Phenotypes of disease severity in a cohort of hospitalized COVID-19 patients: Results from the IMPACC study

BACKGROUND

Better understanding of the association between characteristics of patients hospitalized with coronavirus disease 2019 (COVID-19) and outcome is needed to further improve upon patient management.

METHODS

Immunophenotyping Assessment in a COVID-19 Cohort (IMPACC) is a prospective, observational study of 1164 patients from 20 hospitals across the United States. Disease severity was assessed using a 7-point ordinal scale based on degree of respiratory illness. Patients were prospectively surveyed for 1 year after discharge for post-acute sequalae of COVID-19 (PASC) through quarterly surveys. Demographics, comorbidities, radiographic findings, clinical laboratory values, SARS-CoV-2 PCR and serology were captured over a 28-day period. Multivariable logistic regression was performed.

FINDINGS

The median age was 59 years (interquartile range [IQR] 20); 711 (61%) were men; overall mortality was 14%, and 228 (20%) required invasive mechanical ventilation. Unsupervised clustering of ordinal score over time revealed distinct disease course trajectories. Risk factors associated with prolonged hospitalization or death by day 28 included age ≥ 65 years (odds ratio [OR], 2.01; 95% CI 1.28-3.17), Hispanic ethnicity (OR, 1.71; 95% CI 1.13-2.57), elevated baseline creatinine (OR 2.80; 95% CI 1.63- 4.80) or troponin (OR 1.89; 95% 1.03-3.47), baseline lymphopenia (OR 2.19; 95% CI 1.61-2.97), presence of infiltrate by chest imaging (OR 3.16; 95% CI 1.96-5.10), and high SARS-CoV2 viral load (OR 1.53; 95% CI 1.17-2.00). Fatal cases had the lowest ratio of SARS-CoV-2 antibody to viral load levels compared to other trajectories over time (p=0.001). 589 survivors (51%) completed at least one survey at follow-up with 305 (52%) having at least one symptom consistent with PASC, most commonly dyspnea (56% among symptomatic patients). Female sex was the only associated risk factor for PASC.

INTERPRETATION

Integration of PCR cycle threshold, and antibody values with demographics, comorbidities, and laboratory/radiographic findings identified risk factors for 28-day outcome severity, though only female sex was associated with PASC. Longitudinal clinical phenotyping offers important insights, and provides a framework for immunophenotyping for acute and long COVID-19.

FUNDING

NIH.

Targeted transcriptomic analyses of RNA isolated from formalin-fixed and paraffin-embedded human menisci

Formalin-fixed and paraffin-embedded (FFPE) biospecimens are a valuable and widely-available resource for diagnostic and research applications. With biobanks of tissue samples available in many institutions, FFPE tissues could prove to be a valuable resource for translational orthopaedic research. The purpose of this study was to characterize the molecular profiles and degree of histologic degeneration on archival fragments of FFPE human menisci obtained during arthroscopic partial meniscectomy. We used FFPE menisci for multiplexed gene expression analysis using the NanoString nCounter® platform, and for histological assessment using a quantitative scoring system. In total, 17 archival specimens were utilized for integrated histologic and molecular analyses. The median patient age was 22 years (range: 14-62). We found that the genes with the highest normalized counts were those typically expressed in meniscal fibrocartilage. Gene expression differences were identified in patient cohorts based on age (≤40 years), including genes associated with the extracellular matrix and tissue repair. The majority of samples showed mild to moderate histologic degeneration. Based on these data, we conclude that FFPE human menisci can be effectively utilized for molecular evaluation following a storage time as long as 11 years. Statement of Clinical Significance: The integration of histological and transcriptomic analyses described in this study will be useful for future studies investigating the basis for biological classification of meniscus specimens in patients. Further exploration into the genes and pathways uncovered by this study may suggest targets for biomarker discovery and identify patients at greater risk for osteoarthritis once the meniscus is torn.

Expression of alarmins in a murine rotator cuff tendinopathy model

The aim of this study was to investigate the presence of alarmins in a novel murine rotator cuff tendinopathy model. Alarmins have been described as essential early activators of an immune response to tissue damage. Subacromial impingement was induced in both shoulders of 37 male C57Bl/6 mice by placement of a small metal clip in the subacromial space. Animals were allocated to different time points up to 6 weeks. The morphology and cellularity of the supraspinatus tendon were evaluated by hematoxylin-eosin staining, alcian blue, and picrosirius red. The expression and localization of alarmins interleukin-33 (IL-33), c (HMGB1), hypoxia-inducible factor-1 subunit α (HIF1α), and S100A9 were evaluated by immunohistochemical staining and quantitative polymerase chain reaction. The percentage of positively stained cells with HMGB1 and IL-33 was significantly increased in the impingement group at 1w, 4w, and 6w. HIF1α staining was higher in the impingement group at 1w and 6w compared with the control group. HMGB1 gene expression was higher in the 5d impingement group and 6w impingement group. The gene expression of HIF1α was upregulated at all-time points in the impingement group (5d, 2w, 4w, and 6w). The expression of the S100A9 gene was also upregulated in the 5d impingement group. This is the first study to demonstrate the involvement of alarmins in the early phase of tendinopathy using a reproducible animal model. Alarmins may play an important role in the early phases of the development of tendinopathy They may represent potential therapeutic targets for treatment of tendinopathy.

Matrix Metalloproteinase Inhibition With Doxycycline Affects the Progression of Posttraumatic Osteoarthritis After Anterior Cruciate Ligament Rupture: Evaluation in a New Nonsurgical Murine ACL Rupture Model

BACKGROUND

Doxycycline has broad-spectrum activity as a matrix metalloproteinase (MMP) inhibitor and thus could reduce the progression of posttraumatic osteoarthritis (PTOA) after anterior cruciate ligament (ACL) rupture.

HYPOTHESIS

Doxycycline would inhibit progression of PTOA in a murine ACL rupture model.

STUDY DESIGN

Controlled laboratory study.

METHODS

For the in vitro study, cadaveric C57BL/6 male mice knees (N = 108) were used for the development of a nonsurgical ACL rupture model. For the in vivo study, 24 C57BL/6 male mice then underwent ACL rupture with our manual procedure and were divided into 4 groups: untreated control; doxycycline, 10 mg/kg/d; doxycycline, 50 mg/kg/d; and doxycycline, 100 mg/kg/d. Doxycycline was administered in drinking water beginning immediately after ACL rupture. Radiographic imaging and paw prints were evaluated at 3, 7, 14, and 28 days. The foot length and toe spread were analyzed as measures of function. Histology and MMP-13 immunohistochemistry were done at 4 weeks.

RESULTS

Radiographs demonstrated anterior tibial subluxation and meniscal extrusion after ACL rupture, confirming knee joint instability without fractures. Statistically significant differences in gait were found between the intact and experimental groups. Histologic examination demonstrated cartilage damage, meniscal tears, and mild osteoarthritis after ACL rupture, similar to what occurs in human patients. Hypertrophy of the posterior horn of the medial and lateral meniscus was found, and tears of the posterior horn of the menisci were common. All doxycycline groups had a lower score than the untreated control group, indicating less cartilage damage. The posterior tibia of the untreated group had the most cartilage damage as compared with the 3 doxycycline groups, with a significant difference between the untreated and 50-mg/kg/d doxycycline groups, suggesting that the latter dose may protect against proteoglycan loss and decrease the progression of osteoarthritis. The nondoxycycline group had the highest synovial inflammation score among all groups, indicating that doxycycline has an inhibitory effect on synovitis. There was significantly lower MMP-13 expression on the tibia in the doxycycline-treated groups, with a positive correlation between doxycycline concentration and MMP-13 inhibition.

CONCLUSION

Modulation of MMP-13 activity by doxycycline treatment may offer a novel biological pathway to decrease the progression of PTOA after ACL rupture.

CLINICAL RELEVANCE

Doxycycline is an approved, readily available drug with infrequent side effects of photosensitivity and gastrointestinal symptoms. Future clinical trials could evaluate doxycycline to reduce or prevent progressive cartilage damage after ACL rupture.

Long-term Evaluation of Meniscal Tissue Formation in 3-dimensional-Printed Scaffolds With Sequential Release of Connective Tissue Growth Factor and TGF-β3 in an Ovine Model

BACKGROUND

Artificial meniscal scaffolds are being developed to prevent development of osteoarthritis after meniscectomy. Previously, it was reported that 3-dimensional (3D) anatomic scaffolds loaded with connective tissue growth factor (CTGF) and transforming growth factor β3 (TGF-β3) achieved meniscal regeneration in an ovine model. This was a relatively short-term study (3 months postoperative), and outcome analyses did not include magnetic resonance imaging (MRI).

PURPOSE

To evaluate long-term outcome of meniscal replacement with growth factor-laden poly-ε-caprolactone (PCL) scaffolds.

STUDY DESIGN

Controlled laboratory study.

METHODS

Anatomically shaped ovine meniscal scaffolds were fabricated from PCL with a 3D printer based on MRI data. Skeletally mature sheep (N = 34) were randomly allocated to 3 groups: scaffold without growth factor (0-µg group), scaffold with CTGF microspheres (µS) (5 µg) + TGF-β3 µS (5 µg) (5-µg group), and scaffold with CTGF µS (10 µg) + TGF-β3 µS (10 µg) (10-µg group). Unilateral medial meniscal replacement was performed. Animals were euthanized at 6 or 12 months. Regenerated meniscus, articular cartilage status, and synovial reaction were evaluated quantitatively with gross inspection, histology, and MRI. Kruskal-Wallis and Dunn tests were used to compare the 3 groups.

RESULTS

Remnants of the PCL scaffold were evident in the 6-month specimens and were decreased but still present at 12 months in most animals. There were no significant differences among groups in gross inspection, histology, or MRI for either meniscal regeneration or articular cartilage protection. All experimental groups exhibited articular cartilage degeneration as compared with control (nonoperated). In terms of synovitis, there were no clear differences among groups, suggesting that growth factors did not increase inflammation and fibrosis. MRI revealed that meniscal extrusion was observed in most animals (82.7%).

CONCLUSION

Previously, the combination of CTGF and TGF-β3 was shown to stimulate mesenchymal stem cells into a fibrochondrocyte lineage. CTGF and TGF-β3 did not aggravate synovitis, suggesting no adverse response to the combination of 3D-printed PCL scaffold combined with CTGF and TGF-β3. Further work will be required to improve scaffold fixation to avoid meniscal extrusion.

CLINICAL RELEVANCE

A significant advantage of this technique is the ability to print custom-fit scaffolds from MRI-generated templates. In addition, average-size menisci could be printed and available for off-the-shelf applications. Based on the 1-year duration of the study, the approach appears to be promising for meniscal regeneration in humans.