Injection Of IL-1β Research Articles

C-section and systemic inflammation synergize to disrupt the neonatal gut microbiota and brain development in a model of prematurity

Infants born very preterm (below 28 weeks of gestation) are at high risk of developing neurodevelopmental disorders, such as intellectual deficiency, autism spectrum disorders, and attention deficit. Preterm birth often occurs in the context of perinatal systemic inflammation due to chorioamnionitis and postnatal sepsis. In addition, C-section is often performed for very preterm neonates to avoid hypoxia during a vaginal delivery. We have developed and characterized a mouse model based on intraperitoneal injections of IL-1β between postnatal days one and five to reproduce perinatal systemic inflammation. This model replicates several neuropathological, brain imaging, and behavioral deficits observed in preterm infants. We hypothesized that C-sections could synergize with systemic inflammation to induce more severe brain abnormalities. We observed that C-sections significantly exacerbated the deleterious effects of IL-1β on reduced gut microbial diversity, increased levels of circulating peptidoglycans, abnormal microglia/macrophage reactivity, impaired myelination, and reduced functional connectivity in the brain relative to vaginal delivery plus intraperitoneal saline. These data demonstrate the deleterious synergistic effects of C-section and neonatal systemic inflammation on brain maldevelopment and malfunction, two conditions frequently observed in very preterm infants, who are at high risk of developing neurodevelopmental disorders.

Muscle-derived IL-1β regulates EcSOD expression via the NBR1-p62-Nrf2 pathway in muscle during cancer cachexia.

Oxidative stress contributes to the loss of skeletal muscle mass and function in cancer cachexia. However, this outcome may be mitigated by an improved endogenous antioxidant defence system. Here, using the well-established oxidative stress-inducing muscle atrophy model of Lewis lung carcinoma (LLC) in 13-week-old male C57BL/6J mice, we demonstrate that extracellular superoxide dismutase (EcSOD) levels increase in the cachexia-prone extensor digitorum longus muscle. LLC transplantation significantly increased interleukin-1β (IL-1β) expression and release from extensor digitorum longus muscle fibres. Moreover, IL-1β treatment of C2C12 myotubes increased NBR1, p62 phosphorylation at Ser351, Nrf2 nuclear translocation and EcSOD protein expression. Additional studies in vivo indicated that intramuscular IL-1β injection is sufficient to stimulate EcSOD expression, which is prevented by muscle-specific knockout of p62 and Nrf2 (i.e. in p62 skmKO and Nrf2 skmKO mice, respectively). Finally, since an increase in circulating IL-1β may lead to unwanted outcomes, we demonstrate that targeting this pathway at p62 is sufficient to drive muscle EcSOD expression in an Nrf2-dependent manner. In summary, cancer cachexia increases EcSOD expression in extensor digitorum longus muscle via muscle-derived IL-1β-induced upregulation of p62 phosphorylation and Nrf2 activation. These findings provide further mechanistic evidence for the therapeutic potential of p62 and Nrf2 to mitigate cancer cachexia-induced muscle atrophy. KEY POINTS: Oxidative stress plays an important role in muscle atrophy during cancer cachexia. EcSOD, which mitigates muscle loss during oxidative stress, is upregulated in 13-week-old male C57BL/6J mice of extensor digitorum longus muscles during cancer cachexia. Using mouse and cellular models, we demonstrate that cancer cachexia promotes muscle EcSOD protein expression via muscle-derived IL-1β-dependent stimulation of the NBR1-p62-Nrf2 signalling pathway. These results provide further evidence for the potential therapeutic targeting of the NBR1-p62-Nrf2 signalling pathway downstream of IL-1β to mitigate cancer cachexia-induced muscle atrophy.

Silencing DDX3 Attenuates Interleukin-1β-Induced Intervertebral Disc Degeneration Through Inhibiting Pyroptosis.

Intervertebral disc degeneration (IVDD) is a common disorder associated with chronic inflammation and cell death. In this study, an IVDD rat model was created through Interleukin-1β (IL-1β) injection. The degeneration of intervertebral disc tissues was assessed using magnetic resonance imaging (MRI), followed by hematoxylin and eosin (H&E) and terminal deoxynucleotidyl transferase biotin-dUTP nick end labeling (TUNEL) staining. RNA sequencing was performed to identify differentially expressed genes (DEGs) between the IVDD model and control rats. The expression levels of DEGs (DEAD-box polypeptide 3 (DDX3), lysine-specific demethylase 5D (KDM5D), interferon-induced gene-1 (IFIT1), ribosomal protein S10 (RPS10), tenomodulin (TNMD), and pentraxin 3 (PTX3)) were measured by real-time quantitative polymerase chain reaction (RT-qPCR). The regulatory effect of DDX3 on pyroptosis in IL-1β-treated nucleus pulpous (NP) cells was assessed after transfection with siRNA of DDX3. A total of 601 DEGs were identified from the IVDD model rat, and were abundant in extracellular matrix (ECM) organization, ECM-receptor interaction, and inflammatory pathways, including the PI3K-Akt, TNF, and AMPK signaling pathways. DDX3, KDM5D, and IFIT1 levels were notably elevated, whereas RPS10, TNMD, and PTX3 levels were decreased in the IL-1β-induced IVDD rat model. Moreover, silencing DDX3 promoted cell proliferation and abolished IL-1β-induced cell apoptosis and pyroptosis. This study revealed the role of DDX3 in IVDD pyroptosis, providing potential target for IVDD management.

Keratinocyte-Derived Cytokine in the Hippocampus Disrupts Extinction of Conditioned Fear Memory in Tumor-Bearing Mice.

While patients with cancer show a higher prevalence of psychiatric disorders than the general population, the mechanism underlying this interaction remains unclear. The present study examined whether tumor-bearing (TB) mice show psychological changes using the conditioned fear paradigm and the role of cytokines in these changes. TB mice were established by transplantation with mouse osteosarcoma AXT cells. These TB mice were then found to exhibit disruption in extinction of conditioned fear memory. Eighteen cytokines in serum were increased in TB mice, among which i.c.v. injection of interleukin (IL)-1β and IL-6 strengthened fear memory in normal mice. Contents of IL-17 and keratinocyte-derived cytokine (KC) in the amygdala and KC in the hippocampus were increased in TB mice. KC mRNA in both the amygdala and hippocampus was also increased in TB mice, and i.c.v. injection of KC dose-dependently strengthened fear memory in normal mice. In addition, injection of IL-1β, but not IL-6, increased KC mRNA in the amygdala and hippocampus. In TB mice KC mRNA was increased in both astrocytes and microglia of the amygdala and hippocampus. The microglia inhibitor minocycline, but not the astrocyte inhibitor fluorocitrate, alleviated disruption in extinction of conditioned fear memory in TB mice. Microinjection of KC into the hippocampus, but not into the amygdala, increased fear memory in normal mice. These findings indicate that TB mice show an increase in serum cytokines, including IL-1β, that increases KC production in microglia of the hippocampus, which then disrupts extinction of fear memory.

Blockade of Piezo2 Pathway Attenuates Inflammatory and Neuropathic Pain in the Orofacial Area.

Although previous studies suggest that Piezo2 regulates chronic pain in the orofacial area, few studies have reported the direct evidence of Piezo2's involvement in inflammatory and neuropathic pain in the orofacial region. In this study, we used male Sprague Dawley rats to investigate the role of the Piezo2 pathway in the development of inflammatory and neuropathic pain. The present study used interleukin (IL)-1β-induced pronociception as an inflammatory pain model. Subcutaneous injection of IL-1β produced significant mechanical allodynia and thermal hyperalgesia. Subcutaneous injection of a Piezo2 inhibitor significantly blocked mechanical allodynia and thermal hyperalgesia induced by subcutaneously injected IL-1β. Furthermore, the present study also used a neuropathic pain model caused by the misplacement of a dental implant, leading to notable mechanical allodynia as a consequence of inferior alveolar nerve injury. Western blot analysis revealed increased levels of Piezo2 in the trigeminal ganglion and the trigeminal subnucleus caudalis after inferior alveolar nerve injury. Furthermore, subcutaneous and intracisternal injections of a Piezo2 inhibitor blocked neuropathic mechanical allodynia. These results suggest that the Piezo2 pathway plays a critical role in the development of inflammatory and neuropathic pain in the orofacial area. Therefore, blocking the Piezo2 pathway could be the foundation for developing new therapeutic strategies to treat orofacial pain conditions.

Sinomenine Ameliorates IL-1β-Induced Intervertebral Disc Degeneration in Rats Through Suppressing Inflammation and Oxidative Stress via Keap1/Nrf2/NF-κB Signaling Pathways.

To investigate the molecular mechanism underlying the inhibitory effect of sinomenine (SN) on interleukin-1β (IL-1β)-induced apoptosis in nucleus pulposus cells (NPCs), and to evaluate the potential role of SN in preventing intervertebral disk degeneration (IDD). The Rat NPCs were cultured in vitro and identified using Hematoxylin-Eosin (HE) staining, toluidine blue staining, and immunofluorescence analysis. NPCs were pretreated with or without SN, then induced with IL-1β to assess cell viability, ROS levels, apoptotic rates, and wound healing ability. Relevant protein expression was detected using Elisa, qPCR and Western Blot techniques. NPCs were pretreated with SN, either alone or in combination with Nrf2-IN-1 or SC, before being induced to undergo apoptosis by IL-1β. Apoptosis was detected using Hoechst staining, while qPCR and Western Blot techniques assessed protein expression. Rat caudal intervertebral discs were induced with IDD, with or without SN injection, and then co-injected with IL-1β. The levels of IDD were evaluated using HE staining and modified saffron-O-fix green cartilage staining. Relevant protein expression was detected using Elisa, qPCR, and Western Blot techniques. IL-1β significantly reduced NPC activity, induced ROS accumulation and apoptosis, decreased cell healing rate, promoted the expression and secretion of inflammatory factors, and inhibited extracellular matrix synthesis. However, pretreatment with SN effectively reversed these effects. Inhibition of the Keap1/Nrf2 signaling pathway or activation of the NF-κB signaling pathway significantly attenuated the cytoprotective effects of SN and increased apoptosis. Acupuncture combined with IL-1β injection markedly induced intervertebral disc degeneration in rat caudal spine, upregulated inflammatory factors expression and secretion, and downregulated extracellular matrix synthesis. SN intervention notably enhanced antioxidant enzyme expression and reversed these outcomes. SN can prevent IL-1β-induced apoptosis of NPCs and ameliorate IDD by activating the Keap1/Nrf2 pathway and inhibiting the NF-κB signaling pathway.

Expression of circadian regulatory genes is dysregulated by increased cytokine production in mice subjected to concomitant intestinal injury and parenteral nutrition.

We have developed a mouse model of Parenteral Nutrition Associated Cholestasis (PNAC) in which combining intestinal inflammation and PN infusion results in cholestasis, hepatic macrophage activation, and transcriptional suppression of bile acid and sterol signaling and transport. In the liver, the master circadian gene regulators Bmal/Arntl and Clock drive circadian modulation of hepatic functions, including bile acid synthesis. Once activated, Bmal and Clock are downregulated by several transcription factors including Reverbα (Nr1d1), Dbp (Dbp), Dec1/2 (Bhlhe40/41), Cry1/2 (Cry1/2) and Per1/2 (Per1/2). The aim of this study was to examine the effects of PN on expression of hepatic circadian rhythm (CR) regulatory genes in mice. WT, IL1KO or TNFRKO mice were exposed to dextran sulfate sodium (DSS) for 4 days followed by soy-oil lipid emulsion-based PN infusion through a central venous catheter for 14 days (DSS-PN) and the expression of key CR regulatory transcription factors evaluated. Animals were NPO on a 14 hr light-dark cycle and were administered PN continuously over 24 hrs. Mice were sacrificed, and hepatic tissue obtained at 9-10AM (Zeitgeber Z+3/Z+4 hrs). PNAC was defined by increased serum aspartate aminotransferase, alanine aminotransferase, total bile acids, and total bilirubin and the effect of i.p. injection of recombinant IL-1β (200ng/mouse) or TNFα (200ng/mouse) on CR expression was examined after 4 hrs. In the PNAC model, DSS-PN increased serum biomarkers of hepatic injury (ALT, AST, serum bile acids) which was suppressed in both DSS-PN IL1KO and DSS-PN TNFRKO mice. In WT DSS-PN, mRNA expression of Arntl and Dec1 was suppressed corresponding to increased Nr1d1, Per2, Dbp and Dec2. These effects were ameliorated in both DSS-PN IL1KO and DSS-PN TNFRKO groups. Western analysis of the circadian transcription factor network revealed in WT mice DSS-PN significantly suppressed Reverbα, Bmal, Dbp, Per2 and Mtnr1b. With the exception of Dbp, DSS-PN mediated suppression was ameliorated by both IL1KO and TNFRKO. Intraperitoneal injection of IL-1β or TNFα into WT mice increased serum AST and ALT and suppressed mRNA expression of Nr1d1, Arntl and Clock and increased Dbp and Per2. Altered expression of CR-dependent regulatory genes during PNAC accompanies cholestasis and is, in part, due to increased cytokine (IL-1β and TNFα) production. Evaluation of the effects of modulating CR in PNAC thus deserves further investigation.

Microglia-Neuron Interactions Promote Chronic Itch via the NLRP3-IL-1β-GRPR Axis.

Spinal astrocytes contribute to chronic itch via sensitization of itch-specific neurons expressing gastrin-releasing peptide receptor (GRPR). However, whether microglia-neuron interactions contribute to itch remains unclear. In this study, we aimed to explore how microglia interact with GRPR+ neurons and promote chronic itch. RNA sequencing, quantitative real-time PCR, western blot, immunohistochemistry, RNAscope ISH, pharmacologic and genetic approaches were performed to examine the roles of spinal NLRP3 (The NOD-like receptor family, pyrin containing domain 3) inflammasome activation and IL-1β-IL1R1 signaling in chronic itch. Grpr-eGFP and Grpr KO mice were used to investigate microglia-GRPR+ neuron interactions. We observed NLRP3 inflammasome activation and IL-1β production in spinal microglia under chronic itch conditions. Blockade of microglial activation and the NLRP3/caspase-1/IL-1β axis attenuated chronic itch and neuronal activation. Type 1 IL-1 receptor (IL-1R1) was expressed in GRPR+ neurons, which are essential for the development of chronic itch. Our studies also find that IL-1β+ microglia are localized in close proximity to GRPR+ neurons. Consistently, intrathecal injection of IL1R1 antagonist or exogenous IL-1β indicate that the IL-1β-IL-1R1 signaling pathway enhanced the activation of GRPR+ neurons. Furthermore, our results demonstrate that the microglial NLRP3/caspase-1/IL-1β axis contributes to several different chronic itch triggered by small molecules and protein allergens from the environment and drugs. Our findings reveal a previously unknown mechanism in which microglia enhance the activation of GRPR+ neurons through the NLRP3/caspase-1/IL-1β/IL1R1 axis. These results will provide new insights into the pathophysiology of pruritus and novel therapeutic strategies for patients with chronic itch.

Amplification of Inflammation by Lubricin Deficiency Implicated in Incident, Erosive Gout Independent of Hyperuricemia.

In gout, hyperuricemia promotes urate crystal deposition, which stimulates the NLRP3 inflammasome and interleukin-1β (IL-1β)-mediated arthritis. Incident gout without background hyperuricemia is rarely reported. To identify hyperuricemia-independent mechanisms driving gout incidence and progression, we characterized erosive urate crystalline inflammatory arthritis in a young female patient with normouricemia diagnosed as having sufficient and weighted classification criteria for gout according to the American College of Rheumatology (ACR)/EULAR gout classification criteria (the proband). We conducted whole-genome sequencing, quantitative proteomics, whole-blood RNA-sequencing analysis using serum samples from the proband. We used a mouse model of IL-1β-induced knee synovitis to characterize proband candidate genes, biomarkers, and pathogenic mechanisms of gout. Lubricin level was attenuated in human proband serum and associated with elevated acute-phase reactants and inflammatory whole-blood transcripts and transcriptional pathways. The proband had predicted damaging gene variants of NLRP3 and of inter-α trypsin inhibitor heavy chain 3, an inhibitor of lubricin-degrading cathepsin G. Changes in the proband's serum protein interactome network supported enhanced lubricin degradation, with cathepsin G activity increased relative to its inhibitors, SERPINB6 and thrombospondin 1. Activation of Toll-like receptor 2 (TLR-2) suppressed levels of lubricin mRNA and lubricin release in cultured human synovial fibroblasts (P < 0.01). Lubricin blunted urate crystal precipitation and IL-1β induction of xanthine oxidase and urate in cultured macrophages (P < 0.001). In lubricin-deficient mice, injection of IL-1β in knees increased xanthine oxidase-positive synovial resident M1 macrophages (P < 0.05). Our findings linked normouricemic erosive gout to attenuated lubricin, with impaired control of cathepsin G activity, compounded by deleterious NLRP3 variants. Lubricin suppressed monosodium urate crystallization and blunted IL-1β-induced increases in xanthine oxidase and urate in macrophages. The collective activities of articular lubricin that could limit incident and erosive gouty arthritis independently of hyperuricemia are subject to disruption by inflammation, activated cathepsin G, and synovial fibroblast TLR-2 signaling.

Intrahippocampal injection of IL-1β upregulates Siah1-mediated degradation of synaptophysin by activation of the ERK signaling in male rat.

Interleukin-1β (IL-1β) has been described to exert important effect on synapses in the brain. Here, we explored if the synapses in the hippocampus would be adversely affected following intracerebral IL-1β injection and, if so, to clarify the underlying molecular mechanisms. Adult male Sprague-Dawley rats were divided into control, IL-1β, IL-1β + PD98059, and IL-1β + MG132 groups and then sacrificed for detection of synaptophysin (syn) protein level, synaptosome glutamate release, and synapse ultrastructure by western blotting, glutamate kit and electron microscopy, respectively. These rats were tested by Morris water maze for learning and memory ability. It was determined by western blotting whether IL-1β exerted the effect of on syn and siah1 expression in primary neurons via extracellular regulated protein kinases (ERK) signaling pathway. Intrahippocampal injection of IL-1β in male rats and sacrificed at 8d resulted in a significant decrease in syn protein, damage of synapse structure, and abnormal release of neurotransmitters glutamate. ERK inhibitor and proteosome inhibitor treatment reversed the above changes induced by IL-1β both in vivo and in vitro. In primary cultured neurons incubated with IL-1β, the expression level of synaptophysin was significantly downregulated coupled with abnormal glutamate release. Furthermore, use of PD98059 had confirmed that ERK signaling pathway was implicated in synaptic disorders caused by IL-1β treatment. The present results suggest that exogenous IL-1β can suppress syn protein level and glutamate release. A possible mechanism for this is that IL-1β induces syn degradation that is regulated by the E3 ligase siah1 via the ERK signaling pathway.

Targeting the brain 5-HT7 receptor to prevent hypomyelination in a rodent model of perinatal white matter injuries

Approximately 15 million babies are born prematurely every year and many will face lifetime motor and/or cognitive deficits. Children born prematurely are at higher risk of developing perinatal brain lesions, especially white matter injuries (WMI). Evidence in humans and rodents demonstrates that systemic inflammation-induced neuroinflammation, including microglial and astrocyte reactivity, is the prominent processes of WMI associated with preterm birth. Thus, a new challenge in the field of perinatal brain injuries is to develop new neuroprotective strategies to target neuroinflammation to prevent WMI. Serotonin (5-HT) and its receptors play an important role in inflammation, and emerging evidence indicates that 5-HT may regulate brain inflammation by the modulation of microglial reactivity and astrocyte functions. The present study is based on a mouse model of WMI induced by intraperitoneal (i.p.) injections of IL-1β during the first 5 days of life. In this model, certain key lesions of preterm brain injuries can be summarized by (i) systemic inflammation, (ii) pro-inflammatory microglial and astrocyte activation, and (iii) inhibition of oligodendrocyte maturation, leading to hypomyelination. We demonstrate that Htr7 mRNA (coding for the HTR7/5-HT7 receptor) is significantly overexpressed in the anterior cortex of IL-1β-exposed animals, suggesting it as a potential therapeutic target. LP-211 is a specific high-affinity HTR7 agonist that crosses the blood–brain barrier (BBB). When co-injected with IL-1β, LP-211 treatment prevented glial reactivity, the down-regulation of myelin-associated proteins, and the apparition of anxiety-like phenotypes. Thus, HTR7 may represent an innovative therapeutic target to protect the developing brain from preterm brain injuries.

Targeting FoxO transcription factors with HDAC inhibitors for the treatment of osteoarthritis

ObjectivesOsteoarthritis (OA) features ageing-related defects in cellular homeostasis mechanisms in articular cartilage. These defects are associated with suppression of forkhead box O (FoxO) transcription factors. FoxO1 or FoxO3 deficient mice...

A Therapeutically Actionable Protumoral Axis of Cytokines Involving IL-8, TNFα, and IL-1β.

IL-8 attracts immunosuppressive protumor myeloid cells to the tumor microenvironment, and IL-8 levels correlate with poor response to checkpoint inhibitors. TNFα and IL-1β are identified as major inducers of IL-8 expression on malignant cells across cancer types and models in a manner that is druggable with clinically available neutralizing agents. This article is highlighted in the In This Issue feature, p. 2007.

Abstract 3826: A therapeutically actionable pro-tumoral axis of cytokines involving interleukin-8, TNFα and IL-1β

Abstract Background: Interleukin-8 produced in the tumor microenvironment correlates with poor response to checkpoint inhibitors and is known to chemoattract and activate immunosuppressive myeloid leukocytes. An important question is what are the mechanisms that control IL-8 transcription in tumors. Various factors have been described but the main common denominator is NF-кB activation. In this regard, considering inflammatory mediators present in the tumor and whose receptors act as NF-кB inducers, TNFα and IL-1β became obvious candidates. In this study, we provide multiple lines of evidence that TNFα and IL-1β are able to elicit functional IL-8 from malignant cells in a manner that can be inhibited by clinically grade blockade agents. Methods: Short-term cultured human tumor cell lines, fresh human tumor explants and primary organoids were stimulated with TNFα or IL-1β to test for IL-8 induction. Moreover, syngeneic and xenografted tumors were also used to study IL-8 induction in response to TNFα or to IL-1β. Correlation between these cytokines and IL-8 transcripts were studied in TCGA and other databases to search. Results: We have been able to correlate IL-8 mRNA levels with IL-1β and TNFα transcripts in human cancers. Both cytokines induced IL-8 functional expression from a broad variety of human cancer cell lines, primary colon carcinoma organoids and fresh human tumor explants. Although IL-8 is absent from the mouse genome, a similar murine axis in which TNFα and IL-1β upregulate CXCL1 and CXCL2 in several mouse tumor cells was revealed. Furthermore, intratumoral injection of TNFα and IL-1β induced IL-8 release from human malignant cells xenografted in immunodeficient mice. In all these cases, the clinically used TNFα-blockers infliximab and etanercept, or the IL-1β inhibitor anakinra were able to interfere with this pathogenic cytokine loop. Moreover, treatment with checkpoint inhibitors augments TNFα in syngeneic and xenografted tumors thereby turning on this immunosuppressive chemokine-driven axis. However, we have demonstrated that co-blockade of TNFα and IL-1β could equally enhance anti-tumor efficacy of αPD1+αCTLA-4 regimens as CXCR1/CXCR2 inhibitors, reparixin and AZD5069, did. Conclusions: In this study, we have identified TNFα and IL-1β as major inducers of IL-8 transcription on human cancers. In keeping with these findings, both TNFα and IL-1β induce functional IL-8 release from all tested human tumor cell lines representing a variety of tissue origins, as well as from primary organoids and fresh human cancer explants. In all these cases, including xenografted human tumors, IL-8 induction could be blunted by the pharmacological blockade of TNFα or IL-1β. Finally, inhibition of this pathogenic cytokine loop could increase the anti-tumoral effect of checkpoint inhibitors. Citation Format: Irene Olivera, Rebeca Sanz-Pamplona, Elixabet Bolaños, Inmaculada Rodriguez, Iñaki Etxeberria, Assunta Cirella, Saray Garasa, Itziar Migueliz, Iñaki Eguren, Miguel F. Sanmamed, Javier Glez-Vaz, Arantza Azpilikueta, Maite Alvarez, Maria C. Ochoa, Carlos E. De Andrea, Pedro Berraondo, Álvaro Teijeira, Ignacio Melero. A therapeutically actionable pro-tumoral axis of cytokines involving interleukin-8, TNFα and IL-1β [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 3826.

Excessive dietary salt promotes neuroinflammation to worsen retinopathy in mice with streptozotocin-induced diabetes

ObjectiveDiabetic retinopathy (DR) includes vascular and neural tissue injury. Persistent low-grade inflammation may contribute to DR. Increased salt intake has been shown to promote autoimmunity in the brain. This study determined the role of salt intake in DR development. MethodsEight-week-old C57BL/6 J male mice received streptozotocin to induce diabetes. Diabetic or non-diabetic mice were fed a diet containing normal, low and high amounts of salt. The retinal function, structure and inflammatory response were determined 8 weeks after the establishment of diabetes. Interleukin (IL)-1β or a NLR family pyrin domain containing 3 (NLRP3) inhibitor was injected intravitreally and the retinal changes were evaluated. ResultsA high salt diet worsened the functional and structural damage of retinal cells and increased IL-1β in the retina of diabetic mice. IL-1β injection impaired the function of photoreceptors and retinal structure in the diabetic mice. Blocking NLRP3 inhibited IL-1β increase in the mouse bone marrow macrophages cultured in high sodium medium. NLRP3 inhibition attenuated retinal injury of diabetic mice on high salt diet. A low-salt diet also triggered inflammation and cell damage in the retina of diabetic mice but at a lower grade than those induced by high salt diet. A low or high salt diet for 8 weeks did not induce inflammation or cell injury in the retina of mice without diabetes. ConclusionThese results indicate that high salt intake has deleterious effects in DR development through NLRP3 inflammasome activation and the subsequent production of IL-1β. Limiting salt intake may not attenuate DR development.

Interleukin-10 Attenuates Behavioral, Immune and Neurotrophin Changes Induced by Chronic Central Administration of Interleukin-1β in Rats

Background: Activated microglia can trigger pro-inflammatory cytokine releases and neuroinflammation, which may inhibit astrocytes to produce neurotrophins and anti-inflammatory factors. Both eventually lead to neuron apoptosis or death. Furthermore, effective antidepressant or anti-dementia treatments can reduce pro-inflammatory cytokines, while enhance interleukin (IL)-10 production. However, the underline mechanism by which IL-10 modulates glial cell function, hence improves cognitive impairment or depression-like behavior is unknown. This study evaluated whether and how IL-10 attenuated chronic IL-1β administration-induced behavioral changes and the possible involved mechanisms. Methods: Rats received intracerebroventricular injection of IL-1β and/or IL-10 for 14 days. Then animal memory and depression-like behavior, pro-inflammatory cytokines, glial activities, expression of brain-derived neurotrophic factor (BDNF), Trk B, p75, and apoptosis-related genes were studied. Results: Compared to controls, significantly increased latent time and swimming distance in the Morris-water-maze, decreased sucrose consumption, and decreased locomotor and center zone entries in the open-field were found in rats administrated with IL-1β. These changes were associated with the reduction of GFAP expression, and concentrations of BDNF and anti-inflammatory cytokine IL-10, but the increase in the expressions of CD11b, TrkB, p75, and Caspase-3, the ratio of Bax/Bcl-2, and the concentrations of IL-1β, tumor necrosis factor-α, and IL-6. IL-10 treatment markedly attenuated IL-1β-induced above changes, except for the expressions of neurotrophin receptors. Conclusion: IL-10-improved behavioral changes may be through suppressing microglia activity and inflammation, while restoring astrocyte function and BDNF expression.

Intraamniotic LPS, IL-1β or U.parvum injection is uniquely associated with altered intrauterine microbiome in primates

Chorioamnionitis is associated with just over 1/3 of PTBs. Historically, it is thought to be a result of ascending infection with relatively low-virulence organisms. However, pathophysiology studies in humans suggest that it results from focal membrane colonization. Here, we aimed to determine if sterile intraamniotic injection (IAI) of IL1β, LPS, or Ureaplasma parvum (UP) induced-chorioamnionitis in primates is associated with alterations in the resident metagenomic composition and its function.

LPS, IL-1β or U. parvum-induced chorioamnionitis shows pro-inflammatory signatures in amniotic fluid and placental tissue

Historically, chorioamnionitis has been thought to result from ascending microbes driving inflammation of the chorioamnion, and is associated with PTB, perinatal morbidity, and adverse fetal outcomes. However, pathophysiology studies in humans suggest that it results from focal membrane colonization. Here, we studied the extent and spread of chorioamnionitis in non-human primates induced by sterile intraamniotic injection (IA) of IL1β, LPS, or Ureaplasma parvum (UP).

Inhibition of neutral sphingomyelinase 2 reduces extracellular vesicle release from neurons, oligodendrocytes, and activated microglial cells following acute brain injury

Extracellular Vesicles (EVs) are implicated in the spread of pathogenic proteinsin a growing number of neurological diseases. Given this, there is rising interest in developing inhibitors of Neutral Sphingomyelinase 2 (nSMase2), an enzyme critical in EV biogenesis. Our group recently discovered phenyl(R)‐(1‐(3‐(3,4‐dimethoxyphenyl)‐2,6‐dimethylimidazo[1,2‐b]pyridazin‐8‐yl)pyrrolidin‐3‐yl)carbamate (PDDC), the first potent, selective, orally-available, and brain-penetrable nSMase2 inhibitor, capable of dose-dependently reducing EVs release in vitro and in vivo. Herein, using multiplexed Surface Plasmon Resonance imaging (SPRi), we evaluated which brain cell-derived EVs were affected by PDDC following acute brain injury. Mice were fed PDDC-containing chow at doses which gave steady PDDC brain exposures exceeding its nSMase2 IC50. Mice were then administered an intra-striatal IL-1β injection and two hours later plasma and brain were collected. IL-1β injection significantly increased striatal nSMase2 activity which was completely normalized by PDDC. Using SPRi, we found that IL-1β-induced injury selectively increased plasma levels of CD171 + and PLP1 + EVs; this EV increase was normalized by PDDC. In contrast, GLAST1 + EVs were unchanged by IL-1β or PDDC. IL-1β injection selectively increased EVs released from activated versus non-activated microglia, indicated by the CD11b+/IB4 + ratio. The increase in EVs from CD11b + microglia was dramatically attenuated with PDDC. Taken together, our data demonstrate that following acute injury, brain nSMase2 activity is elevated. EVs released from neurons, oligodendrocytes, and activated microglial are increased in plasma and inhibition of nSMase2 with PDDC reduced these IL-1β-induced changes implicating nSMase2 inhibition as a therapeutic target for acute brain injury.

Brain Perivascular Macrophages Do Not Mediate Interleukin-1-Induced Sickness Behavior in Rats.

Sickness behavior, characterized by on overall reduction in behavioral activity, is commonly observed after bacterial infection. Sickness behavior can also be induced by the peripheral administration of Gram-negative bacterial lipopolysaccharide (LPS) or interleukin-1beta (IL-1β), a pro-inflammatory cytokine released by LPS-activated macrophages. In addition to the microglia, the brain contains perivascular macrophages, which express the IL-1 type 1 receptor (IL-1R1). In the present study, we assessed the role of brain perivascular macrophages in mediating IL-1β-induced sickness behavior in rats. To do so, we used intracerebroventricular (icv) administration of an IL-1β-saporin conjugate, known to eliminate IL-R1-expressing brain cells, prior to systemic or central IL-1β injection. Icv IL-1β-saporin administration resulted in a reduction in brain perivascular macrophages, without altering subsequent icv or ip IL-1β-induced reductions in food intake, locomotor activity, and social interactions. In conclusion, the present work shows that icv IL-1β-saporin administration is an efficient way to target brain perivascular macrophages, and to determine whether these cells are involved in IL-1β-induced sickness behavior.