CD4+ T-Cell Dysfunction in Severe COVID-19 Disease Is Tumor Necrosis Factor-α/Tumor Necrosis Factor Receptor 1-Dependent

Rationale: Lymphopenia is common in severe coronavirus disease (COVID-19), yet the immune mechanisms are poorly understood. As inflammatory cytokines are increased in severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection, we hypothesized a role in contributing to reduced T-cell numbers. Objectives: We sought to characterize the functional SARS-CoV-2 T-cell responses in patients with severe versus recovered, mild COVID-19 to determine whether differences were detectable. Methods: Using flow cytometry and single-cell RNA sequence analyses, we assessed SARS-CoV-2-specific responses in our cohort. Measurements and Main Results: In 148 patients with severe COVID-19, we found lymphopenia was associated with worse survival. CD4⁺ lymphopenia predominated, with lower CD4⁺/CD8⁺ ratios in severe COVID-19 compared with patients with mild disease (P < 0.0001). In severe disease, immunodominant CD4⁺ T-cell responses to Spike-1 (S1) produced increased in vitro TNF-α (tumor necrosis factor-α) but demonstrated impaired S1-specific proliferation and increased susceptibility to activation-induced cell death after antigen exposure. CD4⁺TNF-α⁺ T-cell responses inversely correlated with absolute CD4⁺ counts from patients with severe COVID-19 (n = 76; R = -0.797; P < 0.0001). In vitro TNF-α blockade, including infliximab or anti-TNF receptor 1 antibodies, strikingly rescued S1-specific CD4⁺ T-cell proliferation and abrogated S1-specific activation-induced cell death in peripheral blood mononuclear cells from patients with severe COVID-19 (P < 0.001). Single-cell RNA sequencing demonstrated marked downregulation of type-1 cytokines and NFκB signaling in S1-stimulated CD4⁺ cells with infliximab treatment. We also evaluated BAL and lung explant CD4⁺ T cells recovered from patients with severe COVID-19 and observed that lung T cells produced higher TNF-α compared with peripheral blood mononuclear cells. Conclusions: Together, our findings show CD4⁺ dysfunction in severe COVID-19 is TNF-α/TNF receptor 1-dependent through immune mechanisms that may contribute to lymphopenia. TNF-α blockade may be beneficial in severe COVID-19.

A possible dose-response equation: Viral load after plasma infusion in COVID-19 patients and anti-SARS-CoV-2 antibody titers in convalescent plasma

BACKGROUND

Clinical trials of convalescent plasma therapy for coronavirus disease 2019 (COVID-19) are extensive, but the relationship between antibody titers, infused volume of plasma and virus clearance in patients remains unknown. This study proposed a possible estimating equation for clinical use of high antibody titer convalescent plasma.

METHODS

A total of 38 patients were recruited in the Guanggu District Maternal and Child Health Hospital of Hubei Province from March 1 to 30, 2020. COVID-19 convalescent plasma was collected and high-titer (≥1:640) anti-S-RBD units used. The SARS-CoV-2 nucleic acid viral load was measured 24 h before and 72 h after convalescent plasma infusion.

RESULTS

Convalescent plasma therapy was associated with reduced viral load in patients with moderate and severe severity. The viral negative rate at 72 h was 65.8%. The disappearance of viral nucleic acid in study patients was positively correlated with infuscate antibody titer and volume (r = 0.3375, p = 0.04). A possible estimation equation was as follows: Log₁₀ (Reduction in viral load) = 0.18 + 0.001 × (Log₂ S-RBD antibody titer × Plasma infusion volume) (r = 0.424, p = 0.009). In a single case, the viral nucleic acid persisted 14 days after the fourth plasma infusion.

CONCLUSIONS

This study proposes a potential dose-response equation that adds a convenient way to estimate the dose of convalescent plasma product. It is beneficial to facilitate the rational allocation of plasma with high antibody titers and provide an individualised use strategy for convalescent plasma therapy.

Analysis of viral load in different specimen types and serum antibody levels of COVID-19 patients

BACKGROUND

COVID-19 has caused a global pandemic and the death toll is increasing. However, there is no definitive information regarding the type of clinical specimens that is the best for SARS-CoV-2 detection, the antibody levels in patients with different duration of disease, and the relationship between antibody level and viral load.

METHODS

Nasopharyngeal swabs, anal swabs, saliva, blood, and urine specimens were collected from patients with a course of disease ranging from 7 to 69 days. Viral load in different specimen types was measured using droplet digital PCR (ddPCR). Meanwhile, anti-nucleocapsid protein (anti-N) IgM and IgG antibodies and anti-spike protein receptor-binding domain (anti-S-RBD) IgG antibody in all serum samples were tested using ELISA.

RESULTS

The positive detection rate in nasopharyngeal swab was the highest (54.05%), followed by anal swab (24.32%), and the positive detection rate in saliva, blood, and urine was 16.22%, 10.81%, and 5.41%, respectively. However, some patients with negative nasopharyngeal swabs had other specimens tested positive. There was no significant correlation between antibody level and days after symptoms onset or viral load.

CONCLUSIONS

Other specimens could be positive in patients with negative nasopharyngeal swabs, suggesting that for patients in the recovery period, specimens other than nasopharyngeal swabs should also be tested to avoid false negative results, and anal swabs are recommended. The antibody level had no correlation with days after symptoms onset or the viral load of nasopharyngeal swabs, suggesting that the antibody level may also be affected by other factors.

Effect of Convalescent Plasma Therapy on Time to Clinical Improvement in Patients With Severe and Life-threatening COVID-19: A Randomized Clinical Trial

Importance

Convalescent plasma is a potential therapeutic option for patients with coronavirus disease 2019 (COVID-19), but further data from randomized clinical trials are needed.

Objective

To evaluate the efficacy and adverse effects of convalescent plasma therapy for patients with COVID-19.

Design, Setting, and Participants

Open-label, multicenter, randomized clinical trial performed in 7 medical centers in Wuhan, China, from February 14, 2020, to April 1, 2020, with final follow-up April 28, 2020. The trial included 103 participants with laboratory-confirmed COVID-19 that was severe (respiratory distress and/or hypoxemia) or life-threatening (shock, organ failure, or requiring mechanical ventilation). The trial was terminated early after 103 of a planned 200 patients were enrolled.

Intervention

Convalescent plasma in addition to standard treatment (n = 52) vs standard treatment alone (control) (n = 51), stratified by disease severity.

Main Outcomes and Measures

Primary outcome was time to clinical improvement within 28 days, defined as patient discharged alive or reduction of 2 points on a 6-point disease severity scale (ranging from 1 [discharge] to 6 [death]). Secondary outcomes included 28-day mortality, time to discharge, and the rate of viral polymerase chain reaction (PCR) results turned from positive at baseline to negative at up to 72 hours.

Results

Of 103 patients who were randomized (median age, 70 years; 60 [58.3%] male), 101 (98.1%) completed the trial. Clinical improvement occurred within 28 days in 51.9% (27/52) of the convalescent plasma group vs 43.1% (22/51) in the control group (difference, 8.8% [95% CI, -10.4% to 28.0%]; hazard ratio [HR], 1.40 [95% CI, 0.79-2.49]; P = .26). Among those with severe disease, the primary outcome occurred in 91.3% (21/23) of the convalescent plasma group vs 68.2% (15/22) of the control group (HR, 2.15 [95% CI, 1.07-4.32]; P = .03); among those with life-threatening disease the primary outcome occurred in 20.7% (6/29) of the convalescent plasma group vs 24.1% (7/29) of the control group (HR, 0.88 [95% CI, 0.30-2.63]; P = .83) (P for interaction = .17). There was no significant difference in 28-day mortality (15.7% vs 24.0%; OR, 0.59 [95% CI, 0.22-1.59]; P = .30) or time from randomization to discharge (51.0% vs 36.0% discharged by day 28; HR, 1.61 [95% CI, 0.88-2.95]; P = .12). Convalescent plasma treatment was associated with a negative conversion rate of viral PCR at 72 hours in 87.2% of the convalescent plasma group vs 37.5% of the control group (OR, 11.39 [95% CI, 3.91-33.18]; P < .001). Two patients in the convalescent plasma group experienced adverse events within hours after transfusion that improved with supportive care.

Conclusion and Relevance

Among patients with severe or life-threatening COVID-19, convalescent plasma therapy added to standard treatment, compared with standard treatment alone, did not result in a statistically significant improvement in time to clinical improvement within 28 days. Interpretation is limited by early termination of the trial, which may have been underpowered to detect a clinically important difference.

Trial Registration

Chinese Clinical Trial Registry: ChiCTR2000029757.

[Extraction of polysaccharide from Penthorum chinense]

OBJECTIVE

To study the extraction technology of polysaccharide from Penthorum chinense.

METHODS

Single factor test and orthogonal experiment design methods L9 (3(3)) were applied to analyze the influence of solid-liquid rate, extraction temperature and time on the extraction percent of polysaccharide from Penthorum chinense.

RESULTS

The temperature significantly affected the extraction percent of the soluble polysaccharide, and the optimum conditions for the extraction technology were as follows: solid-liquid rate at 1:15, temperature at 95 degrees C, time for 3h. Under this condition, the extraction percent of polysaccharide from Penthorum chinense was 1.12%, RSD = 1.21%.

CONCLUSION

The research can provide a theoretical foundation for further development and utilization of polysaccharide from Penthorum chinense.

Induction of hyporesponsiveness to intact foreign protein via retroviral-mediated gene expression: the IgG scaffold is important for induction and maintenance of immune hyporesponsiveness

IgG molecules can be highly tolerogenic carriers for associated antigens. Previously, we reported that recipients of bone marrow or lipopolysaccharide-stimulated B-cell blasts, both of which were retrovirally gene-transferred with an immunodominant peptide in-frame with the variable region of a murine IgG heavy chain, were rendered profoundly unresponsive to that epitope. To further investigate whether tolerance to larger molecules can be achieved via this approach and whether the IgG scaffold is important for induction and maintenance of immunological tolerance, we engineered two retroviral constructs encoding the cI lambda repressor (MBAE-1-102 and MBAE-1-102-IgG) for gene transfer. Our results show that recipients of bone marrow or peripheral B cells, transduced with the MBAE-1-102-IgG recombinant, are hyporesponsive to p1-102. In addition, the self-IgG scaffold enhanced the induction and maintenance of such an immune hyporesponsiveness. Thus, our studies demonstrate that in vivo-expressed IgG heavy chain fusion protein can be processed and presented on the appropriate MHC class II, resulting in hyporesponsiveness to that antigen and offering an additional therapeutic approach to autoimmune diseases.

Identification and characterization of Escherichia coli DNA helicase II mutants that exhibit increased unwinding efficiency

Using a combination of both ethyl methanesulfonate and site-directed mutagenesis, we have identified a region in DNA helicase II (UvrD) from Escherichia coli that is required for biological function but lies outside of any of the seven conserved motifs (T. C. Hodgman, Nature 333:22-23, 1988) associated with the superfamily of proteins of which it is a member. Located between amino acids 403 and 409, alterations in the amino acid sequence DDAAFER lead to both temperature-sensitive and dominant uvrD mutations. The uvrD300 (A406T) and uvrD301 (A406V) alleles produce UV sensitivity at 44 degrees C but do not affect sensitivity to methyl methanesulfonate (MMS). In contrast, the uvrD303 mutation (D403AD404A) causes increased sensitivity to both UV and MMS and is dominant to uvrD+ when present at six to eight copies per cell. Several of the alleles demonstrated a strong antimutator phenotype. In addition, conjugal recombination is reduced 10-fold in uvrD303 strains. Of all of the amino acid substitutions tested, only an alanine-to-serine change at position 406 (uvrD302) was neutral. To determine the biochemical basis for the observed phenotypes, we overexpressed and purified the UvrD303 protein from a uvrD delta294 deletion background and characterized its enzymatic activities. The highly unusual UvrD303 protein exhibits a higher specific activity for ATP hydrolysis than the wild-type control, while its Km for ATP binding remains unchanged. More importantly, the UvrD303 protein unwinds partial duplex DNA up to 10 times more efficiently than wild-type UvrD. The DNA binding affinities of the two proteins appear comparable. Based on these results, we propose that the region located between amino acids 403 and 409 serves to regulate the unwinding activity of DNA helicase II to provide the proper balance between speed and overall effectiveness in the various DNA repair systems in which the protein participates.

Conserved motifs II to VI of DNA helicase II from Escherichia coli are all required for biological activity

There are seven conserved motifs (IA, IB, and II to VI) in DNA helicase II of Escherichia coli that have high homology among a large family of proteins involved in DNA metabolism. To address the functional importance of motifs II to VI, we employed site-directed mutagenesis to replace the charged amino acid residues in each motif with alanines. Cells carrying these mutant alleles exhibited higher UV and methyl methanesulfonate sensitivity, increased rates of spontaneous mutagenesis, and elevated levels of homologous recombination, indicating defects in both the excision repair and mismatch repair pathways. In addition, we also changed the highly conserved tyrosine(600) in motif VI to phenylalanine (uvrD309, Y600F). This mutant displayed a moderate increase in UV sensitivity but a decrease in spontaneous mutation rate, suggesting that DNA helicase II may have different functions in the two DNA repair pathways. Furthermore, a mutation in domain IV (uvrD307, R284A) significantly reduced the viability of some E. coli K-12 strains at 30 degrees C but not at 37 degrees C. The implications of these observations are discussed.