Skin in the game: a review of single-cell and spatial transcriptomics in dermatological research

Single-cell RNA sequencing (scRNA-seq) and spatial transcriptomics (ST) are two emerging research technologies that uniquely characterize gene expression microenvironments on a cellular or subcellular level. The skin, a clinically accessible tissue composed of diverse, essential cell populations, serves as an ideal target for these high-resolution investigative approaches. Using these tools, researchers are assembling a compendium of data and discoveries in healthy skin as well as a range of dermatologic pathophysiologies, including atopic dermatitis, psoriasis, and cutaneous malignancies. The ongoing advancement of single-cell approaches, coupled with anticipated decreases in cost with increased adoption, will reshape dermatologic research, profoundly influencing disease characterization, prognosis, and ultimately clinical practice.

Immunosequencing applications in cutaneous T-cell lymphoma

Immunosequencing has emerged as a newer clinical test for assessment of T-cell clonality in the blood and skin of cutaneous T-cell lymphoma (CTCL) patients. Utilization of immunosequencing, also known as high-throughput sequencing of the T-cell receptor (HTS-TCR), enables identification and quantification of the precise genetic signature of dominant T-cell clones. Although immunosequencing is more sensitive than commonly used methods such as polymerase chain reaction (PCR) paired with capillary electrophoresis or flow cytometry, it remains underutilized for CTCL management. Nonetheless, incorporation of HTS-TCR in clinical practice offers distinct advantages compared to other molecular analyses that may improve diagnostic evaluation, prognostication, and disease monitoring in CTCL. The objective of this comprehensive review is to provide a thorough explanation of the application of immunosequencing in the context of CTCL. We describe the significance of T-cell clonality and the methods used to detect it, including a detailed comparison between PCR paired with capillary electrophoresis and HTS-TCR. The utilization of immunosequencing in the blood and skin of CTCL patients is discussed in depth, specifically outlining how HTS-TCR can assist in diagnosing CTCL, predicting outcomes, and tracking disease progression. Finally, we address the potential applications of immunosequencing in clinical management and research as well as the novel challenges it presents.

Utility of T-cell immunosequencing in distinguishing mycosis fungoides progression from treatment related cutaneous adverse events

Cutaneous adverse events of both topical and systemic drugs in patients with mycosis fungoides (MF) present a diagnostic challenge as it is often difficult to distinguish drug associated rash from disease progression in the skin. Mogamulizumab and mechlorethamine gel are approved treatments for MF, both of which can cause treatment related cutaneous adverse events. It can often be challenging to distinguish mogamulizumab associated rash (MAR) and mechlorethamine gel associated hypersensitivity dermatitis from MF progression both clinically and histologically. High-throughput sequencing (HTS) of the T-cell receptor (TCR), also known as immunosequencing, can be used to assess T-cell clonality to support a diagnosis of MF. After identification of the malignant TCR clone at baseline, immunosequencing can track the established malignant TCR sequence and its frequency over time with high sensitivity. As a result, immunosequencing clone tracking can aid in distinguishing disease progression from treatment side effects. Here, we present a case series to demonstrate how monitoring of the malignant T-cell frequency by immunosequencing can aid in diagnosis of mogamulizumab and mechlorethamine gel cutaneous adverse events.

The Impact of Preoperative Symptom Duration on Patient Outcomes After Posterior Cervical Decompression and Fusion

STUDY DESIGN

Retrospective Cohort Study.

OBJECTIVES

To determine if decreased preoperative symptom duration is associated with greater clinical improvement in function and myelopathic symptoms after posterior cervical decompression and fusion (PCDF).

METHODS

All patients over age 18 who underwent primary PCDF for cervical myelopathy or myeloradiculopathy at a single institution between 2014 and 2020 were retrospectively identified. Patient demographics, surgical characteristics, duration of symptoms, and preoperative and postoperative patient reported outcomes measures (PROMs) including modified Japanese Orthopaedic Association (mJOA), Neck Disability Index (NDI), Visual Analogue Scale (VAS) Neck, VAS Arm, and SF-12 were collected. Univariate and multivariate analyses were performed to compare change in PROMs and minimum clinically important difference achievement (%MCID) between symptom duration groups (< 6 months, 6 months-2 years, > 2 years).

RESULTS

Preoperative symptom duration groups differed significantly by sex and smoking status. Patients with < 6 months of preoperative symptoms improved significantly in all PROMs. Patients with 6 months-2 years of preoperative symptoms did not improve significantly in mJOA, Physical Component Scores (PCS), or NDI. Patients with > 2 years of symptoms failed to demonstrate significant improvement in mJOA, NDI, or Mental Component Scores (MCS). Univariate analysis demonstrated significantly decreased improvement in mJOA with longer symptom durations. Increased preoperative symptom duration trended toward decreased %MCID for mJOA and MCS. Regression analysis demonstrated that preoperative symptom duration of > 2 years relative to < 6 months predicted decreased improvement in mJOA and NDI and decreased MCID achievement for mJOA and MCS.

CONCLUSION

Increased duration of preoperative symptoms (> 2 years) before undergoing PCDF was associated with decreased postoperative improvement in myelopathic symptoms.

Cessation of Routine Jejunostomy Tube Placement at Time of Minimally Invasive Ivor Lewis Esophagectomy and Impact on Body Mass Index

Jejunostomy tubes are frequently placed at time of esophagectomy. The purpose of this study is to evaluate cessation of routine j-tube placement on postoperative body mass index (BMI), return to the emergency room, and time until adjuvant therapy. We performed a retrospective review of an institutional database for consecutive patients undergoing minimally invasive Ivor Lewis Esophagectomy from 2014-2021 (after January 2019, routine j-tube placement was abandoned). Data was analyzed using Pearson's Chi-squared tests and Student's t test with 2-sided significance level of P < 0.05. In total,179 patients were included, 95 underwent j-tube placement and 84 did not. Cohorts had comparable baseline BMI's (no j-tube: 30.48 vs j-tube: 28.64, P = 0.06) and anastomotic leak rates (2.4% vs 4.2%, P = 0.5). Patients with no jejunostomy tubes were more likely to receive total parenteral nutrition (14.3% vs 5.3%, P < 0.05), but were no more likely to require total parenteral nutrition at discharge and had comparable durations of TPN requirement (7 days vs 12 days, P = 0.53). There was no difference in mean BMI reduction at 2 weeks (2.54 vs 2.09, P = 0.49) and 3-6 months postoperatively (6.11 vs 4.45 P = 0.15). There was no difference in return to the emergency room (8.3% vs 8.4%, P = 0.98) or readmissions (13.1% vs 11.6%, P = 0.76). There was a no difference in mean time to adjuvant therapy (83.5 days vs 72.6 days, P = 0.67). At esophagectomy centers with low anastomotic leak rates, cessation of routine j-tube placement at time of minimally esophagectomy can be undertaken without increasing risk of readmission, time until initiation of adjuvant therapy, or significantly impacting postoperative BMI loss.

Instrumentation Across the Cervicothoracic Junction Does Not Improve Patient-reported Outcomes in Multilevel Posterior Cervical Decompression and Fusion

STUDY DESIGN

This was a retrospective cohort.

OBJECTIVE

The objective of this study was to determine if instrumentation across the cervicothoracic junction (CTJ) in elective multilevel posterior cervical decompression and fusion (PCF) is associated with improved patient-reported outcome measures (PROMs).

SUMMARY OF BACKGROUND DATA

Fusion across the CTJ may result in lower revision rates at the expense of prolonged operative duration. However, it is unclear whether constructs crossing the CTJ affect PROMs.

MATERIALS AND METHODS

Standard Query Language (SQL) identified patients with PROMs who underwent elective multilevel PCF (≥3 levels) at our institution. Patients were grouped based on anatomic construct: crossing the CTJ (crossed) versus not crossing the CTJ (noncrossed). Subgroup analysis compared constructs stopping at C7 or T1. Independent t tests and χ 2 tests were utilized for continuous and categorical data, respectively. Regression analysis controlled for baseline demographics. The α was set at 0.05.

RESULTS

Of the 160 patients included, the crossed group (92, 57.5%) had significantly more levels fused (5.27 vs. 3.71, P <0.001), longer operative duration (196 vs. 161 min, P =0.003), greater estimated blood loss (242 vs. 160 mL, P =0.021), and a decreased revision rate (1.09% vs. 10.3%, P =0.011). Neither crossing the CTJ (vs. noncrossed) nor constructs spanning C3-T1 (vs. C3-C7) were independent predictors of ∆PROMs (change in preoperative minus postoperative patient-reported outcomes) on regression analysis. However, C3-C7 constructs had a greater revision rate than C3-T1 constructs (15.6% vs. 1.96%, P =0.030).

CONCLUSION

Crossing the CTJ in patients undergoing elective multilevel PCF was not an independent predictor of improvement in PROMs at 1 year, but they experienced lower revision rates.

LEVEL OF EVIDENCE

Level III.

Neurons survive simultaneous injury to axons and dendrites and regrow both types of processes in vivo

Neurons extend dendrites and axons to receive and send signals. If either type of process is removed, the cell cannot function. Rather than undergoing cell death, some neurons can regrow axons and dendrites. Axon and dendrite regeneration have been examined separately and require sensing the injury and reinitiating the correct growth program. Whether neurons in vivo can sense and respond to simultaneous axon and dendrite injury with polarized regeneration has not been explored. To investigate the outcome of simultaneous axon and dendrite damage, we used a Drosophila model system in which neuronal polarity, axon regeneration, and dendrite regeneration have been characterized. After removal of the axon and all but one dendrite, the remaining dendrite was converted to a process that had a long unbranched region that extended over long distances and a region where shorter branched processes were added. These observations suggested axons and dendrites could regrow at the same time. To further test the capacity of neurons to implement polarized regeneration after axon and dendrite damage, we removed all neurites from mature neurons. In this case a long unbranched neurite and short branched neurites were regrown from the stripped cell body. Moreover, the long neurite had axonal plus-end-out microtubule polarity and the shorter neurites had mixed polarity consistent with dendrite identity. The long process also accumulated endoplasmic reticulum at its tip like regenerating axons. We conclude that neurons in vivo can respond to simultaneous axon and dendrite injury by initiating growth of a new axon and new dendrites.

Total serum cholesterol by isotope dilution/mass spectrometry: a candidate definitive method

We describe a highly accurate and precise method for determination of total cholesterol in serum by isotope dilution/mass spectrometry. The method was developed for a Study Group of the Committee on Standards of the American Association for Clinical Chemistry, for use in establishing the accuracy of a candidate reference method for total cholesterol, and fulfills their criteria for a definitive method. Cholesterol-d7 is added to serum, with the weight ratio of cholesterol-d7 to total serum cholesterol kept near to 1:1. The esters are hydrolyzed and the cholesterol is separated and converted into the trimethylsilyl ether derivative for measurement by combined gas chromatography/mass spectrometry. The intensity ratio of the molecular ions at m/z 465 and 458 is measured for each sample and for two calibration mixtures, according to a prescribed bracketing protocol. A weight ratio for the sample is obtained by linear interpolation of the ion-intensity ratios, and the total cholesterol is then calculated. The method was applied four times over several weeks to each of five serum pools. Statistical analysis involving consideration of both replication error and variability between weeks gave a coefficient of variation for a single measurement of 0.36%. The absence of interferences in the method was demonstrated by measurements at several other masses.

Alirocumab safety in people with and without diabetes mellitus: pooled data from 14 ODYSSEY trials

AIM

To evaluate the safety of the proprotein convertase subtilisin/kexin type 9 (PCSK9) inhibitor alirocumab according to diabetes mellitus status.

METHODS

Safety data from 14 trials (8-104-week durations) were analysed by treatment (alirocumab or placebo/ezetimibe control) and diabetes status (yes/no, defined by medical history). Adverse event data were assessed using descriptive statistics and Cox models.

RESULTS

Of the 5234 trial participants, 1554 (29.7%) had diabetes. Overall, treatment-emergent adverse events were similar in the alirocumab and control groups, except for more frequent local injection site reactions with alirocumab. Fewer people with diabetes experienced local injection site reactions [alirocumab, 3.5%, control, 2.9%; hazard ratio 1.24 (95% CI 0.68-2.25)] than those without diabetes [alirocumab, 7.5%; control, 4.9%; hazard ratio 1.51 (95% CI 1.13-2.01)]. Those with diabetes reported a greater number of serious adverse events (alirocumab, 19.4%; control, 19.7%) than those without diabetes (alirocumab, 14.5%; control, 13.5%). In people with diabetes, major adverse cardiac events occurred in 2.7% of alirocumab-treated people [control, 3.3%; hazard ratio 0.74 (95% CI 0.41-1.35)]; in those without diabetes, 1.8% of alirocumab-treated people had major adverse cardiac events [control, 1.7%; hazard ratio 0.95 (95% CI 0.56-1.62)]. Overall, no increase in HbA1c or fasting plasma glucose vs control treatment groups was observed, regardless of diabetes status.

CONCLUSION

This pooled analysis across 14 trials demonstrated similar safety for alirocumab vs control treatment, irrespective of diabetes status, except for more frequent local injection site reactions with alirocumab. People with diabetes reported fewer local injection site reactions than those without diabetes.

Follow-up care for survivors of lymphoma who have received curative-intent treatment

OBJECTIVE

This evidence summary set out to assess the available evidence about the follow-up of asymptomatic survivors of lymphoma who have received curative-intent treatment.

METHODS

The medline and embase databases and the Cochrane Database of Systematic Reviews were searched for evidence published between 2000 and August 2015 relating to lymphoma survivorship follow-up. The evidence summary was developed by a Working Group at the request of the Cancer Care Ontario Survivorship and Cancer Imaging programs because of the absence of evidence-based practice documents in Ontario for the follow-up and surveillance of asymptomatic patients with lymphoma in complete remission.

RESULTS

Eleven retrospective studies met the inclusion criteria. The proportion of relapses initially detected by clinical manifestations ranged from 13% to 78%; for relapses initially detected by imaging, the proportion ranged from 8% to 46%. Median time for relapse detection ranged from 8.6 to 19 months for patients initially suspected because of imaging and from 8.6 to 33 months for those initially suspected because of clinical manifestations. Only one study reported significantly earlier relapse detection for patients initially suspected because of clinical manifestations (mean: 4.5 months vs. 6.0 months, p = 0.042). No benefit in terms of overall survival was observed for patients depending on whether their relapse was initially detected because of clinical manifestations or surveillance imaging.

SUMMARY

Findings in the present study support the importance of improving awareness on the part of survivors and clinicians about the symptoms that might be associated with recurrence. The evidence does not support routine imaging for improving outcomes in this patient population.

Probabilities for separating sets of order statistics

Consider a set of order statistics that arise from sorting samples from two different populations, each with their own, possibly different distribution functions. The probability that these order statistics fall in disjoint, ordered intervals and that of the smallest statistics, a certain number come from the first populations is given in terms of the two distribution functions. The result is applied to computing the joint probability of the number of rejections and the number of false rejections for the Benjamini-Hochberg false discovery rate procedure.