During development, nephron structures are derived from a SIX2+ stem cell population. After 36 weeks of gestation, these cells are exhausted, and no new nephrons are formed. We have previously described a non-invasive strategy to isolate and expand the native SIX2+ kidney stem cells from the urine of preterm neonates, named neonatal kidney stem/progenitor cells (nKSPC). Here, we investigated the safety and feasibility of administering nKSPC into human kidneys discarded for transplantation during normothermic machine perfusion (NMP) and evaluated the regenerative and immunomodulatory potential of nKSPC treatment. We found that nKSPC administration during NMP is safe and feasible. Interestingly, nKSPC induced the de novo expression of SIX2 in proximal tubular cells of the donor kidneys and upregulated regenerative markers such as SOX9 and VEGF. This is the first time that SIX2 re-expression is observed in adult human kidneys. Moreover, nKSPC administration significantly lowered levels of kidney injury biomarkers and reduced inflammatory cytokine levels via the tryptophan-IDO-kynurenine pathway. In conclusion, nKSPC is a novel cell type to be applied in kidney-targeted cell therapy, with the potential to induce an endogenous regenerative process and immunomodulation. During development, nephron structures are derived from a SIX2+ stem cell population. After 36 weeks of gestation, these cells are exhausted, and no new nephrons are formed. We have previously described a non-invasive strategy to isolate and expand the native SIX2+ kidney stem cells from the urine of preterm neonates, named neonatal kidney stem/progenitor cells (nKSPC). Here, we investigated the safety and feasibility of administering nKSPC into human kidneys discarded for transplantation during normothermic machine perfusion (NMP) and evaluated the regenerative and immunomodulatory potential of nKSPC treatment. We found that nKSPC administration during NMP is safe and feasible. Interestingly, nKSPC induced the de novo expression of SIX2 in proximal tubular cells of the donor kidneys and upregulated regenerative markers such as SOX9 and VEGF. This is the first time that SIX2 re-expression is observed in adult human kidneys. Moreover, nKSPC administration significantly lowered levels of kidney injury biomarkers and reduced inflammatory cytokine levels via the tryptophan-IDO-kynurenine pathway. In conclusion, nKSPC is a novel cell type to be applied in kidney-targeted cell therapy, with the potential to induce an endogenous regenerative process and immunomodulation.
The CD4 receptor is the primary entry receptor for the human immunodeficiency virus. Besides this detrimental function, the CD4 receptor is crucial for positive selection and development of CD4+ T cells as well as for proper functioning of the immune system. During T cell activation, the CD4 receptor can fulfill an adhesion function, act as a signaling molecule and enhance the sensitivity of T cells to antigens. In addition, the CD4 receptor was suggested to be involved in differentiation towards the T helper 2 subset and in chemotaxis of T cells. In other types of immune cells, diverging functions are attributed to the CD4 receptor. The immunological importance of the CD4 receptor makes it an interesting target for immunosuppression. This is demonstrated by the immunosuppressive potential of several anti-CD4 monoclonal antibodies. These antibodies may have several modes of action, such as (1) inhibition of CD4+ T cell activation by steric hindrance of the CD4/major histocompatibility complex class II interaction resulting in antigen-specific tolerance, (2) down-modulation of the CD4 receptor, (3) switching from a pro-inflammatory T helper 1 to a more immunomodulatory T helper 2 type immune response, (4) induction of regulatory T cells and enhancement of their activity, or (5) delivery of a negative or attenuated signal into the CD4+ T cell. In addition, medicinal drugs that target CD4 are interesting alternatives for immunosuppressive treatment. The small molecule cyclotriazadisulfonamide (CADA) that down-modulates the CD4 receptor in a unique way by signal peptide-dependent inhibition of ER co-translational translocation is currently under investigation as a novel immunosuppressive drug.
BACKGROUND: Disruption of the nasal epithelial barrier is believed to play a role in Coronavirus Disease-2019 (COVID-19) outcomes. Fluticasone propionate has been shown to restore the nasal epithelial barrier in allergic rhinitis to the level of healthy controls. The therapeutic potential of nasal steroid sprays in COVID-19 has recently been reported. However, further insight into the mode of action is warranted. OBJECTIVES: To explore the in vitro mechanisms of the preventive potential of fluticasone propionate in SARS-CoV-2 infection. METHODS: Human air liquid interface cultures of Calu-3 cells and primary nasal epithelial cells isolated from healthy donors were used to investigate the preventive effect of fluticasone propionate on SARS-CoV-2 induced barrier disruption, virus replication and ACE2 expression. RESULTS: 48 hours pre-treatment with fluticasone propionate prevented the SARS-CoV-2 induced increase in fluorescein isothiocyanate-dextran 4 kDa permeability and reduced infection with SARS-CoV-2. Pre-treatment with fluticasone propionate also decreased ACE2 expression in SARS-CoV-2 infected Calu-3 cells. Conclusion: Fluticasone propionate pre-treatment prevented SARS-CoV-2 increased epithelial permeability, reduced ACE2 expression and SARS-CoV-2 infection, underscoring the therapeutic potential of fluticasone propionate in the context of COVID-19.
In order to infect a target cell, the HIV envelope glycoprotein gp120 has to interact with the CD4 receptor, which serves as the primary virus receptor. For most HIV strains, the successful infection of their target cells is mainly dependent on the expression of the CD4 surface molecule which can be considered as an ideal target with multiple windows of opportunity for therapeutic intervention. Therefore, drugs that interfere with the CD4 receptor, and thus inhibit viral entry, may be promising agents for the treatment of AIDS. Here we describe the discovery and characterization of the CD4-targeted HIV entry inhibitors cyclotriazadisulfonamides. They repesent a novel class of small molecule antiviral agents with an unique mode of action. The lead compound, CADA, specifically interferes with cellular CD4 receptor expression and is active against a wide variety of HIV strains at submicromolar levels when evaluated in different cell-types such as T cells, monocytes and dendritic cells. Moreover, a strict correlation has been demonstrated between anti-HIV activity and CD4 down-modulation of about 20 different CADA analogs. In addition, CADA acted synergistically in combination with other FDA-approved anti-HIV drugs. The broad spectrum antiviral activity of CADA against several different subtypes of HIV supports the possible application of this compound as a microbicide. Finally, the development of fluorescent CADA analogs made it feasible to study receptor and its down-modulator simultaneously. These CADA-compounds with reversible CD4 down-modulating potency will be valuable tools in further studies on receptor modulation, and in deciphering the process that plays a role during the complicated interactions between HIV-gp120 and the cellular membrane, which ultimately will lead to a more efficient treatment of HIV-infections.
Despite recent advancements in the development of vaccines and monoclonal antibody therapies for Ebola virus disease, treatment options remain limited. Moreover, management and containment of Ebola virus outbreaks is often hindered by the remote nature of the locations in which the outbreaks originate. Small-molecule compounds offer the advantage of being relatively cheap and easy to produce, transport and store, making them an interesting modality for the development of novel therapeutics against Ebola virus disease. Furthermore, the repurposing of small-molecule compounds, previously developed for alternative applications, can aid in reducing the time needed to bring potential therapeutics from bench to bedside. For this purpose, the Medicines for Malaria Venture provides collections of previously developed small-molecule compounds for screening against other infectious diseases. In this study, we used biologically contained Ebola virus to screen over 4,200 small-molecule drugs and drug-like compounds provided by the Medicines for Malaria Venture (i.e., the Pandemic Response Box and the COVID Box) and the Centre for Drug Design and Discovery (CD3, KU Leuven, Belgium). In addition to confirming known Ebola virus inhibitors, illustrating the validity of our screening assays, we identified eight novel selective Ebola virus inhibitors. Although the inhibitory potential of these compounds remains to be validated in vivo, they represent interesting compounds for the study of potential interventions against Ebola virus disease and might serve as a basis for the development of new therapeutics.
