Single cell transcriptomic analysis of renal allograft rejection reveals insights into intragraft TCR clonality

Bulk analysis of renal allograft biopsies (rBx) identified RNA transcripts associated with acute cellular rejection (ACR); however, these lacked cellular context critical to mechanistic understanding of how rejection occurs despite immunosuppression (IS). We performed combined single cell RNA transcriptomic and TCRα/β sequencing on rBx from patients with ACR under differing IS: tacrolimus, iscalimab, and belatacept. We found distinct CD8+ T cell phenotypes (e.g., effector, memory, exhausted) depending upon IS type, particularly within clonally expanded cells (CD8EXP). Gene expression of CD8EXP identified therapeutic targets that were influenced by IS type. TCR analysis revealed a highly restricted number of CD8EXP, independent of HLA mismatch or IS type. Subcloning of TCRα/β cDNAs from CD8EXP into Jurkat76 cells (TCR-/-) conferred alloreactivity by mixed lymphocyte reaction. Analysis of sequential rBx samples revealed persistence of CD8EXP that decreased, but were not eliminated, after successful anti-rejection therapy. In contrast, CD8EXP were maintained in treatment-refractory rejection. Finally, most rBx-derived CD8EXP were also observed in matching urine samples, providing precedent for using urine-derived CD8EXP as a surrogate for those found in the rejecting allograft. Overall, our data define the clonal CD8+ T cell response to ACR, paving the next steps to improve detection, assessment, and treatment of rejection.

Single cell transcriptomic analysis of renal allograft rejection reveals novel insights into intragraft TCR clonality

Bulk analysis of renal allograft biopsies (rBx) identified RNA transcripts associated with acute cellular rejection (ACR); however, these lacked cellular context critical to mechanistic understanding. We performed combined single cell RNA transcriptomic and TCRα/β sequencing on rBx from patients with ACR under differing immunosuppression (IS): tacrolimus, iscalimab, and belatacept. TCR analysis revealed a highly restricted CD8 ⁺ T cell clonal expansion (CD8 _EXP ), independent of HLA mismatch or IS type. Subcloning of TCRα/β cDNAs from CD8 _EXP into Jurkat76 cells (TCR ^-/- ) conferred alloreactivity by mixed lymphocyte reaction. scRNAseq analysis of CD8 _EXP revealed effector, memory, and exhausted phenotypes that were influenced by IS type. Successful anti-rejection treatment decreased, but did not eliminate, CD8 _EXP , while CD8 _EXP were maintained during treatment-refractory rejection. Finally, most rBx-derived CD8 _EXP were also observed in matching urine samples. Overall, our data define the clonal CD8 ⁺ T cell response to ACR, providing novel insights to improve detection, assessment, and treatment of rejection.

The identification and characterization of a STAT5 gene signature in hematologic malignancies

BACKGROUND

The JAK-STAT pathway is an important signaling pathway downstream of multiple cytokine and growth factor receptors. Dysregulated JAK-STAT signaling has been implicated in the pathogenesis of multiple human malignancies.

OBJECTIVE

Given this pivotal role of JAK-STAT dysregulation, it is important to identify patients with an overactive JAK-STAT pathway for possible treatment with JAK inhibitors.

METHODS

We developed a gene signature assay to detect overactive JAK-STAT signaling. The cancer cell line encyclopedia and associated gene-expression data were used to correlate the activation status of STAT5 with the induction of a set of STAT5 target genes.

RESULTS

Four target genes were identified (PIM1, CISH, SOCS2, and ID1), the expression of which correlated significantly with pSTAT5 status in 40 hematologic tumor cell lines. In pSTAT5-positive models, the expression of the gene signature genes decreased following ruxolitinib treatment, which corresponded to pSTAT5 downmodulation. In pSTAT5-negative cell lines, neither pSTAT5 modulation nor a change in signature gene expression was observed following ruxolitinib treatment.

CONCLUSIONS

The gene signature can potentially be used to stratify or enrich for patient populations with activated JAK-STAT5 signaling that might benefit from treatments targeting JAK-STAT signaling. Furthermore, the 4-gene signature is a predictor of the pharmacodynamic effects of ruxolitinib.

Effect of vesical outlet obstruction on detrusor contractility and passive properties in rabbits

Outlet obstruction was induced in 16 New Zealand rabbits by implanting a polyethylene tube (20 F) for a period of three months. The tube was slit longitudinally and placed around the bladder neck, between the ureters and vasa deferentia. It was left open to induce moderate obstruction and closed by a suture to induce severe obstruction. The animals were studied by cutting consecutive rings from each bladder, which were subjected to the following studies: morphology, contractility and mechanical properties. Morphology. Histology sections of the rings, studied by Hematoxylin and Eosin and Masson-Trichrome stains, demonstrated smooth muscle hypertrophy in moderate obstruction, while hyperplasia was the predominant response in severe obstruction. The average nuclear count per square millimeter of smooth muscle was 251 in controls, 87 in moderate obstruction and 705 in severe obstruction. Bladder wall thickness was significantly increased after both moderate and severe obstruction, as compared to controls. Contractility and mechanical properties. Each ring was tested in a muscle chamber under conditions of maximal electrical stimulation (100 V, 2 ms, 40 Hz). For each ring, full force-length relationships (active and passive) were obtained by stretching the rings in successive increments until length of maximal active force development was reached. Force was normalized per unit cross-sectional area (stress), and length according to a "reference" underformed state (per cent of unloaded length). The maximum active stress of the rings was taken as a measure of bladder contractility, and the rate of increase in passive force as a measure of detrusor stiffness. In all groups, the body of the detrusor exerted better contractility, as compared to a rigid, less contractile base. In the obstructed groups, detrusor contractility was significantly decreased at the body level, with increased stiffness, as compared to controls. The length at which maximum contractility was exerted, however, increased in moderate obstruction, and decreased in severe obstruction.

A new catheter to measure urethral compliance in females: normal values

We describe a new probe made of several F5 Vinyl tubes glued and staggered together in such a way that the catheter progressively increases in size (from F5 to F30), as more tubes are joined. At each size, pressure is recorded through a single side hole in one of the tubes. Pressure within the urethra is thus successively recorded from F5 to F30 as the catheter is further introduced. A single pressure transducer is used since the lines of the probe are separately and successively connected to the transducer through a 6-channel manifold, as one proceeds to the next diameter. Pressure diameter curves are obtained and reported on a graph. The data are analyzed by fitting the graphs with a one exponential equation P = PoeaD; 2 parameters are computed: Po, the initial pressure when the urethra is catheter free, and a, the rate of exponential increase in pressure as higher diameters are introduced to measure urethral wall stiffness. This catheter was used to measure the maximum urethral pressure in 10 young nulliparous volunteers, at each level of stretch. The values of Po and a were found to be respectively 74.4 +/- 7.7 cm. H2O and 0.08 +/- 0.02. The quantitative measurement of urethral compliance constitutes for us an integral part in the urodynamics assessment of female patients presenting with lower urinary tract dysfunction.

Abnormal urethral compliance in females diagnosis, results and treatment. Preliminary study

We measured urethral compliance in 57 patients using a catheter of increasing diameter. The measurement makes it possible to differentiate clearly between rigidity and hyperlaxity of the female urethra. In both instances, the initial pressure (Po) is lower than normal, but the rate of pressure increase (a), with larger catheter sizes, is significantly higher in cases of urethral rigidity and on the contrary parallel to normal in cases of hyperlaxity. This distinction allows for more accuracy in the determination of therapeutic indication. An inversely proportional correlation was found between the initial urethral pressure and the rate of pressure increase (r = 0.74). The initial pressure is generally lower in older women (r = 0.56).

Effect of diethylstilbestrol on bladder contractility in male rats

The effect of diethylstilbestrol (DES) on bladder contractility was studied in vitro in 8 rats while 5 untreated animals were used as normal controls. Of the treated animals, 4 received 0.05 mg./day of DES during 8 weeks while another 4 were treated for 14 weeks with the same dose. We studied the animals by cutting consecutive rings from each bladder and testing them in a muscle chamber, under conditions of maximal electrical stimulation which had been previously determined in 3 animals. Parameters that produced maximal contractions were: 100 V, 40 Hz, and 2 msec. For each ring, we obtained full force-length relationships by stretching the rings in successive increments until length of maximal active force development was reached. For each bladder, alternate rings were tested in the muscle chambers while the remaining rings were used to determine collagen percentage with Woessner assay. In all animals, the ring with the largest diameter which was obtained from the widest portion of the bladder gave the highest contraction. The maximal active force of this ring was taken as a measure of contractility of the bladder. For controls, the maximal active force was 7.30 +/- 0.3 g. After 8 weeks of DES treatment, it decreased to 5.9 +/- 0.79 g and after 14 weeks, it further decreased to 2.15 +/- 0.99 g. The reduction in active force from controls after 8 and 14 weeks were statistically significant. Passive force and collagen content, however, did not change after either 8 or 14 weeks. In conclusion, these data show that DES decreases bladder contractility in male rats without affecting passive forces and muscle-collagen ratio.

The elastic behavior of the urinary bladder for large deformations

The purpose of this paper is to investigate the theoretical basis for the pressure-distension behavior of the urinary bladder. A finite strain theory is developed for hollow spherical structures and it is shown that the Treloar model is a good prototype only for rubber balloons. The pressure-extension ratio relationship is inverted to lead a general form of strain energy function, and fitted by an empirical relation involving one exponential. The following form of strain energy function is derived: W(lambda, lambda, lambda -2) = C1 (P(1), a) + P(1)C2 (a, lambda)ea(lambda -1). Where C1(P(1), a) is a constant (N m-2), P(1) is the initial pressure, a is the rate of pressure increase and C2 (a, lambda) a third degree polynomial relation. P(1) and a are experimentally determined through volumetric pressure-distension data. It is verified that this type of energy function is also valid for uniaxial loading experiments by testing strips coming from the same bladder for which P(1) and a were computed. There is a good agreement between the experimental points and the theoretical stress-strain relation. Finally, the strain energy function is plotted as a function of the first strain invariant and appears to be of an exponential nature.

The stop-flow technique: a way to measure detrusor strength

Maximum intravesical isometric pressure, obtained by stopping the urinary flow in progress, measures detrusor strength and allows an accurate evaluation of bladder contraction. Micturition studies were performed on 7 normal subjects and 48 patients with urinary obstruction, enuresis, neurogenic vesical dysfunction or stress incontinence. In the case of obstruction maximum isometric pressure appears to relate to the degree of detrusor compensation and allows a prognosis as to the future of detrusor function after the obstruction is removed. An unexpected large proportion of patients with enuresis were found to have high maximum isometric pressure usually associated with elevated urethral resistance, suggesting that urinary obstruction may not uncommon as an etiological factor of enuresis.

Viscoelastic properties of bladder strips: standardization of a technique

The standardization of a stretching technique for bladder strips was carried out as a step towards its clinical use. Six variables were studied on specimens of prefrozen bladders taken from human cadavers. Repeated elongations change the nature of the muscle. Viscoelastic coefficients of mucosa are markedly higher than those of muscle. It is necessary to study specimens that have essentially the same direction of fibers and that are located in the same portion of the bladder. The thickness of the specimen does not affect coefficients significantly. The percentage of muscular elongation, in relationship to specimen length, should not exceed 20 per cent in order to have linear reproducible results.