Amyloid and the macrophage: it's all about local production of IL-1β

The role of M1/M2 macrophage polarization in the pathogenesis of obesity-related kidney disease and related pathologies

Obesity is a rapidly growing health problem worldwide, affecting both adults and children and increasing the risk of chronic diseases such as type 2 diabetes, hypertension and cardiovascular disease (CVD). In addition, obesity is closely linked to chronic kidney disease (CKD) by either exacerbating diabetic complications or directly causing kidney damage. Obesity-related CKD is characterized by proteinuria, lipid accumulation, fibrosis and glomerulosclerosis, which can gradually impair kidney function. Among the immune cells of the innate and adaptive immune response involved in the pathogenesis of obesity-related diseases, macrophages play a crucial role in the inflammation associated with CKD. In obese individuals, macrophages enter a pro-inflammatory state known as M1 polarization, which contributes to chronic inflammation. This polarization promotes tissue damage, inflammation and fibrosis, leading to progressive loss of kidney function. In addition, macrophage-induced oxidative stress is a key feature of CKD as it also promotes cell damage and inflammation. Macrophages also contribute to insulin resistance in type 2 diabetes by releasing inflammatory molecules that impair glucose metabolism, complicating the management of diabetes in obese patients. Hypertension and atherosclerosis, which are often associated with obesity, also contribute to the progression of CKD via immune and inflammatory pathways. Macrophages influence blood pressure regulation and contribute to vascular inflammation, particularly via the renin-angiotensin system. In atherosclerosis, macrophages accumulate in arterial plaques, leading to chronic inflammation and plaque instability, which may increase the risk of CVD in CKD patients. This review focuses on the involvement of macrophages in CKD and highlights their role as a critical link between CKD and other pathologies. Targeting macrophage polarization and the ensuing macrophage-induced inflammation could be an effective therapeutic strategy for CKD and related diseases and improve outcomes for patients with obesity-related kidney disease.

Role of Macrophage in Type 2 Diabetes Mellitus: Macrophage Polarization a New Paradigm for Treatment of Type 2 Diabetes Mellitus

Metabolic diseases such as type 2 diabetes mellitus are usually associated with meta-inflammation. β-cell failure is a marked feature observed in the pathogenesis of type 2 diabetes mellitus. Type 2 diabetes mellitus (T2DM) is a heterogeneous situation that is accompanied by not only defective insulin secretion but also peripheral insulin resistance. β-cells are the primary organ for insulin secretion; hence, it is crucial to maintain a significant β-cell mass in response to a variety of changes. Insulin resistance is a chief cause of T2DM, leading to increased free fatty acid (FFA) levels, which in turn elevates β-cell mass and insulin secretion as compensation for insulin insensitivity. It has recently been established that amplified numbers of innate immune cells, cytokines, and chemokines result in detrimental effects on islets in chronic conditions. Macrophage migration inhibitory factor (MIF) is the lymphokine that prevents arbitrary migration of macrophages and assembles macrophages at inflammatory loci. Inflammation is known to trigger monocytes to differentiate into macrophages. Progress of complications associated with type 2 diabetes mellitus, as indicated through recent findings, is also dependent on the buildup of macrophages in tissues vulnerable to diabetic injury. The present article scientifically evaluates the present knowledge concerning the mechanisms of monocyte and macrophage-mediated injury recruitment in complications associated with type 2 diabetes mellitus. It also describes some of the established and experimental therapies that might bring about a reduction in these inflammatory complications. Recent discoveries in the field of drug delivery have facilitated phenotype-specific targeting of macrophages. This review highlights the pathophysiology of type 2 diabetes mellitus, how macrophage induces type 2 diabetes mellitus and potential therapeutics for type 2 diabetes mellitus via macrophage-specific delivery.

The Soybean Peptide Vglycin Preserves the Diabetic β-cells through Improvement of Proliferation and Inhibition of Apoptosis

Replenishment of insulin-producing pancreatic β-cells would be beneficial in diabetes. The number of β-cells is maintained primarily by self-neogenesis to compensate for β-cell failure, loss or dedifferentiation. We present here a polypeptide vglycin, which was isolated and purified from germinating pea seeds. Vglycin exhibited positive effects in our diabetic models by promoting the proliferation and suppressing the apoptosis and dedifferentiation of β-cells. Vglycin promoted the restoration of β-cells in both young streptozotocin (STZ)-induced type 1 diabetic SD rats and in aged high-fat diet with (or without) STZ-induced type 2 diabetic C57BL/6 mice. We demonstrated that vglycin triggers this positive signaling by activating the insulin receptor and corresponding transcription factors. Impaired insulin sensitivity and glucose tolerance in aged T2DM mice were dramatically improved after long-term vglycin treatment, consistent with the altered level of inflammatory factor IL-1β/6. In addition, energy expenditure and body weights were significantly decreased in the mouse models after vglycin therapy. These results provide insight into the protective effects of vglycin on ameliorating β-cell function in standing glucolipotoxicity. Thus, vglycin may represent a new therapeutic agent for preventing and treating diabetes by replenishing endogenous insulin-positive cells.