Therapeutic potentials of mesenchymal stem cells in the treatment of inflammatory bowel disease in rats

Interleukin-1beta (IL-1β) and interleukin-17A (IL-17A) have strong pro-inflammatory activities that are involved in inflammatory bowel diseases (IBDs). Mesenchymal stem cell (MSC) therapy is considered a promising treatment for IBD. This study was performed to understand the role of rat Nlrp3 inflammasome, Hmgb1, and pro-inflammatory cytokines (IL-1β and IL-17a) in the pathogenesis of IBD. Also, to evaluate the role of human umbilical cord blood-MSCs (hUCB-MSCs) in the management of IBD. The rats were in four groups: normal controls, indomethacin-induced IBD group, indomethacin-induced IBD rats that received phosphate-buffered saline (PBS), and the IBD group that received hUCB-MSCs as a treatment. The messenger RNA (mRNA) expression levels of rat Nlrp3, Hmgb1, IL-1β, and IL-17a were evaluated by quantitative real-time polymerase chain reaction. Histopathological examination of the small intestinal tissues of the studied rats was performed. There was a significant upregulation of the rat Nlrp3, IL-1β, IL-17a mRNA expression (p < 0.001 for the three parameters), and Hmgb1 (p < 0.05) in the untreated IBD group compared to the normal control group. In the MSC-treated group, IL-1β, IL-17a, and rat Nlrp3 mRNA expression significantly decreased compared to both the untreated IBD group and PBS group (p < 0.05 for all). hUCB-MSCs ameliorated IBD in rats by downregulating the pro-inflammatory cytokines (IL-1β and IL-17a) and other inflammatory mediators such as Hmgb1 and rat Nlrp3.

Hmgb1 Silencing in the Amygdala Inhibits Pain-Related Behaviors in a Rat Model of Neuropathic Pain

Chronic pain presents a therapeutic challenge due to the highly complex interplay of sensory, emotional-affective and cognitive factors. The mechanisms of the transition from acute to chronic pain are not well understood. We hypothesized that neuroimmune mechanisms in the amygdala, a brain region involved in the emotional-affective component of pain and pain modulation, play an important role through high motility group box 1 (Hmgb1), a pro-inflammatory molecule that has been linked to neuroimmune signaling in spinal nociception. Transcriptomic analysis revealed an upregulation of Hmgb1 mRNA in the right but not left central nucleus of the amygdala (CeA) at the chronic stage of a spinal nerve ligation (SNL) rat model of neuropathic pain. Hmgb1 silencing with a stereotaxic injection of siRNA for Hmgb1 into the right CeA of adult male and female rats 1 week after (post-treatment), but not 2 weeks before (pre-treatment) SNL induction decreased mechanical hypersensitivity and emotional-affective responses, but not anxiety-like behaviors, measured 4 weeks after SNL. Immunohistochemical data suggest that neurons are a major source of Hmgb1 in the CeA. Therefore, Hmgb1 in the amygdala may contribute to the transition from acute to chronic neuropathic pain, and the inhibition of Hmgb1 at a subacute time point can mitigate neuropathic pain.

Machine learning and single cell RNA sequencing analysis identifies regeneration-related hepatocytes and highlights a Birc5-related model for identifying cell proliferative ability

BACKGROUND

Partial hepatectomy (PHx) has been shown to induce rapid regeneration of adult liver under emergency conditions. Therefore, an in-depth investigation of the underlying mechanisms that govern liver regeneration following PHx is crucial for a comprehensive understanding of this process.

METHOD

We analyzed scRNA-seq data from liver samples of normal and PHx-48-hour mice. Seven machine learning algorithms were utilized to screen and validate a gene signature that accurately identifies and predicts this population. Co-immunostaining of zonal markers with BIRC5 to investigate regional characteristics of hepatocytes post-PHx.

RESULTS

Single cell sequencing results revealed a population of regeneration-related hepatocytes. Transcription factor analysis emphasized the importance of Hmgb1 transcription factor in liver regeneration. HdWGCNA and machine learning algorithm screened and obtained the key signature characterizing this population, including a total of 17 genes and the function enrichment analysis indicated their high correlation with cell cycle pathway. It is note-worthy that we inferred that Hmgb1 might be vital in the regeneration-related hepatocytes of PHx_48h group. Parallelly, Birc5 might be closely related to the regulation of liver regeneration, and positively correlated with Hmgb1.

CONCLUSIONS

Our study has identified a distinct population of hepatocytes that are closely associated with liver regeneration. Through machine learning algorithms, we have identified a set of 17 genes that are highly indicative of the regenerative capacity of hepatocytes. This gene signature has enabled us to assess the proliferation ability of in vitro cultured hepatocytes using sequencing data alone.

Blocking toll-like receptor 4 mitigates static loading induced pro-inflammatory expression in intervertebral disc motion segments

While the anabolic effects of mechanical loading on the intervertebral disc (IVD) have been extensively studied, inflammatory responses to loading have not been as well characterized. Recent studies have highlighted a significant role of innate immune activation, particularly that of toll-like receptors (TLRs), in IVD degeneration. Biological responses of intervertebral disc cells to loading depend on many factors that include magnitude and frequency. The goals of this study were to characterize the inflammatory signaling changes in response to static and dynamic loading of IVD and investigate the contributions of TLR4 signaling in response to mechanical loading. Rat bone-disc-bone motion segments were loaded for 3 hr under a static load (20 % strain, 0 Hz) with or without an additional low-dynamic (4 % dynamic strain, 0.5 Hz) or high-dynamic (8 % dynamic strain, 3 Hz) strain, and results were compared to unloaded controls. Some samples were also loaded with or without TAK-242, an inhibitor of TLR4 signaling. The magnitude of NO release into the loading media (LM) was correlated with the applied frequency and strain magnitudes across different loading groups. Injurious loading profiles, such as static and high-dynamic, significantly increased Tlr4 and Hmgb1 expression while this result was not observed in the more physiologically relevant low-dynamic loading group. TAK-242 co-treatment decreased pro-inflammatory expression in static but not dynamic loaded groups, suggesting that TLR4 plays a direct role in mediating inflammatory responses of IVD to static compression. Overall, the microenvironment induced by dynamic loading diminished the protective effects of the TAK-242, suggesting that TLR4 plays a direct role in mediating inflammatory responses of IVD to static loading injury.

[HMGB1gene expression changes in the striatum and amigdal of the rat's brain under alcoholization and ethanol withdrawal]

Intracellular signaling mediated by the HMGB1 protein, an agonist of TLRs, is considered as a possible target for the correction of pathologies of the neuroimmune system, however, the expression level of the Hmgb1 gene has not been previously studied in various brain structures of rats exposed to prolonged alcoholization followed by ethanol withdrawal. The study showed that long-term use of ethanol caused to an increase in the level of Hmgb1 mRNA in the striatum of rat brain. Alcohol withdrawal changed the level Hmgb1 mRNA in the striatum and amygdala on the 1st and 14th day. The data obtained may indicate that in different structures of the brain there are multidirectional changes in the molecular mechanisms of the neuroimmune response with prolonged use of ethanol and its withdrawal.

The Complement Cascade as a Mediator of Human Malignant Hematopoietic Cell Trafficking

The complement cascade (ComC) cleavage fragments C3a and C5a regulate the trafficking of normal, differentiated hematopoietic cells, although they do not chemoattract more primitive hematopoietic stem/progenitor cells (HSPCs). By contrast, human myeloid and lymphoid leukemia cell lines and clonogenic blasts from chronic myelogenous leukemia (CML) and acute myelogenous leukemia (AML) patients respond to C3 and C5 cleavage fragments by chemotaxis and increased adhesion. Consistent with this finding, C3a and C5a receptors are expressed by leukemic cells at the mRNA (RT-PCR) and protein (FACS) levels, and these cells respond to C3a and C5a stimulation by phosphorylation of p44/42 MAPK and AKT. However, neither of these ComC cleavage fragments have an effect on cell proliferation or survival. In parallel, we found that inducible heme oxygenase 1 (HO-1)-an anti-inflammatory enzyme, is a negative regulator of ComC-mediated trafficking of malignant cells and that stimulation of these cells by C3 or C5 cleavage fragments downregulates HO-1 expression in a p38 MAPK-dependent manner, rendering cells exposed to C3a or C5a more mobile. We propose that, while the ComC is not directly involved in the proliferation of malignant hematopoietic cells, its activation in leukemia/lymphoma patients (e.g., as a result of accompanying infections or sterile inflammation after radio-chemotherapy) enhances the motility of malignant cells and contributes to their dissemination in a p38 MAPK-HO-1 axis-dependent manner. Based on this idea, we propose that inhibition of p38 MAPK or upregulation of HO-1 by available small-molecule modulators would have a beneficial effect on ameliorating expansion and dissemination of leukemia/lymphoma cells in clinical situations in which the ComC becomes activated. Finally, since we detected expression of C3 and C5 mRNA in human leukemic cell lines, further study of the potential role of the complosome in regulating the behavior of these cells is needed.

High Mobility Group Box 1 Regulates Uterine Decidualization through Bone Morphogenetic Protein 2 and Plays a Role in Kruppel-Like Factor 5-Induced Stromal Differentiation

BACKGROUND/AIMS

High mobility group box 1 (Hmgb1) is associated with a variety of physiological processes including embryonic development, cell proliferation and differentiation, but little information is available regarding its biological role in decidualization.

METHODS

In situ hybridization, real-time PCR, RNA interference, gene overexpression and MTS assay were used to analyze the spatiotemporal expression of Hmgb1 in mouse uterus during the pre-implantation period, and explore its function and regulatory mechanisms during uterine decidualization.

RESULTS

Hmgb1 mRNA was obviously observed in uterine epithelium on day 2 and 3 of pregnancy, but its expression was scarcely detected on day 4 of pregnancy. With the onset of embryo implantation, abundant Hmgb1 expression was noted in the subluminal stromal cells around the implanting blastocyst at implantation sites. Meanwhile, the accumulation of Hmgb1 mRNA was visualized in the decidual cells. Hmgb1 advanced the proliferation of uterine stromal cells and induced the expression of prolactin family 8, subfamily a, member 2 (Prl8a2), a reliable differentiation marker for decidualization. In uterine stromal cells, cAMP analogue 8-Br-cAMP up-regulated the expression of Hmgb1, but the up-regulation was abrogated by protein kinase A (PKA) inhibitor H89. Silencing of Hmgb1 by specific siRNA impeded the induction of 8-Br-cAMP on Prl8a2. Further analysis evidenced that Hmgb1 was a critical mediator of Kruppel-like factor 5 (Klf5) function in stromal differentiation. Knockdown of bone morphogenetic protein 2 (Bmp2) prevented the up-regulation of Prl8a2 elicited by Hmgb1 overexpression, whereas addition of exogenous recombinant Bmp2 protein (rBmp2) reversed the repression of Hmgb1 siRNA on Prl8a2 expression.

CONCLUSION

Hmgb1 may play an important role during mouse uterine decidualization.

Hmgb1 inhibits Klotho expression and malignant phenotype in melanoma cells by activating NF-κB

The molecular and cellular mechanisms behind the involvement of inflammation in melanoma have not been fully elucidated. In this study, knockdown of Hmgb1 expression increased apoptosis, reduced invasion and p-NF-κB expression, but increased Klotho protein level in melanoma tumor cells. The effect of Hmgb1 knockdown was overcome by LPS. Introduction of exogenous Hmgb1 significantly decreased apoptosis, increased invasion, elevated p-NF-κB, but lowered Klotho protein level in melanoma cells. The effect of exogenous Hmgb1 was agonized by NF-κB inhibitor CAPE. Hmgb1 knockdown activated, but exogenous Hmgb1 inactivated, p-IGF1R/p-PI3K p-85/p-Akt/p-mTOR signaling. Knockdown of Klotho gene expression significantly decreased apoptosis, increased invasion in melanoma cells, and inhibited xenograft A375 tumor growth. A significantly high percentage of cells stained positive for p-NF-κB, but negative for Klotho, in melanoma tissues compared to normal and benign skin tissues. The positive p-NF-κB and negative Klotho protein expression correlated with poor prognosis in melanoma patients. Multivariate analysis revealed an independent association between p-NF-κB / Klotho protein level and overall survival. In conclusion, Hmgb1 can inhibit Klotho gene expression and malignant phenotype in melanoma cells through activation of NF-κB signaling.

A long noncoding RNA, lincRNA-Tnfaip3, acts as a coregulator of NF-κB to modulate inflammatory gene transcription in mouse macrophages

Long intergenic noncoding RNAs (lincRNAs) are long noncoding transcripts (>200 nt) from the intergenic regions of annotated protein-coding genes. We report here that the lincRNA gene lincRNA-Tnfaip3, located at mouse chromosome 10 proximal to the tumor necrosis factor α-induced protein 3 (Tnfaip3) gene, is an early-primary response gene controlled by nuclear factor-κB (NF-κB) signaling in murine macrophages. Functionally, lincRNA- Tnfaip3 appears to mediate both the activation and repression of distinct classes of inflammatory genes in macrophages. Specifically, induction of lincRNA-Tnfaip3 is required for the transactivation of NF-κB-regulated inflammatory genes in response to bacterial LPSs stimulation. LincRNA-Tnfaip3 physically interacts with the high-mobility group box 1 (Hmgb1), assembling a NF-κB/Hmgb1/lincRNA-Tnfaip3 complex in macrophages after LPS stimulation. This resultant NF-κB/Hmgb1/lincRNA-Tnfaip3 complex can modulate Hmgb1-associated histone modifications and, ultimately, transactivation of inflammatory genes in mouse macrophages in response to microbial challenge. Therefore, our data indicate a new regulatory role of NF-κB-induced lincRNA-Tnfaip3 to act as a coactivator of NF-κB for the transcription of inflammatory genes in innate immune cells through modulation of epigenetic chromatin remodeling.-Ma, S., Ming, Z., Gong, A.-Y., Wang, Y., Chen, X., Hu, G., Zhou, R., Shibata, A., Swanson, P. C., Chen, X.-M. A long noncoding RNA, LincRNA-Tnfaip3, acts as a coregulator of NF-κB to modulate inflammatory gene transcription in mouse macrophages.

Secreted HMGB1 from Wnt activated intestinal cells is required to maintain a crypt progenitor phenotype

BACKGROUND AND AIMS

Colorectal cancer (CRC) arises via multiple genetic changes. Mutation of the tumour suppressor gene APC, a key regulator of Wnt signalling, is recognised as a frequent early driving mutation in CRC. We have previously shown that conditional loss of Apc within the murine small intestine (Apcfloxmice) results in acute Wnt signalling activation, altered crypt-villus architecture and many hallmarks of neoplasia. Our transctipomic profiling (Affymetrix Microarrays) and proteomic profiling (iTRAQ-QSTAR) of Apc-deficient intestine inferred the involvement of High Mobility Group Box 1 (Hmgb1) in CRC pathogenesis. Here we assess the contribution of HMGB1 to the crypt progenitor phenotype seen following Apc loss.

RESULTS

Elevated HMGB1 was confirmed in intestinal epithelia and serum following conditional loss of Apc. Treatment of Apcflox mice with anti-HMGB1 neutralising antibody significantly reduced many of the crypt progenitor phenotypes associated with Apc loss; proliferation and apoptosis levels were reduced, cell differentiation was restored and the expansion of stem cell marker expression was eradicated.

METHODS

Hmgb1 levels in intestinal epithelia and serum in Apcflox and ApcMin mice were assessed using qRT-PCR, Western blot and ELISA assays. The functional importance of elevated extracellular Hmgb1 was assessed using an anti-HMGB1 neutralising antibody in Apcflox mice.

CONCLUSIONS

HMGB1 is expressed and secreted from intestinal epithelial cells in response to Wnt signalling activation. This secreted HMGB1 is required to maintain nearly all aspects of the crypt progenitor phenotype observed following Apc loss and add to the body of accumulating evidence indicating that targeting HMGB1 may be a viable novel therapeutic approach.

AAL exacerbates pro-inflammatory response in macrophages by regulating Mincle/Syk/Card9 signaling along with the Nlrp3 inflammasome assembly

Previously, we demonstrated that Agrocybe aegerita lectin (AAL), a galectin isolated from edible mushroom Agrocybe aegerita, exerts potent anti-tumor activity, while the mechanisms by which AAL suppresses tumor growth are yet to be elucidated. Here, we conducted studies with focus for its impact on the cecal ligation and puncture (CLP)-induced innate immune response. Administration of AAL significantly exacerbated the severity of CLP-induced septic shock as manifested the increased lethality. AAL promoted inflammatory cytokine production by preferentially regulating macrophage activation and recruitment. Mechanistic studies revealed that AAL likely targets macrophages through receptor Mincle to activate Syk/Card9 signaling, which then couples to the Nlrp3 inflammasome assembly. It was further noted that AAL markedly promotes H3K4 di- and trimethylation, by which it enhances Hmgb1 expression. Specifically, AAL induced macrophages secretion of copious amount of Hmgb1 as manifested the Hmgb1 cytoplasmic translocation along with the detection of extracellular Hmgb1. AAL also stimulated a significant increase for nuclear Hmgb1, which then formed a complex with RelA, and thereby enhancing NF-κB transcriptional activity. Together, our data suggest that AAL may possess important pharmaceutical properties in the regulation of innate immune response.

Necrostatin-1 inhibits Hmgb1-IL-23/IL-17 pathway and attenuates cardiac ischemia reperfusion injury

Ischemia reperfusion (IR) injury is a major issue in cardiac transplantation and inflammatory processes play a major role in myocardial IR injury. Necrostatin-1 (Nec-1) is a small molecule capable of inhibiting RIP1 kinase activity and attenuates inflammation-mediated tissue injury. In our study, hearts of C57Bl/6 mice were flushed and stored in cold Bretschneider solution for 8 h and then transplanted into syngeneic recipients. We found that Nec-1 decreased cardiomyocyte necrosis and recruitment of neutrophils and macrophages. Troponin T (TnT) production on 24 h after myocardial IR injury was reduced by Nec-1 administration. Cardiac output at 60 mmHg of afterload pressure was significantly increased in hearts with Nec-1 administration and the cardiac allograft survival in Nec-1-treated animals was significantly prolonged (MST = 90 days in IR + Nec-1 group, P < 0.05 as compared with IR group, MST = 83.5 days). Nec-1 treatment attenuated ROS generation and increased expression of NOS2 and COX-2. The expression of Hmgb1, IL-23, and IL-17A were also decreased with Nec-1 administration. Furthermore, the decreased TnT expression induced by Nec-1 was abrogated with exogenous Hmgb1 administration. In conclusion, Nec-1 played a protective role in cardiomyocyte IR injury, and this was associated with inhibited Hmgb1-IL-23/IL-17 pathway.