Phagocytic Efficiency Research Articles

Neonatal Mouse Bone Marrow Isolation and Preparation of Bone Marrow-Derived Macrophages.

Various techniques for isolating bone marrow from adult mice have been well established. However, isolating bone marrow from neonatal mice is challenging and time-consuming, yet for some models, it is translationally relevant and necessary. This protocol describes an efficient and straightforward method for preparing bone marrow cells from 7-9-day-old pups. These cells can then be further isolated or differentiated into specific cell types of interest. Macrophages are crucial immune cells that play a major role in inflammation and infection. During development, neonatal macrophages contribute significantly to tissue remodeling. Moreover, the phenotype and functions of neonatal macrophages differ from those of their adult counterparts. This protocol also outlines the differentiation of neonatal macrophages from the isolated bone marrow cells in the presence of L929-conditioned medium. Surface markers for differentiated neonatal macrophages were assessed using flow cytometric analysis. To demonstrate functionality, the phagocytic efficiency was also tested using pH-sensitive dye-conjugated Escherichia coli.

Macrophage membrane-coated Eucommia ulmoides polysaccharides-loaded PLGA nanoparticles as an effective antigen-targeted delivery system

Polysaccharides derived from Eucommia ulmoides leaves have immune-regulating, hypoglycemic, anti-tumor, and other beneficial functions. As a drug delivery system, polylactic-glycolic acid copolymer (PLGA) offers advantages like immunogenicity enhancement, improved drug absorption, and increased drug bioavailability. Currently, macrophage membranes are successfully employed in biomimetic nanomaterials to enhance drug utilization and extend drug administration time in the body, exhibiting good immunogenicity and organ targeting. In this study, we developed biomimetic PsEUL PLGA nanoparticles (NPs) coated with macrophage membrane (MM-PPsEUL) and examined their immune activity in vitro and in vivo. In vitro, MM-PPsEUL increased the phagocytic efficiency of macrophages without affecting their activity. In vivo, MM-PPsEUL significantly elevated the immune organ index of mice and upregulated the level of ovalbumin-specific IgG antibodies in serum. Simultaneously, it increased the expressions of cytokines IFN-γ and IL-4, as well as the levels of TLR4, MyD88, TRAF6, and NF-κB p65 proteins in mice spleen. MM-PPsEUL also exhibited a targeting effect on inguinal lymph nodes and slowed down the release rate of antigens, thereby inducing a prolonged immune response. In summary, MM-PPsEUL provides sustained release capabilities and can induce both humoral and cellular immune responses. This makes MM-PPsEUL NPs a promising antigen-targeted delivery system.

Measuring Macrophage Phagocytic Efficiency with Primaquine and Photodynamic Therapy

Measuring Macrophage Phagocytic Efficiency with Primaquine and Photodynamic Therapy

Measuring Macrophage Phagocytic Efficiency with Primaquine and Photodynamic Therapy

Measuring Macrophage Phagocytic Efficiency with Primaquine and Photodynamic Therapy

Antibody surface mobility amplifies FcγR signaling via Arp2/3 during phagocytosis

We report herein that the anti-CD20 therapeutic antibody, rituximab, is rearranged into microclusters within the phagocytic synapse by macrophage Fcγ receptors (FcγR) during antibody-dependent cellular phagocytosis. These microclusters were observed to potently recruit Syk and to undergo rearrangements that were limited by the cytoskeleton of the target cell, with depolymerization of target-cell actin filaments leading to modest increases in phagocytic efficiency. Total internal reflection fluorescence analysis revealed that FcγR total phosphorylation, Syk phosphorylation, and Syk recruitment were enhanced when IgG-FcγR microclustering was enabled on fluid bilayers relative to immobile bilayers in a process that required Arp2/3. We conclude that on fluid surfaces, IgG-FcγR microclustering promotes signaling through Syk that is amplified by Arp2/3-driven actin rearrangements. Thus, the surface mobility of antigens bound by IgG shapes the signaling of FcγR with an unrecognized complexity beyond the zipper and trigger models of phagocytosis.

Sitagliptin, an anti‐diabetic drug, inhibits the pro‐inflammatory microglia reactivity via dipeptidyl peptidase‐4 (DPP4)

Aims/Purpose: Diabetic retinopathy is characterized by a chronic low‐grade retinal neuroinflammation triggered by diabetes and mediated, at least in part, by microglial cells. We previously showed that sitagliptin, an oral drug for type 2 diabetes, developed to inhibit dipeptidyl peptidase 4 (DPP4) and increase insulin release, can prevent retinal neuroinflammation in diabetic rat models and the LPS‐induced morphological changes of microglial cells in retinal organotypic cultures. However, the mechanisms underlying these effects are not clarified. We hypothesize that sitagliptin is able to directly inhibit microglia reactivity via Dpp4.Methods: BV‐2 microglia cell line was exposed to a non‐toxic dose of lipopolysaccharide (LPS, 0.1 μg/mL) in the presence or absence of 200 μM sitagliptin. The expression of Dpp4, iNOS, IL‐1 beta and TNF were assessed by Western Blot and/or RT‐qPCR. The BV‐2 phagocytic efficiency was assessed using fluorescent microbeads. The metabolic activity and proliferation of BV‐2 cells were assessed by resazurin assay and Edu staining, respectively. Dpp4 deletion in BV‐2 cells was generated using Crispr‐cas9 method.Results: Sitagliptin inhibited the LPS‐induced increase in protein levels of iNOS, IL‐1 beta and TNF to 39.9 ± 6.3%, 47.2 ± 8.1% and 34.0 ± 7.2%, respectively, comparing to LPS. Sitagliptin reduced the LPS‐induced increase in phagocytic efficiency by approximately 40%. Sitagliptin did not affect the metabolism and proliferation of BV‐2. BV‐2 cells express Dpp4. Dpp4 deletion does not affect the LPS‐induced phagocytosis but abrogated the effect of sitagliptin on the reduction of BV‐2 phagocytic efficiency (approx. 320% as in LPS).Conclusions: Sitagliptin exerts direct anti‐inflammatory effects on microglia, mediated by DPP4. These results suggest that sitagliptin can potentially be used in retinal pathologies characterized by microglia‐mediated neuroinflammation.Support.FCT‐Portugal: PEst UID/NEU/04539/2013, UIDB/04539/2020 and UIDP/04539/2020 and PTDC/NEU‐OSD/1113/2012. COMPETE‐FEDER.

Ehrlichia chaffeensis Co-Opts Phagocytic Hemocytes for Systemic Dissemination in the Lone Star Tick, Amblyomma americanum

Introduction: Hematophagous arthropods can acquire and transmit several pathogens of medical importance. In ticks, the innate immune system is crucial in the outcome between vector-pathogen interaction and overall vector competence. However, the specific immune response(s) elicited by the immune cells known as hemocytes remains largely undefined in Ehrlichia chaffeensis and its competent tick vector, Amblyomma americanum. Methods: We utilized injection of clodronate liposome to deplete tick granulocytes combined with infection with E. chaffeensis to demonstrate their essential role in microbial infection. Results: Here, we show that granulocytes, professional phagocytic cells, are integral in eliciting immune responses against commensal and pathogen infection. The chemical depletion of granulocytes led to decreased phagocytic efficiency of tissue-associated hemocytes. We demonstrate that E. chaffeensis can infect circulating hemocytes, and both cell-free plasma and hemocytes from E. chaffeensis-infected ticks can establish Ehrlichia infection in recipient ticks. Lastly, we provide evidence to show that granulocytes play a dual role in E. chaffeensis infection. Depleting granulocytic hemocytes increased Ehrlichia load in the salivary gland and midgut tissues. In contrast, granulocyte depletion led to a reduced systemic load of Ehrlichia. Conclusion: This study has identified multiple roles for granulocytic hemocytes in the control and systemic dissemination of E. chaffeensis infection.

Dietary administration of mangosteen, Garcinia mangostana, peel extract enhances the growth, and physiological and immunoendocrinological regulation of prawn, Macrobrachiumrosenbergii.

In this study, we investigated the potential immunostimulatory effects of mangosteen (Garcinia mangostana) peel extract on Macrobrachium rosenbergii, specifically in enhancing immunity and resistance against Lactococcus garvieae. We employed a dietary administration approach to assess the impact of different extract preparations from mangosteen peel, namely mangosteen peel powder (MPP), boiled mangosteen peel powder (MPB), and mangosteen peel extract (MPE). Following the administration of mangosteen peel extract, we evaluated growth performance, innate immune parameters, and disease resistance in the prawns. The results revealed a significant increase in total haemocyte count (THC), differential haemocyte count (DHC), phenoloxidase (PO) activity, respiratory bursts (RBs), as well as phagocytic activity and clearance efficiency against L. garvieae. Based on these findings, we suggest that mangosteen peel extract can be utilized as an immunostimulant for prawns through dietary administration, regulating immune responses and enhancing resistance against pathogens by modulating carbohydrate metabolism.

Primaquine, an antimalarial drug that controls the growth of cryptococcal cells.

The treatment of Cryptococcus neoformans with fluconazole and amphotericin B is, at times, characterised by clinical failure. Therefore, this study sought to re-purpose primaquine (PQ) as an anti-Cryptococcus compound. The susceptibility profile of some cryptococcal strains towards PQ was determined using EUCAST guidelines, and PQ's mode of action was examined. In the end, the ability of PQ to enhance in vitro macrophage phagocytosis was also assessed. We show that PQ had a significant inhibitory effect on the metabolic activity of all tested cryptococcal strains, with 60µM, defined as MIC50 in this preliminary study, as it reduced the metabolic activity by more than 50%. Moreover, at this concentration, the drug was able to affect mitochondrial function adversely, as treated cells displayed significant (p<0.05) loss of mitochondrial membrane potential, cytochrome c (cyt c) leakage and overproduction of reactive oxygen species (ROS) when compared to non-treated cells. It is our reasoned summation that the produced ROS targeted the cell walls and cell membranes, inducing observable ultrastructural changes and a significant (p<0.05) increase in membrane permeability when compared to non-treated cells. Concerning the PQ effect on macrophages, it was noted that it significantly (p<0.05) enhanced macrophage phagocytic efficiency compared to non-treated macrophages. This preliminary study highlights the potential of PQ to inhibit the in vitro growth of cryptococcal cells. Moreover, PQ could control the proliferation of cryptococcal cells inside macrophages, which they often manipulate in a Trojan horse-like manner.

Ultrasonic Treatment Enhances the Antioxidant and Immune-Stimulatory Properties of the Polysaccharide from Sinopodophyllum hexandrum Fruit.

We aimed to assess the potential of ultrasonic treatment on the processing of polysaccharides as functional foods or food additives. The polysaccharide from Sinopodophyllum hexandrum fruit (SHP, 52.46 kDa, 1.91 nm) was isolated and purified. SHP was treated with various levels of ultrasound (250 W and 500 W), resulting in the formation of two polysaccharides, SHP1 (29.37 kD, 1.40 nm) and SHP2 (36.91 kDa, 0.987 nm). Ultrasonic treatment was found to reduce the surface roughness and molecular weight of the polysaccharides, leading to thinning and fracturing. The effect of ultrasonic treatment on polysaccharide activity was evaluated in vitro and in vivo. In vivo experiments showed that ultrasonic treatment improved the organ index. Simultaneously, it enhanced the activity of superoxide dismutase, total antioxidant capacity, and decreased the content of malondialdehyde in the liver. In vitro experiments demonstrated that ultrasonic treatment also promoted proliferation, nitric oxide secretion, phagocytic efficiency, costimulatory factors (CD80+, CD86+) expression, and cytokine(IL-6, IL-1β) production of RAW264.7 macrophages.

ARE DENDRITIC CELLS A POTENTIAL TOOL FOR MASTITIS VACCINE DEVELOPMENT?

Mastitis is one of the main disease causing big economic losses to dairy farmers. This disease is caused mainly by bacteria. Because of not efficient vaccines, there are necessary to develop new immunotherapy of vaccination strategy to reduce this disease in dairy farms. Dendritic cells are antigen-presenting cells which are able to present antigen to lymphocytes. They are able to induce activation of T naïve lymphocytes. Dendritic cells were used for development of dendritic cell-based anti-tumor vaccines. Development of vaccines against bovine mastitis has many limitations as high number of various pathogens that are able to cause inflammation of mammary gland in cattle; absence of mucus barrier in mammary gland; reduced phagocytic efficiency because of casein and fat globules etc. To this day, it is not available vaccine against bovine mastitis with high efficiency. Development of new immunotherapy or vaccine against mastitis would be very desirable. In this mini review, we are considering possibilities for development of new dendritic cell-based vaccine against bovine mastitis.

The immunostimulatory effects of Theobroma cacao L. pod husk extract via injection and dietary administrations on Macrobrachium rosenbergii and its resistance against Lactococcus garvieae

The extract from Theobroma cacao L, pod husk served as the immunostimulant to enhance the immunity and resistance against Lactococcus garvieae of Macrobrachium rosenbergii. In this study, we employed the injection method and dietary administration method to determine the effect of cocoa pod husk (CPH) on M. rosenbergii. The non-specific immune parameters and disease resistance were evaluated after the prawn injected with 1 μg prawn−1 CPH extract (C1), 3 μg prawn−1 CPH extract (C3), and 5 μg prawn−1 CPH extract (C5) for 1, 3, and 7 days. The results showed a significant increase of total haemocyte count (THC), differential haemocyte count (DHC), phenoloxidase (PO) activity, respiratory bursts (RBs), and phagocytic activity and clearance efficiency to L. garvieae. The non-specific immune parameters, physiological parameters, and disease resistance and growth performance were evaluated after the prawn fed with 1 g kg−1 CPH extract diet (CD1), 3 g kg−1 CPH extract diet (CD3) and 5 g kg−1 CPH extract diet (CD5). The results showed a significant increase in all immune parameters and showed a significant decrease in physiological parameters. No significant difference was observed in growth performance of prawn fed with the CPH containing diet. Both injection and dietary method showed a significant increase in disease resistance against to L. garvieae. We therefore recommend that CPH extract can be used as a immunostimulant for prawn by dietary administration to regulate immune responses, and carbohydrate metabolism lead to enhance resistance against pathogen.

Alcohol impairs recognition and uptake of Mycobacterium tuberculosis by suppressing toll-like receptor 2 expression.

Alcohol impairs pulmonary innate immune function and is associated with an increased risk of tuberculosis (TB). Toll-like receptor 2 (TLR2) is a pattern recognition receptor on alveolar macrophages that recognizes Mycobacterium tuberculosis (Mtb). The expression of TLR2 depends, in part, on granulocyte-macrophage colony-stimulating factor (GM-CSF) signaling. Given our prior work demonstrating the suppression of GM-CSF signaling following chronic alcohol ingestion, we hypothesized that alcohol impairs TLR2 expression via the suppression of GM-CSF and thereby reduces the ability of the macrophage to recognize and phagocytose Mtb. Primary alveolar macrophages were isolated from control-fed and alcohol-fed rats. Prior to cell isolation, some alcohol-fed rats were treated with intranasal GM-CSF and then endotracheally inoculated with an attenuated strain of Mtb. Primary macrophages were then isolated and immunofluorescence was used to determine phagocytic efficiency and TLR2 expression in the presence and absence of GM-CSF treatment and phagocytic efficiency in the presence and absence of TLR2 neutralization. TLR2 expression and phagocytosis of Mtb were significantly lower in the alveolar macrophages of alcohol-fed rats than control-fed rats. In parallel, blocking TLR2 signaling recapitulated this decreased phagocytosis of Mtb. In contrast, intranasal GM-CSF treatment restored TLR2 expression and Mtb phagocytosis in the alveolar macrophages of alcohol-fed rats to levels comparable to those of control-fed rats. Chronic alcohol ingestion reduces TLR2 protein expression and phagocytosis of Mtb, likely due to impaired GM-CSF signaling. GM-CSF restores membrane-bound TLR2 expression and phagocytic function.

The effect of banana blossom on growth performance, immune response, disease resistance, and anti-hypothermal stress of Macrobrachium rosenbergii

Banana (Musa acuminata) blossom contains high nutritional value and bioactive compounds. In this study, Macrobrachium rosenbergii were fed with diets containing banana blossom powder (BBP) at 10 and 20 g kg−1, hot-banana blossom (BBH) extract at 10 and 20 g kg−1, and the basal diet for 56 days. The growth performance, physiological response and immune parameters were evaluated. The results showed that a significantly higher percentage weight gain (PWG) and percentage length gain (PLG) in prawns fed with BBH diet. The feed efficiency (FE) significantly increased in prawns fed BBP. The prawn fed both BBH and BBP diet showed higher survival rate than control group. The prawn fed with BBH showed a significant increase in total haemocyte count (THC) and different haemocyte count (DHC), whereas phenoloxidase (PO) activity and respiratory bursts (RBs) significant increase in prawns fed both BBP and BBH diet. Furthermore, M. rosenbergii fed with both BBP and BBH diets showed significantly higher phagocytic activity and clearance efficiency against Lactococcus garvieae infection. At the end of the 56 days of feeding trial, the susceptibility of prawns to L. garvieae infection and hypothermal (18 °C) stress were evaluated. The results showed that prawns fed BBH diets had a significantly higher survival rate against L. garvieae than those of fed with the basal diet. Anti-hypothermal stress was observed in prawns fed both BBP and BBH diets showing no significant difference in haemolymph glucose in prawns subjected to 18 °C and 28 °C, whereas the norepinephrine level in haemolymph of prawns fed with BBH diets subjected to 18 °C was significantly lower than in prawns subjected to 28 °C. In summary, we recommend addition of hot-banana blossom extract to the diet of M. rosenbergii at 20 g kg−1 to promote growth performance, improve physiological function, enhance immunity, increase anti-hypothermal stress, and to increase resistance against L. gavieae.

Pectin from dry cacao pod husk mediates growth performance, immune resistance responses and carbohydrate metabolism of Litopenaeus vannamei through dietary administration

The sustainable uses of cacao, Theobroma cacao L, pod husk (CPH) produced from cacao bean industry bring environment great benefits. Botanical polysaccharides possessing a variety of physiological functions are therefore referred to as biological response modifiers, and those are also found in CPH. In this study, the weight gain rate (WGR), length gain rate (LGR), feeding efficiency (FE), and survival rate (SR) of shrimp, Litopenaeus vannamei, fed diets containing CPH pectin at 0 (CON), 1.0 (CPH1), 3.0 (CPH3) and 6.0 (CPH6) g/kg were calculated every 7 days within 56 days of feeding. The non-specific immune parameters, disease resistance, tolerance to hypothermal stress and stress indicators were also evaluated after the shrimp fed with CPH pectin containing diets. Shrimp that were fed with CPH3 after 56 days had higher WGR, LGR, and FE than those in CPH0. The SR significantly increased for shrimp challenged with Vibrio alginolyticus, and subjected to hypothermal (14 °C) stress when they were fed diets containing CPH3 and CPH6, and CPH6 after 14 or 28 days of feeding, respectively. Dietary CPH3 and/or CPH6 showed a significant increase of total hemocyte count (THC), differential hemocyte count (DHC), phenoloxidase (PO) activity, respiratory bursts (RBs), and phagocytic activity and clearance efficiency to V. alginolyticus at 14 and/or 28 days. Furthermore, shrimp fed with CPH pectin-contained diets after 14 and 28 days retarded secretion of dopamine (DA) and norepinephrine (NE), and decreased the level of glucose and lactate in plasma under cold stress. We therefore recommend that CPH pectin can be used as a physiomodulator for shrimp by dietary administration at 3.0 g/kg for 56 days to promote growth; and at 3.0–6.0 g/kg within an appropriate time frame (28 days) to regulate neuroendocrine and immune responses, and carbohydrate metabolism lead to enhance resistance against pathogen and hypothermal stress.

Synbiotic combination of prebiotic, cacao pod husk pectin and probiotic, Lactobacillus plantarum, improve the immunocompetence and growth of Litopenaeus vannamei

To reach the sustainable development goals on waste recycling, cacao pod husk (CPH), produced as an agricultural waste byproduct during the cacao bean processing was applied to manufacture CPH pectin for developing the potential for diverse application in aquaculture, minimizing CPH impact to the environment and bringing benefits to the agriculture and aquaculture industries. In this study, CPH pectin (5 g/kg diet) and Lactobacillus plantarum (LP; 1010 cfu/kg diet) were separately introduced to the diets of Litopenaeus vannamei for a 56-day feeding trial, and two synbiotic combinations of CPH pectin and LP (CPH pectin at 5 g/kg diet + LP at 107 cfu/kg diet or at 1010 cfu/kg diet) were also conducted. After the 56-day feeding trial, significantly elevated percent weight gain, percent length gains and feeding efficiency in L. vannamei were only observed in synbiotic combination of CPH pectin at 5 g/kg diet and LP at 107 cfu/kg diet treatment, and the remainder of the treatments remained consistently similar to the control. Significantly increases in total haemocyte count, granular cells, phenoloxidase activity, and respiratory bursts were observed in L. vannamei fed with synbiotics at 7–28 days of feeding, accompanied by significant promotion of phagocytic activity and clearance efficiency in response to V. alginolyticus challenge during 56 days of feeding trial. Furthermore, at the end of the 56 days of feeding trial, shrimp receiving CPH pectin and/or LP treatments showed a significantly higher survival ratio against V. alginolyticus infection and hypothermal stress. It was therefore concluded that CPH pectin or LP was confirmed as an immunostimulant for L. vannamei to trigger immunocompetence through oral administration without negative effects within 56 days of feeding trial, and the synbiotic combination of CPH pectin and LP exhibited complementary and synergistic effects on growth performance and immunocompetence in L. vannamei.

Preparation of Let-7b Nanocomposite and Its Effect on the Level of Inflammatory Factors in Cerebrospinal Fluid of Purulent Meningitis

This study was to explore the effect and mechanism of Let-7b nanocomposite on the expression of inflammatory factors in the cerebrospinal fluid (CSF) of purulent meningitis. 45 patients with purulent meningitis (PM) were selected as observation group (group A), and 38 patients with normal CSF without central nervous system diseases were selected as the control group (group B). The CSF of the two groups were collected to detect the inflammatory factors interleukin-8 (IL-8), macrophage inflammatory protein-1α (MIP-1α), matrix metalloproteinase 9 (MMP9), interleukin 1β (IL-1β), tumor necrosis factor-α (TNF-α), and Let-7b level with the double antibody sandwich enzyme-linked immunosorbent assay (ELISA). The Let-7b nanocomposite was prepared, and its morphology, particle size, and Zeta potential were analyzed. In addition, the degradation kinetics, cytotoxicity, and phagocytic efficiency (PE) of Let-7b nanocapsules were detected. 36 healthy adult New Zealand (NZL) rabbits were randomly grouped into a control group (group C) (0.9% normal saline (NS)), a model group (Escherichia coli (E. coli) modeling, group D), and a test group (E. coli modeling + Let-7b nanocapsules, group E), with 12 rabbits in each group. The changes of inflammatory factors in CSF of the three groups were detected and compared. It was found that the expression levels of IL-8 and IL-1 β in the group A were much higher than those in the group B (P &lt; 0.01), and the MMP9 and TNF-α levels in the group B were much lower in contrast to the group A (P &lt; 0.001). The expression of Let-7b in the group A was lower obviously in contrast to the group B (P &lt; 0.001). Let-7b nanocapsules were irregularly spherical, with an average particle size (APS) of 23.1 nm, a polydispersity index (PDI) of 0.232, and the Zeta potential of around +15 mV. Let-7b nanocapsules showed obvious polymer shell absorption peaks at 1,015 cm-1, 1,228 cm-1, and 1,547 cm-1. The IL-8 and IL-1β levels of the group D were greatly different from those in the other two groups (P &lt; 0.01). The levels of TNF-α and MMP9 in the group D were greatly different in contrast to the group C (P &lt; 0.001) and the group E (P &lt; 0.01). It indicated that Let-7b nanocomposite could lower the expression levels of IL-8, IL-1β, MMP9, and TNF-α in the CSF of patients with purulent meningitis dramatically, which provides a reliable basis for immunotherapy of purulent meningitis with Let-7b.

Eucommia ulmoides Leaf Polysaccharide in Conjugation with Ovalbumin Act as Delivery System Can Improve Immune Response.

In this investigation, to maximize the desired immunoenhancement effects of PsEUL and stimulate an efficient humoral and cellular immune response against an antigen, PsEUL and the model antigen ovalbumin (OVA) were coupled using the N-(3-dimethylaminopropyl)-N′-ethylcarbodiimide hydrochloride (EDC) reaction to yield a novel delivery system (PsEUL-OVA). The physicochemical characteristics and immune regulation effects of this new system were investigated. We found the yield of this EDC method to be 46.25%. In vitro, PsEUL-OVA (200 μg mL−1) could enhance macrophage proliferation and increase their phagocytic efficiency. In vivo, PsEUL-OVA could significantly increase the levels of OVA-specific antibody (IgG, IgG1, IgG2a, and IgG2b) titers and cytokine (IL-2, IL-4, IL-6, IFN-γ) levels. Additionally, it could activate T lymphocytes and facilitate the maturation of dendritic cells (DCs). These findings collectively suggested that PsEUL-OVA induced humoral and cellular immune responses by promoting the phagocytic activity of macrophages and DCs. Taken together, these results revealed that PsEUL-OVA had the potential to improve immune responses and provide a promising theoretical basis for the design of a novel delivery system.

Honokiol Restores Microglial Phagocytosis by Reversing Metabolic Reprogramming.

Dysfunction of microglia has been increasingly recognized as a causative factor in Alzheimer's disease (AD); thus, developing medicines capable of restoring microglial functions is critically important and constitutes a promising therapeutic strategy. Honokiol is a natural neuroprotective compound extracted from Magnolia officinalis, which may play roles in AD therapy. This study aimed to evaluate the role and the underlying mechanisms of honokiol in microglial phagocytosis. MTT and flow cytometry were used to assess the cell viability and apoptosis, respectively. Phagocytic capacity, mitochondrial reactive oxygen species production, and membrane potential were evaluated using fluorescence microscopy. Seahorse XF24 extracellular flux analyzer was for cell glycolysis and oxidative phosphorylation detection. Mass spectrometry was applied for metabolites measurement. Quantitative real-time polymerase chain reaction and western blotting were performed to detect the mRNA and protein level of PPARγ and PGC1α, respectively. Honokiol alleviated Aβ42-induced BV2 neurotoxicity. Honokiol promoted phagocytic efficiency of BV2 cells through reversing a metabolic switch from oxidative phosphorylation to anaerobic glycolysis and enhancing ATP production. Meanwhile, honokiol reduced mitochondrial reactive oxygen species production and elevated mitochondrial membrane potential. Moreover, honokiol increased the expression of PPARγ and PGC1α, which might play positive roles in energy metabolism and microglial phagocytosis. In this study, honokiol was identified as an effect natural product capable of enhancing mitochondrial function thus promoting microglial phagocytic function.

Mannose-Modified Chitosan Poly(lactic-co-glycolic acid) Microspheres Act as a Mannose Receptor-Mediated Delivery System Enhancing the Immune Response.

The mannose receptor (MAN-R)-targeted delivery system is commonly used to deliver antigens to macrophages or immature dendritic cells (DCs) to promote the efficiency of antigen presentation. To maximize the enhancement effects of chitosan (CS) and induce an efficient humoral and cellular immune response against an antigen, we encapsulated ovalbumin (OVA) in poly(lactic-co-glycolic acid) (PLGA) microspheres (MPs) and conjugated it with MAN-modified CS to obtain MAN-R-targeting nano-MPs (MAN-CS-OVA-PLGA-MPs). The physicochemical properties, drug loading rate, and immunomodulation activity of MAN-CS-OVA-PLGA-MPs were evaluated. In vitro, MAN-CS-OVA-PLGA-MPs (80 μg mL−1) could enhance the proliferation of DCs and increase their phagocytic efficiency. In vivo, MAN-CS-OVA-PLGA-MPs significantly increased the ratio of CD3+CD4+/CD3+CD8+ T cells, increased CD80+, CD86+, and MHC II expression in DCs, and improved OVA-specific IgG, IgG1, IgG2a, and IgG2b antibodies. Moreover, MAN-CS-OVA-PLGA-MPs promoted cytokine (IFN-γ, IL-4, and IL-6) production in mice. Taken together, our results show that MAN-CS-OVA-PLGA-MPs may act by activating the T cells to initiate an immune response by promoting the maturation of dendritic cells and improving their antigen presentation efficiency. The current study provides a basis for the use of MAN-CS-OVA-PLGA-MPs as an antigen and adjuvant delivery system targeting the MAN-R on the surface of macrophages and dendritic cells.