RANK Ligand Helps Immunity to Leishmania major by Skewing M2-Like Into M1 Macrophages

ER Stress, the Unfolded Protein Response and Osteoclastogenesis: A Review

Endoplasmic reticulum (ER) stress and its adaptive mechanism, the unfolded protein response (UPR), are triggered by the accumulation of unfolded and misfolded proteins. During osteoclastogenesis, a large number of active proteins are synthesized. When an imbalance in the protein folding process occurs, it causes osteoclasts to trigger the UPR. This close association has led to the role of the UPR in osteoclastogenesis being increasingly explored. In recent years, several studies have reported the role of ER stress and UPR in osteoclastogenesis and bone resorption. Here, we reviewed the relevant literature and discussed the UPR signaling cascade response, osteoclastogenesis-related signaling pathways, and the role of UPR in osteoclastogenesis and bone resorption in detail. It was found that the UPR signal (PERK, CHOP, and IRE1-XBP1) promoted the expression of the receptor activator of the nuclear factor-kappa B ligand (RANKL) in osteoblasts and indirectly enhanced osteoclastogenesis. IRE1 promoted osteoclastogenesis via promoting NF-κB, MAPK signaling, or the release of pro-inflammatory factors (IL-6, IL-1β, and TNFα). CREBH promoted osteoclast differentiation by promoting NFATc1 expression. The PERK signaling pathway also promoted osteoclastogenesis through NF-κB and MAPK signaling pathways, autophagy, and RANKL secretion from osteoblasts. However, salubrinal (an inhibitor of eIF2α dephosphorylation that upregulated p-eIF2α expression) directly inhibited osteoclastogenesis by suppressing NFATc1 expression and indirectly promoted osteoclastogenesis by promoting RANKL secretion from osteoblasts. Therefore, the specific effects and mechanisms of p-PERK and its downstream signaling on osteoclastogenesis still need further experiments to confirm. In addition, the exact role of ATF6 and BiP in osteoclastogenesis also required further exploration. In conclusion, our detailed and systematic review provides some references for the next step to fully elucidate the relationship between UPR and osteoclastogenesis, intending to provide new insights for the treatment of diseases caused by osteoclast over-differentiation, such as osteoporosis.

Role of Mast-Cell-Derived RANKL in Ovariectomy-Induced Bone Loss in Mice

Mast cells may contribute to osteoporosis development, because patients with age-related or post-menopausal osteoporosis exhibit more mast cells in the bone marrow, and mastocytosis patients frequently suffer from osteopenia. We previously showed that mast cells crucially regulated osteoclastogenesis and bone loss in ovariectomized, estrogen-depleted mice in a preclinical model for post-menopausal osteoporosis and found that granular mast cell mediators were responsible for these estrogen-dependent effects. However, the role of the key regulator of osteoclastogenesis, namely, receptor activator of NFκB ligand (RANKL), which is secreted by mast cells, in osteoporosis development has, to date, not been defined. Here, we investigated whether mast-cell-derived RANKL participates in ovariectomy (OVX)-induced bone loss by using female mice with a conditional Rankl deletion. We found that this deletion in mast cells did not influence physiological bone turnover and failed to protect against OVX-induced bone resorption in vivo, although we demonstrated that RANKL secretion was significantly reduced in estrogen-treated mast cell cultures. Furthermore, Rankl deletion in mast cells did not influence the immune phenotype in non-ovariectomized or ovariectomized mice. Therefore, other osteoclastogenic factors released by mast cells might be responsible for the onset of OVX-induced bone loss.

Role of Treg, Breg and other cytokine sets in host protection and immunopathology during human leishmaniasis: Are they potential valuable markers in clinical settings and vaccine evaluation?

Leishmaniasis is a vector-borne disease caused by obligate intracellular protozoan parasites that can infect humans and other mammals. Pro- and anti-inflammatory cytokines are important regulators of innate and specific responses in Leishmania infection. Resistance to leishmaniasis is related to T helper 1 (Th1) response with the production of pro-inflammatory cytokines: IL-12, IL-1β, IFN-γ, TNF-α, IL-2 leading to activation of macrophages and parasite killing. Instead, a more intense Th2 (IL-4, IL-5, IL-13), Treg (IL-10 and TGF-β) and Breg response (IL-10 and IL-35) are related to parasite persistence through the inhibition of macrophage activation, which promotes the escape from host immune system. Interestingly, a cytokine involved in the parasite killing in one form of leishmaniasis may be "pathogen friendly" in another form of the disease. To date, few studies are focusing on the role of Treg and Breg cytokines in human models of leishmaniasis; therefore, further investigations are needed to clarify their potential role in the diagnosis and prognosis of such protozoan infections, as well as in the development of vaccines against leishmaniasis. This review summarizes the current knowledge about the role of cytokines produced by Th1, Th2, Treg, and Breg cells involved in Leishmania disease progression and host protection. Some cytokines might play a role as diagnostic and prognostic clinical markers, or they could represent a novel approach leading to new anti-leishmaniasis therapies. Overall, advances in knowledge of the complex network of cytokines secreted by immune cells could help to better understand signaling pathways and host immune responses during Leishmania infection. This approach would allow these mediators to be used as therapeutic strategies against leishmaniasis.

Commensal bacteria-derived extracellular vesicles suppress ulcerative colitis through regulating the macrophages polarization and remodeling the gut microbiota

Background

The extracellular vesicles (EVs) traffic constitutes an essential pathway of cellular communication. And the molecules in EVs produced by procaryotes help in maintaining homeostasis, addressing microbial imbalance and infections, and regulating the immune system. Despite the fact that Clostridium butyricum (C. butyricum) is commonly used for treating ulcerative colitis (UC), the potential role of C. butyricum-secreted EVs in commensals-host crosstalk remains unclear.

Results

Here, we performed flow cytometry, western blot, immunohistochemistry and 16S rRNA analysis to explore the role of C. butyricum-derived EVs on macrophage polarization and gut microbiota composition in a dextran sulfate sodium (DSS)-induced UC mouse model. The antibiotic cocktail-induced microbiome depletion and faecal transplantations were used to further investigate the mechanisms by which EVs regulate macrophage balance. Our findings showed that C. butyricum-derived EVs improved the remission of murine colitis and polarized the transformation of macrophages to the M2 type. Furthermore, C. butyricum-derived EVs restored gut dysbiosis and altered the relative abundance of Helicobacter, Escherichia-Shigella, Lactobacillus, Akkermansia and Bacteroides, which, in turn, faecal transplantations from EVs-treated mice relieved the symptoms of UC and improved the impact of EVs on the reprogramming of the M2 macrophages.

Conclusion

C. butyricum-derived EVs could protect against DSS-induced colitis by regulating the repolarization of M2 macrophages and remodelling the composition of gut microbiota, suggesting the potential efficacy of EVs from commensal and probiotic Clostridium species against UC.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12934-022-01812-6.

miR-195-3p alleviates homocysteine-mediated atherosclerosis by targeting IL-31 through its epigenetics modifications

Atherosclerosis is a serious age-related disease, which has a tremendous impact on health care globally. Macrophage inflammation is crucial for the initiation and progression of atherosclerosis, and microRNAs (miRNAs) recently have emerged as potent modulators of inflammation, while the underlying mechanisms of its involvement in homocysteine (Hcy)-mediated macrophage inflammation of atherosclerosis remain largely unknown. Here, we demonstrated that elevated Hcy inhibits the expression of miR-195-3p, which in turn enhances IL-31 expression and thereby causes the secretion of macrophages pro-inflammatory factors IL-1β, IL-6 and TNF-α and accelerate atherosclerosis. Furthermore, we identified that Hcy can induce DNA hypermethylation and H3K9 deacetylation of miR-195-3p promoter due to the increased the binding of DNMT3a and HDAC11 at its promoter. More importantly, Sp1 interacts with DNMT3a suppressed the binding of HDAC11 at miR-195-3p promoter and promoted its transcription. In summary, our results revealed a novel mechanism that transcriptional and epigenetic regulation of miR-195-3p inhibits macrophage inflammation through targeting IL-31, which provides a candidate diagnostic marker and novel therapeutic target in cardiovascular diseases induced by Hcy.

New Therapeutic Tools to Shape Monocyte Functional Phenotypes in Leishmaniasis

In the innate immunity to Leishmania infection tissue-resident macrophages and inflammatory monocytes accumulate host-cell, effector, and efferocytosis functions. In addition, neutrophils, as host, effector, and apoptotic cells, as well as tissue-resident and monocyte-derived dendritic cells (DCs) imprint innate and adaptive immunity to Leishmania parasites. Macrophages develop phenotypes ranging from antimicrobial M1 to parasite-permissive M2, depending on mouse strain, Leishmania species, and T-cell cytokines. The Th1 (IFN-γ) and Th2 (IL-4) cytokines, which induce classically-activated (M1) or alternatively-activated (M2) macrophages, underlie resistance versus susceptibility to leishmaniasis. While macrophage phenotypes have been well discussed, new developments addressed the monocyte functional phenotypes in Leishmania infection. Here, we will emphasize the role of inflammatory monocytes to access how potential host-directed therapies for leishmaniasis, such as all-trans-retinoic acid (ATRA) and the ligand of Receptor Activator of Nuclear Factor-Kappa B (RANKL) might modulate immunity to Leishmania infection, by directly targeting monocytes to develop M1 or M2 phenotypes.

A Comprehensive High-Efficiency Protocol for Isolation, Culture, Polarization, and Glycolytic Characterization of Bone Marrow-Derived Macrophages

Macrophages are among the most important antigen-presenting cells. Many subsets of macrophages have been identified with unique metabolic signatures. Macrophages are commonly classified as M1-like (inflammatory) and M2-like (anti-inflammatory) subtypes. M1-like macrophages are pro-inflammatory macrophages that get activated by LPS and/or pro-inflammatory cytokines such as INF-γ, IL-12 & IL-2. M1-like polarized macrophages are involved in various diseases by mediating the host's defense to a variety of bacteria and viruses. That is very important to study LPS induced M1-like macrophages and their metabolic states in inflammatory diseases. M2-like macrophages are considered anti-inflammatory macrophages, activated by anti-inflammatory cytokines and stimulators. Under the pro-inflammatory state, macrophages show increased glycolysis in glycolytic function. The glycolytic function has been actively investigated in the context of glycolysis, glycolytic capacity, glycolytic reserve, compensatory glycolysis, or non-glycolytic acidification using extracellular flux (XF) analyzers. This paper demonstrates how to assess the glycolytic states in real-time with easy-to-follow steps when the bone marrow-derived macrophages (BMDMs) are respiring, consuming, and producing energy. Using specific inhibitors and activators of glycolysis in this protocol, we show how to obtain a systemic and complete view of glycolytic metabolic processes in the cells and provide more accurate and realistic results. To be able to measure multiple glycolytic phenotypes, we provide an easy, sensitive, DNA-based normalization method for polarization assessment of BMDMs. Culturing, activation/polarization and identification of the phenotype and metabolic state of the BMDMs are crucial techniques that can help to investigate many different types of diseases. In this paper, we polarized the naïve M0 macrophages to M1-like and M2-like macrophages with LPS and IL4, respectively, and measured a comprehensive set of glycolytic parameters in BMDMs in real-time and longitudinally over time, using extracellular flux analysis and glycolytic activators and inhibitors.

Effects of statins on cytokines levels in gingival crevicular fluid and saliva and on clinical periodontal parameters of middle-aged and elderly patients with type 2 diabetes mellitus

Objective

To analyze the effect of statins on cytokines levels in gingival crevicular fluid (GCF) and saliva and on clinical periodontal parameters of middle-aged and elderly patients with type 2 diabetes mellitus (T2DM).

Methods

Systemically healthy controls (C group, n = 62), T2DM patients not taking statins (D group, n = 57) and T2DM patients taking statins (S group, n = 24) were recruited. In each group, subjects (40–85 years) were subclassified into the h (periodontal health)group, the g (gingivitis)group or the p (periodontitis) group according to different periodontal conditions. 17 cytokines in gingival crevicular fluid (GCF) and saliva samples of each subject were measured utilizing the Luminex technology kit. Further, HbA1c (glycated hemoglobin), FPG (fasting plasma glucose), PD (probing depth), CAL (clinical attachment level), BOP (bleeding on probing), GI (gingival index) and PI (periodontal index) were recorded. Data distribution was tested through the Shapiro-Wilk test, upon which the Kruskal-Wallis test was applied followed by Mann-Whitney U test and Bonferroni’s correction.

Results

Levels of IFN-γ, IL-5, IL-10 and IL-13 in the saliva of the Dh group were significantly lower than those in the Ch group, while factor IL-4 was higher (p<0.05). Levels of MIP-3α, IL-7 and IL-2 in GCF of the Dh group were considerably higher than those in the Ch group (p<0.05), while that of IL-23 was considerably lower. Compared with the Cg group, levels of IFN-γ, IL-4, IL-5, IL-6, IL-10 and IL-13 were significantly lower in the saliva of the Dg group (p<0.05). Lower levels of IFN-γ, IL-5 and IL-10 were detected in the Sg group than those in the Cg group (p<0.05). At the same time, levels of IL-1β, IL-6, IL-7, IL-13, IL-17, IL-21 and MIP-3α in the gingival crevicular fluid of the Sg group were lower in comparison with the Dg group. In addition, lower levels of IL-4 and higher levels of IL-7 in GCF were identified in the Dg group than those in the Cg group, while in the Sg group, lower levels of IL-4, MIP-1αand MIP-3αwere observed than those in the Cg group (p<0.05). Lower levels of IFN-γ, IL-6, IL-10, IL-13 and I-TAC were found in the Sp group compared with those in the Cp group. The IFN-γ, IL-6 and IL-10 levels were lower in the Dp group than those in the Cp group (p<0.05). Meanwhile, in the Sp group, lower levels of pro-inflammatory factors IFN-γ, IL-1β, IL-2, IL-6, IL-7, IL-21 and TNF-α, in addition to higher levels of anti-inflammatory factors IL-4 and IL-5 in gingival crevicular fluid, were identified than those in the Dp group. Higher levels of IFN-γ,IL-1β,IL-2,IL-7,IL-21 and TNF-α and a lower level of IL-5 in the Dp group were identified than those in the Cp group (p<0.05). Moreover, statins were able to substantially reduce PD in T2DM patients with periodontitis, indicating an obvious influence on the levels of cytokines secreted by Th1 cells, Th2 cells and Th17 cells, as revealed by PCA (principal component analysis).

Conclusion

Statins are associated with reduced PD and cytokines levels in the GCF and saliva of T2DM patients with periodontitis.