Regulation of a lymphocyte-endothelial-IL-6 trans-signaling axis by fever-range thermal stress: hot spot of immune surveillance

Alternative splicing of modulatory immune receptors in T lymphocytes: a newly identified and targetable mechanism for anticancer immunotherapy

Alternative splicing (AS) is a mechanism that generates translational diversity within a genome. Equally important is the dynamic adaptability of the splicing machinery, which can give preference to one isoform over others encoded by a single gene. These isoform preferences change in response to the cell's state and function. Particularly significant is the impact of physiological alternative splicing in T lymphocytes, where specific isoforms can enhance or reduce the cells' reactivity to stimuli. This process makes splicing isoforms defining features of cell states, exemplified by CD45 splice isoforms, which characterize the transition from naïve to memory states. Two developments have accelerated the use of AS dynamics for therapeutic interventions: advancements in long-read RNA sequencing and progress in nucleic acid chemical modifications. Improved oligonucleotide stability has enabled their use in directing splicing to specific sites or modifying sequences to enhance or silence particular splicing events. This review highlights immune regulatory splicing patterns with potential significance for enhancing anticancer immunotherapy.

Interleukin-6 serves as a critical factor in various cancer progression and therapy

Interleukin-6 (IL-6), a pro-inflammatory cytokine, plays a crucial role in host immune defense and acute stress responses. Moreover, it modulates various cellular processes, including proliferation, apoptosis, angiogenesis, and differentiation. These effects are facilitated by various signaling pathways, particularly the signal transducer and activator of transcription 3 (STAT3) and Janus kinase 2 (JAK2). However, excessive IL-6 production and dysregulated signaling are associated with various cancers, promoting tumorigenesis by influencing all cancer hallmarks, such as apoptosis, survival, proliferation, angiogenesis, invasiveness, metastasis, and notably, metabolism. Emerging evidence indicates that selective inhibition of the IL-6 signaling pathway yields therapeutic benefits across diverse malignancies, such as multiple myeloma, prostate, colorectal, renal, ovarian, and lung cancers. Targeting key components of IL-6 signaling, such as IL-6Rs, gp130, STAT3, and JAK via monoclonal antibodies (mAbs) or small molecules, is a heavily researched approach in preclinical cancer studies. The purpose of this study is to offer an overview of the role of IL-6 and its signaling pathway in various cancer types. Furthermore, we discussed current preclinical and clinical studies focusing on targeting IL-6 signaling as a therapeutic strategy for various types of cancer.

Effects of unburned tobacco smoke on inflammatory and oxidative mediators in the rat prefrontal cortex

Although the Food and Drug Administration has authorized the marketing of "heat-not-burn" (HnB) electronic cigarettes as a modified risk tobacco product (MRTP), toxicological effects of HnB smoke exposure on the brain are still unexplored. Here, paramagnetic resonance of the prefrontal cortex (PFC) of HnB-exposed rats shows a dramatic increase in reactive radical species (RRS) yield coupled with an inflammatory response mediated by NF-κB-target genes including TNF-α, IL-1β, and IL-6 and the downregulation of peroxisome proliferator-activated receptor (PPAR) alpha and gamma expression. The PFC shows higher levels of 8-hydroxyguanosine, a marker of DNA oxidative damage, along with the activation of antioxidant machinery and DNA repair systems, including xeroderma pigmentosum group C (XPC) protein complex and 8-oxoguanine DNA glycosylase 1. HnB also induces the expression of drug-metabolizing enzymes such as CYP1A1, CYP2A6, CYP2B6, and CYP2E, particularly involved in the biotransformation of nicotine and several carcinogenic agents such as aldehydes and polycyclic aromatic hydrocarbons here recorded in the HnB stick smoke. Taken together, these effects, from disruption of redox homeostasis, inflammation, PPAR manipulation along with enhanced bioactivation of neurotoxicants, and upregulation of cMYC protooncogene to impairment of primary cellular defense mechanisms, suggest a possible increased risk of brain cancer. Although the HnB device reduces the emission of tobacco toxicants, our findings indicate that its consumption may carry a risk of potential adverse health effects, especially in non-smokers so far. Further studies are needed to fully understand the long-term effects of these devices.

Interleukin 6: at the interface of human health and disease

Interleukin 6 (IL-6) is a pleiotropic cytokine executing a diverse number of functions, ranging from its effects on acute phase reactant pathways, B and T lymphocytes, blood brain barrier permeability, synovial inflammation, hematopoiesis, and embryonic development. This cytokine empowers the transition between innate and adaptive immune responses and helps recruit macrophages and lymphocytes to the sites of injury or infection. Given that IL-6 is involved both in the immune homeostasis and pathogenesis of several autoimmune diseases, research into therapeutic modulation of IL-6 axis resulted in the approval of a number of effective treatments for several autoimmune disorders like neuromyelitis optica spectrum disorder (NMOSD), rheumatoid arthritis, juvenile idiopathic arthritis, polyarticular juvenile idiopathic arthritis, giant cell arteritis (GCA), and cytokine release syndrome, associated with SARS-CoV2 pneumonia. This review discusses downstream inflammatory pathways of IL-6 expression and therapeutic applications of IL-6 blockade, currently investigated for the treatment of several other autoimmune conditions such as autoimmune encephalitis, autoimmune epilepsy, as well as myelin oligodendrocyte glycoprotein associated demyelination (MOGAD). This review further highlights the need for clinical trials to evaluate IL-6 blockade in disorders such neuropsychiatric lupus erythematosus (SLE), sarcoidosis and Behcet's.

Therapeutic hyperthermia for the treatment of infection-a narrative review

Modulating body temperature, mostly through the use of antipyretics, is a commonly employed therapeutic intervention in medical practice. However, emerging evidence suggests that hyperthermia could serve as an adjuvant therapy for patients with infection. We performed a narrative review to explore the application of therapeutic hyperthermia in the treatment of infection. A number of studies have been performed in the pre-antibiotic era, enrolling patients with neurosyphilis and gonococcal infections, with reported cure rates at around 60%-80%. We have outlined the potential molecular and immunological mechanisms explaining the possible beneficial effects of therapeutic hyperthermia. For some pathogens increased temperature exerts a direct negative effect on virulence; however, it is presumed that temperature driven activation of the immune system is probably the most important factor affecting microbial viability. Lastly, we performed a review of modern-era studies where modulation of body temperature has been used as a treatment strategy. In trials of therapeutic hypothermia in patients with infection worse outcomes have been observed in the hypothermia group. Use of antipyretics has not been associated with any improvement in clinical outcomes. In modern-era therapeutic hyperthermia achieved by physical warming has been studied in one pilot trial, and better survival was observed in the hyperthermia group. To conclude, currently there is not enough data to support the use of therapeutic hyperthermia outside clinical trials; however, available studies are in favor of at least a temperature tolerance strategy for non-neurocritical patients.

Evaluation of systemic IL-6 trans-signalling in patients with primary open-angle glaucoma

PURPOSE

To evaluate systemic trans-signalling of interleukin (IL)-6 in patients with primary open-angle glaucoma (POAG).

METHODS

Fifty-one POAG patients and 47 matched healthy controls were enrolled. Serum concentrations of IL-6, sIL-6R, and sgp130 were quantified.

RESULTS

Serum levels of IL-6, sIL-6R, and IL-6/sIL-6R ratios in the POAG group were significantly higher than those in control group, while only the sgp130/sIL-6R/IL-6 ratio was decreased. Among POAG subjects, advanced-stage patients exhibited significantly higher intraocular pressure (IOP), serum IL-6 and sgp130 levels, and IL-6/sIL-6R ratio than those in the early to moderate stage. The ROC curve analysis revealed that the IL-6 level and IL-6/sIL-6R ratio performed better than other parameters in diagnosing POAG and discriminating POAG severity. Serum IL-6 level was moderately correlated with IOP and C/D ratio, while a weak correlation was observed between sIL-6R levels with C/D ratio. IL-6 and sIL-6R levels were correlated with each other in POAG patients but not in healthy controls.

CONCLUSION

Overstimulation of systemic IL-6 trans-signalling has been implicated in POAG.

Protective effect of berberine against LPS-induced injury in the intestine: a review

Sepsis is a systemic inflammatory condition caused by an unbalanced immunological response to infection, which affects numerous organs, including the intestines. Lipopolysaccharide (LPS; also known as endotoxin), a substance found in Gram-negative bacteria, plays a major role in sepsis and is mostly responsible for the disease's morbidity and mortality. Berberine is an isoquinoline alkaloid found in a variety of plant species that has anti-inflammatory properties. For many years, berberine has been used to treat intestinal inflammation and infection. Berberine has been reported to reduce LPS-induced intestinal damage. The potential pathways through which berberine protects against LPS-induced intestinal damage by inhibiting NF-κB, suppressing MAPK, modulating ApoM/S1P pathway, inhibiting COX-2, modulating Wnt/Beta-Catenin signaling pathway, and/or increasing ZIP14 expression are reviewed.Abbreviations: LPS, lipopolysaccharide; TLR, Toll-like receptor; MD-2, myeloid differentiation factor 2; CD14, cluster of differentiation 14; LBP, lipopolysaccharide-binding protein; MYD88, myeloid differentiation primary response 88; NF-κB, nuclear factor kappa light-chain enhancer of activated B cells; MAPK, mitogen-activated protein kinase; IL, interleukin; TNFα, tumor necrosis factor-alpha; Caco-2, cyanocobalamin uptake by human colon adenocarcinoma cell line; MLCK, myosin light-chain kinase; TJ, tight junction; IκBα, nuclear factor of kappa light polypeptide gene enhancer in B-cells inhibitor, alpha; IBS, irritable bowel syndrome; ERK, extracellular signal-regulated kinase; JNK, c-Jun N-terminal kinase (JNK; GVB, gut-vascular barrier; ApoM, apolipoprotein M; S1P, sphingosine-1-phosphate; VE-cadherin, vascular endothelial cadherin; AJ, adherens junction; PV1, plasmalemma vesicle-associated protein-1; HDL, high-density lipoprotein; Wnt, wingless-related integration site; Fzd, 7-span transmembrane protein Frizzled; LRP, low-density lipoprotein receptor-related protein; TEER, transendothelial/transepithelial electrical resistance; COX-2, cyclooxygenase-2; iNOS, inducible nitric oxide synthase; IGF, insulin-like growth factor; IGFBP, insulin-like growth factor-binding protein; ZIP, Zrt-Irt-like protein; PPAR, peroxisome proliferator-activated receptors; p-PPAR, phosphorylated-peroxisome proliferator-activated receptors; ATF, activating transcription factors; SOD, superoxide dismutase; GSH-Px, glutathione peroxidase; SARA, subacute ruminal acidosis; IPEC-J2, porcine intestinal epithelial cells; ALI, acute lung injury; ARDS, acute respiratory distress syndrome.

Laser ablation: Heating up the anti-tumor response in the intracranial compartment

Immunotherapies, such as immune checkpoint inhibition (ICI), have had limited success in treating intracranial malignancies. These failures are due partly to the restrictive blood-brain-barrier (BBB), the profound tumor-dependent induction of local and systemic immunosuppression, and immune evasion exhibited by these tumors. Therefore, novel approaches must be explored that aim to overcome these stringent barriers. LITT is an emerging treatment for brain tumors that utilizes thermal ablation to kill tumor cells. LITT provides an additional therapeutic benefit by synergizing with ICI and systemic chemotherapies to strengthen the anti-tumor immune response. This synergistic relationship involves transient disruption of the BBB and local augmentation of immune function, culminating in increased CNS drug penetrance and improved anti-tumor immunity. In this review, we will provide an overview of the challenges facing immunotherapy for brain tumors, and discuss how LITT may synergize with the endogenous anti-tumor response to improve the efficacy of ICI.

Locoregional therapies and their effects on the tumoral microenvironment of pancreatic ductal adenocarcinoma

Pancreatic ductal adenocarcinoma (PDAC) is expected to become the second leading cause of death from cancer by 2030. Despite intensive research in the field of therapeutics, the 5-year overall survival is approximately 8%, with only 20% of patients eligible for surgery at the time of diagnosis. The tumoral microenvironment (TME) of the PDAC is one of the main causes for resistance to antitumoral treatments due to the presence of tumor vasculature, stroma, and a modified immune response. The TME of PDAC is characterized by high stiffness due to fibrosis, with hypo microvascular perfusion, along with an immunosuppressive environment that constitutes a barrier to effective antitumoral treatment. While systemic therapies often produce severe side effects that can alter patients' quality of life, locoregional therapies have gained attention since their action is localized to the pancreas and can thus alleviate some of the barriers to effective antitumoral treatment due to their physical effects. Local hyperthermia using radiofrequency ablation and radiation therapy - most commonly using a local high single dose - are the two main modalities holding promise for clinical efficacy. Recently, irreversible electroporation and focused ultrasound-derived cavitation have gained increasing attention. To date, most of the data are limited to preclinical studies, but ongoing clinical trials may help better define the role of these locoregional therapies in the management of PDAC patients.

Interplay between Prokineticins and Histone Demethylase KDM6A in a Murine Model of Bortezomib-Induced Neuropathy

Chemotherapy-induced neuropathy (CIN) is a major adverse effect associated with many chemotherapeutics, including bortezomib (BTZ). Several mechanisms are involved in CIN, and recently a role has been proposed for prokineticins (PKs), a chemokine family that induces proinflammatory/pro-algogen mediator release and drives the epigenetic control of genes involved in cellular differentiation. The present study evaluated the relationships between epigenetic mechanisms and PKs in a mice model of BTZ-induced painful neuropathy. To this end, spinal cord alterations of histone demethylase KDM6A, nuclear receptors PPARα/PPARγ, PK2, and pro-inflammatory cytokines IL-6 and IL-1β were assessed in neuropathic mice treated with the PK receptors (PKRs) antagonist PC1. BTZ treatment promoted a precocious upregulation of KDM6A, PPARs, and IL-6, and a delayed increase of PK2 and IL-1β. PC1 counteracted allodynia and prevented the increase of PK2 and of IL-1β in BTZ neuropathic mice. The blockade of PKRs signaling also opposed to KDM6A increase and induced an upregulation of PPAR gene transcription. These data showed the involvement of epigenetic modulatory enzymes in spinal tissue phenomena associated with BTZ painful neuropathy and underline a role of PKs in sustaining the increase of proinflammatory cytokines and in exerting an inhibitory control on the expression of PPARs through the regulation of KDM6A gene expression in the spinal cord.

Structural characterization, anticancer, hypoglycemia and immune activities of polysaccharides from Russula virescens

Russula virescens is an edible wild mushroom that is widely distributed in south of China. This research aimed to analyze the structure characterization and evaluate the hypoglycemic, anticancer and immunological activities of two water soluble polysaccharides RVP-1 and RVP-2 from R. virescens. The results showed RVP-1 and RVP-2 were non-triple helix structured hetero-polysaccharides with different weight-average molecular weight 14,883 and 13,301 Da, respectively. Both RVP-1 and RVP-2 were composed of galactose, glucose, mannose and fructose, and the sugar residues were mainly linked by 1,6→, 1,2→, 1→ and 1,3,6→ glycosidic bonds. Moreover, the antidiabetic, anticancer and immune activities of RVP-1 and RVP-2 were explored in vitro methods. The two polysaccharides have potential for inhibiting α-glucosidase and α-amylase activities, suppressing HepG-2, A549 and MCF-7 cancer cells proliferation, and activating macrophage RAW 264.7 cells to secret immune cytokines for mediating cellular immune response. These findings provided a scientific basis for further utilization of polysaccharide from R. virescens.

Marginal Zone B Cells Assist With Neutrophil Accumulation to Fight Against Systemic Staphylococcus aureus Infection

In addition to regulating immune responses by producing antibodies that confer humoral immunity, B cells can also affect these responses by producing cytokines. How B cells participate in the clearance of pathogenic infections via functions other than the production of pathogen-specific antibodies is still largely unknown. Marginal zone (MZ) B cells can quickly respond to bacterial invasion by providing the initial round of antibodies. After a bloodborne bacterial infection, neutrophils promptly migrate to the MZ. However, the mechanisms regulating neutrophil accumulation in the MZ during the initial phase of infection also remain obscure. Here, we found that MZ B cell-deficient mice are more susceptible to systemic Staphylococcus aureus (S. aureus) infection compared with wildtype mice. The expression levels of interleukin (IL)-6 and CXCL1/CXCL2 in MZ B cells increased significantly in mice at 3–4 h after infection with S. aureus, then decreased at 24 h post-infection. After systemic S. aureus infection, splenic neutrophils express increased CXCR2 levels. Our results from confocal microscopy imaging of thick-section staining demonstrate that neutrophils in wildtype mice form cell clusters and are in close contact with MZ B cells at 3 h post-infection. This neutrophil cluster formation shortly after infection was diminished in both MZ B cell-deficient mice and IL-6-deficient mice. Blocking the action of CXCL1/CXCL2 by injecting anti-CXCL1 and anti-CXCL2 antibodies 1 h before S. aureus infection significantly suppressed the recruitment of neutrophils to the MZ at 3 h post-infection. Compared with peptidoglycan stimulation alone, peptidoglycan stimulation with neutrophil co-culture further enhanced MZ B-cell activation and differentiation. Using a Förster resonance energy transfer by fluorescence lifetime imaging (FLIM-FRET) analysis, we observed evidence of a direct interaction between neutrophils and MZ B cells after peptidoglycan stimulation. Furthermore, neutrophil depletion in mice resulted in a reduced production of S. aureus-specific immunoglobulin (Ig)M at 24 h post-infection. Together, our results demonstrate that MZ B cells regulate the rapid neutrophil swarming into the spleen during the early phase of systemic S. aureus infection. Interaction with neutrophils assists MZ B cells with their differentiation into IgM-secreting cells and contributes to the clearance of systemic bacterial infections.

Skeletal Muscle Interleukin-6 Contributes to the Innate Immune Response in Septic Mice

ABSTRACT

Interleukin-6 (IL-6) is a major cytokine released by skeletal muscle. Although IL-6 plays complex but well-known roles in host defense, the specific contribution of skeletal muscle IL-6 to innate immunity remains unknown. We tested its functional relevance by exposing inducible skeletal muscle IL-6 knockdown (skmIL-6KD) mice to a cecal slurry model of polymicrobial peritonitis and compared responses to strain-matched controls and skeletal muscle Cre-matched controls at 3, 6, and 12 h postinfection. In both sexes, skmIL-6KD mice at 6 h of infection exhibited marked changes to leukocyte trafficking in the peritoneum, characterized by ∼1.75-fold elevation in %neutrophils, a ∼3-fold reduction in %lymphocytes and a ∼2 to 3-fold reduction in %basophils. A similar pattern was seen at 12 h. No changes were observed in plasma leukocyte counts. Circulating cytokines in female skmIL-6KD mice at 6 h consistently showed modest reductions in IL-6, but marked reductions in a broad range of both pro- and anti-inflammatory cytokines, e.g., TNFα and IL-10. In both sexes at 12 h, a generalized suppression of plasma cytokines was also seen after the effects of Cre-induction with raloxifene were addressed. There were no significant effects of skmIL-6KD on mortality in either sex. Collectively, our results are consistent with skmIL-6 playing an important and previously unrecognized role in immune cell trafficking and cytokine regulation during septic shock.

Effect of berberine on LPS-induced expression of NF-B/MAPK signalling pathway and related inflammatory cytokines in porcine intestinal epithelial cells

Berberine is an alkaloid extracted from medicinal plants such as Coptis chinensis and Phellodendron chinense. It possesses anti-inflammatory, anti-tumour and anti-oxidation properties, and regulates Glc and lipid metabolism. This study explored the mechanisms of the protective effects of berberine on barrier function and inflammatory damage in porcine intestinal epithelial cells (IPEC-J2) induced by LPS. We first evaluated the effects of berberine and LPS on cell viability. IPEC-J2 cells were treated with 5 μg/ml LPS for 1 h to establish an inflammatory model, and 75, 150 and 250 μg/ml berberine were used in further experiments. The expression of IL-1β, IL-6 and TNF-α was measured by RT-PCR. The key proteins of the NF-κB/MAPK signalling pathway (IκBα, p-IκBα, p65, p-p65, c-Jun N-terminal kinase (JNK), p-JNK, p38, p-p38, ERK1/2 and p-ERK1/2) were detected by Western blot. Upon exposure to LPS, IL-1β, IL-6 and TNF-α mRNA levels and p-IκBα p-p65 protein levels were significantly enhanced. Pre-treatment with berberine reduced the expression of inflammatory factors and was positively correlated with its concentration, and dose dependently inhibited the expression of IκBα, p-IκBα, p-p65, p-p38 and JNK. These results demonstrated that pre-treating intestinal epithelial cells with berberine was useful in preventing and treating diarrhoea induced by Escherichia coli in weaned pigs.

The Role of Hyperthermia in the Multidisciplinary Treatment of Malignant Tumors

Hyperthermia is often used in combination with chemotherapy and radiotherapy for cancer treatment. Recently, immunotherapy has become a popular research area, breaking exciting new ground with concurrent immunotherapy and hyperthermia. Much evidence has demonstrated the effectiveness of multidisciplinary synergistic therapy, and the underlying mechanism has been gradually explored. In this review, we focus on the mechanism of various cancer treatments in the current literature and recent advances in hyperthermia. Additionally, we review clinical studies of hyperthermia combined with other therapies in the previous 10 years and propose future prospects for hyperthermia in multidisciplinary synergistic therapy.

Exercise as an anti-inflammatory therapy for cancer cachexia: a focus on interleukin-6 regulation

Cancer cachexia is a complicated disorder of extreme, progressive skeletal muscle wasting. It is directed by metabolic alterations and systemic inflammation dysregulation. Numerous studies have demonstrated that increased systemic inflammation promotes this type of cachexia and have suggested that cytokines are implicated in the skeletal muscle loss. Exercise is firmly established as an anti-inflammatory therapy that can attenuate or even reverse the process of muscle wasting in cancer cachexia. The interleukin IL-6 is generally considered to be a key player in the development of the microenvironment of malignancy; it promotes tumor growth and metastasis by acting as a bridge between chronic inflammation and cancerous tissue and it also induces skeletal muscle atrophy and protein breakdown. Paradoxically, a beneficial role for IL-6 has also been identified recently, and that is its status as a “founding member” of the myokine class of proteins. Skeletal muscle is an important source of circulating IL-6 in people who participate in exercise training. IL-6 acts as an anti-inflammatory myokine by inhibiting TNFα and improving glucose uptake through the stimulation of AMPK signaling. This review discusses the action of IL-6 in skeletal muscle tissue dysfunction and the role of IL-6 as an “exercise factor” that modulates the immune system. This review also sheds light on the main considerations related to the treatment of muscle wasting in cancer cachexia.

Racial Differences in Immunological Landscape Modifiers Contributing to Disparity in Prostate Cancer

Prostate cancer affects African Americans disproportionately by exhibiting greater incidence, rapid disease progression, and higher mortality when compared to their Caucasian counterparts. Additionally, standard treatment interventions do not achieve similar outcome in African Americans compared to Caucasian Americans, indicating differences in host factors contributing to racial disparity. African Americans have allelic variants and hyper-expression of genes that often lead to an immunosuppressive tumor microenvironment, possibly contributing to more aggressive tumors and poorer disease and therapeutic outcomes than Caucasians. In this review, we have discussed race-specific differences in external factors impacting internal milieu, which modify immunological topography as well as contribute to disparity in prostate cancer.

Active roles of dysfunctional vascular endothelium in fibrosis and cancer

Chronic inflammation is the underlying pathological condition that results in fibrotic diseases. More recently, many forms of cancer have also been linked to chronic tissue inflammation. While stromal immune cells and myofibroblasts have been recognized as major contributors of cytokines and growth factors that foster the formation of fibrotic tissue, the endothelium has traditionally been regarded as a passive player in the pathogenic process, or even as a barrier since it provides a physical divide between the circulating immune cells and the inflamed tissues. Recent findings, however, have indicated that endothelial cells in fact play a crucial role in the inflammatory response. Endothelial cells can be activated by cytokine signaling and express inflammatory markers, which can sustain or exacerbate the inflammatory process. For example, the activated endothelium can recruit and activate leukocytes, thus perpetuating tissue inflammation, while sustained stimulation of endothelial cells may lead to endothelial-to-mesenchymal transition that contributes to fibrosis. Since chronic inflammation has now been recognized as a significant contributing factor to tumorigenesis, it has also emerged that activation of endothelium also occurs in the tumor microenvironment. This review summarizes recent findings characterizing the molecular and cellular changes in the vascular endothelium that contribute to tissue fibrosis, and potentially to cancer formation.

Physical proximity and functional cooperation of glycoprotein 130 and glycoprotein VI in platelet membrane lipid rafts

OBJECTIVE

Clinical and laboratory studies have demonstrated that platelets become hyperactive and prothrombotic in conditions of inflammation. We have previously shown that the proinflammatory cytokine interleukin (IL)-6 forms a complex with soluble IL-6 receptor α (sIL-6Rα) to prime platelets for activation by subthreshold concentrations of collagen. Upon being stimulated with collagen, the transcription factor signal transducer and activator of transcription (STAT) 3 in platelets is phosphorylated and dimerized to act as a protein scaffold to facilitate the catalytic action between the kinase Syk and the substrate phospholipase Cγ2 (PLCγ2) in collagen-induced signaling. However, it remains unknown how collagen induces phosphorylation and dimerization of STAT3.

METHODS AND RESULTS

We conducted complementary in vitro experiments to show that the IL-6 receptor subunit glycoprotein 130 (GP130) was in physical proximity to the collagen receptor glycoprotein VI (GPVI in membrane lipid rafts of platelets. This proximity allows collagen to induce STAT3 activation and dimerization, and the IL-6-sIL-6Rα complex to activate the kinase Syk and the substrate PLCγ2 in the GPVI signal pathway, resulting in an enhanced platelet response to collagen. Disrupting lipid rafts or blocking GP130-Janus tyrosine kinase (JAK)-STAT3 signaling abolished the cross-activation and reduced platelet reactivity to collagen.

CONCLUSION

These results demonstrate cross-talk between collagen and IL-6 signal pathways. This cross-talk could potentially provide a novel mechanism for inflammation-induced platelet hyperactivity, so the IL-6-GP130-JAK-STAT3 pathway has been identified as a potential target to block this hyperactivity.

CSTP1 inhibits IL-6 expression through targeting Akt/FoxO3a signaling pathway in bladder cancer cells

CSTP1, a recently identified protein phosphotase, is frequently repressed in bladder cancers. Previous results showed that CSTP1 over-expression inhibited cell cycle progression and promoted apoptosis through dephosphorylating Akt kinase at Ser473 site in bladder cancer cells, but the mechanisms how CSTP1 exerted tumor suppressive activity remains unclear. In this study, we analyzed the gene expression profile changes that affected by CSTP1 overexpression by microarray, and reported that CSTP1 decreased IL-6 expression/secretion in bladder cancer cells and re-expression of IL-6 abrogated CSTP1's tumor suppressive activity. We also found that FoxO3a occupy IL-6 gene promoter and repressed IL mRNA transcription. Further results showed that decreased expression of IL-6 in CSTP1-overexpressing cells inactivated Stat3 transcriptional factor, which resulted in the down-regulation of cyclin D1, Bcl-xl expression. Spearman correlation analysis revealed that the mRNA level of CSTP1 correlated inversely with that of IL-6 in bladder cancer tissues. In conclusion, our studies revealed that protein phosphotase CSTP1 inhibited IL-6 expression through targeting Akt/FoxO3a signaling pathway and IL-6 inactivated Stat3 was necessary for CSTP1's tumor suppressive function.

Novel Role of T Cells and IL-6 (Interleukin-6) in Angiotensin II-Induced Microvascular Dysfunction

Hypertension is an established risk factor for subsequent cardiovascular diseases, with Ang II (angiotensin II) playing a major role in mediating thrombotic and inflammatory abnormalities. Although T cells and IL-6 (interleukin-6) play an important role in adaptive immune responses, little is known about their role(s) in the thromboinflammatory responses associated with Ang II. Here we show using intravital microscopy coupled with the light/dye injury model that Rag-1 deficient (Rag-1-/-) and IL-6 deficient (IL-6-/-) mice are afforded protection against Ang II-induced thrombosis. Blocking IL-6 receptors (using CD126 and gp130 antibodies) significantly diminished Ang II-mediated thrombosis and inflammatory cell recruitment in mice. Furthermore, the adoptive transfer of IL-6-/--derived T cells into Rag-1-/- mice failed to accelerate Ang II-induced thrombosis compared with Rag-1-/- mice reconstituted with wild-type-derived T cells, suggesting T cell IL-6 mediates the thrombotic abnormalities associated Ang II hypertension. Interestingly, adoptive transfer of WT T cells into Rag-1-/-/Ang II mice resulted in increased numbers of immature platelets, which constitutes a more active platelet population, that is, prothrombotic and proinflammatory. To translate our in vivo findings, we used clinical samples to demonstrate that IL-6 also predisposes platelets to an interaction with collagen receptors, thereby increasing the propensity for platelets to aggregate and cause thrombosis. In summary, we provide compelling evidence for the involvement of IL-6, IL-6R, and T-cell-dependent IL-6 signaling in Ang II-induced thromboinflammation, which may provide new therapeutic possibilities for drug discovery programs for the management of hypertension.

Role of CINC-1 and CXCR2 receptors on LPS-induced fever in rats

The classic model of fever induction is based on the administration of lipopolysaccharide (LPS) from Gram-negative bacteria in experimental animals. LPS-induced fever results in the synthesis/release of many mediators that assemble an LPS-fever cascade. We have previously demonstrated that cytokine-induced neutrophil chemoattractant (CINC)-1, a Glu-Leu-Arg (ELR) + chemokine, centrally administered to rats, induces fever and increases prostaglandin E₂ in the cerebrospinal fluid. We now attempt to investigate the involvement of CINC-1 and its functional receptor CXCR2 on the fever induced by exogenous and endogenous pyrogens in rats. We also investigated the effect of reparixin, an allosteric inhibitor of CXCR1/CXCR2 receptors, on fever induced by either systemic administration of LPS or intracerebroventricular injection of CINC-1, as well as TNF-α, IL-1β, IL-6, or ET-1, known mediators of febrile response. Our results show increased CINC-1 mRNA expression in the liver, hypothalamus, CSF, and plasma following LPS injection. Moreover, reparixin administered right before CINC-1 or LPS abolished the fever induced by CINC-1 and significantly reduced the response induced by LPS. In spite of these results, reparixin does not modify the fever induced by IL-1β, TNF-α, and IL-6, but significantly reduces ET-1-induced fever. Therefore, it is plausible to suggest that CINC-1 might contribute to LPS-induced fever in rats by activating CXCR2 receptor on the CNS. Moreover, it can be hypothesized that CINC-1 is placed upstream TNF-α, IL-1β, and IL-6 among the prostaglandin-dependent fever-mediator cascade and amidst the prostaglandin-independent synthesis pathway of fever.

Reverse Engineering the Febrile System

Fever, the elevation of core body temperature by behavioral or physiological means, is one of the most salient aspects of human sickness, yet there is debate regarding its functional role. In this paper, we demonstrate that the febrile system is an evolved adaptation shaped by natural selection to coordinate the immune system to fight pathogens. First, we show that previous arguments in favor of fever being an adaptation are epistemologically inadequate, and we describe how an adaptationist strategy addresses this issue more effectively. Second, we argue that the mechanisms producing fever provide clear indications of adaptation. Third, we demonstrate that there are many beneficial immune system responses activated during fever and that these responses are not mere byproducts of heat on chemical reactions. Rather, we show that natural selection appears to have modified several immune system effects to be coordinated by fever. Fourth, we argue that there are some adaptations that coordinate the febrile system with other important fitness components, particularly growth and reproduction. Finally, we discuss evidence that the febrile system may also have evolved an antitumor function, providing suggestions for future research into this area. This research informs the debate on the functional value of fever and antipyretic use.

Equisetum arvense L. Extract Induces Antibacterial Activity and Modulates Oxidative Stress, Inflammation, and Apoptosis in Endothelial Vascular Cells Exposed to Hyperosmotic Stress

Background

The antimicrobial activity of the Equisetum arvense L. extract and the mechanisms involved in the in vitro effects on endothelial vascular cells exposed to hyperosmotic stress were evaluated.

Methods

Antimicrobial activity was evaluated by disk diffusion method and minimum inhibitory concentration (MIC) determination, and oxidative stress, inflammation, and apoptosis, in pretreatment with Equisetum arvense L., caffeic acid, and cathechin, were quantified.

Results

The results have shown that Equisetum arvense L. exhibited antibacterial effects only on pathogenic gram-positive cocci. The modulatory activity of Equisetum arvense L. on endothelial cells exposed to hypertonic medium was different and depended on the concentration used. Low concentrations of tested compounds exerted antioxidant effect and diminished the activity of caspase-8 and also increased IκB expression while in high doses, Equisetum arvense L. was prooxidant, induced apoptosis, and decreased IL-6 secretion.

Conclusions

These experimental findings suggest that Equisetum arvense L. has antibacterial effects on gram-positive cocci and, administered in low dose, may be a new therapeutic approach for diseases associated with hypertonic conditions or oxidative stress and apoptosis.

Interleukin-6 in Allogeneic Stem Cell Transplantation: Its Possible Importance for Immunoregulation and As a Therapeutic Target

Allogeneic stem cell transplantation is associated with a high risk of treatment-related mortality mainly caused by infections and graft-versus-host disease (GVHD). GVHD is characterized by severe immune dysregulation and impaired regeneration of different tissues, i.e., epithelial barriers and the liver. The balance between pro- and anti-inflammatory cytokine influences the risk of GVHD. Interleukin-6 (IL-6) is a cytokine that previously has been associated with pro-inflammatory effects. However, more recent evidence from various autoimmune diseases (e.g., inflammatory bowel disease, rheumatoid arthritis) has shown that the IL-6 activity is more complex with important effects also on tissue homeostasis, regeneration, and metabolism. This review summarizes the current understanding of how pro-inflammatory IL-6 effects exerted during the peritransplant period shapes T-cell polarization with enhancement of Th17 differentiation and suppression of regulatory T cells, and in addition we also review and discuss the results from trials exploring non-selective IL-6 inhibition in prophylaxis and treatment of GVHD. Emerging evidence suggests that the molecular strategy for targeting of IL-6-initiated intracellular signaling is important for the effect on GVHD. It will therefore be important to further characterize the role of IL-6 in the pathogenesis of GVHD to clarify whether combined IL-6 inhibition of both trans- (i.e., binding of the soluble IL-6/IL-6 receptor complex to cell surface gp130) and cis-signaling (i.e., IL-6 ligation of the IL-6 receptor/gp130 complex) or selective inhibition of trans-signaling should be tried in the prophylaxis and/or treatment of GVHD in allotransplant patients.

Interleukin-6 Signaling Pathway and Its Role in Kidney Disease: An Update

Interleukin-6 (IL-6) is a pleiotropic cytokine that not only regulates the immune and inflammatory response but also affects hematopoiesis, metabolism, and organ development. IL-6 can simultaneously elicit distinct or even contradictory physiopathological processes, which is likely discriminated by the cascades of signaling pathway, termed classic and trans-signaling. Besides playing several important physiological roles, dysregulated IL-6 has been demonstrated to underlie a number of autoimmune and inflammatory diseases, metabolic abnormalities, and malignancies. This review provides an overview of basic concept of IL-6 signaling pathway as well as the interplay between IL-6 and renal-resident cells, including podocytes, mesangial cells, endothelial cells, and tubular epithelial cells. Additionally, we summarize the roles of IL-6 in several renal diseases, such as IgA nephropathy, lupus nephritis, diabetic nephropathy, acute kidney injury, and chronic kidney disease.

Transient Surface CCR5 Expression by Naive CD8+ T Cells within Inflamed Lymph Nodes Is Dependent on High Endothelial Venule Interaction and Augments Th Cell-Dependent Memory Response

In inflamed lymph nodes, Ag-specific CD4(+) and CD8(+) T cells encounter Ag-bearing dendritic cells and, together, this complex enhances the release of CCL3 and CCL4, which facilitate additional interaction with naive CD8(+) T cells. Although blocking CCL3 and CCL4 has no effect on primary CD8(+) T cell responses, it dramatically impairs the development of memory CD8(+) T cells upon Ag rechallenge. Despite the absence of detectable surface CCR5 expression on circulating native CD8(+) T cells, these data imply that naive CD8(+) T cells are capable of expressing surface CCR5 prior to cognate Ag-induced TCR signaling in inflamed lymph nodes; however, the molecular mechanisms have not been characterized to date. In this study, we show that CCR5, the receptor for CCL3 and CCL4, can be transiently upregulated on a subset of naive CD8(+) T cells and that this upregulation is dependent on direct contact with the high endothelial venule in inflamed lymph node. Binding of CD62L and CD11a on T cells to their ligands CD34 and CD54 on the high endothelial venule can be enhanced during inflammation. This enhanced binding and subsequent signaling promote the translocation of CCR5 molecules from intracellular vesicles to the surface of the CD8(+) T cell. The upregulation of CCR5 on the surface of the CD8(+) T cells increases the number of contacts with Ag-bearing dendritic cells, which ultimately results in increased CD8(+) T cell response to Ag rechallenge.

Interleukin-6 Receptor Inhibition Prevents Descending Thoracic Aortic Aneurysm Formation

BACKGROUND

Thoracic aortic aneurysms (TAA) and abdominal aortic aneurysms (AAA) represent related but distinct disease processes. Interleukin-6 (IL-6) is known to be significantly upregulated in human TAA and AAA. We hypothesize that loss of IL-6 is protective in experimental TAA and AAA.

METHODS

Murine TAAs or AAAs were created using a novel model in C57/B6 mice by treating the intact aorta with elastase. Cytokine profiles were analyzed with antibody arrays (n = 5 per group). Separately, to determine the role of IL-6, thoracic (n = 7) or abdominal (n = 7) aortas of wild type mice and IL-6 knockout (KO) mice were treated with elastase. Additionally, thoracic animals treated with either the IL-6 receptor antagonist tocilizumab (n = 8) or vehicle (n = 5). Finally, human TAA and AAA were analyzed with human cytokine array.

RESULTS

Elastase treatment of thoracic aortas yielded dilation of 86.8% ± 9.6%, and abdominal aortas produced dilation of 85.6% ± 16.2%. Murine IL-6, CXCL13, and matrix metalloproteinase-9 were significantly elevated in TAA compared with AAA (p = 0.004, 0.028, and 0.001, respectively). The IL-6KO mice demonstrated significantly smaller TAA size relative to wild type mice (wild type 100.1% versus IL-6KO 76.5%, p = 0.04). The IL-6KO mice did not show protection from AAA (p = 0.732). Pharmacologic inhibition of IL-6 resulted in significant reduction in TAA size (tocilizumab 71.5% ± 13.2% versus vehicle 103.6% ± 20.7%, p = 0.005). Human TAA showed significantly greater IL-6 (p < 0.0001) compared with AAA and normal thoracic and abdominal aorta.

CONCLUSIONS

Interleukin-6 is significantly greater in both murine and human TAA compared with AAA, suggesting fundamental differences in these disease processes. Interleukin-6 receptor antagonism attenuates experimental TAA formation, indicating that IL-6 may be a potential target for human thoracic aneurysmal disease.

Temperature matters! And why it should matter to tumor immunologists

A major goal of cancer immunology is to stimulate the generation of long-lasting, tumor antigen-specific immune responses that recognize and destroy tumor cells. This article discusses advances in thermal medicine with the potential to improve cancer immunotherapy. Accumulating evidence indicates that survival benefits are accorded to individuals who achieve an increase in body temperature (i.e. fever) following infection. Furthermore, accumulating evidence indicates that physiological responses to hyperthermia impact the tumor microenvironment through temperature-sensitive check-points that regulate tumor vascular perfusion, lymphocyte trafficking, inflammatory cytokine expression, tumor metabolism, and innate and adaptive immune function. Nevertheless, the influence of thermal stimuli on the immune system, particularly the antitum or immune response, remains incompletely understood. In fact, temperature is still rarely considered as a critical variable in experimental immunology. We suggest that more attention should be directed to the role of temperature in the regulation of the immune response and that thermal therapy should be tested in conjunction with immunotherapy as a multi-functional adjuvant that modulates the dynamics of the tumor microenvironment.

Shifts in temperature within the physiologic range modify strand-specific expression of select human microRNAs

Previous studies have revealed that clinically relevant changes in temperature modify clinically relevant gene expression profiles through transcriptional regulation. Temperature dependence of post-transcriptional regulation, specifically, through expression of miRNAs has been less studied. We comprehensively analyzed the effect of 24 h exposure to 32°C or 39.5°C on miRNA expression profile in primary cultured human small airway epithelial cells (hSAECs) and its impact on expression of a targeted protein, protein kinase C α (PKCα). Using microarray, and solution hybridization-based nCounter assays, with confirmation by quantitative RT-PCR, we found significant temperature-dependent changes in expression level of only five mature human miRNAs, representing only 1% of detected miRNAs. Four of these five miRNAs are the less abundant passenger (star) strands. They exhibited a similar pattern of increased expression at 32°C and reduced expression at 39.5°C relative to 37°C. As PKCα mRNA has multiple potential binding sites for three of these miRNAs, we analyzed PKCα protein expression in HEK 293T cells and hSAECs. PKCα protein levels were lowest at 32°C and highest at 39.5°C and specific miRNA inhibitors reduced these effects. Finally, we analyzed cell-cycle progression in hSAECs and found 32°C cells exhibited the greatest G1 to S transition, a process known to be inhibited by PKCα, and the effect was mitigated by specific miRNA inhibitors. These results demonstrate that exposure to clinically relevant hypothermia or hyperthermia modifies expression of a narrow subset of miRNAs and impacts expression of at least one signaling protein involved in multiple important cellular processes.

Fever and the thermal regulation of immunity: the immune system feels the heat

Fever is a cardinal response to infection that has been conserved in warm-blooded and cold-blooded vertebrates for more than 600 million years of evolution. The fever response is executed by integrated physiological and neuronal circuitry and confers a survival benefit during infection. In this Review, we discuss our current understanding of how the inflammatory cues delivered by the thermal element of fever stimulate innate and adaptive immune responses. We further highlight the unexpected multiplicity of roles of the pyrogenic cytokine interleukin-6 (IL-6), both during fever induction and during the mobilization of lymphocytes to the lymphoid organs that are the staging ground for immune defence. We also discuss the emerging evidence suggesting that the adrenergic signalling pathways associated with thermogenesis shape immune cell function.

Fever, immunity, and molecular adaptations

The heat shock response (HSR) is an ancient and highly conserved process that is essential for coping with environmental stresses, including extremes of temperature. Fever is a more recently evolved response, during which organisms temporarily subject themselves to thermal stress in the face of infections. We review the phylogenetically conserved mechanisms that regulate fever and discuss the effects that febrile-range temperatures have on multiple biological processes involved in host defense and cell death and survival, including the HSR and its implications for patients with severe sepsis, trauma, and other acute systemic inflammatory states. Heat shock factor-1, a heat-induced transcriptional enhancer is not only the central regulator of the HSR but also regulates expression of pivotal cytokines and early response genes. Febrile-range temperatures exert additional immunomodulatory effects by activating mitogen-activated protein kinase cascades and accelerating apoptosis in some cell types. This results in accelerated pathogen clearance, but increased collateral tissue injury, thus the net effect of exposure to febrile range temperature depends in part on the site and nature of the pathologic process and the specific treatment provided.

Single-dose oral quercetin improves redox status but does not affect heat shock response in mice

Inflammation and oxidative stress are considered as likely contributors to heat injury. However, their roles in regulating the heat shock response in vivo remain unclear. We tested the hypothesis that acute quercetin treatment would improve redox status and reduce heat shock responses in mice. Mice underwent two heat tests before and after single oral administration of either quercetin (15 mg/kg) or vehicle. We measured physiologic and biochemical responses in mice during and 18 to 22 hours after heat tests, respectively. There were no significant differences in core temperature, heart rate, or blood pressure between quercetin and vehicle groups during heat exposure. Mice with relatively severe hyperthermia during the pretreatment heat test showed a significant trend toward a lower peak core temperature during the heat test after quercetin treatment. Compared with mice not exposed to heat, quercetin-treated mice had significantly lower interleukin 6 (P < .01) and higher superoxide dismutase levels (P < .01), whereas vehicle-treated mice had significantly lower total glutathione and higher 8-isoprostane levels in the circulation after heat exposure. Heat exposure significantly elevated heat shock proteins (HSPs) 72 and 90 and heat shock factor 1 levels in mouse liver, heart, and skeletal muscles, but no significant differences in tissue HSPs and heat shock factor 1 were found between quercetin- and vehicle-treated mice. These results suggest that a single moderate dose of quercetin is sufficient to alter redox status but not heat stress response in mice. Acute adaptations of peripheral tissues to heat stress may not be mediated by systemic inflammatory and redox state in vivo.

The two faces of IL-6 in the tumor microenvironment

Within the tumor microenvironment, IL-6 signaling is generally considered a malevolent player, assuming a dark visage that promotes tumor progression. Chronic IL-6 signaling is linked to tumorigenesis in numerous mouse models as well as in human disease. IL-6 acts intrinsically on tumor cells through numerous downstream mediators to support cancer cell proliferation, survival, and metastatic dissemination. Moreover, IL-6 can act extrinsically on other cells within the complex tumor microenvironment to sustain a pro-tumor milieu by supporting angiogenesis and tumor evasion of immune surveillance. A lesser known role for IL-6 signaling has recently emerged in which it plays a beneficial role, presenting a fairer face that opposes tumor growth by mobilizing anti-tumor T cell immune responses to attain tumor control. Accumulating evidence establishes IL-6 as a key player in the activation, proliferation and survival of lymphocytes during active immune responses. IL-6 signaling can also resculpt the T cell immune response, shifting it from a suppressive to a responsive state that can effectively act against tumors. Finally, IL-6 plays an indispensable role in boosting T cell trafficking to lymph nodes and to tumor sites, where they have the opportunity to become activated and execute their cytotoxic effector functions, respectively. Here, we discuss the dual faces of IL-6 signaling in the tumor microenvironment; the dark face that drives malignancy, and the fairer aspect that promotes anti-tumor adaptive immunity.

IL-17 promotes neutrophil entry into tumor-draining lymph nodes following induction of sterile inflammation

Blood-borne neutrophils are excluded from entering lymph nodes across vascular portals termed high endothelial venules (HEVs) because of lack of expression of the CCR7 homeostatic chemokine receptor. Induction of sterile inflammation increases neutrophil entry into tumor-draining lymph nodes (TDLNs), which is critical for induction of antitumor adaptive immunity following treatments such as photodynamic therapy (PDT). However, the mechanisms controlling neutrophil entry into TDLNs remain unclear. Prior evidence that IL-17 promotes neutrophil emigration to sites of infection via induction of CXCL2 and CXCL1 inflammatory chemokines raised the question of whether IL-17 contributes to chemokine-dependent trafficking in TDLNs. In this article, we demonstrate rapid accumulation of IL-17-producing Th17 cells in the TDLNs following induction of sterile inflammation by PDT. We further report that nonhematopoietic expression of IL-17RA regulates neutrophil accumulation in TDLNs following induction of sterile inflammation by PDT. We show that HEVs are the major route of entry of blood-borne neutrophils into TDLNs through interactions of l-selectin with HEV-expressed peripheral lymph node addressin and by preferential interactions between CXCR2 and CXCL2 but not CXCL1. CXCL2 induction in TDLNs was mapped in a linear pathway downstream of IL-17RA-dependent induction of IL-1β. These results define a novel IL-17-dependent mechanism promoting neutrophil delivery across HEVs in TDLNs during acute inflammatory responses.

Preconditioning thermal therapy: flipping the switch on IL-6 for anti-tumour immunity

Cancer immunotherapy aims to generate long-lived, tumour-specific adaptive immunity to limit dysregulated tumour progression and metastasis. Tumour vasculature has emerged as a critical checkpoint controlling the efficacy of immunotherapy since it is the main access point for cytotoxic T cells to reach tumour cell targets. Therapeutic success has been particularly challenging to achieve because of the local, cytokine-rich inflammatory milieu that drives a pro-tumourigenic programme supporting the growth and survival of malignant cells. Here, we focus on recent evidence that systemic thermal therapy can switch the activities of the inflammatory cytokine, interleukin-6 (IL-6), to a predominantly anti-tumourigenic function that promotes anti-tumour immunity by mobilising T cell trafficking in the recalcitrant tumour microenvironment.

Rosuvastatin reduced deep vein thrombosis in ApoE gene deleted mice with hyperlipidemia through non-lipid lowering effects

INTRODUCTION

Statins, particularly rosuvastatin, have recently become relevant in the setting of venous thrombosis. The objective of this study was to study the non-lipid lowering effects of rosuvastatin in venous thrombosis in mice with hyperlipidemia.

MATERIALS AND METHODS

An inferior vena cava ligation model of venous thrombosis in mice was utilized. Saline or 5mg/kg of rosuvastatin was administered by gavage 48hs previous to thrombosis. Blood, the inferior vena cava, thrombus, and liver were harvested 3, 6hours, and 2days post-thrombosis. Thrombus weight, inflammatory markers, and plasminogen activator inhibitor-1 expression and plasma levels were measured. Also, neutrophil migration to the IVC was assessed.

RESULTS

Rosuvastatin significantly decreased thrombus weight, plasminogen activator inhibitor-1 expression and plasma levels, expression of molecules related to the interleukin-6 pathway, and neutrophil migration into the vein wall.

CONCLUSIONS

This work supports the beneficial effects of rosuvastatin on venous thrombosis in mice with hyperlipidemia, due to its non-lipid lowering effects.

The Jak/STAT signaling pathway is downregulated at febrile temperatures

BACKGROUND

The Janus family of kinases (JAKs), Jak1, Jak2, Jak3, and Tyk2, constitute a subgroup of non-receptor protein tyrosine kinases. Upon cytokine binding, the receptor-associated kinases are activated and phosphorylate tyrosine residues in their cognate cytokine receptors. Their activities are controlled at several levels and include cellular concentration, auto-activation, and degradation.

PRINCIPAL FINDINGS

Our findings show that elevated temperatures in the fever range irreversibly aggregate Jak2 and considerably reduce functional Jak2 protein levels. Jak2 synthesis remains unaltered. We observed that also the protein level of the signal transducer and activator of transcription, STAT5b, is transiently decreased at temperatures above 37°C. Consequently, the signaling response, e.g. via the growth hormone receptor, is reduced.

CONCLUSIONS/SIGNIFICANCE

These findings predict that elevated body temperatures lower the responsiveness of cytokine receptors.

Neutralizing IL-6 reduces human arterial allograft rejection by allowing emergence of CD161+ CD4+ regulatory T cells

Perioperative injuries to an allograft exacerbate graft rejection, which in humans is primarily mediated by effector memory T cells. IL-6 transcripts in human coronary artery segments rapidly increase posttransplantation into immunodeficient mouse hosts compared with those of pretransplant specimens and fall dramatically by 30 d. Adoptive transfer of human PBMCs allogeneic to the artery 2 d postoperatively results in T cell infiltrates and intimal expansion 4 wk later. Ab neutralization of human IL-6 reduces the magnitude of intimal expansion and total T cell infiltration but increases the relative expression of CD161 while decreasing other Th17 markers. Coculture of MHC class II-expressing human endothelial cells (ECs) with allogeneic CD4(+) memory T cells results in T cell activation and EC secretion of IL-6. Neutralizing IL-6 in primary allogeneic T cell-EC cocultures results in enhanced T cell proliferation of CD161(+) CD4(+) T cells, reduces total T cell proliferation upon restimulation in secondary cultures (an effect dependent on CD161(+) T cells), increases expression of FOXP3 in CD161(+) T cells, and generates T cells that suppress proliferation of freshly isolated T cells. These data suggest that IL-6 released from injured allograft vessels enhances allogeneic T cell infiltration and intimal expansion in a model of human allograft rejection by inhibiting an increase in CD161(+) regulatory T cells.

IL-6 trans-signaling licenses mouse and human tumor microvascular gateways for trafficking of cytotoxic T cells

Immune cells are key regulators of neoplastic progression, which is often mediated through their release of cytokines. Inflammatory cytokines such as IL-6 exert tumor-promoting activities by driving growth and survival of neoplastic cells. However, whether these cytokines also have a role in recruiting mediators of adaptive anticancer immunity has not been investigated. Here, we report that homeostatic trafficking of tumor-reactive CD8+ T cells across microvascular checkpoints is limited in tumors despite the presence of inflammatory cytokines. Intravital imaging in tumor-bearing mice revealed that systemic thermal therapy (core temperature elevated to 39.5°C ± 0.5°C for 6 hours) activated an IL-6 trans-signaling program in the tumor blood vessels that modified the vasculature such that it could support enhanced trafficking of CD8+ effector/memory T cells (Tems) into tumors. A concomitant decrease in tumor infiltration by Tregs during systemic thermal therapy resulted in substantial enhancement of Tem/Treg ratios. Mechanistically, IL-6 produced by nonhematopoietic stromal cells acted cooperatively with soluble IL-6 receptor-α and thermally induced gp130 to promote E/P-selectin- and ICAM-1-dependent extravasation of cytotoxic T cells in tumors. Parallel increases in vascular adhesion were induced by IL-6/soluble IL-6 receptor-α fusion protein in mouse tumors and patient tumor explants. Finally, a causal link was established between IL-6-dependent licensing of tumor vessels for Tem trafficking and apoptosis of tumor targets. These findings suggest that the unique IL-6-rich tumor microenvironment can be exploited to create a therapeutic window to boost T cell-mediated antitumor immunity and immunotherapy.

Roles of IL-6-gp130 Signaling in Vascular Inflammation

Interleukin-6 (IL-6) is a well-established, independent indicator of multiple distinct types of cardiovascular disease and all-cause mortality. In this review, we present current understanding of the multiple roles that IL-6 and its signaling pathways through glycoprotein 130 (gp130) play in cardiovascular homeostasis. IL-6 is highly inducible in vascular tissues through the actions of the angiotensin II (Ang II) peptide, where it acts in a paracrine manner to signal through two distinct mechanisms, the first being a classic membrane receptor initiated pathway and the second, a trans-signaling pathway, being able to induce responses even in tissues lacking the IL-6 receptor. Recent advances and new concepts in how its intracellular signaling pathways operate via the Janus kinase (JAK)-Signal Transducer and Activator of Transcription (STAT) are described. IL-6 has diverse actions in multiple cell types of cardiovascular importance, including endothelial cells, monocytes, platelets, hepatocytes and adipocytes. We discuss central roles of IL-6 in endothelial dysfunction, cellular inflammation by affecting monocyte activation/differentiation, cellular cytoprotective functions from reactive oxygen species (ROS) stress, modulation of pro-coagulant state, myocardial growth control, and its implications in metabolic control and insulin resistance. These multiple actions indicate that IL-6 is not merely a passive biomarker, but actively modulates adaptive and pathological responses to cardiovascular stress.

Fine-tuning immune surveillance by fever-range thermal stress

An effectively orchestrated immune response to infection and disease depends on efficient trafficking of lymphocytes across vascular beds at distinct tissue sites. Local inflammation and systemic fever increase immune surveillance to immune-relevant sites throughout the body. During the initiation phase of inflammation, this tightly regulated process improves leukocyte trafficking to the secondary lymphoid organs where they undergo activation and expansion in response to cognate antigen. In the resolution phase following the clearance of the invading pathogen, lymphocyte entry is rapidly returned to baseline conditions. Specialized blood vessels termed high endothelial venules (HEVs) have emerged as critical 'hotspots' controlling the rate of lymphocyte entry into lymphoid organs during both phases of inflammation. In this review, we will examine the remarkably tight regulation of lymphocyte trafficking across HEVs conferred by inflammatory cues associated with the thermal element of fever. These studies have revealed a novel role for interleukin-6 (IL-6) trans-signaling in eliciting systemic effects on lymphocyte trafficking patterns to fine-tune immune surveillance.

Site-specific production of IL-6 in the central nervous system retargets and enhances the inflammatory response in experimental autoimmune encephalomyelitis

IL-6 is crucial for the induction of many murine models of autoimmunity including experimental autoimmune encephalomyelitis (EAE), an animal model for multiple sclerosis. To establish the role of site-specific production of IL-6 in autoimmunity, we examined myelin oligodendrocyte glycoprotein immunization-induced EAE in transgenic mice (GFAP-IL6) with IL-6 production restricted to the cerebellum. Myelin oligodendrocyte glycoprotein-immunized (Mi-) GFAP-IL6 mice developed severe ataxia but no physical signs of spinal cord involvement, which was in sharp contrast to Mi-wild type (WT) animals that developed classical EAE with ascending paralysis. Immune pathology and demyelination were nearly absent from the spinal cord, but significantly increased in the cerebellum of Mi-GFAP-IL6 mice. Tissue damage in the cerebellum in the Mi-GFAP-IL6 mice was accompanied by increased total numbers of infiltrating leukocytes and increased proportions of both neutrophils and B-cells. With the exception of IL-17 mRNA, which was elevated in both control immunized and Mi-GFAP-IL6 cerebellum, the level of other cytokine and chemokine mRNAs were comparable with Mi-WT cerebellum whereas significantly higher levels of IFN-gamma and TNF-alpha mRNA were found in Mi-WT spinal cord. Thus, site-specific production of IL-6 in the cerebellum redirects trafficking away from the normally preferred antigenic site the spinal cord and acts as a leukocyte "sink" that markedly enhances the inflammatory cell accumulation and disease. The mechanisms underlying this process likely include the induction of specific chemokines, activation of microglia, and activation and loss of integrity of the blood-brain barrier present in the cerebellum of the GFAP-IL6 mice before the induction of EAE.

The T cell STAT signaling network is reprogrammed within hours of bacteremia via secondary signals

The delicate balance between protective immunity and inflammatory disease is challenged during sepsis, a pathologic state characterized by aspects of both a hyperactive immune response and immunosuppression. The events driven by systemic infection by bacterial pathogens on the T cell signaling network that likely control these responses have not been illustrated in great detail. We characterized how intracellular signaling within the immune compartment is reprogrammed at the single cell level when the host is challenged with a high level of pathogen. To accomplish this, we applied flow cytometry to measure the phosphorylation potential of key signal transduction proteins during acute bacterial challenge. We modeled the onset of sepsis by i.v. administration of avirulent strains of Listeria monocytogenes and Escherichia coli to mice. Within 6 h of bacterial challenge, T cells were globally restricted in their ability to respond to specific cytokine stimulations as determined by assessing the extent of STAT protein phosphorylation. Mechanisms by which this negative feedback response occurred included SOCS1 and SOCS3 gene up-regulation and IL-6-induced endocystosis of the IL-6 receptor. Additionally, macrophages were partially tolerized in their ability to respond to TLR agonists. Thus, in contrast to the view that there is a wholesale immune activation during sepsis, one immediate host response to blood-borne bacteria was induction of a refractory period during which leukocyte activation by specific stimulations was attenuated.

The role of interleukin-6 in lipopolysaccharide-induced fever by mechanisms independent of prostaglandin E2

Fever has been shown to be elicited by prostaglandin E(2) (PGE(2)) binding to its receptors on thermoregulatory neurons in the anterior hypothalamus. The signals that trigger PGE(2) production are thought to include proinflammatory cytokines, such as IL-6. However, although the presence of IL-6 is critical for fever, IL-6 by itself is not or only weakly pyrogenic. Here we examined the relationship between IL-6 and PGE(2) in lipopolysaccharide (LPS)-induced fever. Immune-challenged IL-6 knockout mice did not produce fever, in contrast to wild-type mice, but the expression of the inducible PGE(2)-synthesizing enzymes, cyclooxygenase-2 and microsomal prostaglandin E synthase-1, was similarly up-regulated in the hypothalamus of both genotypes, which also displayed similarly elevated PGE(2) levels in the cerebrospinal fluid. Nevertheless, both wild-type and knockout mice displayed a febrile response to graded concentrations of PGE(2) injected into the lateral ventricle. There was no major genotype difference in the expression of IL-1beta and TNFalpha or their receptors, and pretreatment of IL-6 knockout mice with soluble TNFalpha receptor ip or intracerebroventricularly or a cyclooxygenase-2 inhibitor ip did not abolish the LPS unresponsiveness. Hence, although IL-6 knockout mice have both an intact PGE(2) synthesis and an intact fever-generating pathway downstream of PGE(2), endogenously produced PGE(2) is not sufficient to produce fever in the absence of IL-6. The findings suggest that IL-6 controls some factor(s) in the inflammatory cascade, which render(s) IL-6 knockout mice refractory to the pyrogenic action of PGE(2), or that it is involved in the mechanisms that govern release of synthesized PGE(2) onto its target neurons.

miRNA regulation of cytokine genes

In this review we discuss specific examples of regulation of cytokine genes and focus on a new mechanism involving post-transcriptional regulation via miRNAs. The post-transcriptional regulation of cytokine genes via the destabilizing activity of AU-rich elements [AREs] and miRNAs is a pre-requisite for regulating the half-life of many cytokines and achieving the temporal and spatial distributions required for regulation of these genes.

Thermal facilitation of lymphocyte trafficking involves temporal induction of intravascular ICAM-1

OBJECTIVE

Fever is associated with improved survival, although its beneficial mechanisms are poorly understood. Previous studies indicate that the thermal element of fever augments lymphocyte migration across high endothelial venules (HEVs) of lymphoid organs by increasing the intravascular display of a gatekeeper trafficking molecule, intercellular adhesion molecule-1 (ICAM-1). Here, we evaluated the spatio-temporal relationship between the thermal induction of intravascular ICAM-1 and lymphocyte trafficking.

METHODS

Intravascular ICAM-1 density was quantified by immunofluorescence staining in mice exposed to fever-range whole-body hyperthermia (39.5+/-0.5 degrees C). ICAM-1-dependent lymphocyte trafficking was measured in short-term homing assays.

RESULTS

A linear relationship was observed between the duration of heat treatment and intravascular ICAM-1 density in HEVs with maximal responses requiring sustained (i.e., five hours) thermal stress. Circulating lymphocytes were found to sense incremental changes in ICAM-1 on HEVs, such that trafficking is proportional to the intravascular density of ICAM-1. We further identified a hydroxamate-sensitive shedding mechanism that restores ICAM-1 expression to homeostatic levels following the cessation of thermal stress.

CONCLUSIONS

The time-dependent response to thermal stress indicates that ICAM-1 density governs the efficiency of lymphocyte interactions with HEVs in vivo. These studies highlight the dynamic role of the microcirculation in promoting immune surveillance during febrile inflammatory responses.