Genipin attenuates sepsis-induced immunosuppression through inhibition of T lymphocyte apoptosis

Therapeutic potentials of iridoids derived from Rubiaceae against in vitro and in vivo inflammation: A scoping review

Acute inflammation may develop into chronic, life-threatening inflammation-related diseases if left untreated or if there are persistent triggering factors. Cancer, diabetes mellitus, stroke, cardiovascular diseases, and neurodegenerative disorders are some of the inflammation-related diseases affecting millions of people worldwide. Despite that, conventional medical therapy such as non-steroidal anti-inflammatory drugs (NSAIDs) is associated with serious adverse effects; hence, there is an urgent need for a newer and safer therapeutic alternative from natural sources. Iridoids are naturally occurring heterocyclic monoterpenoids commonly found in Rubiaceae plants. Plant extracts from the Rubiaceae family were demonstrated to have medicinal benefits against neurodegeneration, inflammation, oxidative stress, hyperglycaemia, and cancer. However, the therapeutic effects of natural iridoids derived from Rubiaceae as well as their prospective impacts on inflammation in vitro and in vivo have not been thoroughly explored. The databases of PubMed, Scopus, and Web of Science were searched for pertinent articles in accordance with PRISMA-ScR guidelines. A total of 31 pertinent articles from in vitro and in vivo studies on the anti-inflammatory potentials of iridoids from Rubiaceae were identified. According to current research, genipin, geniposide, and monotropein are the most researched iridoids from Rubiaceae that reduce inflammation. These iridoids primarily act by attenuating inflammatory cytokines and mediators via inhibition of the NF-κB signalling pathway in various disease models. A comprehensive overview of the current research on the anti-inflammatory properties of iridoids from the Rubiaceae family is presented in this review, highlighting the characteristics of the experimental models used as well as the mechanisms of action of these iridoids. To develop an alternative therapeutic agent from iridoids, more studies are needed to elucidate the effects and mechanism of action of iridoids in a wide variety of experimental models as well as in clinical studies pertaining to inflammation-related diseases.

Early immune system alterations in patients with septic shock

This study aims to investigate the early changes in the immune systems of patients with septic shock. A total of 243 patients with septic shock were included in this study. The patients were classified as survivors (n = 101) or nonsurvivors (n = 142). Clinical laboratories perform tests of the immune system's function. Each indicator was studied alongside healthy controls (n = 20) of the same age and gender as the patients. A comparative analysis of every two groups was conducted. Univariate and multivariate logistic regression analyses were performed to identify mortality risk factors that are independent of one another. In septic shock patients, neutrophil counts, infection biomarkers (C-reactive protein, ferritin, and procalcitonin levels), and cytokines (IL-1β, IL-2R, IL-6, IL-8, IL-10, and TNF-α) increased significantly. Lymphocyte and their subset counts (T, CD4+ T, CD8+ T, B, and natural killer cell counts), lymphocyte subset functions (the proportions of PMA/ionomycin-stimulated IFN-γ positive cells in CD4+ T cells), immunoglobulin levels (IgA, IgG, and IgM), and complement protein levels (C3 and C4) decreased significantly. Compared to survivors, nonsurvivors had higher levels of cytokines (IL-6, IL-8, and IL-10) but lower levels of IgM, complement C3 and C4, and lymphocyte, CD4+, and CD8+ T cell counts. Low IgM or C3 concentrations and low lymphocyte or CD4+ T cell counts were independent risk factors for mortality. These alterations should be considered in the future development of immunotherapies aimed at treating septic shock.

ICU and Sepsis: Role of Myeloid and Lymphocyte Immune Cells

Sepsis is a severe immune system reaction to infection and a major cause of ICU-related fatalities. Because of the high mortality, high cost of treatment, and complex aetiology of sepsis, sepsis has a huge impact on healthcare. Some of the health complications in sepsis are abnormal cardiac functions, hypoperfusion, hypotension, tissue damage, multiple organ failure, and ultimately death. Individuals with weak immune systems and chronic medical conditions are highly vulnerable to sepsis. In sepsis, a patient shows the extreme immune response in the initial stage while prolonged immunosuppression in the later stages. Sepsis-driven immunosuppression ushers in death because sepsis cases develop secondary infections postrecovery. The later immunocompromised state in sepsis is attributed myeloid-derived suppressor cell upregulation and reduced immune activity displayed by lymphocytes (lymphocyte anergy). As a result, it is currently suggested that regulating the immune response is a better therapeutic approach than focusing on inflammation to improve the immune system's capacity to fight infections. Moreover, finding novel and accurate prognostic biomarkers that can help in rapid sepsis diagnoses and deciding better therapeutic strategies will significantly lower clinical case mortality rates.

Phosphodiesterase-4 Inhibitor Roflumilast-Mediated Protective Effect in Sepsis-Induced Late-Phase Event of Acute Kidney Injury: A Narrative Review

Severe infections such as viral, bacterial, or fungal sepsis can cause an inflammatory response in the host, leading to organ failure and septic shock—phosphodiesterase-4 (PDE-4) inhibiting related agents from suppressing cyclic adenosine monophosphate (cAMP) degradation. Regulatory organisations have approved some substances in this category to reduce the risk of chronic obstructive pulmonary disease (COPD) exacerbations in patients with chronic bronchitis and a history of COPD exacerbations. Roflumilast has been shown to alleviate inflammatory responses, thus regulating airway inflammation. Additionally, roflumilast therapy dramatically enhanced B-cell lymphoma 2 (Bcl-2) expression, an anti-apoptotic marker lowered in septic animals. Previous research has indicated that roflumilast may help reverse sepsis-induced liver and lung harm, but whether it is also effective in reversing sepsis-induced renal impairment remains unknown. Therefore, this review determines whether roflumilast protects against renal dysfunction, inflammatory response, and apoptosis in sepsis-induced kidney damage. Additionally, we discussed the molecular mechanism through which roflumilast exerts its protective effect to uncover a possible treatment agent for sepsis-induced renal impairment.

Electroacupuncture at ST36 (Zusanli) Prevents T-Cell Lymphopenia and Improves Survival in Septic Mice

Purpose

Sepsis is the main cause of death in intensive care unit. Maladaptive cytokine storm and T-cell lymphopenia are critical prognosis predictors of sepsis. Electroacupuncture (EA) is expected to be an effective intervention to prevent sepsis. This study aims to determine the potential of EA at ST36 (Zusanli) to prevent experimental septic mice.

Methods

Mice were randomly assigned into PBS, LPS, or EA+LPS group. EA (0.1 mA, continuous wave, 10 Hz) was performed stimulating the ST36 for 30 min, once a day for 3 days. After the third day, all mice were challenged with PBS or LPS (4 mg/kg) simultaneously. Mice were evaluated for survival, ear temperature, and other clinical symptoms. Lung and small intestine tissue injuries were analyzed by hematoxylin and eosin staining. Bio-Plex cytokine assay was used to analyze the concentration of cytokines. T lymphocytes were analyzed by flow cytometry and Western blot assays. The role of T cells in preventing sepsis by EA was analyzed by using nude mice lacking T lymphocytes.

Results

EA at ST36 improved survival, symptom scores, and ear temperature of endotoxemic mice. EA also improved dramatically pulmonary and intestinal injury by over 50% as compared to untreated mice. EA blunted the inflammatory cytokine storm by inducing a lasting inhibition of the production of major inflammatory factors (TNF-α, IL-1β, IL-5, IL-6, IL-10, IL-17A, eotaxin, IFN-γ, MIP-1β and KC). Flow cytometry and Western blot analyses showed EA significantly reduced T-lymphocyte apoptosis and pyroptosis. Furthermore, T lymphocytes were critical for the effects of EA at ST36 stimulation blunted serum TNF-α levels in wild-type but not in nude mice.

Conclusion

EA halted systemic inflammation and improved survival in endotoxemic mice. These effects are associated with the protective effect of EA on T lymphocytes, and T cells are required in the anti-inflammatory effects of EA in sepsis.

EGFR promotes the apoptosis of CD4+ T lymphocytes through TBK1/Glut1 induced Warburg effect in sepsis

INTRODUCTION

Sepsis-induced apoptosis leads to lymphopenia including the decrease of CD4⁺ T cells thus favoring immunosuppression.

OBJECTIVES

Although epidermal growth factor receptor (EGFR) inhibitors significantly improve the survival rate of septic mice, the effect of EGFR on the function and metabolism of CD4⁺ T cells in sepsis remained unknown.

METHODS

CD4⁺ T cells from septic mice and patients were assessed for apoptosis, activation, Warburg metabolism and glucose transporter 1 (Glut1) expression with or without the interference of EGFR activation.

RESULTS

EGFR facilitates CD4⁺ T cell activation and apoptosis through Glut1, which is a key enzyme that controls glycolysis in T cells. EGFR, TANK binding kinase 1 (TBK1) and Glut1 form a complex to facilitate Glut1 transportation from cytoplasm to cell surface. Both the levels of membrane expression of EGFR and Glut1 and the activation levels of CD4⁺ T cells were significantly higher in patients with sepsis as compared with healthy subjects.

CONCLUSION

Our data demonstrated that through its downstream TBK1/Exo84/RalA protein system, EGFR regulates Glut1 transporting to the cell surface, which is a key step for inducing the Warburg effect and the subsequent cellular activation and apoptosis of CD4⁺ T lymphocytes and may eventually affect the immune functional status, causing immune cell exhaustion in sepsis.

Association between miR-126, miR-21, inflammatory factors and T lymphocyte apoptosis in septic rats

MicroRNAs (miRs) serve an important role in regulating expression levels of inflammatory factors but the underlying mechanism is still unclear. The present study aimed to observe miR-126 and miR-21 expression and apoptosis in T lymphocytes and to analyze their association with cytokine release in septic rats. The septic model rats were given intraperitoneal lipopolysaccharide (LPS) and divided into 0, 12, 24, 48 and 72 h groups. Peripheral blood was collected from each group to isolate T lymphocytes. The expression levels of miR-126 and miR-21 in T lymphocytes were observed, as well as cytokine release and apoptosis. Finally, the association between miR-126, miR-21, cytokines and apoptosis in T lymphocytes was analyzed. The release of TNF-α and IL-6 in septic rats was initially elevated but then decreased. miR-126 and miR-21 levels in T lymphocytes in septic rats were lower than those of NC rats. miR-126 and miR-21 initially decreased and then increased, whereas of apoptosis of T lymphocytes increased and then decreased, in septic rats. The expression of miR-126 was positively correlated with that of miR-21 (r=0.316; P=0.029) and negatively correlated with that of TNF-α (r=-0.480; P=0.001) and IL-6 (r=-0.626; P<0.001), as well as the apoptotic rate of T lymphocytes (r=-0.377; P=0.008). Furthermore, expression levels of miR-126 were negatively corrlated with caspase-3 expression levels (r=-0.606; P<0.001) and activity (r=-0.541; P<0.001). There was a negative correlation between miR-21 and levels of TNF-α (r=-0.311; P=0.032) and IL-6 (r=-0.439; P=0.002), as well as caspase-3 expression (r=-0.398; P=0.005) and activity (r=-0.378; P=0.008). However, there miR-126 expression was not correlated with apoptotic rate of T lymphocytes. Altered expression levels of miR-126 and miR-21 reflected the severity of inflammatory response and indicated levels of T lymphocyte apoptosis in septic rats.

Roflumilast improves resolution of sepsis-induced acute kidney injury by retarding late phase renal interstitial immune cells infiltration and leakage in urinary sediments

Some evidence has demonstrated that both inflammation and immune cell dysregulation are coincident at late phase (post 24 h) of sepsis. The present study was designed to determine the pathological role of hyperinflammation and renal immune cells mobilization during late phase of sepsis induced acute kidney injury (S-AKI) and tests the pharmacological effects of PDE-4 inhibitor on these events. Sepsis was induced by cecal ligation puncture and renal function, oxidative-inflammatory stress biomarkers were assessed after 24 h. PDE-4 inhibitor was administered for 7 days prior to induction of S-AKI. Renal immune cells infiltration during sepsis was analyzed by H&E staining and papanicolaou staining method was used for detecting leukocytes and cast in urinary sediments, periodic acid schiff (PAS) staining was used for detection of brush border loss. AKI developed 24 h post sepsis insult as depicted by increase in serum creatinine, blood urea nitrogen (BUN), renal oxidative stress, and elevated inflammatory biomarkers levels. Moreover, septic rats displayed increased bacterial load, renal expression of phosphodiesterase-4B, 4D isoforms, enhanced vascular permeability, caspase-3 and myeloperoxidase activity, electrolyte imbalance, reduced Na⁺ K⁺ ATPase activity, declined cAMP levels, increased interstitial leukocyte infiltration, and leakage in urinary sediments along with histological alterations. Pre-treatment with roflumilast at high dose completely prevented the various AKI associated manifestations in septic rats. Renal hyper-inflammation and leukocyte infiltration was detected in late phase of S-AKI. Roflumilast pre-treatment resolved sepsis induced renal dysfunction and histological damage by suppressing late phase renal immune cells invasion and anti-inflammatory effects mediated by up-regulation of renal cAMP levels.

Lessons Learned Comparing Immune System Alterations of Bacterial Sepsis and SARS-CoV-2 Sepsis

Background

Bacterial sepsis has been used as a prototype to understand the pathogenesis of severe coronavirus disease 2019 (COVID-19). In addition, some management programs for critically ill COVID-19 patients are also based on experience with bacterial sepsis. However, some differences may exist between these two types of sepsis.

Methods

This retrospective study investigated whether there are differences in the immune system status of these two types of sepsis. A total of 64 bacterial sepsis patients and 43 patients with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) sepsis were included in this study. Demographic data were obtained from medical records. Laboratory results within 24 h after the diagnosis of sepsis were provided by the clinical laboratory.

Results

The results of blood routine (neutrophil, lymphocyte, and monocyte counts), infection biomarkers (C-reactive protein, ferritin, and procalcitonin levels), lymphocyte subset counts (total T lymphocyte, CD4+ T cell, CD8+ T cell, B cell, and NK cell counts), and lymphocyte subset functions (the proportions of PMA/ionomycin-stimulated IFN-γ positive cells in CD4+, CD8+ T cells, and NK cells) were similar in bacterial sepsis patients and SARS-CoV-2 sepsis patients. Cytokine storm was milder, and immunoglobulin and complement protein levels were higher in SARS-CoV-2 sepsis patients.

Conclusions

There are both similarities and differences in the immune system status of bacterial sepsis and SARS-CoV-2 sepsis. Our findings do not support blocking the cytokine storm or supplementing immunoglobulins in SARS-CoV-2 sepsis, at least in the early stages of the disease. Treatments for overactivation of the complement system and lymphocyte depletion may be worth exploring further.

Early Activation of Myeloid-Derived Suppressor Cells Participate in Sepsis-Induced Immune Suppression via PD-L1/PD-1 Axis

Background: Myeloid derived suppressor cells (MDSCs) have been reported to keep elevating during sepsis. The current study was performed to investigate the immunosuppressive effect of MDSCs and their subsets with the underlying mechanisms. Methods: The immunosuppressive status was manifested by the apoptosis of splenocytes, quantity of T cells and PD-1 expression. The dynamics of quantity and PD-L1 level of MDSCs and the subsets were determined over time. The subset of MDSCs with high PD-L1 level was co-cultured with T cells to observe the suppressive effect. Results: Abdominal abscess was observed after 7 days post-sepsis. Five biomarkers related to organ functions were all significantly higher in the CLP group. The survival rate was consistent with the middle grade severity of sepsis model. Apoptosis of splenocytes increased over time during sepsis; CD4 + T cell decreased from day 1 post-sepsis; CD8+ T cells significantly reduced at day 7. The PD-1 expression in spleen was upregulated from an early stage of sepsis, and negatively related with the quantity of T cells. MDSCs were low at day 1 post-sepsis, but increased to a high level later; the dynamics of PMN-MDSC was similar to MDSCs. PD-L1 on MDSCs was highest at day 1 post-sepsis; PMN-MDSC was the main subset expressing PD-L1. The PMN-MDSC with high PD-L1 expression level extracted on day 1 after surgery from CLP mice significantly inhibited the proliferation of T cells. Conclusions: Sepsis-induced immunosuppression is initiated from a very early stage, a high expression level of PD-L1 on MDSCs and the main subset, PMN-MDSC might play a critical role suppressive role on T cells through PD-L1/PD-1 axis.

Gardenia jasminoides extract and its constituent, genipin, inhibit activation of CD3/CD28 co-stimulated CD4+ T cells via ORAI1 channel

Gardenia jasminoides (GJ) is a widely used herbal medicine with anti-inflammatory properties, but its effects on the ORAI1 channel, which is important in generating intracellular calcium signaling for T cell activation, remain unknown. In this study, we investigated whether 70% ethanolic GJ extract (GJ_EtOH) and its subsequent fractions inhibit ORAI1 and determined which constituents contributed to this effect. Whole-cell patch clamp analysis revealed that GJ_EtOH (64.7% ± 3.83% inhibition at 0.1 mg/ml) and all its fractions showed inhibitory effects on the ORAI1 channel. Among the GJ fractions, the hexane fraction (GJ_HEX, 66.8% ± 9.95% at 0.1 mg/ml) had the most potent inhibitory effects in hORAI1-hSTIM1 co-transfected HEK293T cells. Chemical constituent analysis revealed that the strong ORAI1 inhibitory effect of GJ_HEX was due to linoleic acid, and in other fractions, we found that genipin inhibited ORAI1. Genipin significantly inhibited I_ORAI1 and interleukin-2 production in CD3/CD28-stimulated Jurkat T lymphocytes by 35.9% ± 3.02% and 54.7% ± 1.32% at 30 μM, respectively. Furthermore, the same genipin concentration inhibited the proliferation of human primary CD4⁺ T lymphocytes stimulated with CD3/CD28 antibodies by 54.9% ± 8.22%, as evaluated by carboxyfluorescein succinimidyl ester assay. Our findings suggest that genipin may be one of the active components of GJ responsible for T cell suppression, which is partially mediated by activation of the ORAI1 channel. This study helps us understand the mechanisms of GJ in the treatment of inflammatory diseases.

Therapeutic potential of genipin in various acute liver injury, fulminant hepatitis, NAFLD and other non-cancer liver diseases: More friend than foe

Genipin is an aglycone derived from the geniposide, the most abundant iridoid glucoside constituent of Gardenia jasminoides Ellis. For decades, genipin is the focus of studies as a versatile compound in the treatment of various pathogenic conditions. In particularly, Gardenia jasminoides Ellis has long been used in traditional Chinese medicine for the prevention and treatment of liver disease. Mounting experimental data has proved genipin possesses therapeutic potential for cholestatic, septic, ischemia/reperfusion-triggered acute liver injury, fulminant hepatitis and NAFLD. This critical review is a reflection on the valuable lessons from decades of research regarding pharmacological activities of genipin. Of note, genipin represents choleretic effect by potentiating bilirubin disposal and enhancement of genes in charge of the efflux of a number of organic anions. The anti-inflammatory capability of genipin is mediated by suppression of the production and function of pro-inflammatory cytokines and inflammasome. Moreover, genipin modulates various transcription factor and signal transduction pathway. Genipin appears to trigger the upregulation of several key genes encoding antioxidant and xenobiotic-metabolizing enzymes. Furthermore, the medicinal impact of genipin extends to modulation of regulated cell death, including autophagic cell death, apoptosis, necroptosis and pyroptosis, and modulation of quality of cellular organelle. Another crucial effect of genipin appears to be linked to dual role in targeting uncoupling protein 2 (UCP2). As a typical UCP2-inhibiting compound, genipin could inhibit AMP-activated protein kinase or NF-κB in circumstance. On the contrary, reactive oxygen species production and cellular lipid deposits mediated by genipin through the upregulation of UCP2 is observed in liver steatosis, suggesting the precise role of genipin is disease-specific. Collectively, we comprehensively summarize the mechanisms and pathways associated with the hepatoprotective activity of genipin and discuss potential toxic impact. Notably, our focus is the direct medicinal effect of genipin itself, whereas its utility as a crosslinking agent in tissue engineering is out of scope for the current review. Further studies are therefore required to disentangle these complicated pharmacological properties to confer this natural agent a far greater potency.

Histone Deacetylation Inhibitors as Modulators of Regulatory T Cells

Regulatory T cells (T_regs) are important mediators of immunological self-tolerance and homeostasis. Being cluster of differentiation 4⁺Forkhead box protein3⁺ (CD4⁺FOXP3⁺), these cells are a subset of CD4⁺ T lymphocytes and can originate from the thymus (tT_regs) or from the periphery (pT_regs). The malfunction of CD4⁺ T_regs is associated with autoimmune responses such as rheumatoid arthritis (RA), multiple sclerosis (MS), type 1 diabetes (T1D), inflammatory bowel diseases (IBD), psoriasis, systemic lupus erythematosus (SLE), and transplant rejection. Recent evidence supports an opposed role in sepsis. Therefore, maintaining functional T_regs is considered as a therapy regimen to prevent autoimmunity and allograft rejection, whereas blocking T_reg differentiation might be favorable in sepsis patients. It has been shown that T_regs can be generated from conventional naïve T cells, called iT_regs, due to their induced differentiation. Moreover, T_regs can be effectively expanded in vitro based on blood-derived tT_regs. Taking into consideration that the suppressive role of T_regs has been mainly attributed to the expression and function of the transcription factor Foxp3, modulating its expression and binding to the promoter regions of target genes by altering the chromatin histone acetylation state may turn out beneficial. Hence, we discuss the role of histone deacetylation inhibitors as epigenetic modulators of T_regs in this review in detail.

Tumor Necrosis Factor-α-Induced Protein 8-like 2 Downregulation Reduces CD4⁺ T Lymphocyte Apoptosis in Mice with Thermal Injury

Background

Cellular immunity plays a crucial role in sepsis, and lymphocyte apoptosis is a key factor in immune homeostasis. Tumor necrosis factor-α (TNF-α)-induced protein 8-like 2 (TIPE2) is suggested to play a critical role in maintaining immune homeostasis. This study investigated the role of TIPE2 in CD4⁺ T lymphocyte apoptosis based on a mouse model of thermal injury.

Material/Methods

BALB/c male mice were randomized into 6 groups: sham, burn, burn with siTIPE2, burn with siTIPE2 control, burn with TIPE2, and burn with TIPE2 control groups. Splenic CD4⁺ T lymphocytes were collected by use of a magnetic cell sorting system.

Results

We found that TIPE2 downregulation reduced the CD4⁺ T lymphocytes apoptosis in the burn with siTIPE2 group, and the protein expression of P-smad2/P-Smad3 were remarkably downregulated. In the burn with siTIPE2 group, Bcl-2 expression was increased compared with that in the sham group (P<0.05), and Bim expression was reduced (P<0.05). In the burn with TIPE2 group, the mitochondrial membrane potential was markedly reduced (P<0.01), while cytochrome C expression was clearly higher than that in the other groups (P<0.01). Activities of caspase-3, -8, and -9 were notably higher in the burn with TIPE2 group relative to those for other groups (P<0.05).

Conclusions

Downregulation of TIPE2 in vivo can reduce the apoptosis of CD4⁺ T lymphocytes following thermal damage, and activate the TGFβ downstream signaling of Smad2/Smad3, upregulating Bim, and downregulating Bcl-2.

Exosomes derived from plasma of septic patients inhibit apoptosis of T lymphocytes by down-regulating bad via hsa-miR-7-5p

Immunosuppression is currently a vital pathophysiological characteristic and core problem of sepsis. Apoptosis of T lymphocyte contribute to immunosuppression by decreasing immune effector cells. A report has recently revealed the potential regulatory role of exosomal miRNAs derived from plasma of septic patients on immune system, but the underlying mechanism is unclear. We discovered the antiapoptotic effect of circulating exosomes derived from plasma of septic patients (Sepsis-Exos) on T lymphocytes and further investigated the molecular mechanism. Next-generation sequencing (NGS) indicated that sepsis induces prominent change of exosomal miRNA expression profile, including the overexpressed hsa-miR-7-5p. Gene Bad, which is in the cGMP-PKG signaling pathway, was negatively regulated by hsa-miR-7-5p by dual luciferase reporter assay. Sepsis-Exos were demonstrated to downregulate the mRNA and protein levels of proapoptotic gene Bad, active Caspase-3 and Bax, while upregulate that of antiapoptotic gene Bcl-2 via hsa-miR-7-5p, thus inhibited apoptosis of T lymphocytes induced by lipopolysaccharide (LPS) in vitro. Furthermore, Sepsis-Exos was verified to inhibit T lymphocytes apoptosis during sepsis in vivo, reducing mortality rate of septic model mice. In conclusion, we provide evidence that Sepsis-Exos participate in ameliorating apoptosis of T lymphocytes by directly suppressing Bad via hsa-miR-7-5p.

New iridoids from Verbascum nobile and their effect on lectin-induced T cell activation and proliferation

The Verbascum species are widely used traditional herb remedies against respiratory, inflammatory conditions and disorders. In the present study methanol extract of the aerial parts of the endemic Verbascum nobile Velen, was investigated and two novel iridoid glycosides 1 and 2, together with nine known constituents: iridoids, phenylethanoids, and saponins characteristic of Verbascum genus were identified. Further, the biological activity of the extract and selected isolated compounds on concanavalin (Con A)-induced T cell proliferation and activation of human Jurkat T cell line and splenic murine CD3 T cells was evaluated. T cell growth was studied by colorimetric-based WST proliferation assay while DNA content, cell cycling, dynamic of cell proliferation, expression of activation markers, intracellular expression of cytokine IFN-γ, and phosphorylation of ERK were analyzed by flow cytometry. Caspase-mediated apoptosis resulting in a poly (ADP-ribose) polymerase (PARP) cleavage was assessed by colorimetric in-cell kit. It was found that the extract, and all tested compounds (1, 2, 3 and 9) inhibited lectin-induced cell growth of Jurkat T cell line. The novel compounds decreased the frequencies of cells in S phase without causing a significant cell cycle arrest at G1 phase, caspases-mediated apoptosis and/or a profound change in the dynamic of splenic murine CD3⁺ T cell proliferation. Both compounds showed stronger inhibitory effect on Con A-induced ERK phosphorylation than the known bioactive compounds 3 and 9, and suppressed the expression of early activation marker CD69, the intracellular level of IFN-γ, and the generation of CD3⁺IFN-γ⁺ effectors. Our data suggest that the novel iridoid glycosides might have a potential to modulate T cell-related pathologies.

TLR4 Signaling Pathway Modulators as Potential Therapeutics in Inflammation and Sepsis

Toll-Like Receptor 4 (TLR4) signal pathway plays an important role in initiating the innate immune response and its activation by bacterial endotoxin is responsible for chronic and acute inflammatory disorders that are becoming more and more frequent in developed countries. Modulation of the TLR4 pathway is a potential strategy to specifically target these pathologies. Among the diseases caused by TLR4 abnormal activation by bacterial endotoxin, sepsis is the most dangerous one because it is a life-threatening acute system inflammatory condition that still lacks specific pharmacological treatment. Here, we review molecules at a preclinical or clinical phase of development, that are active in inhibiting the TLR4-MyD88 and TLR4-TRIF pathways in animal models. These are low-molecular weight compounds of natural and synthetic origin that can be considered leads for drug development. The results of in vivo studies in the sepsis model and the mechanisms of action of drug leads are presented and critically discussed, evidencing the differences in treatment results from rodents to humans.

Rhodiola rosea suppresses thymus T-lymphocyte apoptosis by downregulating tumor necrosis factor-α-induced protein 8-like-2 in septic rats

In recent years, several studies have shown that Rhodiola rosea can enhance cellular immunity and humoral immune function in mice, and thus, it has become a research hotspot. However, its underlying mechanism of action has remained elusive. The present study investigated whether Rhodiola rosea was able to downregulate the expression of tumor necrosis factor-α-inducible protein 8-like 2 (TIPE2), thereby inhibiting the expression of apoptotic genes, attenuating T-lymphocyte apoptosis and improving immunity in septic mice. A mouse model of caecal ligation and puncture (CLP)-induced sepsis was established, and animals in the treatment group were pre-treated with an intraperitoneal injection of Rhodiola rosea extract, while animals in the control group and sham-operated group were injected with an equivalent amount of normal saline. TIPE2, B-cell lymphoma 2 (Bcl-2), Fas and Fas ligand (FasL) mRNA and protein levels in thymic T cells were determined using reverse transcription quantitative polymerase chain reaction and western blot analysis, respectively. Furthermore, the thymus T-lymphocyte apoptosis rate, thymus T-lymphocyte count and thymus T-lymphocyte sub-sets were assessed using flow cytometry. Levels of T-helper cell type 1 (Th1) cytokines [Interleukin (IL)-2, IL-12 and interferon (IFN)-γ] and Th2 cytokines (IL-4 and IL-10) were determined using ELISA. The results showed that, compared to that in the CLP group, the expression of TIPE2, Fas and FasL in the treatment group was significantly decreased, while the expression of Bcl-2 was increased (P<0.05). The thymus lymphocyte count in the CLP group was significantly higher compared with that in the treatment group (P<0.05). Furthermore, the apoptotic rate of thymus T-lymphocytes in the treatment group was significantly lower than that in the CLP group (P<0.05). In addition, treatment with Rhodiola rosea rescued decreased in the counts of the CD3⁺ T and CD4⁺ T sub-sets of thymus T lymphocytes in the CLP group (P<0.05), while not affecting the increased levels of Th2 cytokines (IL-4 and IL-10) in the CLP group compared with those in the control groups. In addition, the Th1 cytokines (IL-12, IL-2 and IFN-γ) were significantly increased (P<0.05) in the CLP group, and treatment with Rhodiola rosea led to further increases. The thymus index of septic mice treated with Rhodiola rosea as well as their survival rate were improved as compared with those in the CLP group. These findings suggested that Rhodiola rosea has protective effects against sepsis by decreasing apoptosis, increasing Th1 cytokines and enhancing the host’s immunity via the regulation of TIPE2 expression.