Critically Ill Coronavirus Disease 2019 Patients Exhibit Hyperactive Cytokine Responses Associated With Effector Exhausted Senescent T Cells in Acute Infection.

BACKGROUND: Coronavirus disease 2019 (COVID-19) can progress to severe pneumonia with respiratory failure and is aggravated by the deregulation of the immune system causing an excessive inflammation including the cytokine storm. METHODS: In this study, we report that severe acutely infected patients have high levels of both type-1 and type-2 cytokines. RESULTS: Our results show abnormal cytokine levels upon T-cell stimulation, in a nonpolarized profile. Furthermore, our findings indicate that this hyperactive cytokine response is associated with a significantly increased frequency of late-differentiated T cells with particular phenotype of effector exhausted/senescent CD28-CD57+ cells. Of note, we demonstrated for the first time an increased frequency of CD3+CD4+CD28-CD57+ T cells with expression of programmed death 1, one of the hallmarks of T-cell exhaustion. CONCLUSIONS: These findings reveal that COVID-19 is associated with acute immunodeficiency, especially within the CD4+ T-cell compartment, and points to possible mechanisms of loss of clonal repertoire and susceptibility to viral relapse and reinfection events.

The hypertrophic cartilage induction influences the building-block capacity of human adipose stem/stromal cell spheroids for biofabrication.

As an alternative to the classical tissue engineering approach, bottom-up tissue engineering emerges using building blocks in bioassembly technologies. Spheroids can be used as building blocks to reach a highly complex ordered tissue by their fusion (bioassembly), representing the foundation of biofabrication. In this study, we analyzed the biomechanical properties and the fusion capacity of human adipose stem/stromal cell (ASC) we spheroids during an in vitro model of hypertrophic cartilage established by our research group. Hypertrophic induced-ASC spheroids showed a statistically significant higher Young's modulus at weeks 2 (P < .001) and 3 (P < .0005) compared with non-induced. After fusion, non-induced and induced-ASC spheroids increased the contact area and decreased their pairs' total length. At weeks 3 and 5, induced-ASC spheroids did not fuse completely, and the cells migrate preferentially in the fusion contact region. Alizarin red O staining showed the highest intensity of staining in the fused induced-ASC spheroids at week 5, together with intense staining for collagen type I and osteocalcin. Transmission electron microscopy and element content analysis (X-ray Energy Dispersive Spectroscopy) revealed in the fused quartet at week 3 a crystal-like structure. Hypertrophic induction interferes with the intrinsic capacity of spheroids to fuse. The measurements of contact between spheroids during the fusion process, together with the change in viscoelastic profile to the plastic, will impact the establishment of bioassembly protocols using hypertrophic induced-ASC spheroids as building blocks in biofabrication.

Bone crestal height and bone density after third-molar extraction and grafting: a long-term follow-up study.

The objective of this study was to evaluate the long-term influence of xenogenic grafts on bone crestal height and radiographic density following extraction of teeth. The right and left third lower molars of 22 patients were surgically extracted, and one randomly chosen socket was filled with a xenogenic graft (Gent-Tech). The contralateral molar was left to heal naturally, serving as a paired control. Digital intraoral radiographies were taken at surgery and 2, 6, and 24 months after, to evaluate bone density (BD) and alveolar bone crest to cementoenamel junction distance. The data obtained were subjected to two-way analysis of variance and Tukey's test (α = 0.05). The significant decrease in cementoenamel junction distance observed for both groups was limited to the first 6 months. BD values increased significantly in the first 6 months, with no alterations observed up to 24 months for both groups. BD was higher for the experimental group at all time points (p < 0.05). Socket grafting with the xenogenic materials tested did not changed bone crestal height and bone radiographic density in the long term.

Phosphatase activity characterization on the surface of intact bloodstream forms of Trypanosoma brucei.

Procyclic forms of Trypanosoma brucei possess a phosphatase activity on their external cell surface. This activity, while it dephosphorylates [(32)P]phosphocasein, is inhibited weakly by NaF and tartrate but strongly by vanadate. In this work, we describe the presence of an external phosphatase activity in intact bloodstream forms of T. brucei. With p-nitrophenyl phosphate (pNPP) as substrate, these intact cells produced 3-5 nmol pNP min(-1) mg(-1), linearly for up to at least 30 min. The activity was not significantly increased by Mg(2+), Mn(2+), Ca(2+) and Co(2+), but was inhibited by vanadate, NaF, p-chloromercuribenzoate and Zn(2+) and was insensitive to okadaic acid. Membrane-enriched fractions of parasites contained an acid phosphatase activity, with a pH optimum in the range of 4.5-5.5. This activity hydrolyzed phosphotyrosine (40 nmol phosphate min(-1) mg(-1)) better than phosphothreonine or phosphoserine. Partial purification of this phosphatase yielded a single activity band following gel electrophoresis, a K(m) value of 0.29 mM with pNPP and was insensitive to the Fe(2+)/H(2)O(2)/ascorbate system.