Activated STAT3 signaling pathway by ligature-induced periodontitis could contribute to neuroinflammation and cognitive impairment in rats

Abstract Background Increasing evidence suggests a causal link between periodontitis and cognitive disorders. Systemic inflammation initiated by periodontitis may mediate the development of cognitive impairment. Our study aims to investigate the effect of ligature-induced periodontitis on cognitive function and the role of signal transducers and activators of transcription 3 (STAT3) in this process. Materials and methods Ligature-induced periodontitis was established, and the rats were treated intraperitoneally with/without the pSTAT3 inhibitor cryptotanshinone (CTS). Alveolar bone resorption and periodontal inflammation were detected by micro-computed tomography analysis and histopathological evaluation. Locomotor activity and cognitive function were evaluated by the open field test and the Morris water maze test, respectively. The activation of microglia and astrocytes in the hippocampus and cortex was assessed by immunohistochemistry (IHC). The expression of interleukins (IL-1β, IL-6, IL-8, IL-21) in both the periphery and cortex was evaluated by RT-PCR and ELISA. The expression of TLR/NF-κB and ROS cascades was evaluated by RT-PCR. The expression of pSTAT3 and the activation of the STAT3 signaling pathway (JAK2, STAT3, and pSTAT3) in the periodontal tissue and cortex were assessed by IHC and Western blot. The expression of amyloid precursor protein (APP) and its key secretases was evaluated by RT-PCR. The level of amyloid β-protein (Aβ) and the ratio of Aβ1-40/1-42 were measured via ELISA in the plasma and cortex while IHC was used to detect the level of Aβ1-42 in the brain. Results In periodontal ligature rats, significant alveolar bone resorption and local inflammatory cell infiltration were present. Apparent increases in inflammatory cytokines (IL-1β, IL-6, IL-8, and IL-21) were detected in peripherial blood and brain. Additionally, spatial learning and memory ability was impaired, while locomotor activity was not affected. Activated microglia and astrocytes were found in the cortex and hippocampus, presenting as enlarged cell bodies and irregular protrusions. Levels of TLR/NF-kB, PPAR and ROS were altered. The STAT3 signaling pathway was activated in both the periodontal tissue and cortex, and the processing of APP by β- and γ-secretases was promoted. The changes mentioned above could be relieved by the pSTAT3 inhibitor CTS. Conclusions Ligature-induced periodontitis in rats resulted in systemic inflammation and further abnormal APP processing, leading to cognitive impairments. In this progress, the activation of the STAT3 signaling pathway may play an important role by increasing inflammatory load and promoting neuroinflammation.

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Activated STAT3 Signaling Pathway by Ligature-induced Periodontitis Could Contribute to Neuroinflammation and Cognitive Impairment in Rats

10.21203/rs.3.rs-116001/v1 ◽

2020 ◽

Author(s):

Yi Hu ◽

Xu Zhang ◽

Jing Zhang ◽

Xinyi Xia ◽

Huxiao Li ◽

...

Keyword(s):

Cognitive Impairment ◽

Cognitive Function ◽

Locomotor Activity ◽

Bone Resorption ◽

Oral Cavity ◽

Signaling Pathway ◽

Alveolar Bone ◽

Rt Pcr ◽

Stat3 Signaling ◽

Stat3 Signaling Pathway

Abstract Background: Increasing evidence suggests a causal link between periodontitis and cognitive disorders. Systemic inflammation initiated by periodontitis may mediate the development of cognitive impairment. Our study aims to investigate the effect of ligature-induced periodontitis on cognitive function and the role of Signal transducers and activators of transcription 3 (STAT3) in this process.Materials and Methods: Ligature-induced periodontitis was established, and the rats were treated intraperitoneally with/without the pSTAT3 inhibitor cryptotanshinone (CTS). Alveolar bone resorption and periodontal inflammation were detected by micro-computed tomography (micro-CT) analysis and histopathological evaluation. Locomotor activity and cognitive function were evaluated by the Open field test (OFT) and the Morris water maze test (MWM), respectively. The activation of microglia and astrocytes in hippocampus and cortex was assessed by immunohistochemistry (IHC). The expression of interleukins (IL-1β, IL-6, IL-8, IL-21) in both periphery and cortex was evaluated by RT-PCR and ELISA. The expression of pSTAT3 and the activation of the STAT3 signaling pathway (JAK2, STAT3, and pSTAT3) in both oral cavity and cortex was assessed by IHC and Western blotting. The expression of amyloid precursor protein (APP) and its key secretase enzymes were evaluated by RT-PCR. The level of amyloid β-protein (Aβ) and the ratio of Aβ1-40/1-42 were measured via ELISA in plasma and cortex while IHC was used to detect the level of Aβ1-42 in brain.Results: In periodontal ligature rats, significant alveolar bone resorption and local inflammatory cell infiltration were present. Apparent increases in inflammatory cytokines (IL-1β, IL-6, IL-8 and IL-21) were detected. in both periphery and brain. Additionally, spatial learning and memory ability was impaired, while locomotor activity was not affected. Activated microglia and astrocytes were found in the cortex and hippocampus, presenting as enlarged cell bodies and irregular protrusions. The STAT3 signaling pathway was activated in both oral cavity and cortex and the processing of APP by β- and γ-secretases was promoted. Change mentioned above could be relieved by the pSTAT3 inhibitor CTS. Conclusions: Ligature-induced periodontitis in rats resulted in systemic inflammation and further abnormal APP processing, leading to cognitive impairments. In this progress, the activation of the STAT3 signaling pathway may play an important role by increasing inflammatory load and promoting neuroinflammation.

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STAT3 signaling pathway could be involved in the progress of cognitive dysfunction caused by ligature-induced periodontitis

10.21203/rs.2.23488/v1 ◽

2020 ◽

Author(s):

Yi Hu ◽

Xu Zhang ◽

Jing Zhang ◽

Huxiao Li ◽

Xinyi Xia ◽

...

Keyword(s):

Cognitive Function ◽

Locomotor Activity ◽

Bone Resorption ◽

Inflammatory Cytokines ◽

Systemic Inflammation ◽

Alveolar Bone ◽

Signalling Pathway ◽

Morris Water Maze Test ◽

Rt Pcr ◽

Stat3 Signalling

Abstract Background: Increasing evidence suggests a causal link between periodontitis and Alzheimer’s disease (AD). Systemic inflammation initiated by periodontitis may mediate the development of AD. Our study aims to investigate the effect of ligature-induced periodontitis on cognitive function and the role of STAT3 in this process.Materials and Methods: Ligature-induced periodontitis was established, and the rats were treated intraperitoneally with/without the pSTAT3 inhibitor cryptotanshinone (CTS, 5 mg/kg). Alveolar bone resorption and periodontal inflammation were detected by micro-computed tomography (micro-CT) analysis and histopathological evaluation. The expression of cytokines (IL-1β, IL-6, IL-8, IL-21) in the periphery was evaluated by RT-PCR and ELISA. Locomotor activity and cognitive function were evaluated by the open field test and the Morris water maze test, respectively. The activation of microglia and astrocytes was assessed by immunohistochemistry. In the cortex, the cytokines mentioned above were also detected, while the activation of the STAT3 signalling pathway (JAK2, STAT3, and pSTAT3) was assessed by Western blotting. The expression of amyloid precursor protein (APP) and its key secretase enzymes was evaluated by RT-PCR, while the total Aβ and the ratio of Aβ1-40/1-42 were measured via ELISA.Results: In periodontal ligature rats, significant alveolar bone resorption and local inflammatory cell infiltration were present. Apparent increases in inflammatory cytokines (IL-1β, IL-6, IL-8 and IL-21) were detected; this change was relieved by the pSTAT3 inhibitor CTS. Additionally, spatial learning and memory function was impaired, while locomotor activity was not affected. Activated microglia and astrocytes were found in the cortex and hippocampus. In the cortex, these inflammatory cytokines showed similar changes when the STAT3 signalling pathway was activated. The processing of APP by β- and γ-secretases was promoted, and both the total Aβ and the ratio of Aβ1-40/1-42 were upregulated. Changes in the brain were also attenuated by CTS.Conclusions: Ligature-induced periodontitis in rats resulted in systemic inflammation and further impairments in cognitive function, leading to AD-like pathology. The activation of the STAT3 signalling pathway may play an important role in this process by increasing inflammatory load in both the periphery and brain, promoting neuroinflammation and modulating APP processing. This study may provide novel insights into periodontal intervention strategies and potential targets for AD prevention.

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JAK2/STAT3 Signaling Pathway Plays a Key Role in Nicotine Mediated Neuroinflammation Suppression in an Ischemic Rat Model

10.21203/rs.3.rs-222193/v1 ◽

2021 ◽

Author(s):

Qi Wang ◽

Tingting Han ◽

Ruihe Lai ◽

Dalong Zhang ◽

Yao Diao ◽

...

Keyword(s):

Cognitive Impairment ◽

Signaling Pathway ◽

Rat Model ◽

Inflammatory Factors ◽

Spatial Learning And Memory ◽

Sham Operation ◽

Micropet Imaging ◽

Stat3 Signaling ◽

Stat3 Signaling Pathway ◽

Significant Difference

Abstract BackgroundTo explore the mechanism of nicotine mediated improvement of cognitive impairment in an established ischemic rat model. MethodsEndothelin-1 (ET-1) was injected into the left thalamic region in adult male Sprague-Dawley (SD) rats to establish ischemia model. 6 groups of rats (6 rats in each group) were then treated with nicotine, nicotine+DHβE, DHβE, AG490, nicotine +AG490 and saline respectively via intraperitoneal injection for 9 days. Another sham operation group was treated with saline as above. Morris Water Maze (MWM) test was performed for 6 consecutive days starting on the 4th day after operation to detect the cognitive function of rats in each group. 2-[18F]-A-85380 microPET imaging was performed on day 10 to evaluate the changes of α4β2 nAChRs in different brain regions of rats. Real-time PCR and Western blot were used to detect the amount of α4β2 nAChRs, JAK2, STAT3 and inflammatory factors in thalamus of rats in each group. ResultsThe results of MWM test showed the spatial learning and memory abilities of rats in the nicotine and sham operation groups were significantly better than the saline treating group in this ischemic rat model (p<0.05). There was no significant difference in other groups (p>0.05). MicroPET imaging showed more uptake of 2-[18F]-A-85380 in the nicotine, nicotine+AG490 and sham operation groups than in saline treating group, while there was no significant difference found in other groups (p>0.05). The expression of α4- and β2-nAChR in nicotine, nicotine+AG490 and sham operation groups was significantly higher than the saline treating group (p<0.05). In the nicotine group, the expression of p-JAK2 and p-STAT3 in left thalamus of rats was significantly higher than the saline treating group (p<0.05), and the expression of IL-1β and IL-6 protein was found to be lower than the saline treating group (p<0.05). While the expression of p-JAK2, p-STAT3 and inflammatory factors was not significantly different in all the other groups (p>0.05). ConclusionThe study suggests nicotine inhibits the expression of inflammatory factors by activating α4β2 nAChRs through the activation of JAK2-STAT3 signaling pathway to improve cognitive impairment in ischemic rats.

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Acute Monocytic Leukemia Associated Antigen MLAA-34 up-Regulates JAK2/STAT3 Expression and JAK2/STAT3 Enhances MLAA-34 Activation in a Positive Feedback Loop

Blood ◽

10.1182/blood.v126.23.1393.1393 ◽

2015 ◽

Vol 126 (23) ◽

pp. 1393-1393

Author(s):

Bo Lei ◽

Ju Bai ◽

Wanggang Zhang ◽

Aili He ◽

Yinxia Chen ◽

...

Keyword(s):

Western Blot ◽

Signaling Pathway ◽

Expression Vectors ◽

Acute Monocytic Leukemia ◽

U937 Cells ◽

Rt Pcr ◽

Monocytic Leukemia ◽

Stat3 Pathway ◽

Stat3 Signaling ◽

Stat3 Signaling Pathway

Abstract Backgroud: The MLAA-34 gene (GenBank no. AY288977.2) was first discovered in acute monocytic leukemia (M5) in an effort to identify monocytic leukemia-associated antigens by serologic analysis of a recombinant cDNA expression library (SEREX). Previous study showed that high MLAA-34 levels were independently associated with a poorer relapse-free survival and overall survival in AML patients. The MLAA-34 is located on 13q14.2 and has been confirmed to be a novel splice variant of CAB39L (calcium binding protein 39-like). Both mRNA and protein levels of MLAA-34 were found to be higher in U937 cells and M5 patients. The study confirmed that MLAA-34 plays a role in the antiapoptosis of U937 cells, and has the function of oncogenes. Objective: This study is to explore the relationship of MLAA-34 and JAK2/STAT3 signaling pathway so as to further clarify antiapoptotic mechanisms of MLAA-34. Method: Potential binding sites for STAT3 was identified by computer-assisted analysis of the core promoter of MLAA-34 gene. We analyzed the role of STAT3 in the regulation of MLAA-34 gene expression in U937 cells by site-specific mutation, chromatin immunoprecipitation (ChIP) and electrophoretic mobility shift assay (EMSA). The expression of MLAA-34 was detected by RT-PCR and western blot after over-expressing and interfering STAT3. Through the different concentrations of AG490 (JAK2 inhibitors) and different concentrations of IL- 6 (JAK2 activator) study JAK2/STAT3 signaling pathway upregulated MLAA-34 expression. The gene chip and co-IP were applied to study the MLAA-34-induced JAK2/STAT3 activation. Peripheral blood mononuclear cells and bone marrow (BM) cells of M5 patients were obtained. In M5 patients, mRNA and protein expression of JAK-2, STAT3, p-STAT3 and MLAA-34 were determined by quantitative RT-PCR and western blot respectively to verify the forward feedback regulation pathway. Result: The reporter assay showed that the activity of reporter gene was downregulated after the mutation of STAT3 binding sites. ChIP assay and EMSA showed that STAT3 can directly bind to MLAA-34 gene promoter. The expression vectors of MLAA-34 as well as siRNA eukaryotic expression vectors respectively targeting STAT3 were successfully constructed. RT-PCR and western blot results showed that STAT3 can increase the level of MLAA-34. Research of administration of different concentrations of AG490 and different concentrations of IL-6 showed that JAK2/STAT3 signaling pathway could upregulate MLAA-34 expression. AML-M5 NOD / SCID mice leukemia model was successfully constructed,.Konckdown of MLAA-34 gene can promote apoptosis of leukemia cells, inhibit tumor growth and prolong survival time. Total RNA from shRNA-MLAA-34/U937 and Vec/U937 cells were analyzed by Human Genome U133 chip. Heat-map showed reduced expression of JAK2/STAT3 pathway genes. The result was verified by qPCR and western blot. CO-IP showed that MLAA-34 could form a complex with endogenous JAK2 under the enhanced role of IL-6. Thereby activating JAK2 may directly or indirectly dependent on the presence of MLAA-34. Furthermore, we detected JAK-2, STAT3, P-STAT3 and MLAA-34 gene and protein level in M5 patients, the results showed that they have a positive correlation. Conclusion: JAK2/STAT3 pathway up-regulates MLAA-34 transcription, and MLAA-34 enhances JAK2/STAT3 pathway activation. The forward feedback regulation may have profound therapeutic implications for M5 and could help invent novel approaches in treatment for acute monocytic leukemia. Disclosures No relevant conflicts of interest to declare.

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Yi Shen Juan Bi Pill Regulates the Bone Immune Microenvironment via the JAK2/STAT3 Signaling Pathway in Vitro

Frontiers in Pharmacology ◽

10.3389/fphar.2021.746786 ◽

2021 ◽

Vol 12 ◽

Author(s):

Ya Xia ◽

Danping Fan ◽

Xiaoya Li ◽

Xiangchen Lu ◽

Qinbin Ye ◽

...

Keyword(s):

Bone Resorption ◽

Bone Loss ◽

Signaling Pathway ◽

Bone Erosion ◽

Immune Microenvironment ◽

Stat3 Signaling ◽

Single Culture ◽

Stat3 Signaling Pathway ◽

Stat Signaling

Rheumatoid arthritis (RA) is characterized by an impaired articular bone immune microenvironment, which is associated with regulatory T cells (Tregs) hypofunction and osteoclasts (OCs) hyperfunction and leads to articular bone erosion and systemic bone loss. Studies have shown that Tregs slow bone loss in RA by regulating the bone resorption function of OCs and the JAK/STAT signaling pathway can regulate the immunosuppressive function of Tregs and reduce the bone erosion function of OCs. Yi Shen Juan Bi Pill (YSJB) is a classic Chinese herbal compound for the treatment of RA. However, whether YSJB regulates bone immune microenvironment homeostasis through JAK/STAT signaling pathway remains unclear. Based on in vitro OC single culture, Treg single culture and OC-Treg coculture systems, treatments were performed using drug-containing serum, AG490 and JAK2 siRNA to explore whether YSJB-containing serum regulates the homeostasis of the bone immune microenvironment through the JAK/STAT signaling pathway. In vitro, YSJB treatment decreased the number of TRAP+ cells and the areas of bone resorption and inhibited the expression of RANK, NFATc1, c-fos, JAK2, and STAT3 in both the OC single culture system and the OC-Treg coculture system. Tregs further reduced the number of TRAP+ cells and the areas of bone resorption in the coculture system. YSJB promoted the secretion of IL-10 while inhibiting the expression of JAK2 and STAT3 in Tregs. Moreover, inhibiting the expression of JAK2 with the JAK2 inhibitor AG490 and JAK2 siRNA improved the immunosuppressive functions of Treg, inhibited OC differentiation and bone resorption. Our study demonstrates that YSJB can regulate OC-mediated bone resorption and Treg-mediated bone immunity through the JAK2/STAT3 signaling pathway. This study provides a new strategy for regulating the bone immune microenvironment in RA with traditional Chinese medicine.

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Nicotine Activating α4β2 Nicotinic Acetylcholine Receptors to Suppress Neuroinflammation via JAK2-STAT3 Signaling Pathway in Ischemic Rats and Inflammatory Cells

10.21203/rs.3.rs-1150604/v1 ◽

2021 ◽

Author(s):

Qi Wang ◽

Jinyu Gou ◽

Shenrui Guo ◽

Feng Wei ◽

Tingting Han ◽

...

Keyword(s):

Cognitive Impairment ◽

Signaling Pathway ◽

Nicotinic Acetylcholine Receptors ◽

Acetylcholine Receptors ◽

Inflammatory Cells ◽

Inflammatory Factors ◽

Cognitive Improvement ◽

Stat3 Signaling ◽

Tyrosine Kinase 2 ◽

Stat3 Signaling Pathway

Abstract Nicotine plays a role in inhibiting the inflammatory factors, which contributes to improving cognitive impairment by activating α4β2 nAChRs in ischemic rats, but the underling mechanism has not been fully elucidated. Janus tyrosine kinase 2-signal transducer and activator of transcription 3 (JAK2-STAT3) signaling pathway is involved in cognitive improvement, and there seems a relationship between nAChRs and JAK2-STAT3 as well. This study was designed to investigate the role of JAK2-STAT3 signaling pathway in nicotine-mediated anti-inflammation effect. Nicotine, DHβE (the most potent competitive antagonist of α4β2 nAChRs) and AG490 (a specific JAK2-STAT3 blocker) were adopted for intervention treatment in ischemic rats and HEK-293T-hα4β2 cells. Morris Water Maze (MWM) test and 2-[18F]-A-85380 PET imaging were performed to detect the cognition and α4β2 nAChRs in ischemic rats. The results demonstrated that nicotine intervention increased the density of α4β2 nAChRs and improved cognitive impairment, but this effect would be blocked by AG490, while receptors were still upregulated. Essentially, when JAK2-STAT3 signaling pathway was blocked, nicotine could only upregulate the expression of α4β2 nAChRs, but not improve the cognitive function. The results were further confirmed by PCR and Western blot analysis. The cell experiments also showed that nicotine could reduce inflammatory factors stimulated by LPS and upregulate the expression of pJAK2 and pSTAT3 in HEK-293T-hα4β2 cells, while AG490 and DHβE reversed nicotine’s effect. In summary, our work indicated that JAK2-STAT3 signaling pathway played an important role in nicotine-induced cognitive improvement by up-regulating α4β2 nAChRs in ischemic rats.

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