mIgM-mediated splenic marginal zone B cells targeting of folic acid for immunological evasion.

Folic acid is a fully oxidized synthetic folate with high bioavailability and stability which has been extensively prescribed to prevent congenital disabilities. Here we revealed the immunosuppressive effect of folic acid by targeting splenic marginal zone B (MZB) cells. Folic acid demonstrates avid binding with the Fc domain of immunoglobulin M (IgM), targeting IgM positive MZB cells in vivo to destabilize IgM-B cell receptor (BCR) complex and block immune responses. The induced anergy of MZB cells by folic acid provides an immunological escaping window for antigens. Covalent conjugation of folic acid with therapeutic proteins and antibodies induces immunological evasion to mitigate the production of anti-drug antibodies, which is a major obstacle to the long-term treatment of biologics by reducing curative effects and/or causing adverse reactions. Folic acid acts as a safe and effective immunosuppressant via IgM-mediated MZB cells targeting to boost the clinical outcomes of biologics by inhibiting the production of anti-drug antibodies, and also holds the potential to treat other indications that adverse immune responses need to be transiently shut off.

Folic Acid Enables Targeting Delivery of Lipodiscs by Circumventing IgM-Mediated Opsonization.

Folic acid (FA) is one of the most widely utilized small-molecule ligands for cancer targeted drug delivery. Natural IgM was recently found to avidly absorb on the surface of FA-functionalized liposomes (FA-sLip), negatively regulating the in vivo performance by efficiently activating complement. Herein, FA-functionalized lipodiscs (FA-Disc) were constructed to successfully circumvent IgM-mediated opsonization and retained binding activity with folate receptors in vivo. The FA moiety along with the bound IgM was restricted to the highly curved rim of lipodiscs, leading to IgM incapability of presenting the membrane-bound conformation to trigger complement activation. The C1q docking, C3 binding, and C5a release were blocked and accelerated blood clearance phenomenon was mitigated of FA-Disc. FA-Disc retained folate binding activity and could effectively target folate receptor positive tumors in vivo. The present study provides a useful solution to avoid the negative regulation by IgM and achieve FA-enabled targeting by exploring disc-shaped nanocarriers.

Protein corona: challenges and opportunities for targeted delivery of nanomedicines.

INTRODUCTION: Targeted drug delivery has been widely explored as a promising way to improve the performance of nanomedicines. However, protein corona formed on the nano-surface represents a major issue that has great impacts on the in vivo fate of targeting nanomedicines, which has been overlooked in the past. With the increasing understanding of protein corona in the recent decade, many efforts have been made to improve targeting efficacy. AREAS COVERED: In this review, we briefly summarize insights of targeted delivery systems inspired by protein corona, and discuss the promising strategies to regulate protein corona for better targeting. EXPERT OPINION: The interaction between nanomedicines and endogenous proteins brings great uncertainty and challenges, but it also provides great opportunities for the development of targeting nanomedicines at the same time. With increasing understanding of protein corona, the strategies to regulate protein corona pave new avenues for the development of targeting nanomedicines.

Melatonin regulates proliferation and apoptosis of endometrial stromal cells via MT1.

Endometrial dysfunction is an important factor for implantation failure. The function of the endometrium is regulated by multiple factors like sex hormones and circadian rhythms. Endometrial stromal cells (ESCs) are a major cellular component in the endometrium, which is essential for proper physiological activities of the endometrium and the establishment of pregnancy. Melatonin, as a circadian-controlled hormone, plays beneficial roles in the regulation of reproductive processes. MT1, a melatonin receptor, can regulate cell proliferation and apoptosis. Whether melatonin-MT1 signal affects biological function of ESCs remains unknown. Here, we showed that MT1 was expressed in human ESCs (hESCs), which could be regulated by estrogen and progesterone. MT1 knockdown inhibited proliferative activity and promoted apoptosis of hESCs by activating caspase-3 and upregulating the Bax/Bcl2 ratio. Melatonin could reverse the effect of MT1 knockdown on proliferative activity and apoptosis of hESCs. Melatonin could promote proliferative activity of hESCs via the JNK/P38 signal pathway and repress the apoptosis of hESCs via the JNK signal pathway. Moreover, in vivo experiments showed that MT1 expression was decreased in endometrial cells from mice with disrupted circadian rhythm, accompanied by increased apoptosis and suppressed proliferative activity, which could be alleviated by administration of melatonin. These results showed the regulatory effect of melatonin-MT1 signal on biological behaviors of ESCs, which might provide a novel therapeutic strategy for endometrial dysfunction induced by disrupted circadian rhythm.

Melatonin-MT1 signal is essential for endometrial decidualization.

Deficient decidualization of endometrial stromal cells (ESCs) can cause adverse pregnancy outcomes including miscarriage, intrauterine growth restriction, and pre-eclampsia. Decidualization is regulated by multiple factors such as hormones and circadian genes. Melatonin, a circadian-controlled hormone, is reported to be important for various reproductive processes, including oocyte maturation and placenta development. Its receptor, MT1, is considered to be related to intrauterine growth restriction and pre-eclampsia. However, the role of melatonin-MT1 signal in decidualization remains unknown. Here, we reported that decidual stromal cells from miscarriages displayed deficient decidualization with decreased MT1 expression. The expression level of MT1 is gradually increased with the process of decidualization induction in vitro. MT1 knockdown suppressed the decidualization level, while the overexpression of MT1 promoted the decidualization process. Moreover, changing MT1 level could regulate the expression of decidualization-related transcription factor FOXO1. Melatonin promoted decidualization and reversed the decidualization deficiency due to MT1 knockdown. Using in vitro and in vivo experiments, we further identified that lipopolysaccharide (LPS) could induce inflammation and decidualization resistance with downregulated MT1 expression, and melatonin could reverse the inflammation and decidualization resistance induced by LPS. These results suggested that the melatonin-MT1 signal might be essential for decidualization and might provide a novel therapeutic target for decidualization deficiency-associated pregnancy complications.

Self-Adjuvant Effect by Manipulating the Bionano Interface of Liposome-Based Nanovaccines.

Nanovaccines are of increasing scrutiny due to their plasticity in size, composition, and surface properties to enhance antigenicity. However, inevitable absorption of plasma proteins affects the in vivo fate of nanovaccines by reshaping biological identity. Herein IgM was validated as a self-adjuvant by regulating antigen-presenting cells recognition of liposome-based nanovaccines. DCDX-modified liposomes with loading of ovalbumin (DCDX-sLip/OVA) heavily absorbed IgM via electrostatic interaction, demonstrating significant splenic B cells targeting. IgM absorbed on DCDX-sLip/OVA enhanced antigen uptake and presentation by both IgM-complement and IgM-FcµR pathways. DCDX-sLip/OVA induced a stronger IgG1 titer than ovalbumin-loaded plain liposomes (sLip/OVA) while maintaining a comparably high level of IgG2a titer with high biosafety, indicating that IgM absorption after DCDX modification could improve the antigenicity by enhancing the Th2-polarized immune response. The present work suggested manipulation of IgM absorption may provide a new impetus to improve in vivo performance of nanovaccines.

TORC2/3-mediated DUSP1 upregulation is essential for human decidualization.

Decidualization is the functional transformation process of endometrium in response to ovarian steroids dedicated to support embryo development. Defective decidualization is closely associated with various pregnancy complications such as recurrent miscarriage (RM). Dual specificity MAPK phosphatases (MKPs) are a family of phosphatases specifically regulating mitogen-activated protein kinase (MAPK) signaling with dual specificity for threonine and tyrosine. Here, using RNA-seq,we found that dual specificity phosphatase 1 (DUSP1) expression was prominently elevated among the MKP family members in db-cAMP treated primary human endometrial stromal cells (ESCs). We verified that its induction by db-cAMP in ESCs was in a dose- and time-dependent manner and that primary human decidual stromal cells (DSCs) present higher expression of DUSP1 than ESCs. A protein kinase A (PKA) inhibitor H-89 abolished its induction in ESCs, but not ESI-09, an EPAC1/2 inhibitor. Knock-down of TORC2/3 but not CREB by siRNA in ESCs diminished its induction by db-cAMP. Furthermore, knock-down of DUSP1, as well as TORC2/3 by siRNA caused abnormal activation of JNK during db-cAMP induction in ESCs, accompanied by decreased IGFBP1 expression, an ESC decidualization indicator, which could be fully rescued by a JNK inhibitor SP600125. In addition, Western blot showed that DUSP1 expression was reduced in the DSCs of patients with RM, along with JNK overactivation and decreased IGFBP1 expression. In conclusion, our results demonstrated that TORC2/3-mediated DUSP1 upregulation in response to the cAMP/PKA signaling safeguards IGFBP1 expression via restraining JNK activity, indicating its involvement in ESC decidualization, and that aberrant expression of DUSP1 in DSCs might engage in the pathogenesis of RM.

Brain-targeted drug delivery by manipulating protein corona functions.

Protein corona presents a major obstacle to bench-to-bedside translation of targeted drug delivery systems, severely affecting targeting yields and directing unfavorable biodistribution. Corona-mediated targeting provides a new impetus for specific drug delivery by precisely manipulating interaction modes of functional plasma proteins on nano-surface. Here bio-inspired liposomes (SP-sLip) were developed by modifying liposomal surface with a short nontoxic peptide derived from Aß1-42 that specifically interacts with the lipid-binding domain of exchangeable apolipoproteins. SP-sLip absorb plasma apolipoproteins A1, E and J, consequently exposing receptor-binding domain of apolipoproteins to achieve brain-targeted delivery. Doxorubicin loaded SP-sLip (SP-sLip/DOX) show significant enhancement of brain distribution and anti-brain cancer effect in comparison to doxorubicin loaded plain liposomes. SP-sLip preserve functions of the absorbed human plasma ApoE, and the corona-mediated targeting strategy works in SP modified PLGA nanoparticles. The present study may pave a new avenue to facilitate clinical translation of targeted drug delivery systems.

Peptide ligand-mediated targeted drug delivery of nanomedicines.

Targeted drug delivery is emerging as a promising strategy to achieve better clinical outcomes. Actively targeted drug delivery that utilizes overexpressed receptors or antigens on diseased tissues is receiving increasing scrutiny, especially due to the uncertainty of existence of the enhanced permeability and retention (EPR) effect in cancer patients. Peptide ligands are advantageous over other classes of targeting ligands due to their accessibility of high-throughput screening, ease of synthesis, high specificity and affinity, etc. In this review, we briefly summarize the resources of peptide ligands and discuss the pitfalls and perspectives of peptide ligand-mediated targeted delivery of nanomedicines.

Short Peptide-Mediated Brain-Targeted Drug Delivery with Enhanced Immunocompatibility.

Peptide ligands have been exploited as versatile tools to facilitate targeted delivery of nanocarriers. However, the effects of peptide ligands on immunocompatibility and therapeutic efficacy of liposomes remain intricate. Here, a short and stable brain targeted peptide ligand D8 was modified on the surface of doxorubicin-loaded liposomes (D8-sLip/DOX), demonstrating prolonged blood circulation and lower liver distribution in comparison to the long and stable D-peptide ligand DCDX-modified doxorubicin-loaded liposomes (DCDX-sLip/DOX) by mitigating natural IgM absorption. Despite the improved pharmacokinetic profiles, D8-sLip/DOX exhibited comparable brain targeting capacity in ICR mice and antiglioblastoma efficacy to DCDX-sLip/DOX in nude mice bearing intracranial glioblastoma. However, dramatic accumulation of DCDX-sLip/DOX in liver (especially during the first 8 h after intravenous injection) resulted in pathological symptoms, including nuclei swelling, necrosis of liver cells, and inflammation. These results suggest that short peptide ligand-mediated brain-targeted drug delivery systems possessing enhanced immunocompatibility are promising to facilitate efficient brain transport with improved biosafety.

Enhanced immunocompatibility of ligand-targeted liposomes by attenuating natural IgM absorption.

Targeting ligands are anticipated to facilitate the precise delivery of therapeutic agents to diseased tissues; however, they may also severely affect the interaction of nanocarriers with plasma proteins. Here, we study the immunocompatibility of brain-targeted liposomes, which inversely correlates with absorbed natural IgM. Modification of long, stable positively charged peptide ligands on liposomes is inclined to absorb natural IgM, leading to rapid clearance and enhanced immunogenicity. Small peptidomimetic D8 developed by computer-aided peptide design exhibits improved immunocompatibility by attenuating natural IgM absorption. The present study highlights the effects of peptide ligands on the formed protein corona and in vivo fate of liposomes. Stable positively charged peptide ligands play double-edged roles in targeted delivery, preserving in vivo bioactivities for binding receptors and long-term unfavorable interactions with the innate immune system. The development of D8 provides insights into how to rationally design immunocompatible drug delivery systems by modulating the protein corona composition.