a scoring system that allows intra- and inter-study comparison of decellularization strategies. Application of the scoring system to our experimental data showed that decellularization with 1% SDS at 4 °C provided the highest structural and composition scores, while 1% SDC at 4 °C had lower structural and composition but a significantly better cell performance score. Inclusion of multiple published studies in the scoring matrix for comparison identified the highest structural and composition scores when decellularization was performed with SDS at low concentration, for a short period of time and at low temperature. Furthermore, the scoring system indicated that cell attachment and viability cannot be concluded from any other parameter and should therefore always be included in evaluation of decellularization strategies.

Upregulation of myocardial estrogen receptors in human aortic stenosis.

BACKGROUND: Estrogen receptor (ER)-mediated effects have been associated with the modulation of myocardial hypertrophy in animal models and in humans, but ER expression in the human heart and its relation to hypertrophy-mediated gene expression have not yet been analyzed. We therefore investigated sex- and disease-dependent alterations of myocardial ER expression in human aortic stenosis together with the expression of hypertrophy-related genes. METHODS AND RESULTS: ER-alpha and -beta, calcineurin A-beta, and brain natriuretic peptide (BNP) mRNA were quantified by real-time polymerase chain reaction in left ventricular biopsies from patients with aortic valve stenosis (n=14) and control hearts with normal systolic function (n=17). ER protein was quantified by immunoblotting and visualized by immunofluorescence confocal microscopy. ER-alpha mRNA and protein were increased 2.6-fold (P=0.003) and 1.7-fold (P=0.026), respectively, in patients with aortic valve stenosis. Left ventricular ER-beta mRNA was increased 2.6-fold in patients with aortic valve stenosis (P<0.0001). ER-alpha and -beta were found in the cytoplasm and nuclei of human hearts. A strong inverse correlation exists between ER-beta and calcineurin A-beta mRNA in patients with aortic valve stenosis (r=-0.83, P=0.002) but not between ER-alpha or -beta and BNP mRNA. CONCLUSIONS: ER-alpha and -beta in the human heart are upregulated by myocardial pressure load.

Sustained BK viruria as an early marker for the development of BKV-associated nephropathy: analysis of 4128 urine and serum samples.

BACKGROUND: BKV reactivation plays the causative role in the development of BKV-associated nephropathy (BKVAN). Because of the lack of effective therapy, early diagnosis of BKV reactivation is paramount for the prevention of BKVAN. Resting in uroepithelial cells, BKV is excreted first in urine before it can be detected in plasma. The present study analyzed predictive value of BK viruria for the development of BK viremia and its possible advantage for the early BKVAN prediction. METHODS: Total of 4128 urine and serum samples obtained from renal transplant patients were analyzed for BKV positivity by real-time polymerase chain reaction in 433 patients in cross-sectional and in 233 patients in longitudinal manner, respectively. The prospective longitudinal analysis included seven measurements during the first posttransplant year. RESULTS: A total of 7% and 19% patients were positive for BKV in serum and urine, respectively. Sustained BK viruria showed sensitivity of 100% and specificity of 94% for BK viremia and was associated with significantly higher level of BK load than the patients with transient viruria (P<0.01). Interestingly, BK viremia was preceded by BK viruria: the peak of viral load and number of positive patients appeared during the third and fifth posttransplant month for urine and serum, respectively. BKVAN diagnosed in 21.4% of patient with persistent BK viruria appeared 5 and 11 weeks after BKV reactivation in serum and urine, respectively, was detected. CONCLUSION: Sustained BK viruria is a reliable marker allowing an early identification of patients at high risk of BKVAN development and therefore assure precocious therapeutic interventions.