Biomaterial-Driven Immunomodulation: Cell Biology-Based Strategies to Mitigate Severe Inflammation and Sepsis

An integrative model with HLA-DR, CD64, and PD-1 for the diagnostic and prognostic evaluation of sepsis

BACKGROUND

Sepsis is a life-threatening organ dysfunction caused by a dysregulated host response to infection and progressive immunosuppression with high mortality. HLA-DR, CD64, and PD-1 were assumed to be useful biomarkers for sepsis prediction. However, the ability of a combination of these biomarkers has not been clarified.

METHODS

An observational case-control study was conducted that included 30 sepsis patients, 30 critically ill patients without sepsis admitted to the intensive care unit (ICU), and 32 healthy individuals. The levels of HLA-DR, CD64, and PD-1 expression in peripheral blood immune cells and subsets was assayed on Days 1, 3, and 5, and the clinical information of patients was collected. We compared these biomarkers between groups and evaluated the predictive validity of single and combined biomarkers on sepsis mortality.

RESULTS

The results indicate that PD-1 expression on CD4- CD8- T (PD-1+ CD4- CD8- T) (19.19% ± 10.78% vs. 9.88% ± 1.79%, p = .004) cells and neutrophil CD64 index (nCD64 index) (9.15 ± 5.46 vs. 5.33 ± 2.34, p = .001) of sepsis patients were significantly increased, and HLA-DR expression on monocytes (mHLA-DR+ ) was significantly reduced (13.26% ± 8.06% vs. 30.17% ± 21.42%, p = 2.54 × 10-4 ) compared with nonsepsis critically ill patients on the first day. Importantly, the expression of PD-1+ CD4- CD8- T (OR = 0.622, 95% CI = 0.423-0.916, p = .016) and mHLA-DR+ (OR = 1.146, 95% CI = 1.014-1.295, p = .029) were significantly associated with sepsis mortality. For sepsis diagnosis, the mHLA-DR+ , PD-1+ CD4- CD8- T, and nCD64 index showed the moderate individual performance, and combinations of the three biomarkers achieved greater diagnostic value (AUC = 0.899, 95% CI = 0.792-0.962). When adding PCT into the combined model, the AUC increased to 0.936 (95% CI = 0.840-0.983). For sepsis mortality, combinations of PD-1+ CD4- CD8- T and mHLA-DR+ , have a good ability to predict the prognosis of sepsis patients, with an AUC = 0.921 (95% CI = 0.762-0.987).

CONCLUSION

These findings indicate that the combinations of HLA-DR, CD64, and PD-1 outperformed each of the single indicator in diagnosis and predicting prognosis of sepsis.

Development of protein-polymer conjugate nanoparticles for modulation of dendritic cell phenotype and antigen-specific CD4 T cell responses

Polymeric nanoparticles (NPs) comprised of poly(lactic-co-glycolic acid) (PLGA) have found success in modulating antigen (Ag)-specific T cell responses for the treatment multiple immunological diseases. Common methods by which Ags are associated with NPs are through encapsulation and surface conjugation; however, these methods suffer from several limitations, including uncontrolled Ag loading, burst release, and potential immune recognition. To overcome these limitations and study the relationship between NP design parameters and modulation of innate and Ag-specific adaptive immune cell responses, we developed ovalbumin (OVA) protein-PLGA bioconjugate NPs (acNP-OVA). OVA was first modified by conjugation with multiple PLGA polymers to synthesize OVA-PLGA conjugates, followed by precise combination with unmodified PLGA to form acNP-OVA with well-defined Ag loadings, reduced burst release, and reduced antibody recognition. Expression of MHC II, CD80, and CD86 on bone marrow-derived dendritic cells (BMDCs) increased as a function of acNP-OVA Ag loading. NanoString studies using BMDCs showed that PLGA NPs generally induced anti-inflammatory gene expression profiles independent of the Ag delivery method, where S100a9, Sell, and Ppbp were most significantly reduced. Co-culture studies using acNP-OVA-treated BMDCs and OT-II CD4+ T cells revealed that Ag-specific T cell activation, expansion, and differentiation were dependent on Ag loading and formulation parameters. CD25 expression was induced using acNP-OVA with the lowest Ag loading; however, the induction of robust CD4+ T cell proliferative and cytokine responses required acNP-OVA formulations with higher Ag loading, which was supported using a regulatory T cell (Treg) induction assay. The distinct differences in Ag loading required to achieve various T cell responses supported the concept of an Ag loading threshold for Ag-specific immunotherapy. We anticipate this work will help guide NP designs and aid in the future development of NP-based immunotherapies for Ag-specific immunomodulation.

Membrane-camouflaged biomimetic nanoparticles as potential immunomodulatory solutions for sepsis: An overview

Sepsis is a life-threatening organ dysfunction due to dysregulated host responses induced by infection. The presence of immune disturbance is key to the onset and development of sepsis but has remarkably limited therapeutic options. Advances in biomedical nanotechnology have provided innovative approaches to rebalancing the host immunity. In particular, the technique of membrane-coating has demonstrated remarkable improvements to therapeutic nanoparticles (NPs) in terms of tolerance and stability while also improving their biomimetic performance for immunomodulatory purposes. This development has led to the emergence of using cell-membrane-based biomimetic NPs in treating sepsis-associated immunologic derangements. In this minireview, we present an overview of the recent advances in membrane-camouflaged biomimetic NPs, highlighting their multifaceted immunomodulatory effects in sepsis such as anti-infection, vaccination, inflammation control, reversing of immunosuppression, and targeted delivery of immunomodulatory agents.

Modulating neuroinflammation through molecular, cellular and biomaterial-based approaches to treat spinal cord injury

The neuroinflammatory response that is elicited after spinal cord injury contributes to both tissue damage and reparative processes. The complex and dynamic cellular and molecular changes within the spinal cord microenvironment result in a functional imbalance of immune cells and their modulatory factors. To facilitate wound healing and repair, it is necessary to manipulate the immunological pathways during neuroinflammation to achieve successful therapeutic interventions. In this review, recent advancements and fresh perspectives on the consequences of neuroinflammation after SCI and modulation of the inflammatory responses through the use of molecular-, cellular-, and biomaterial-based therapies to promote tissue regeneration and functional recovery will be discussed.

Heparin/Collagen-REDV Modification of Expanded Polytetrafluoroethylene Improves Regional Anti-thrombosis and Reduces Foreign Body Reactions in Local Tissues

Prosthetic implants of expanded polytetrafluoroethylene (ePTFE) in the cardiovascular system have a high failure rate over the long term because of thrombosis and intimal hyperplasia. Although multiple surface modification methods have been applied to improve the anti-thrombotic and in situ endothelialization abilities of ePTFE, none have delivered outstanding results in vivo. Our previous study combined heparin/collagen multilayers and REDV peptides to modify ePTFE, and the in-vitro results showed that modification ePTFE with heparin/collagen-REDV can promote the cytocompatibility and antiplatelet property. This study illustrated the physical change, selective endothelial cells capture ability, and in vivo performance in further. The physical test demonstrated that this modification improved the hydrophilicity, flexibility and strength of ePTFE. A competition experiment of co-cultured endothelial cells and vascular smooth muscle cells verified that the heparin/collagen-REDV modification had high specificity for endothelial cell capture. A rabbit animal model was constructed to evaluate the in vivo performance of modified ePTFE implanted in the right ventricular outflow tract. The results showed that heparin/collagen-REDV modification was safe, promoted endothelialization, and successfully achieved regional anti-thrombosis without influencing body-wide coagulation function. The pathologic manifestations and mRNA expression pattern in tissues in contact with modified ePTFE indicated that this modification method may reduce M2-type macrophage infiltration and the expression of genes related to immune and inflammatory responses. The heparin/collagen-REDV modification may lower the incidence of complications related to ePTFE implantation and has good prospects for clinical use.

Hibiscus, Rooibos, and Yerba Mate for Healthy Aging: A Review on the Attenuation of In Vitro and In Vivo Markers Related to Oxidative Stress, Glycoxidation, and Neurodegeneration

The world is currently undergoing a demographic change towards an increasing number of elderly citizens. Aging is characterized by a temporal decline in physiological capacity, and oxidative stress is a hallmark of aging and age-related disorders. Such an oxidative state is linked to a decrease in the effective mechanisms of cellular repair, the incidence of post-translational protein glycation, mitochondrial dysfunction, and neurodegeneration, just to name some of the markers contributing to the establishment of age-related reduction-oxidation, or redox, imbalance. Currently, there are no prescribed therapies to control oxidative stress; however, there are strategies to elevate antioxidant defenses and overcome related health challenges based on the adoption of nutritional therapies. It is well known that herbal teas such, as hibiscus, rooibos, and yerba mate, are important sources of antioxidants, able to prevent some oxidation-related stresses. These plants produce several bioactive metabolites, have a pleasant taste, and a long-lasting history as safe foods. This paper reviews the literature on hibiscus, rooibos, and yerba mate teas in the context of nutritional strategies for the attenuation of oxidative stress-related glycoxidation and neurodegeneration, and, here, Alzheimer’s Disease is approached as an example. The focus is given to mechanisms of glycation inhibition, as well as neuroprotective in vitro effects, and, in animal studies, to frame interest in these plants as nutraceutical agents related to current health concerns.

Interactions Between Immunomodulatory Biomaterials and Immune Microenvironment: Cues for Immunomodulation Strategies in Tissue Repair

The foreign body response (FBR) caused by biomaterials can essentially be understood as the interaction between the immune microenvironment and biomaterials, which has severely impeded the application of biomaterials in tissue repair. This concrete interaction occurs via cells and bioactive substances, such as proteins and nucleic acids. These cellular and molecular interactions provide important cues for determining which element to incorporate into immunomodulatory biomaterials (IMBs), and IMBs can thus be endowed with the ability to modulate the FBR and repair damaged tissue. In terms of cellular, IMBs are modified to modulate functions of immune cells, such as macrophages and mast cells. In terms of bioactive substances, proteins and nucleic acids are delivered to influence the immune microenvironment. Meanwhile, IMBs are designed with high affinity for spatial targets and the ability to self-adapt over time, which allows for more efficient and intelligent tissue repair. Hence, IMB may achieve the perfect functional integration in the host, representing a breakthrough in tissue repair and regeneration medicine.

Pathogen infection-responsive nanoplatform targeting macrophage endoplasmic reticulum for treating life-threatening systemic infection

Systemic infections caused by life-threatening pathogens represent one of the main factors leading to clinical death. In this study, we developed a pathogen infection-responsive and macrophage endoplasmic reticulum-targeting nanoplatform to alleviate systemic infections. The nanoplatform is composed of large-pore mesoporous silica nanoparticles (MSNs) grafted by an endoplasmic reticulum-targeting peptide, and a pathogen infection-responsive cap containing the reactive oxygen species-cleavable boronobenzyl acid linker and bovine serum albumin. The capped MSNs exhibited the capacity to high-efficiently load the antimicrobial peptide melittin, and to rapidly release the cargo triggered by H₂O₂ or the pathogen-macrophage interaction system, but had no obvious toxicity to macrophages. During the interaction with pathogenic Candida albicans cells and macrophages, the melittin-loading nanoplatform MSNE+MEL+TPB strongly inhibited pathogen growth, survived macrophages, and suppressed endoplasmic reticulum stress together with pro-inflammatory cytokine secretion. In a systemic infection model, the nanoplatform efficiently prevented kidney dysfunction, alleviated inflammatory symptoms, and protected the mice from death. This study developed a macrophage organelle-targeting nanoplatform for treatment of life-threatening systemic infections.

ELECTRONIC SUPPLEMENTARY MATERIAL

Supplementary material (N₂ adsorption curves of the initial synthesized MSNs, FT-IR spectra of MSN, and MSNE, MEL release from the FITC-MEL-loading MSNE + TPB induced by different concentration of H₂O₂, viability of NIH3T3 cells, and DC2.4 cells after treatment of free MEL or the used nanoparticles, effect of MEL on C. albicans growth and macrophage death during the interaction between C. albicans and macrophages, effect of MEL and the nanoparticles on S. aureus growth and macrophage death during the interaction between S. aureus and macrophages, quantification of GRP78 (a) and activated Caspase-3, flow cytometry analysis of kidney non-macrophages with the Alexa Fluor 594 signal, survival curve of the infected mice treated by MEL or MSNE + MEL, kidney burden, blood urea levels and serum TNF-α levels in the infected mice) is available in the online version of this article at 10.1007/s12274-022-4211-z.

Immunomodulatory Nanoparticles Mitigate Macrophage Inflammation via Inhibition of PAMP Interactions and Lactate-Mediated Functional Reprogramming of NF-κB and p38 MAPK

Inflammation is a key homeostatic process involved in the body's response to a multitude of disease states including infection, autoimmune disorders, cancer, and other chronic conditions. When the initiating event is poorly controlled, severe inflammation and globally dysregulated immune responses can occur. To address the lack of therapies that efficaciously address the multiple aspects of the dysregulated immune response, we developed cargo-less immunomodulatory nanoparticles (iNPs) comprised of poly(lactic acid) (PLA) with either poly(vinyl alcohol) (PVA) or poly(ethylene-alt-maleic acid) (PEMA) as stabilizing surfactants and investigated the mechanisms by which they exert their inherent anti-inflammatory effects. We identified that iNPs leverage a multimodal mechanism of action by physically interfering with the interactions between pathogen-associated molecular patterns (PAMPs) and bone marrow-derived macrophages (BMMΦs). Additionally, we showed that iNPs mitigate proinflammatory cytokine secretions induced by LPS via a time- and composition-dependent abrogation of NF-κB p65 and p38 MAPK activation. Lastly, inhibition studies were performed to establish the role of a pH-sensing G-protein-coupled receptor, GPR68, on contributing to the activity of iNPs. These data provide evidence for the multimodal mechanism of action of iNPs and establish their potential use as a novel therapeutic for the treatment of severe inflammation.

Targeting the Oxytocinergic System: A Possible Pharmacological Strategy for the Treatment of Inflammation Occurring in Different Chronic Diseases

Unresolved inflammation represents a central feature of different human pathologies including neuropsychiatric, cardiovascular, and metabolic diseases. The epidemiologic relevance of such disorders justifies the increasing interest in further understanding the mechanisms underpinning the inflammatory process occurring in such chronic diseases to provide potential novel pharmacological approaches. The most common and effective therapies for controlling inflammation are glucocorticoids; however, a variety of other molecules have been demonstrated to have an anti-inflammatory potential, including neuropeptides. In recent years, the oxytocinergic system has seen an explosion of scientific studies, demonstrating its potential to contribute to a variety of physiological processes including inflammation. Therefore, the aim of the present review was to understand the role of oxytocin in the modulation of inflammation occurring in different chronic diseases. The criterion we used to select the diseases was based on the emerging literature showing a putative involvement of the oxytocinergic system in inflammatory processes in a variety of pathologies including neurological, gastrointestinal and cardiovascular disorders, diabetes and obesity. The evidence reviewed here supports a beneficial role of oxytocin in the control of both peripheral and central inflammatory response happening in the aforementioned pathologies. Although future studies are necessary to elucidate the mechanistic details underlying such regulation, this review supports the idea that the modulation of the endogenous oxytocinergic system might represent a new potential pharmacological approach for the treatment of inflammation.

Modulating Mechanical and Shape-Memory Properties while Mitigating Degradation-Induced Inflammation of Polylactides by Pendant Aspirin Incorporation

Synergistically modulating mechanical properties and improving shape-memory performance while mitigating degradation-induced chronic inflammation of polylactide (PLA)-based implants for biomedical applications remain elusive. We test the hypothesis that copolymerizing aspirin-functionalized glycolide with d,l-lactide could enhance the thermal processing, toughness, and shape-memory efficiency of the copolymer while mitigating local inflammatory responses upon its degradation. The content of pendant aspirin was readily modulated by monomer feeds during ring-opening polymerization, and the copolymers with ∼10% or less aspirin pendants exhibited gigapascal-tensile moduli at body temperature and significantly improved fracture toughness and energy dissipation that positively correlated with the aspirin pendant content. The copolymers also exhibited excellent thermal-healing and shape-memory efficacy, achieving a >97% temporary shape fixing ratio at room temperature and facile shape recovery at 50-65 °C. These drastic improvements were attributed to the dynamic hydrophobic aggregations among aspirin pendants that strengthen glassy-state physical entanglement of PLA while readily dissociating under stress/thermal activation. When subcutaneously implanted, the copolymers mitigated degradation-induced inflammation due to concomitant hydrolytic release of aspirin without suppressing early acute inflammatory responses. The incorporation of aspirin pendants in PLA represents a straightforward and innovative strategy to enhance the toughness, shape-memory performance, and in vivo safety of this important class of thermoplastics for biomedical applications.

Nanoparticle-Based Delivery to Treat Spinal Cord Injury-a Mini-review

There is an increasing need to develop improved and non-invasive strategies to treat spinal cord injury (SCI). Nanoparticles (NPs) are an enabling technology to improve drug delivery, modulate inflammatory responses, and restore functional responses following SCI. However, the complex pathophysiology associated with SCI presents several distinct challenges that must be overcome for sufficient NP drug delivery to the spinal cord. The objective of this mini-review is to highlight the physiological challenges and cell types available for modulation and discuss several promising advancements using NPs to improve SCI treatment. We will focus our discussion on recent innovative approaches in NP drug delivery and how the implementation of multifactorial approaches to address the proinflammatory and complex immune dysfunction in SCI offers significant potential to improve outcomes in SCI.

In Vivo Modulation of Angiogenesis and Immune Response on a Collagen Matrix via Extracorporeal Shockwaves

The effective management of tissue integration and immunological responses to transplants decisively co-determines the success of soft and hard tissue reconstruction. The aim of this in vivo study was to evaluate the eligibility of extracorporeal shock wave therapy (ESWT) with respect to its ability to modulate angiogenesis and immune response to a collagen matrix (CM) for tissue engineering in the chorioallantoic membrane (CAM) assay, which is performed with fertilized chicken eggs. CM were placed on the CAM on embryonic development day (EDD) 7; at EDD-10, ESWT was conducted at 0.12 mJ/mm² with 500 impulses each. One and four days later, angiogenesis represented by vascularized area, vessel density, and vessel junctions as well as HIF-1α and VEGF gene expression were evaluated. Furthermore, immune response (iNOS2, MMP-9, and MMP-13 via qPCR) was assessed and compared between ESWT- and non-ESWT-groups. At EDD-14, the vascularized area (+115% vs. +26%) and the increase in vessel junctions (+751% vs. +363%) were significantly higher in the ESWT-group. ESWT significantly increased MMP-9 gene expression at EDD-11 and significantly decreased MMP-13 gene expression at EDD-14 as compared to the controls. Using the CAM assay, an enhanced angiogenesis and neovascularization in CM after ESWT were observed. Furthermore, ESWT could reduce the inflammatory activity after a latency of four days.