Statins promote efferocytosis in atherosclerotic plaques

Impaired efferocytosis by monocytes and monocyte-derived macrophages in patients with poorly controlled type 2 diabetes

BACKGROUND

Deficient efferocytosis (i.e., phagocytic clearance of apoptotic cells) by macrophages has been frequently reported in experimental models of type 2 diabetes (T2D).

AIM

To translate these findings to humans by testing whether the efferocytosis capacity of blood monocytes and monocyte-derived macrophages is impaired in T2D patients.

METHODS

Overall, 30 patients with poorly controlled T2D [glycosylated hemoglobin (HbA1c) ≥ 8.0%] and 30 age- and sex-matched control subjects were enrolled in the study. The efferocytosis capacities of peripheral blood monocytes and monocyte-derived macrophages were assessed by flow cytometry and immunostaining. Macrophage membrane CD14 expression was examined by flow cytometry. Metabolic factors such as 25(OH)D and immune factors such as interleukin-1β were also measured.

RESULTS

The mean monocyte efferocytosis index in the diabetes group was significantly lower than that in the control group. Notably, efferocytosis remained impaired after monocytes differentiated into macrophages. Additionally, the percentages of classical monocytes (CD14⁺⁺CD16^- monocytes) and CD14⁺ macrophages were significantly lower in the diabetes group. Multivariate linear regression analysis in diabetes patients demonstrated that the monocyte efferocytosis index was independently associated with the HbA1c level, and that the macrophage efferocytosis index was significantly associated with the percentage of CD14⁺ macrophages.

CONCLUSION

Impaired efferocytosis was observed in T2D patients, with poor glycemic control affecting both blood monocytes and monocyte-derived macrophages. The efferocytosis index was negatively associated with metrics of glycemic control, and glucotoxicity may impact efferocytosis through reducing CD14 expression on both monocytes and macrophages.

F. F. Statins do not reduce the parasite burden during experimental Trypanosoma cruzi infection

Cardiomyopathy is the most common pathology associated with Trypanosoma cruzi infection. Reports that statins have both cardioprotective and trypanocidal activity have generated interest in their potential as a therapeutic treatment. Using a highly sensitive bioluminescent mouse model, we show that a 5-day treatment with statins has no significant impact on parasite load. The free systemic concentrations fail to reach the level required for potency. Hence, clinical trials to investigate the trypanocidal activity of statins lack experimental justification.

The Role of Macrophages in Atherosclerosis: Participants and Therapists

Currently, atherosclerosis, characterized by the dysfunction of lipid metabolism and chronic inflammation in the intimal space of the vessel, is considered to be a metabolic disease. As the most abundant innate immune cells in the body, macrophages play a key role in the onset, progression, or regression of atherosclerosis. For example, macrophages exhibit several polarization states in response to microenvironmental stimuli; an increasing proportion of macrophages, polarized toward M2, can suppress inflammation, scavenge cell debris and apoptotic cells, and contribute to tissue repair and fibrosis. Additionally, specific exosomes, generated by macrophages containing certain miRNAs and effective efferocytosis of macrophages, are crucial for atherosclerosis. Therefore, macrophages have emerged as a novel potential target for anti-atherosclerosis therapy. This article reviews the role of macrophages in atherosclerosis from different aspects: origin, phenotype, exosomes, and efferocytosis, and discusses new approaches for the treatment of atherosclerosis.

Nanomedomics

Nanomaterials have attractive physicochemical properties. A variety of nanomaterials such as inorganic, lipid, polymers, and protein nanoparticles have been widely developed for nanomedicine via chemical conjugation or physical encapsulation of bioactive molecules. Superior to traditional drugs, nanomedicines offer high biocompatibility, good water solubility, long blood circulation times, and tumor-targeting properties. Capitalizing on this, several nanoformulations have already been clinically approved and many others are currently being studied in clinical trials. Despite their undoubtful success, the molecular mechanism of action of the vast majority of nanomedicines remains poorly understood. To tackle this limitation, herein, this review critically discusses the strategy of applying multiomics analysis to study the mechanism of action of nanomedicines, named nanomedomics, including advantages, applications, and future directions. A comprehensive understanding of the molecular mechanism could provide valuable insight and therefore foster the development and clinical translation of nanomedicines.

Efferocytosis: a double-edged sword in microbial immunity

Efferocytosis is characterized as the rapid and efficient process by which dying or dead cells are removed. This type of clearance is initiated via "find-me" signals, and then, carries on by "eat-me" and "don't-eat-me" ones. Efferocytosis has a critical role to play in tissue homeostasis and innate immunity. However, some evidence suggests it as a double-edged sword in microbial immunity. In other words, some pathogens have degraded efferocytosis by employing efferocytic mechanisms to bypass innate immune detection and promote infection, despite the function of this process for the control and clearance of pathogens. In this review, the efferocytosis mechanisms from the recognition of dying cells to phagocytic engulfment are initially presented, and then, its diverse roles in inflammation and immunity are highlighted. In this case, much focus is also laid on some bacterial, viral, and parasitic infections caused by Mycobacterium tuberculosis (M. tb), Mycobacterium marinum (M. marinum), Listeria monocytogenes (L. monocytogenes), Chlamydia pneumoniae (CP), Klebsiella pneumoniae (KP), Influenza A virus (IAV), human immunodeficiency virus (HIV), and Leishmania, respectively.

In situ hydrogel enhances non-efferocytic phagocytosis for post-surgical tumor treatment

Post-surgical efferocytosis of tumor associated macrophages (TAMs) originates an immunosuppressive tumor microenvironment and facilitates abscopal metastasis of residual tumor cells. Currently, few strategies could inhibit efferocytosis while recovering the tumor-eliminative phagocytosis of TAMs. Herein, we developed an in situ hydrogel that contains anti-CD47 antibody (aCD47) and apocynin (APO), an inhibitor of nicotinamide adenine dinucleotide phosphate oxidase. This hydrogel amplifies the non-efferocytic phagocytosis of TAMs by (1) blocking the extracellular "Don't eat me" signal of efferocytosis with aCD47, which enhances the receptor-mediated recognition and engulfment of tumor cells by TAMs in the post-surgical tumor bed, and (2) by utilizing APO to dispose of tumor debris in a non-efferocytic manner, which prevents acidification and maturation of efferosomes and allows for M1-polarization of TAMs, leading to improved antigen presentation ability. With the complementary intervention of extracellular and intracellular, this hydrogel reverses the immunosuppressive effects of efferocytosis, and induces a potent M1-associated Th1 immune response against tumor recurrence. In addition, the in situ detachment and distal colonization of metastatic tumor cells were efficiently restrained due to the intervention of efferocytosis. Collectively, the hydrogel potentiates surgery treatment of tumor by recovering the tumor-elimination ability of post-surgical TAMs.