Schistosoma japonicum Cystatin Alleviates Sepsis Through Activating Regulatory Macrophages

[Recombinant Schistosoma japonicum cystatin alleviates acute liver injury in mice by inhibiting endoplasmic reticulum stress, inflammation and hepatocyte apoptosis]

OBJECTIVE

To investigate the protective effect of recombinant Schistosoma japonicum cystatin (rSj-Cys) against acute liver injury induced by lipopolysaccharide (LPS) and D-GalN in mice.

METHODS

Adult male C57BL/6J mice with or without LPS/D-GaIN-induced acute liver injury were given intraperitoneal injections of rSj-Cys or PBS 30 min after modeling (n=18), and serum and liver tissues samples were collected from 8 mice in each group 6 h after modeling. The survival of the remaining 10 mice in each group within 24 h was observed. Serum levels of ALT, AST, TNF-α and IL-6 of the mice were measured, and liver pathologies was observed with HE staining. The hepatic expressions of macrophage marker CD68, Bax, Bcl-2 and endoplasmic reticulum stress (ERS)-related proteins were detected using immunohistochemistry or immunoblotting, and TUNEL staining was used to detect hepatocyte apoptosis.

RESULTS

The survival rates of PBS- and rSj-Cys-treated mouse models of acute liver injury were 30% and 80% at 12 h and were 10% and 60% at 24 h after modeling, respectively; no death occurred in the two control groups within 24 h. The mouse models showed significantly increased serum levels of AST, ALT, IL-6 and TNF-α and serious liver pathologies with increased hepatic expressions of CD68 and Bax, lowered expression of Bcl-2, increased hepatocyte apoptosis, and up-regulated expressions of ERS-related signaling pathway proteins GRP78, CHOP and NF-κB p-p65. Treatment of the mouse models significantly lowered the levels of AST, ALT, IL-6 and TNF-α, alleviated liver pathologies, reduced hepatic expressions of CD68, Bax, GRP78, CHOP and NF-κB p-p65, and enhanced the expression of Bcl-2. In the normal control mice, rSj-Cys injection did not produce any significant changes in these parameters compared with PBS.

CONCLUSION

rSj-Cys alleviates LPS/D-GalN-induced acute liver injury in mice by suppressing ERS, attenuating inflammation and inhibiting hepatocyte apoptosis.

Excretory/secretory products from Trichinella spiralis adult worms ameliorate myocardial infarction by inducing M2 macrophage polarization in a mouse model

BACKGROUND

Ischemia-induced inflammatory response is the main pathological mechanism of myocardial infarction (MI)-caused heart tissue injury. It has been known that helminths and worm-derived proteins are capable of modulating host immune response to suppress excessive inflammation as a survival strategy. Excretory/secretory products from Trichinella spiralis adult worms (Ts-AES) have been shown to ameliorate inflammation-related diseases. In this study, Ts-AES were used to treat mice with MI to determine its therapeutic effect on reducing MI-induced heart inflammation and the immunological mechanism involved in the treatment.

METHODS

The MI model was established by the ligation of the left anterior descending coronary artery, followed by the treatment of Ts-AES by intraperitoneal injection. The therapeutic effect of Ts-AES on MI was evaluated by measuring the heart/body weight ratio, cardiac systolic and diastolic functions, histopathological change in affected heart tissue and observing the 28-day survival rate. The effect of Ts-AES on mouse macrophage polarization was determined by stimulating mouse bone marrow macrophages in vitro with Ts-AES, and the macrophage phenotype was determined by flow cytometry. The protective effect of Ts-AES-regulated macrophage polarization on hypoxic cardiomyocytes was determined by in vitro co-culturing Ts-AES-induced mouse bone marrow macrophages with hypoxic cardiomyocytes and cardiomyocyte apoptosis determined by flow cytometry.

RESULTS

We observed that treatment with Ts-AES significantly improved cardiac function and ventricular remodeling, reduced pathological damage and mortality in mice with MI, associated with decreased pro-inflammatory cytokine levels, increased regulatory cytokine expression and promoted macrophage polarization from M1 to M2 type in MI mice. Ts-AES-induced M2 macrophage polarization also reduced apoptosis of hypoxic cardiomyocytes in vitro.

CONCLUSIONS

Our results demonstrate that Ts-AES ameliorates MI in mice by promoting the polarization of macrophages toward the M2 type. Ts-AES is a potential pharmaceutical agent for the treatment of MI and other inflammation-related diseases.

Macrophages immunomodulation induced by Porphyromonas gingivalis and oral antimicrobial peptides

Porphyromonas gingivalis is a keystone pathogen associated with periodontitis development, a chronic inflammatory pathology characterized by the destruction of the supporting teeth structure. Macrophages are recruited cells in the inflammatory infiltrate from patients with periodontitis. They are activated by the P. gingivalis virulence factors arsenal, promoting an inflammatory microenvironment characterized by cytokine production (TNF-α, IL-1β, IL-6), prostaglandins, and metalloproteinases (MMPs) that foster the tissular destruction characteristic of periodontitis. Furthermore, P. gingivalis suppresses the generation of nitric oxide, a potent antimicrobial molecule, through its degradation, and incorporating its byproducts as a source of energy. Oral antimicrobial peptides can contribute to controlling the disease due to their antimicrobial and immunoregulatory activity, which allows them to maintain homeostasis in the oral cavity. This study aimed to analyze the immunopathological role of macrophages activated by P. gingivalis in periodontitis and suggested using antimicrobial peptides as therapeutic agents to treat the disease.

α-Hederin regulates macrophage polarization to relieve sepsis-induced lung and liver injuries in mice

Sepsis is one of the most fatal inflammatory diseases with multiple organ failure caused by pathological infection. α-Hederin, a monodesmosidic triterpenoid saponin, has many biological activities including anti-inflammation. This study aimed to investigate the effect of α-Hederin on lung and liver injuries in septic mice. Mice underwent cecal ligation and puncture-induced sepsis were intraperitoneally injected with 0.3 or 3 mg/kg α-Hederin. α-Hederin treatment dose-dependently attenuated the lung and liver injuries in septic mice. Correspondingly, α-Hederin significantly decreased malondialdehyde production, increased the levels of superoxide dismutase and glutathione in lung tissues, reduced serum alanine aminotransferase and aspartate aminotransferase activities, and suppressed the levels of TNF-α and IL-6 in both tissues and in the serum. Moreover, α-Hederin augmented CD206 level and inhibited the productions of CD86 and iNOS in lung and liver tissues of septic mice. Importantly, p-p65/p65 was suppressed, whereas IκB was elevated by α-Hederin. In conclusion, α-Hederin could improve the lung and liver injuries in mice with sepsis by regulating macrophage M1/M2 polarization and inhibiting the activation of NF-κB signaling pathway.

Dulaglutide provides protection against sepsis-induced lung injury in mice by inhibiting inflammation and apoptosis

Sepsis is a dangerous condition with a high mortality rate. In addition to promoting insulin secretion in a glucose-dependent manner, glucagon-like peptide-1 (GLP-1) also exhibits anti-inflammatory properties. Dulaglutide is a glucagon-like peptide-1 receptor agonist (GLP-1 RA). In this study, we investigated the effects and mechanism of action of dulaglutide (Dul) in lipopolysaccharide (LPS) induced lung injury in mice with sepsis. In mice with LPS (15 mg/kg, ip, qd)-induced acute lung injury, the administration of dulaglutide (0.6 mg/kg, ip, qd) improved weight loss, reduced lung injury, reversed the increase in IL-1β, TNF-α, IL-6, CXCL1, CCL2 and CXCL2 expression in the lung, and reduced the infiltration of neutrophils and macrophages in the lung tissues. The decline in caspase-3, cleaved caspase-3, caspase-8, and Bcl-2/Bax expression and the increase in the number of TUNEL positive cells in the lung were reversed, suggesting that GLP-1RA could play a protective role in the lung by inhibiting inflammation and apoptosis. In addition, GLP-1RA could reduce the expression of P-STAT3 and NLRP3, suggesting that P-STAT3 and NLRP3 may be potential targets against lung injury in sepsis. Collectively, our data demonstrated that GLP-1RA exerts a protective effect against sepsis-induced lung injury through mechanisms related to the inhibition of inflammation, apoptosis, and STAT3 signaling.

Reverse vaccinology assisted design of a novel multi-epitope vaccine to target Wuchereria bancrofti cystatin: An immunoinformatics approach

Proteases are the critical mediators of immunomodulation exerted by the filarial parasites to bypass and divert host immunity. Cystatin is a small (∼15 kDa) immunomodulatory filarial protein and known to contribute in the immunomodulation strategy by inducing anti-inflammatory response through alternative activation of macrophages. Recently, Wuchereria bancrofti cystatin has been discovered as a ligand of human toll-like receptor 4 which is key behind the cystatin-induced anti-inflammatory response in major human antigen-presenting cells. Considering the pivotal role of cystatin in the immunobiology of filariasis, cystatin could be an efficacious target for developing vaccine. Herein, we present the design and in-silico analyses of a multi-epitope-based peptide vaccine to target W. bancrofti cystatin through immune-informatics approaches. The 262 amino acid long antigen construct comprises 9 MHC-I epitopes and MHC-II epitopes linked together by GPGPG peptide alongside an adjuvant (50S ribosomal protein L7/L12) at N terminus and 6 His tags at C terminus. Molecular docking study reveals that the peptide could trigger TLR4-MD2 to induce protective innate immune responses while the induced adaptive responses were found to be mediated by IgG, IgM and Th1 mediated responses. Notably, the designed vaccine exhibits high stability and no allergenicity in-silico. Furthermore, the muti epitope-vaccine was also predicted for its RNA structure and cloned in pET30ax for further experimental validation. Taken together, this study presents a novel multi-epitope peptide vaccine for triggering efficient innate and adaptive immune responses against W. bancrofti to intervene LF through immunotherapy.

The role of lung macrophages in acute respiratory distress syndrome

Acute respiratory distress syndrome (ARDS) is an acute and diffuse inflammatory lung injury in a short time, one of the common severe manifestations of the respiratory system that endangers human life and health. As an innate immune cell, macrophages play a key role in the inflammatory response. For a long time, the role of pulmonary macrophages in ARDS has tended to revolve around the polarization of M1/M2. However, with the development of single-cell RNA sequencing, fate mapping, metabolomics, and other new technologies, a deeper understanding of the development process, classification, and function of macrophages in the lung are acquired. Here, we discuss the function of pulmonary macrophages in ARDS from the two dimensions of anatomical location and cell origin and describe the effects of cell metabolism and intercellular interaction on the function of macrophages. Besides, we explore the treatments for targeting macrophages, such as enhancing macrophage phagocytosis, regulating macrophage recruitment, and macrophage death. Considering the differences in responsiveness of different research groups to these treatments and the tremendous dynamic changes in the gene expression of monocyte/macrophage, we discussed the possibility of characterizing the gene expression of monocyte/macrophage as the biomarkers. We hope that this review will provide new insight into pulmonary macrophage function and therapeutic targets of ARDS.

CRISPR/Cas9-mediated gene knockout of Sj16 in Schistosoma japonicum eggs upregulates the host-to-egg immune response

Schistosomiasis is an important, neglected tropical disease. Schistosoma japonicum can evade host attacks by regulating the host's immunity, causing continuous infection. However, interactions between the host's immune system and S. japonicum are unclear. Our previous research found that the Sj16 protein isolated from S. japonicum has an anti-inflammatory effect in the host. However, the role of Sj16 in the regulation of host immunity in S. japonicum infection is not clear. Here, we applied the CRISPR/Cas9 technique to knockout Sj16 in S. japonicum eggs and investigated the effect of Sj16 in regulating host immunity. We found egg viability decreased after Sj16 knockout. In addition, we found granulomatous inflammation increased, the T-cell immune response enhanced and the immune microenvironment changed in mice model injected with Sj16-knockout eggs by tail vein. These findings suggested that S. japonicum could regulate host immunity through Sj16 to evade the host immune attack and cause continuous infection. In addition, we confirmed the application of CRISPR/Cas9-mediated gene reprogramming for functional genomics in S. japonicum.

Ferroptosis in Macrophage Impairment in Sepsis

Sepsis is a clinical syndrome with high mortality, which can lead to multiple organ dysfunction syndrome. Nonspecific immune dysfunction and immune imbalance are its important pathological features. Macrophages are important immune cells and one of the important components of innate and adaptive immunity. Regulating the function of macrophages may be a potential method for the treatment of sepsis. Up to now, ferroptosis has been proved to be involved in the pathophysiological mechanism of many diseases, such as Alzheimer's disease, cancer, Parkinson's disease, and renal degeneration. At present, relevant studies have reported that ferroptosis may be involved in the occurrence of sepsis This paper reviews the existing mechanisms of iron ptosis in macrophages in sepsis, with a view to providing si'l for future studies on sepsis.

Trichinella spiralis cystatin alleviates polymicrobial sepsis through activating regulatory macrophages

BACKGROUND

Sepsis is a life-threateningorgandysfunction caused by the cytokine storm induced by the severe bacterial infection. Excessive inflammatory responses are responsible for the lethal organ damage during the early stage of sepsis. Helminth infection and helminth-derived proteins have been identified to have the ability to immunomodulate the host immune system by reducing inflammation against inflammatory diseases. Trichinella spiralis cystatin (Ts-Cys) is a cysteine protease inhibitor with strong immunomodulatory functions on host immune system. Our previous studies have shown that excretory-secretory proteins of T. spiralis reduced sepsis-induced inflammation and Ts-Cys was able to inhibit macrophages to produce inflammatory cytokines. Whether Ts-Cys has a therapeutic effect on polymicrobial sepsis and related immunological mechanism are not yet known.

METHODS

Sepsis was induced in BALB/c mice using cecal ligation and puncture (CLP), followed by intraperitoneal injection of 15 µg recombinant Ts-Cys (rTs-Cys). The therapeutic effect of rTs-Cys on sepsis was evaluated by observing the 72-hour survival rates of CLP-induced septic mice and the acute injury of lung and kidney through measuring the wet/dry weight ratio of lung, the levels of blood urea nitrogen (BUN) and creatinine (Cr) in sera and the tissue section pathology. The potential underlying mechanism was investigated using mouse bone marrow-derived macrophages (BMDMs) by observing the effect of rTs-Cys on LPS-stimulated macrophage polarization. The expression of genes associated with macrophage polarization in BMDMs and tissues of septic mice was measured by Western Blotting and qPCR.

RESULTS

In this study, we demonstrated the treatment with rTs-Cys alleviated CLP-induced sepsis in mice with significantly reduced pathological injury in vital organs of lung and kidney and reduced mortality of septic mice. The further study identified that treatment with rTs-Cys promoted macrophage polarization from classically activated macrophage (M1) to alternatively activated macrophage (M2) phenotype via inhibiting TLR2/MyD88 signal pathway and increasing expression of mannose receptor (MR), inhibited pro-inflammatory cytokines (TNF-α, IL-6 and IL-1β) and increased regulatory anti-inflammatory cytokines (IL-10 and TGF-β) in sera and tissues (lung and kidney) of mice with polymicrobial sepsis.

CONCLUSIONS

Our results demonstrated that rTs-Cys had a therapeutic effect on sepsis through activating regulatory macrophages possibly via suppressing TLR2/MyD88 signal pathway. We also identified that rTs-Cys-induced M2 macrophage differentiation was associated with increased expression of MR on the surface of macrophages. Our results underscored the importance of MR in regulating macrophages during the treatment with rTs-Cys, providing another immunological mechanism in which helminths and their derived proteins modulate the host immune system. The findings in this study suggest that rTs-Cys is a potential therapeutic agent for the prevention and treatment of sepsis and other inflammatory diseases.

Dynamic changes of macrophage activation in mice infected with Trichinella spiralis

Trichinellosis is a serious food-borne parasitic zoonosis worldwide. Different host macrophage subsets play various roles during helminth infection; however, the dynamic changes in macrophage subsets following Trichinella spiralis infection have not been reported. Here, flow cytometry and immunofluorescence were used to assess macrophage activation in mesenteric lymph nodes (MLN), spleen, intestine, and muscle from T. spiralis-infected mice at 1, 5, 15, and 30 days post infection (dpi). Macrophages in the intestine, MLN, and spleen tended to be activated M1-type at 1 and 5 dpi, while at 15 dpi, M2-type macrophages started to become a major constituent of the spleen macrophage population, and in the intestine and MLN, macrophages were primarily mixed M1 and M2 type. At 30 dpi, macrophages in the intestine, muscle, MLN, and spleen were all mainly activated M2 cells. Additionally, mouse macrophages were cleared and the adult T. spiralis load were determined to evaluate the impact of macrophages on adult parasite expulsion. The results suggested that predominantly M1 macrophages contribute to adult T. spiralis expulsion in the enteral stage of infection. At the newborn larvae migration stage, M2 macrophage-mediated immunity had a weak scavenging effect on adults, but primarily promoted tissue repair and assisted muscle larva immune escape. Our study reveals further details of the interaction between T. spiralis and the host immune system.

Therapeutic Effect of Schistosoma japonicum Cystatin on Atherosclerotic Renal Damage

Atherosclerosis is a chronic inflammation of the arterial vessel wall driven by lipid metabolism disorders. Although helminthic infection and their derivatives have been identified to attenuate the chronic inflammatory diseases, the immunomodulatory effect of recombinant Schistosoma japonicum cystatin (rSj-Cys) on metabolic diseases and atherosclerosis has not been reported. In this study, we investigated the therapeutic efficacy of rSj-Cys on atherosclerotic renal damage and explored the related immunological mechanism. The results demonstrated that treatment with rSj-Cys significantly reduced body weight gain, hyperlipidemia, and atherosclerosis induced by the high-fat diet in apoE^–/– mice. The treatment of rSj-Cys also significantly improved kidney functions through promoting macrophage polarization from M1 to M2, therefore inhibiting M1 macrophage–induced inflammation. The possible mechanism underlying the regulatory effect of rSj-Cys on reducing atherosclerosis and atherosclerotic renal damage is that rSj-Cys stimulates regulatory T cell and M2 macrophage polarization that produce regulatory cytokines, such as interleukin 10 and transforming growth factor β. The therapeutic effect of rSj-Cys on atherosclerotic renal damage is possibly through inhibiting the activation of TLR2/Myd88 signaling pathway. The results in this study provide evidence for the first time that Schistosoma-derived cystatin could be developed as a therapeutic agent to treat lipid metabolism disorder and atherosclerosis that threats million lives around the world.

Switched phenotypes of macrophages during the different stages of Schistosoma japonicum infection influenced the subsequent trends of immune responses

BACKGROUND

Macrophages play crucial roles in immune responses during the course of schistosomal infections.

METHODS

We currently investigated influence of immunocompetent changes in macrophages via microarray-based analysis, mRNA expression analysis, detection of serum cytokines, and subsequent evaluation of the immune phenotypes following the differentiation of infection-induced lymphocytes in a unique T1/T2 double-transgenic mouse model.

RESULTS

The gradual upregulation of genes encoding YM1, YM2, and interleukin (IL)-4/IL-13 receptors in infected mice indicated the role of type 2 alternatively activated macrophages (M2, AAMφs) in immune responses after Schistosoma japonicum egg production. FACS analysis showed that surface markers MHC class II (IA/IE) and CD8α⁺ of the macrophages also exhibited a dramatic change at the various time points before and after egg-production. The transgenic mouse experiments further demonstrated that the shifting of macrophage phenotypes influenced the percentage of helper T (Th)-2 cells, which was observed to be higher than that of Th1 cells, which increased only at 3 and 5 weeks post-infection. The differentiation of effector B cells showed a similar but more significant trend toward type-2 immunity.

CONCLUSION

These results suggest that the infection of mice with S. japonicum resulted in a final Th2- and Be2-skewed immune response. This may be due to phenotypic changes in the macrophages. The influence of alternatively activated macrophages was also activated by S. japonicum egg production. This study elucidated the existence of variations in immune mechanisms at the schistosome infection stages.

The roles of macrophage polarization in the host immune response to sepsis

Sepsis is a life-threatening clinical syndrome caused by infection. Its pathogenesis is complex and entails coagulation dysfunction, inflammation, and immune disorders. Macrophages are important components of innate and adaptive immunity that are highly heterogeneous and plastic. They can polarize into a multi-dimensional spectrum of phenotypes with different functions relating to immune regulation in response to changes in the microenvironment of specific tissues. We reviewed studies that examined the role of macrophage polarization with a focus on the classical activated (M1-like) and alternative activated (M2-like) macrophages as the two main phenotypes involved in the host immune response to sepsis. A complex regulatory network is involved in the process of macrophage polarization, which is influenced by a variety of signaling molecules, transcription factors, epigenetic modifications, and metabolic reprogramming. M1-like macrophages release large quantities of pro-inflammatory mediators, while M2-like macrophages release large quantities of anti-inflammatory mediators. An imbalance between M1-like and M2-like macrophages induces the occurrence and development of sepsis. Therefore, targeted regulation of the process of macrophage polarization could be a useful approach to normalize the immune balance of the host, offering a new treatment modality for different stages of sepsis.