Osteo-Chondroprogenitor–Specific Deletion of the Selenocysteine tRNA Gene, Trsp, Leads to Chondronecrosis and Abnormal Skeletal Development: A Putative Model for Kashin-Beck Disease

Kashin-Beck disease, a syndrome characterized by short stature, skeletal deformities, and arthropathy of multiple joints, is highly prevalent in specific regions of Asia. The disease has been postulated to result from a combination of different environmental factors, including contamination of barley by mold mycotoxins, iodine deficiency, presence of humic substances in drinking water, and, importantly, deficiency of selenium. This multifunctional trace element, in the form of selenocysteine, is essential for normal selenoprotein function, including attenuation of excessive oxidative stress, and for the control of redox-sensitive molecules involved in cell growth and differentiation. To investigate the effects of skeletal selenoprotein deficiency, a Cre recombinase transgenic mouse line was used to trigger Trsp gene deletions in osteo-chondroprogenitors. Trsp encodes selenocysteine tRNA[Ser]Sec, required for the incorporation of selenocysteine residues into selenoproteins. The mutant mice exhibited growth retardation, epiphyseal growth plate abnormalities, and delayed skeletal ossification, as well as marked chondronecrosis of articular, auricular, and tracheal cartilages. Phenotypically, the mice thus replicated a number of the pathological features of Kashin-Beck disease, supporting the notion that selenium deficiency is important to the development of this syndrome

Prevalent, protective, and convergent IgG recognition of SARS-CoV-2 non-RBD spike epitopes

The molecular composition and binding epitopes of the immunoglobulin G (IgG) antibodies that circulate in blood plasma following SARS-CoV-2 infection are unknown. Proteomic deconvolution of the IgG repertoire to the spike glycoprotein in convalescent subjects revealed that the response is directed predominantly (>80%) against epitopes residing outside the receptor-binding domain (RBD). In one subject, just four IgG lineages accounted for 93.5% of the response, including an N-terminal domain (NTD)-directed antibody that was protective against lethal viral challenge. Genetic, structural, and functional characterization of a multi-donor class of “public” antibodies revealed an NTD epitope that is recurrently mutated among emerging SARS-CoV-2 variants of concern. These data show that “public” NTD-directed and other non-RBD plasma antibodies are prevalent and have implications for SARS-CoV-2 protection and antibody escape

Effect of Hydrocortisone on Mortality and Organ Support in Patients With Severe COVID-19: The REMAP-CAP COVID-19 Corticosteroid Domain Randomized Clinical Trial.

Importance: Evidence regarding corticosteroid use for severe coronavirus disease 2019 (COVID-19) is limited. Objective: To determine whether hydrocortisone improves outcome for patients with severe COVID-19. Design, Setting, and Participants: An ongoing adaptive platform trial testing multiple interventions within multiple therapeutic domains, for example, antiviral agents, corticosteroids, or immunoglobulin. Between March 9 and June 17, 2020, 614 adult patients with suspected or confirmed COVID-19 were enrolled and randomized within at least 1 domain following admission to an intensive care unit (ICU) for respiratory or cardiovascular organ support at 121 sites in 8 countries. Of these, 403 were randomized to open-label interventions within the corticosteroid domain. The domain was halted after results from another trial were released. Follow-up ended August 12, 2020. Interventions: The corticosteroid domain randomized participants to a fixed 7-day course of intravenous hydrocortisone (50 mg or 100 mg every 6 hours) (n = 143), a shock-dependent course (50 mg every 6 hours when shock was clinically evident) (n = 152), or no hydrocortisone (n = 108). Main Outcomes and Measures: The primary end point was organ support-free days (days alive and free of ICU-based respiratory or cardiovascular support) within 21 days, where patients who died were assigned -1 day. The primary analysis was a bayesian cumulative logistic model that included all patients enrolled with severe COVID-19, adjusting for age, sex, site, region, time, assignment to interventions within other domains, and domain and intervention eligibility. Superiority was defined as the posterior probability of an odds ratio greater than 1 (threshold for trial conclusion of superiority >99%). Results: After excluding 19 participants who withdrew consent, there were 384 patients (mean age, 60 years; 29% female) randomized to the fixed-dose (n = 137), shock-dependent (n = 146), and no (n = 101) hydrocortisone groups; 379 (99%) completed the study and were included in the analysis. The mean age for the 3 groups ranged between 59.5 and 60.4 years; most patients were male (range, 70.6%-71.5%); mean body mass index ranged between 29.7 and 30.9; and patients receiving mechanical ventilation ranged between 50.0% and 63.5%. For the fixed-dose, shock-dependent, and no hydrocortisone groups, respectively, the median organ support-free days were 0 (IQR, -1 to 15), 0 (IQR, -1 to 13), and 0 (-1 to 11) days (composed of 30%, 26%, and 33% mortality rates and 11.5, 9.5, and 6 median organ support-free days among survivors). The median adjusted odds ratio and bayesian probability of superiority were 1.43 (95% credible interval, 0.91-2.27) and 93% for fixed-dose hydrocortisone, respectively, and were 1.22 (95% credible interval, 0.76-1.94) and 80% for shock-dependent hydrocortisone compared with no hydrocortisone. Serious adverse events were reported in 4 (3%), 5 (3%), and 1 (1%) patients in the fixed-dose, shock-dependent, and no hydrocortisone groups, respectively. Conclusions and Relevance: Among patients with severe COVID-19, treatment with a 7-day fixed-dose course of hydrocortisone or shock-dependent dosing of hydrocortisone, compared with no hydrocortisone, resulted in 93% and 80% probabilities of superiority with regard to the odds of improvement in organ support-free days within 21 days. However, the trial was stopped early and no treatment strategy met prespecified criteria for statistical superiority, precluding definitive conclusions. Trial Registration: ClinicalTrials.gov Identifier: NCT02735707

Effect of angiotensin-converting enzyme inhibitor and angiotensin receptor blocker initiation on organ support-free days in patients hospitalized with COVID-19

IMPORTANCE Overactivation of the renin-angiotensin system (RAS) may contribute to poor clinical outcomes in patients with COVID-19. Objective To determine whether angiotensin-converting enzyme (ACE) inhibitor or angiotensin receptor blocker (ARB) initiation improves outcomes in patients hospitalized for COVID-19. DESIGN, SETTING, AND PARTICIPANTS In an ongoing, adaptive platform randomized clinical trial, 721 critically ill and 58 non–critically ill hospitalized adults were randomized to receive an RAS inhibitor or control between March 16, 2021, and February 25, 2022, at 69 sites in 7 countries (final follow-up on June 1, 2022). INTERVENTIONS Patients were randomized to receive open-label initiation of an ACE inhibitor (n = 257), ARB (n = 248), ARB in combination with DMX-200 (a chemokine receptor-2 inhibitor; n = 10), or no RAS inhibitor (control; n = 264) for up to 10 days. MAIN OUTCOMES AND MEASURES The primary outcome was organ support–free days, a composite of hospital survival and days alive without cardiovascular or respiratory organ support through 21 days. The primary analysis was a bayesian cumulative logistic model. Odds ratios (ORs) greater than 1 represent improved outcomes. RESULTS On February 25, 2022, enrollment was discontinued due to safety concerns. Among 679 critically ill patients with available primary outcome data, the median age was 56 years and 239 participants (35.2%) were women. Median (IQR) organ support–free days among critically ill patients was 10 (–1 to 16) in the ACE inhibitor group (n = 231), 8 (–1 to 17) in the ARB group (n = 217), and 12 (0 to 17) in the control group (n = 231) (median adjusted odds ratios of 0.77 [95% bayesian credible interval, 0.58-1.06] for improvement for ACE inhibitor and 0.76 [95% credible interval, 0.56-1.05] for ARB compared with control). The posterior probabilities that ACE inhibitors and ARBs worsened organ support–free days compared with control were 94.9% and 95.4%, respectively. Hospital survival occurred in 166 of 231 critically ill participants (71.9%) in the ACE inhibitor group, 152 of 217 (70.0%) in the ARB group, and 182 of 231 (78.8%) in the control group (posterior probabilities that ACE inhibitor and ARB worsened hospital survival compared with control were 95.3% and 98.1%, respectively). CONCLUSIONS AND RELEVANCE In this trial, among critically ill adults with COVID-19, initiation of an ACE inhibitor or ARB did not improve, and likely worsened, clinical outcomes. TRIAL REGISTRATION ClinicalTrials.gov Identifier: NCT0273570

Chondronecrosis in the articular cartilage of Trsp^fl/fl Col2a1-Cre mice.

<p>(A) Triple-stained section of the femoral articular cartilage of a <i>Trsp^fl/fl</i> control mouse; the red staining reveals the presence of glycosaminoglycans in the extracellular matrix surrounding the embedded chondrocytes. (B) Triple-stain of femoral articular cartilage from a representative <i>Trsp^fl/fl Col2a1-Cre</i> mouse, showing marked glycosaminoglycan depletion (pale red regions) in the areas of chondronecrosis (arrowheads). (C) Hematoxylin and eosin-stained section of distal femoral articular cartilage from another <i>Trsp^fl/fl Col2a1-Cre</i> mouse, showing a typical region of chondronecrosis (arrowheads). (D) TUNEL positive apoptotic cells (stained brown) lining an area of chondronecrosis (arrowheads) in the distal femoral articular cartilage of a <i>Trsp^fl/fl Col2a1-Cre</i> mouse knee. Scale bar = 110 µm.</p

Auricular chondronecrosis and hypoplasia in Trsp^fl/fl Col2a1-Cre mice.

<p>(A) Hematoxylin and eosin staining of ear cartilage from a control <i>Trsp^fl/fl</i> mouse, compared with (B) <i>Trsp^fl/fl Col2a1-Cre</i> auricular cartilage that shows a wide band of necrotic chondrocytes. Detection of TUNEL positive cells (stained brown, with methyl-green counterstain) in <i>Trsp^fl/fl</i> control (C) and <i>Trsp^fl/fl Col2a1-Cre</i> (D) auricular cartilage. Note abundance of necrotic cells with scattered TUNEL positive cells in (D). Evidence of apparent regenerative activity of cartilage above and below the band of necrotic cartilage, but not in the control (E), is shown (F). Detection of cell proliferation using anti-PCNA antibody immunostaining on control <i>Trsp^fl/fl</i> (E) and <i>Trsp^fl/fl Col2a1-Cre</i> (F) cartilage; haematoxylin counter stain. Scale bars are as follows: 55 µm (A,B,E,F), 27 µm (C,D).</p

Compromised skeletal development in Trsp^fl/fl Col2a1-Cre mice.

<p>(A) Radiographs of representative <i>Trsp^fl/fl</i> (left) and <i>Trsp^fl/fl Col2a1-Cre</i> (right) mice. Arrows within the magnified areas highlight the irregularly-shaped vertebral bodies and narrowed intervertebral disc spaces in the <i>Trsp^fl/fl Col2a1-Cre</i> spinal column. (B) Ventral and lateral micro-CT views of lumbar vertebrae from <i>Trsp^fl/fl</i> control (left) and <i>Trsp^fl/fl Col2a1-Cre</i> (right) mice showing delayed spinal column ossification and loss of intervertebral disc spaces. (C) Micro-CT scans of the dorsal aspect of control (left) and experimental (right) skulls show smaller overall head size, rounding of the cranium (with possible decreased frontal bone ossification), and nasal bone shortening in the <i>Trsp^fl/fl Col2a1-Cre</i> mouse. (D) Generalized shape images of representative skulls. Ten mutant mice were used to generate this phenotypic average for the <i>Trsp^fl/fl Col2a1-Cre</i> mice (red skull) and nine <i>Trsp^fl/fl</i> controls were used (grey skull); the overlay of the images is presented beneath. Note that skull sizes from the control and experimental groups have been normalized, thus, only differences in shape of the cranium are being revealed by the overlay technique. (E) Anterior micro-CT views of knee joints from control (left) and experimental (right) mice showing smaller overall size in the latter, yet with relatively wide growth plates being present in the <i>Trsp^fl/fl Col2a1-Cre</i> tibia and fibula. (F) Cortical bone thickness difference (p = 0.0005) between the genotypes at the mid-shaft of the femur measured by micro-CT (n = 5). Data are mean+/−SEM, and were from 3.5–4 wk old mice.</p

Tibial epiphyseal growth plate abnormalities in Trsp^fl/fl Col2a1-Cre mice.

<p>Relative sizes and morphological differences between the tibiae of (A) <i>Trsp^fl/fl</i> (control), and (B) <i>Trsp^fl/fl Col2a1-Cre</i> mice (hematoxylin and eosin stained sections) are shown. Note smaller bone size, and the disproportionate widening of the epiphyseal growth plate in the <i>Trsp^fl/fl Col2a1-Cre</i> mice. Higher magnification views of representative growth plate sections from <i>Trsp^fl/fl</i> (C) and <i>Trsp^fl/fl Col2a1-Cre</i> (D) mice; there was widening of both the proliferative (white two-headed arrows) and hypertrophic (black two-headed arrows) zones in the mutant mice. BrdU+ nuclear staining revealed an increase in the number of mitoses within the tibial growth plate proliferative zones of <i>Trsp^fl/fl</i> (E) as compared to <i>Trsp^fl/fl Col2a1-Cre</i> (F) mice (arrows indicate examples of BrdU+ cells). Scale bars were as follows: 450 µm (A and B), 55 µm (C and D) and 27 µm (E and F). (G) Numbers of BrdU+ nuclei (n = 14 <i>Trsp^fl/fl Col2a1-Cre</i> and n = 7 <i>Trsp^fl/fl</i> tibiae), and TUNEL positive apoptotic cells (n = 3 <i>Trsp^fl/fl Col2a1-Cre</i> and n = 5 <i>Trsp^fl/fl</i> tibiae) present in the epiphyseal growth plates. Data are shown as mean+/−SEM.</p