A nonrandomized phase 2 trial of oral thymic peptides in hospitalized patients with Covid-19

BackgroundCoronavirus disease 2019 (Covid-19) active cases continue to demand the development of safe and effective treatments. This is the first clinical trial to evaluate the safety and efficacy of oral thymic peptides.MethodsWe conducted a nonrandomized phase 2 trial with a historic control group to evaluate the safety and efficacy of a daily 250-mg oral dose of thymic peptides in the treatment of hospitalized Covid-19 patients. Comparison based on standard care from registry data was performed after propensity score matching. The primary outcomes were survival, time to recovery and the number of participants with treatment-related adverse events or side effects by day 20.ResultsA total of 44 patients were analyzed in this study, 22 in the thymic peptides group and 22 in the standard care group. There were no deaths in the intervention group, compared to 24% mortality in standard care by day 20 (log-rank P=0.02). The Kaplan-Meier analysis showed a significantly shorter time to recovery by day 20 in the thymic peptides group as compared with standard care (median, 6 days vs. 12 days; hazard ratio for recovery, 2.75 [95% confidence interval, 1.34 to 5.62]; log-rank P=0.002). No side effects or adverse events were reported.ConclusionIn patients hospitalized with Covid-19, the use of thymic peptides reported no side effects, adverse events, or deaths by day 20. When compared with registry data, a significantly shorter time to recovery and mortality reduction was measured. The Catholic University of Honduras Medical Research Group (GIMUNICAH) is working on a more extensive phase 3 trial.Trial registrationClinicalTrials.govNCT04771013. February 25, 2021.

ThymicPeptides Reverse Immune Exhaustion in Patients with Reactivated Human Alphaherpesvirus1 Infections

Recurrent infection with human alphaherpesvirus 1 (HHV-1) may be associated with immune exhaustion that impairs virus elimination. Thymic peptides enhance immune function and thus could overcome immune exhaustion. In this study, we investigated whether reactivation of herpes infections was associated with immune exhaustion. Moreover, we examined the impact of treatment with thymostimulin on the expression of programmed cell death protein 1 (PD-1) and its ligand (PD-L1) on T and B lymphocytes in patients suffering from recurrent HHV-1 reactivation. We also assessed the effector function of peripheral blood mononuclear cells (PBMCs) after stimulation with thymic peptides. We enrolled 50 women with reactivated HHV-1 infections and healthy volunteers. We measured the expression of various activation and exhaustion markers on the surface of PBMCs using flow cytometry. In ex vivo experiments, we measured the secretion of inflammatory cytokines by PBMCs cultured with thymostimulin. Compared with controls, patients with reactivated HHV-1 infections had increased percentages of CD3+ co-expressing CD25, an activation marker (p < 0.001). Moreover, these patients had increased percentages of CD4+ and CD8+ cells co-expressing the inhibitory markers PD-1 and PD-L1. In cultures of PBMCs from the patients, thymostimulin increased the secretion of interferon gamma (p < 0.001) and interleukin (IL)-2 (p = 0.023), but not IL-4 or IL-10.Two-month thymostimulin therapy resulted in no reactivation of HHV-1 infection during this period and the reduction of PD-1 and PD-L1 expression on the surface of T and B lymphocytes (p < 0.001). In conclusion, reactivation of herpes infection is associated with immune exhaustion, which could be reversed by treatment with thymic peptides.

Extrathymic production of thymulin induced by oxidative stress, heat shock, apoptosis, or necrosis

Thymic peptides are immune regulators produced mainly in the thymus. However, thymic peptides such as thymosin-α and thymopoietin have precursors widely expressed outside the thymus, localized in cell nuclei, and involved in vital nuclear functions. In stress-related conditions, they can relocalize. We hypothesized that another thymic peptide, thymulin, could be similarly produced by non-thymic cells during stress and have a precursor therein. Non-thymic cells, including macrophages and fibroblasts, were exposed to oxidative stress, heat, apoptosis, or necrosis. Extracellular thymulin was identified in media of both cell types 2 h after exposure to stress or lethal signals. Therefore, thymulin is released by non-thymic cells. To examine possible thymulin precursors in non-thymic cells, macrophage lysates were analyzed by western blotting. Bands stained with anti-thymulin antibody were detected in two locations, approximately 60 kDa and 10 kDa, which may be a possible precursor and intermediate. All of the exposures except for heat were effective for induction of the 10 kDa protein. BLAST search using thymulin sequence identified SPATS2L, an intranucleolar stress-response protein with molecular weight of 62 kDa, containing thymulin-like sequence. Comparisons of blots stained with anti-thymulin and anti-SPATS2L antibodies indicate that SPATS2L may be a possible candidate for the precursor of thymulin.