single-cell-seeded-human-intestinal-organoids-for-organoid-research

Single Cell-Seeded Human Intestinal Organoids for Organoid Research

Recent developments in organoid technology have enabled the creation of patient-derived intestinal organoids (PDIOs) that recapitulate the structural, ...

Yonsei University College of Medicine

Monocytes recruitment from the blood to inflamed tissues following ischemic stroke is an important immune response to wound healing and tissue repair. Mouse monocytes can be endogenously divided into two distinct populations: pro-inflammatory or classical monocytes that express CCR2CX3CR1 and circulate in blood, and anti-inflammatory or non-classical monocytes that express CCR2CX3CR1 and patrol locally. In this study of transgenic mice with functional CX3CR1 or CX3CR1-CCR2, we found that CCR2CX3CR1 monocytes recruited to the injured brain were cytokine-dependently converted into CCR2CX3CR1 macrophages, especially under the influence of IL-4 and IL-13, thereby attenuating the neuroinflammation following sterile ischemic stroke. The overall data suggest that (1) the regulation of monocyte-switching is one of the ultimate reparative strategies in ischemic stroke, and (2) the adaptation of monocytes in a locally inflamed milieu is vital to alleviating the effects of ischemic stroke through innate immunity.

Reparative System Arising from CCR2(+) Monocyte Conversion Attenuates Neuroinflammation Following Ischemic Stroke.

Agmatine, an endogenous derivative of arginine, has been found to be effective in treating idiopathic pain, convulsion, stress-mediated behavior, and attenuate the withdrawal symptoms of drugs like morphine. In the early stages of ischemic brain injury in animals, exogenous agmatine treatment was found to be neuroprotective. Agmatine is also considered as a putative neurotransmitter and is still an experimental drug. Chemically, agmatine is called agmatine 1-(4-aminobutyl guanidine). Crystallographic study data show that positively-charged guanidine can bind to the protein containing Gly and Asp residues, and the amino group can interact with the complimentary sites of Glu and Ser. In this study, we blocked the amino end of the agmatine by conjugating it with FITC, but the guanidine end was unchanged. We compared the neuroprotective function of the agmatine and agmatine-FITC by treating them in neurons after excitotoxic stimulation. We found that even the amino end blocked neuronal viability in the excitotoxic condition, by NMDA treatment for 1 h, was increased by agmatine-FITC, which was similar to that of agmatine. We also found that the agmatine-FITC treatment reduced the expression of nitric oxide production in NMDA-treated cells. This study suggests that even if the amino end of agmatine is blocked, it can perform its neuroprotective function.

Maintenance of the Neuroprotective Function of the Amino Group Blocked Fluorescence-Agmatine.

Alzheimer's disease (AD) is characterized by memory loss and cognitive decline. Additionally, abnormal extracellular amyloid plaques accumulation and nerve damage caused by intracellular neurofibrillary tangles, and tau protein are characteristic of AD. Furthermore, AD is associated with oxidative stress, impaired mitochondrial structure and function, denormalization, and inflammatory responses. Recently, besides the amyloid β hypothesis, another hypothesis linking AD to systemic diseases has been put forth by multiple studies as a probable cause for AD. Particularly, type 2 diabetes mellitus (T2DM) and its features, including hyperinsulinemia, and chronic hyperglycemia with an inflammatory response, have been shown to be closely related to AD through insulin resistance. The brain cannot synthesize or store glucose, but it does require glucose, and the use of glucose in the brain is higher than that in any other organ in the mammalian body. One of the therapeutic drugs for T2DM, dipeptidyl peptidase-4 (DPP-4) inhibitor, suppresses the degradation of incretins, glucagon-like peptides and glucose-dependent insulinotropic peptide. Sodium-glucose cotransporter 2 (SGLT2) inhibitors, recently used in T2DM treatment, have a unique mechanism of action  inhibition of renal glucose reabsorption, and which is different from the mechanisms of previously used medications. This manuscript reviews the pathophysiological relationship between the two diseases, AD and T2DM, and the pharmacological effects of therapeutic T2DM drugs, especially DPP-4 inhibitors, and SGLT2 inhibitors.

Role of DPP-4 and SGLT2 Inhibitors Connected to Alzheimer Disease in Type 2 Diabetes Mellitus.

Following central nervous system (CNS) injury, the investigation for neuroinflammation is vital because of its pleiotropic role in both acute injury and long-term recovery. Agmatine (Agm) is well known for its neuroprotective effects and anti-neuroinflammatory properties. However, Agm's mechanism for neuroprotection is still unclear. We screened target proteins that bind to Agm using a protein microarray; the results showed that Agm strongly binds to interferon regulatory factor 2 binding protein (IRF2BP2), which partakes in the inflammatory response. Based on these prior data, we attempted to elucidate the mechanism by which the combination of Agm and IRF2BP2 induces a neuroprotective phenotype of microglia.

Agmatine-IRF2BP2 interaction induces M2 phenotype of microglia by increasing IRF2-KLF4 signaling.

Alzheimer's disease (AD) and type 2 diabetes mellitus (T2D) share common features, including insulin resistance. Brain insulin resistance has been implicated as a key factor in the pathogenesis of AD. Recent studies have demonstrated that anti-diabetic drugs sodium-glucose cotransporter-2 inhibitor (SGLT2-i) and dipeptidyl peptidase-4 inhibitor (DPP4-i) improve insulin sensitivity and provide neuroprotection. However, the effects of these two inhibitors on the brain metabolism and insulin resistance remain uninvestigated. We developed a T2D-AD mouse model using a high-fat diet (HFD) for 19 weeks along with a single dose of streptozotocin (100 mg/kg, intraperitoneally) at the fourth week of HFD initiation. Subsequently, the animals were treated with SGLT2-i (empagliflozin, 25 mg/kg/day orally [p.o.]) and DPP4-i (sitagliptin, 100 mg/kg/day p.o.) for 7 weeks. Subsequently, behavioral tests were performed, and the expression of insulin signaling, AD-related, and other signaling pathway proteins in the brain were examined. T2D-AD mice not only showed increased blood glucose levels and body weight but also insulin resistance. SGLT2-i and DPP4-i effectively ameliorated insulin sensitivity and reduced body weight in these mice. Furthermore, SGLT2-i and DPP4-i significantly improved hippocampal-dependent learning, memory, and cognitive functions in the T2D-AD mouse model. Interestingly, SGLT2-i and DPP4-i reduced the hyperphosphorylated tau (pTau) levels and amyloid β (Aβ) accumulation and enhanced brain insulin signaling. SGLT2-i reduced pTau accumulation through the angiotensin converting enzyme-2/angiotensin (1-7)/ mitochondrial assembly receptor axis, whereas DPP4-i reduced Aβ accumulation by increasing insulin-degrading enzyme levels. These findings suggest that SGLT2-i and DPP4-i prevent AD-like pathology and cognitive dysfunction in T2D mice potentially through affecting brain insulin signaling via different mechanisms.

SGLT2 and DPP4 inhibitors improve Alzheimer's disease-like pathology and cognitive function through distinct mechanisms in a T2D-AD mouse model.

Ischemic stroke (IS), characterized by high mortality rate, occurs owing to diminished or blocked blood flow to the brain. Hyperglycemia (HG) is a major contributor to the risk of IS. HG induces augmented oxidative stress and Blood-Brain Barrier breakdown, which increases the influx of blood-derived myeloid cells into the brain parenchyma. In cerebral ischemia, infiltrating monocytes undergo differentiation into pro-inflammatory or anti-inflammatory macrophages, having a large effect on outcomes of ischemic stroke. In addition, interleukin-4 (IL-4) and interleukin-13 (IL-13) engage in post-ischemia repair by polarizing the infiltrating monocytes into an anti-inflammatory phenotype. In this study, we aimed to determine the effect of phenotypic polarization of monocyte-derived macrophages on the prognosis of IS with HG (HG-IS). We first established a hyperglycemic mouse model using streptozotocin (150 mg/kg) and induced transient middle cerebral artery occlusion. We observed that blood-brain barrier permeability increased in HG-IS mice, as per two-photon live imaging and Evans blue staining. We also confirmed the increased infiltration of monocyte-derived macrophages and the downregulation of anti-inflammatory macrophages related to tissue remodeling after inflammation in HG-IS mice through immunohistochemistry, western blotting, and flow cytometry. We observed phenotypic changes in monocyte-derived macrophages, alleviated infarct volume, and improved motor function in HG-IS mice treated with IL-4 and IL-13. These findings suggest that the modulation of phenotypic changes in monocyte-derived macrophages following IS in hyperglycemic mice may influence ischemic recovery.

Modulating monocyte-derived macrophage polarization in cerebral ischemic injury with hyperglycemia.

Sodium-glucose cotransporter 2 inhibitor (SGLT2-i) and dipeptidyl peptidase-4 inhibitor (DPP4-i) are known to ameliorate Alzheimer's disease (AD)-like pathology and cognitive decline through distinct mechanisms. In this study, we investigated how these antidiabetic drugs elevate ketone levels and subsequently reduce amyloid-β (Aβ) and tau pathology via the NLR family pyrin domain containing 3 (NLRP3) inflammasome pathway in microglia, using a type 2 diabetes (T2D)-AD mouse model. Male C57BL/6 mice were fed a high-fat diet and injected with low doses of streptozotocin to establish a T2D-AD model. The mice were then treated with either SGLT2-i or DPP4-i. Our results revealed that both the inhibitors markedly enhanced brain ketone metabolism by upregulating key metabolic enzymes and transporters. They also reduced neuroinflammation by suppressing the expression of pro-inflammatory cytokines, such as IL-1β, and increasing the expression of the anti-inflammatory cytokine IL-4. A critical mechanism for this anti-inflammatory effect involved the inhibition of the expression of the NLRP3 inflammasome, a key driver of neuroinflammation. Notably, SGLT2-i appeared to inhibit NLRP3 inflammasome expression by disrupting the pTau-CX3C1 interaction, whereas DPP4-i exerted its effects through the Aβ-TLR4-NF-κB pathway. Moreover, our results showed that both the inhibitors promoted a shift in microglial activation from the pro-inflammatory M1 phenotype to the anti-inflammatory M2 phenotype, as indicated by the changes in CD206 and CD86 expression. These findings suggest that SGLT2-i and DPP4-i provide neuroprotective benefits through multiple mechanisms, including enhanced ketone metabolism, reduced neuroinflammation, and modulation of microglial activity in T2D-AD mouse model. This research offers a scientific basis for considering these inhibitors as potential therapeutic agents for neurodegenerative diseases, particularly in cognitive impairment patients with metabolic dysfunction.

Neuroprotective roles of SGLT2 and DPP4 inhibitors: Modulating ketone metabolism and suppressing NLRP3 inflammasome in T2D induced Alzheimer's disease.

Article	Year
Reparative System Arising from CCR2(+) Monocyte Conversion Attenuates Neuroinflammation Following Ischemic Stroke. Translational stroke research\| PubMed ID: 33409730	2021
Maintenance of the Neuroprotective Function of the Amino Group Blocked Fluorescence-Agmatine. Neurochemical research\| PubMed ID: 33914233	2021
Role of DPP-4 and SGLT2 Inhibitors Connected to Alzheimer Disease in Type 2 Diabetes Mellitus. Frontiers in neuroscience\| PubMed ID: 34489627	2021
Agmatine-IRF2BP2 interaction induces M2 phenotype of microglia by increasing IRF2-KLF4 signaling. Inflammation research : official journal of the European Histamine Research Society ... [et al.]\| PubMed ID: 37314519	2023
SGLT2 and DPP4 inhibitors improve Alzheimer's disease-like pathology and cognitive function through distinct mechanisms in a T2D-AD mouse model. Biomedicine & pharmacotherapy = Biomedecine & pharmacotherapie\| PubMed ID: 37871560	2023
Modulating monocyte-derived macrophage polarization in cerebral ischemic injury with hyperglycemia. Experimental neurology\| PubMed ID: 38777250	2024
Neuroprotective roles of SGLT2 and DPP4 inhibitors: Modulating ketone metabolism and suppressing NLRP3 inflammasome in T2D induced Alzheimer's disease. Experimental neurology\| PubMed ID: 40294740	2025

A Young Sim

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