SARS-CoV-2 enters host cells through its viral spike protein binding to angiotensin-converting enzyme 2 (ACE2) receptors on the host cells. Here, we show that functionalized nanoparticles, termed “Nanotraps,” completely inhibited SARS-CoV-2 infection by blocking the interaction between the spike protein of SARS-CoV-2 and the ACE2 of host cells. The liposomal-based Nanotrap surfaces were functionalized with either recombinant ACE2 proteins or anti-SARS-CoV-2 neutralizing antibodies and phagocytosis-specific phosphatidylserines. The Nanotraps effectively captured SARS-CoV-2 and completely blocked SARS-CoV-2 infection to ACE2-expressing human cell lines and primary lung cells; the phosphatidylserine triggered subsequent phagocytosis of the virus-bound, biodegradable Nanotraps by macrophages, leading to the clearance of pseudotyped and authentic virus in vitro . Furthermore, the Nanotraps demonstrated an excellent biosafety profile in vitro and in vivo . Finally, the Nanotraps inhibited pseudotyped SARS-CoV-2 infection in live human lungs in an ex vivo lung perfusion system. In summary, Nanotraps represent a new nanomedicine for the inhibition of SARS-CoV-2 infection.

Inverse vaccines that tolerogenically target antigens to antigen-presenting cells (APCs) offer promise in prevention of immunity to allergens and protein drugs and treatment of autoimmunity. We have previously shown that targeting hepatic APCs through intravenous injection of synthetically glycosylated antigen leads to effective induction of antigen-specific immunological tolerance. Here, we demonstrate that targeting these glycoconjugates to lymph node (LN) APCs under homeostatic conditions leads to local and increased accumulation in the LNs compared to unmodified antigen and induces a tolerogenic state both locally and systemically. Subcutaneous administration directs the polymeric glycoconjugate to the draining LN, where the glycoconjugated antigen generates robust antigen-specific CD4+ and CD8+ T cell tolerance and hypo-responsiveness to antigenic challenge via a number of mechanisms, including clonal deletion, anergy of activated T cells, and expansion of regulatory T cells. Lag-3 up-regulation on CD4+ and CD8+ T cells represents an essential mechanism of suppression. Additionally, presentation of antigen released from the glycoconjugate to naïve T cells is mediated mainly by LN-resident CD8+ and CD11b+ dendritic cells. Thus, here we demonstrate that antigen targeting via synthetic glycosylation to impart affinity for APC scavenger receptors generates tolerance when LN dendritic cells are the cellular target.

Interleukin-4 (IL-4) suppresses the development of multiple sclerosis in a murine model of experimental autoimmune encephalomyelitis (EAE). Here, we show in mice with EAE that, compared with the administration of wild-type IL-4 or of the clinically approved drug fingolimod, the systemic injection of serum albumin (SA) fused to IL-4 better accumulates and persists in lymph nodes and in the spleen, leading to higher therapeutic efficacy and to the prevention of disease development in the majority of the mice. We also show that the SA-IL-4 fusion protein prevented immune-cell infiltration in the spinal cord, decreased integrin expression in antigen-specific CD4 + T cells, increased the number of granulocyte-like myeloid-derived suppressor cells (and their expression of programmed-death-ligand-1) in spinal-cord-draining lymph nodes, and decreased the number of T helper 17 cells, a pathogenic cell population in EAE. In mice with chronic EAE, SA-IL-4 inhibited immune-cell infiltration into the spinal cord and completely abrogated immune responses to myelin antigen in the spleen. The SA-IL-4 fusion protein may be prophylactically and therapeutically advantageous in the treatment of multiple sclerosis. Multiple sclerosis (MS) is a potentially disabling autoimmune disease that affects millions globally. Autoreactive immune cells home to the central nervous system (CNS) and cause demyelination and consequently focal damage to white matter 1 . Lymphocytes and macrophages that have infiltrated into the CNS cause axonal damage. Recent studies have shown that Th17 cells, activated in the secondary lymphoid organs (SLOs), migrate to the spinal cord and brain and play a crucial role in the disease development and severity of MS 2, 3 . Thus, inhibition of lymphocyte migration to the CNS and inducing an immune-suppressive microenvironment in the SLOs would provide an effective therapy for MS. FTY720 (fingolimod) and anti-integrin α4 antibody (natalizumab) are used in the clinic for treating MS 4, 5 , sequestering lymphocytes in the LNs and preventing them from reacting with autoantigens in target tissues. Experimental autoimmune encephalomyelitis (EAE) is a widely accepted murine model of MS, reflecting many features of disease progression and developmental mechanism, including lymphocyte migration to the CNS and demyelination.Interleukin (IL)-4 is a pleiotropic anti-inflammatory cytokine that differentiates naïve CD4 + T cells into a Th2 phenotype and results in decreased differentiation into Th1 and Th17 6 . IL-4 suppresses re-activation of committed Th17 cells 6 . Moreover, IL-4 polarizes macrophages toward the M2 phenotype, an antiinflammatory phenotype 7 . IL-4 has been reported to suppress EAE disease incidence and severity 8,9 ; this occurs not only through direct immuno-modulation, as a recent study has shown that intranasally administered IL-4 improved disease outcomes of EAE through IL-4 directly binding to neurons to promote regeneration 10 .Although IL-4 stimulates multiple pathways to suppress EAE, it has yet to be tr...

Objective. Rheumatoid arthritis (RA) is a major autoimmune disease that causes synovitis and joint damage. Although clinical trials have been performed using interleukin-10 (IL-10), an antiinflammatory cytokine, as a potential treatment of RA, the therapeutic effects of IL-10 have been limited, potentially due to insufficient residence in lymphoid organs, where antigen recognition primarily occurs. This study was undertaken to engineer an IL-10-serum albumin (SA) fusion protein and evaluate its effects in 2 murine models of RA.Methods. SA-fused IL-10 (SA-IL-10) was recombinantly expressed. Mice with collagen antibody-induced arthritis (n = 4-7 per group) or collagen-induced arthritis (n = 9-15 per group) were injected intravenously with wild-type IL-10 or SA-IL-10, and the retention of SA-IL-10 in the lymph nodes (LNs), immune cell composition in the paws, and therapeutic effect of SA-IL-10 on mice with arthritis were assessed.Results. SA fusion to IL-10 led to enhanced accumulation in the mouse LNs compared with unmodified IL-10. Intravenous SA-IL-10 treatment restored immune cell composition in the paws to a normal status, elevated the frequency of suppressive alternatively activated macrophages, reduced IL-17A levels in the paw-draining LN, and protected joint morphology. Intravenous SA-IL-10 treatment showed similar efficacy as treatment with an anti-tumor necrosis factor antibody. SA-IL-10 was equally effective when administered intravenously, locally, or subcutaneously, which is a benefit for clinical translation of this molecule.Conclusion. SA fusion to IL-10 is a simple but effective engineering strategy for RA therapy and has potential for clinical translation.

The outbreak of 2019 coronavirus disease (COVID‐19), caused by severe acute respiratory syndrome coronavirus 2 (SARS‐CoV‐2), has resulted in a global pandemic. Despite intensive research, the current treatment options show limited curative efficacies. Here the authors report a strategy incorporating neutralizing antibodies conjugated to the surface of a photothermal nanoparticle (NP) to capture and inactivate SARS‐CoV‐2. The NP is comprised of a semiconducting polymer core and a biocompatible polyethylene glycol surface decorated with high‐affinity neutralizing antibodies. The multifunctional NP efficiently captures SARS‐CoV‐2 pseudovirions and completely blocks viral infection to host cells in vitro through the surface neutralizing antibodies. In addition to virus capture and blocking function, the NP also possesses photothermal function to generate heat following irradiation for inactivation of virus. Importantly, the NPs described herein significantly outperform neutralizing antibodies at treating authentic SARS‐CoV‐2 infection in vivo. This multifunctional NP provides a flexible platform that can be readily adapted to other SARS‐CoV‐2 antibodies and extended to novel therapeutic proteins, thus it is expected to provide a broad range of protection against original SARS‐CoV‐2 and its variants.