Bioinformatics and in-silico findings reveal medical features and pharmacological targets of biochanin A against colorectal cancer and COVID-19.

Severe mortality due to the COVID-19 pandemic resulted from the lack of effective treatment. Although COVID-19 vaccines are available, their side effects have become a challenge for clinical use in patients with chronic diseases, especially cancer patients. In the current report, we applied network pharmacology and systematic bioinformatics to explore the use of biochanin A in patients with colorectal cancer (CRC) and COVID-19 infection. Using the network pharmacology approach, we identified two clusters of genes involved in immune response (IL1A, IL2, and IL6R) and cell proliferation (CCND1, PPARG, and EGFR) mediated by biochanin A in CRC/COVID-19 condition. The functional analysis of these two gene clusters further illustrated the effects of biochanin A on interleukin-6 production and cytokine-cytokine receptor interaction in CRC/COVID-19 pathology. In addition, pathway analysis demonstrated the control of PI3K-Akt and JAK-STAT signaling pathways by biochanin A in the treatment of CRC/COVID-19. The findings of this study provide a therapeutic option for combination therapy against COVID-19 infection in CRC patients.

Interleukin-6 actions in the hypothalamus protects against obesity and is involved in the regulation of neurogenesis.

BACKGROUND: Interleukin-6 (IL6) produced in the context of exercise acts in the hypothalamus reducing obesity-associated inflammation and restoring the control of food intake and energy expenditure. In the hippocampus, some of the beneficial actions of IL6 are attributed to its neurogenesis-inducing properties. However, in the hypothalamus, the putative neurogenic actions of IL6 have never been explored, and its potential to balance energy intake can be an approach to prevent or attenuate obesity. METHODS: Wild-type (WT) and IL6 knockout (KO) mice were employed to study the capacity of IL6 to induce neurogenesis. We used cell labeling with Bromodeoxyuridine (BrdU), immunofluorescence, and real-time PCR to determine the expression of markers of neurogenesis and neurotransmitters. We prepared hypothalamic neuroprogenitor cells from KO that were treated with IL6 in order to provide an ex vivo model to further characterizing the neurogenic actions of IL6 through differentiation assays. In addition, we analyzed single-cell RNA sequencing data and determined the expression of IL6 and IL6 receptor in specific cell types of the murine hypothalamus. RESULTS: IL6 expression in the hypothalamus is low and restricted to microglia and tanycytes, whereas IL6 receptor is expressed in microglia, ependymocytes, endothelial cells, and astrocytes. Exogenous IL6 reduces diet-induced obesity. In outbred mice, obesity-resistance is accompanied by increased expression of IL6 in the hypothalamus. IL6 induces neurogenesis-related gene expression in the hypothalamus and in neuroprogenitor cells, both from WT as well as from KO mice. CONCLUSION: IL6 induces neurogenesis-related gene expression in the hypothalamus of WT mice. In KO mice, the neurogenic actions of IL6 are preserved; however, the appearance of new fully differentiated proopiomelanocortin (POMC) and neuropeptide Y (NPY) neurons is either delayed or disturbed.

Tumor-derived exosomes encapsulating miR-34a promote apoptosis and inhibit migration and tumor progression of colorectal cancer cells under in vitro condition.

BACKGROUND: MicroRNA (miR)-34a, as a master tumor suppressor in colorectal cancer (CRC), could regulate multiple genes participating in tumor proliferation, invasion, immune evasion, and inflammation-induced progression. Exosomes, as novel nano-carriers, were found to be capable of shuttling crucial mediators to various cells. Since the conventional CRC therapeutics currently are a matter of debate, implication of microRNAs in malignancy remedies have been addressed illustrating promising outlooks. OBJECTIVES: In this study, we aimed to investigate the delivery of miR-34a to CRC cell line CT-26 by encapsulating into tumor-derived exosomes (TEXs), in order to evaluate the anti-proliferative and progressive effects of the novel nano-carrier complex under in vitro condition. METHODS: Exosomes were purified from the starved CT-26 cells and then enriched by miR-34a using the calcium chloride (Cacl2) modified solution. Following the detection of miR-34a expression in the enriched TEXs, the viability of CT-26 cells treated by multiplicity concentrations of either TEXs or TEX-miR-34a was examined. Moreover, the apoptosis rate of the cells was evaluated, and the migration of CT-26 cells subjected to both TEX-miR-34a and TEX was also measured. Thereafter, the expressions of miR-34a target genes, as IL-6R, STAT3, PD-L1, and VEGF-A, which play roles in tumor progression, were determined in the treated CT-26 cells. RESULTS: The viability of CT-26 cells was harnessed following the treatment with TEX-miR-34a and the apoptosis levels of the cells were also observed to be enhanced dose-dependently. TEX-miR-34a was able to diminish the migration rate of the TEX-miR-34a treated cells and the expressions of IL-6R, STAT3, PD-L1, and VEGF-A were significantly restricted. Moreover, TEXs alone increased the apoptosis rate of tumor cells and repressed the proliferation and migration of these cells which were boosted by enrichment of TEXs with miR-34a. CONCLUSION: Exosomes isolated from the starved CT-26 cells were found to have a potential to deliver miR-34a into tumor cells properly with high functionality maintenance for miR-34a in case of regulating genes related to tumor progression and TEXs which showed no positive effect favoring cancer cells, presumably act as a favorable adjuvant in the CRC therapy.

HBD Inhibits the Development of Colitis-Associated Cancer in Mice via the IL-6R/STAT3 Signaling Pathway.

Colitis-associated cancer (CAC) is a malignant disease of the colon that is caused by recurrent episodes of chronic intestinal inflammation. Huangqi Baizhu decoction (HBD) is a classic prescription comprised of Radix Astragali and Rhizoma Atractylodis, which are usually used to treat digestive conditions, such as peptic ulcers, colitis, or colorectal carcinoma in clinics. HBD is well known for "tonifying qi and spleen" based on the theories of traditional Chinese medicine, and has the preponderant effect of alleviating chronic intestinal mucosa damage associated with disease. However, the underlying mechanism behind this is still unknown. In the current study, we employed the AOM/DSS mouse model to analyze the effects of HBD on the development of inflammation in colonic carcinoma. The in vivo study showed that HBD could significantly reduce the mortality of mice and control the incidence and size of colonic tumors by inhibiting the IL-6/STAT3 signaling pathway. In vitro, Astragaloside and Atractylenolide (CAA), the main components of HBD, inhibited the proliferation of HCT-116 cells as determined by an MTT assay. Furthermore, CAA notably suppressed the protein expression of IL-6R, STAT3, Survivin, and Cyclin D1 induced by IL-6 in HCT-116 and RAW264.7 cells. These results suggested that HBD exhibits anti-inflammatory and anti-proliferative effects, inhibiting the development of CAC in mice.

Equol suppresses inflammatory response and bone erosion due to rheumatoid arthritis in mice.

Rheumatoid arthritis (RA) is a chronic and systemic autoimmune inflammatory disease. Typical pathological findings of RA include persistent synovitis and bone degradation in the peripheral joints. Equol, a metabolite of the major soybean isoflavone daidzein, shows superior bioactivity than other isoflavones. We investigated the effects of equol administration on inflammatory response and bone erosion in mice with collagen-induced arthritis (CIA). The severity of arthritis symptoms was significantly low in the equol-administered CIA mice. In addition, equol administration improved the CIA-induced bone mineral density decline. In the inflamed area of CIA mice, equol administration suppressed the expression of interleukin-6 and its receptor. Furthermore, equol reduced the expression of genes associated with bone formation inhibition, osteoclast and immature osteoblast specificity and cartilage destruction. These results suggest that equol suppresses RA development and RA-induced bone erosion by regulating inflammation and bone metabolism.

Protective Effect of Areca catechu Leaf Ethanol Extract Against Ethanol-Induced Gastric Ulcers in ICR Mice.

Gastric ulcer is a common digestive disorder that results in considerable suffering. Hence, this digestive pathology has been the focus of a number of recent studies. Although numerous drugs have been developed to treat gastric ulcers, therapeutic approaches for many of the complications associated with these drugs remain to be identified. For this reason, many natural compounds have been explored as alternatives for these drugs. In this study, we have investigated the effectiveness of Areca catechu leaf ethanol extract (ACE) for treating ethanol-induced gastric ulcers in mice. We performed histological as well as immunohistochemical examinations to explore the therapeutic properties of ACE. We also examined the levels of inflammatory signaling molecules to confirm the anti-inflammatory effects of ACE. The histochemical data demonstrate that ACE can protect the mucosal epithelium as well as the vascular supply in the gastric tract. Furthermore, ACE significantly reduced the expression levels of tumor necrosis factor-alpha (TNF-α), interleukin-6 receptor (IL-6R), inducible NO synthase (iNOS), cyclooxygenase 2 (COX2), and nuclear factor-kappa B (NF-κB). Taken together, these data suggest that ACE administration may have the potential as an alternative treatment for gastric ulcer because of its cytoprotective and anti-inflammatory effects and ability to promote the rejuvenation and revascularization of the damaged gastric epithelium.

Anti-interleukin-6 therapy through application of a monogenic protein inhibitor via gene delivery.

Anti-cytokine therapies have substantially improved the treatment of inflammatory and autoimmune diseases. Cytokine-targeting drugs are usually biologics such as antibodies or other engineered proteins. Production of biologics, however, is complex and intricate and therefore expensive which might limit therapeutic application. To overcome this limitation we developed a strategy that involves the design of an optimized, monogenic cytokine inhibitor and the protein producing capacity of the host. Here, we engineered and characterized a receptor fusion protein, mIL-6-RFP-Fc, for the inhibition of interleukin-6 (IL-6), a well-established target in anti-cytokine therapy. Upon application in mice mIL-6-RFP-Fc inhibited IL-6-induced activation of the transcription factor STAT3 and ERK1/2 kinases in liver and kidney. mIL-6-RFP-Fc is encoded by a single gene and therefore most relevant for gene transfer approaches. Gene transfer through hydrodynamic plasmid delivery in mice resulted in hepatic production and secretion of mIL-6-RFP-Fc into the blood in considerable amounts, blocked hepatic acute phase protein synthesis and improved kidney function in an ischemia and reperfusion injury model. Our study establishes receptor fusion proteins as promising agents in anti-cytokine therapies through gene therapeutic approaches for future targeted and cost-effective treatments. The strategy described here is applicable for many cytokines involved in inflammatory and other diseases.

Genetic modulation of the interleukin 6 (IL-6) system in patients with advanced gastric cancer: a background for an alternative target therapy.

BACKGROUND: IL-6 triggers oncogenic/angiogenic signals and the cytokine-dependent pro-cachexia cascade. The prognostic role of the functional IL-6 (promoter) rs1800795 and the IL-6R (receptor) rs8192284 single nucleotide polymorphisms (SNP) was studied in patients with advanced gastric cancer treated with palliative chemotherapy. METHODS: One-hundred-sixty-one patients were genotyped for rs1800795 and rs8192284 SNPs using polymerase chain reaction based restriction fragment length polymorphism (PCR-RFLP) analysis assay. These results were studied for association with overall survival (OS). RESULTS: In 161 assessable patients, frequencies of rs1800795 G/G, G/C and C/C genotypes were 46%, 42% and 12%, respectively. Frequencies of rs8192284 A/A, A/C and C/C genotypes were 36%, 45% and 19%, respectively. Carriers of the rs1800795 G/G and rs8192284 C/C genotypes showed the worst OS. In the multivariate model, rs1800795 G/G (1.69 hazard ratio; 95% confidence interval 1.18-2.42), and rs8192284 C/C (1.78 hazard ratio; 95% confidence interval 1.12-2.83) confirmed an adverse prognostic impact. CONCLUSIONS: In this population, genetic variants that up-regulate the IL-6 system showed impact on OS. This findings sustain the hypothesis that anti-IL-6 compounds deserve clinical studies as novel therapeutics in the palliative treatment of cancer patients.

Inter-relation between interleukin (IL)-1, IL-6 and body fat regulating circuits of the hypothalamic arcuate nucleus.

Interleukin (IL)-1 and IL-6 are immune modulating cytokines that also affect metabolic function because both IL-1 receptor I deficient (IL-1RI⁻/⁻) and IL-6 deficient (IL-6⁻/⁻) mice develop late-onset obesity and leptin resistance. Both IL-1 and IL-6 appear to target the central nervous system (CNS) to increase energy expenditure. The hypothalamic arcuate nucleus (ARC) is a major relay between the periphery and CNS in body fat regulation (e.g. by being a target of leptin). The present study aimed to investigate the possible mechanisms responsible for the effects exerted by endogenous IL-1 and IL-6 on body fat at the level of the ARC, as well as possible interactions between IL-1 and IL-6. Therefore, we measured the gene expression of neuropeptides of the ARC involved in energy balance in IL-1RI⁻/⁻ and IL-6⁻/⁻ mice. We also investigated the interactions between expression of IL-1 and IL-6 in these mice, and mapped IL-6 receptor α (IL-6Rα) in the ARC. The expression of the obesity promoting peptide neuropeptide Y (NPY), found in the ARC, was increased in IL-1RI⁻/⁻ mice. The expression of NPY and agouti-related peptide (AgRP), known to be co-expressed with NPY in ARC neurones, was increased in cold exposed IL-6⁻/⁻ mice. IL-6Rα immunoreactivity was densely localised in the ARC, especially in the medial part, and was partly found in NPY positive cell bodies and also α-melanocyte-stimulating hormone positive cell bodies. The expression of hypothalamic IL-6 was decreased in IL-1RI⁻/⁻ mice, whereas IL-1ß expression was increased in IL-6⁻/⁻ mice. The results of the present study indicate that depletion of the activity of the fat suppressing cytokines IL-1 and IL-6 in knockout mice can increase the expression of the obesity promoting neuropeptide NPY in the ARC. Depletion of IL-1 activity suppresses IL-6 expression, and IL-6Rα-like immunoreactivity is present in neurones in the medial ARC, including neurones containing NPY. Therefore, IL-6, IL-1 and NPY/AgRP could interact at the level of the hypothalamic ARC in the regulation of body fat.

[Influence on electroacupuncture at "Qiangzhuang" acupoints for neuro-immune regulation of sub-acute aged rats].

OBJECTIVE: To explore the underlying mechanism of electroacupuncture for anti-aging. METHODS: Forty Sprague-Dawley rats (female and male take one half for each), 3-month old, were divided into a control group, a model group, a routine electroacupuncture group (current intensity, 1 mA) and a strong electroacupuncture group (current intensity, 4.5 mA), 10 rats in each group. The model of aged rats was established by D-galactose in the latter three groups. The acupoints of "Guanyuan" (CV 4) and "Zusanli" (ST 36) were used for electroacupuncture treatment, six times per week for 4 weeks. After that, the level of interleukin 6 (IL-6) in the serum, as well as the expression of neuropeptide Y mRNA (NPY mRNA) and IL-6 receptor (IL-6R) in the periventricular hypothalamic nucleus (PVN) were examined and compared between each group. RESULTS: In comparison of the control rats, the model rats expressed with the lower level of NPY mRNA in PVN, higher levels of IL-6 in the serum and IL-6R in PVN, which is different from each other (P < 0.05). In both routine electroacupuncture group and strong electroacupuncture group, the level of NPY mRNA in PVN was up-regulated, in contrast, the levels of IL-6 in the serum and IL-6R in PVN were cut down, which were different from those of the model group (both P < 0.05). Furthermore, the therapeutic effect of the strong electroacupuncture group is different from that of the routine electroacupuncture group (P < 0.05). CONCLUSION: Electroacupuncture at "Qiangzhuang" acupoints plays an active role to slow down the aging process on the sub-acute aged rats through regulating the function of neuro-immune system, and the therapeutic effect of strong stimulation is better than that of routine stimulation.

Interleukin-6 is associated with liver lipid homeostasis but not with cell death in experimental hepatic steatosis.

Hepatic steatosis is a risk factor for the progression of non-alcoholic fatty liver disease. The role of pro-inflammatory interleukin (IL)-6 in hepatic steatosis etiology is controversial. We investigated in vivo and in primary hepatocyte cultures whether IL-6 has a modulator role in liver and mitochondria lipid composition and cell death in a choline-deficient (CD) diet rat model of hepatic steatosis. Dietary choline deficiency increased triglycerides and cholesterol, and reduced phosphatidylcholine (PC), phosphatidylethanolamine (PE) and the membrane integrity marker PC:PE ratio in liver. Choline-deficient diet enhanced systemic IL-6, and IL-6 receptor expression and cell death vulnerability in hepatocytes. Derangement of the mitochondrial electron transport chain and of its phospholipid environment was found in CD rat liver mitochondria, which exhibited elevated concentrations of triglycerides, cardiolipin and PC and elevated PC:PE ratio. The cell treatment with IL-6, but not PC, eliminated much of the CD-promoted lipid imbalance in mitochondria but not tumor-necrosis factor (TNF)-alpha-induced cell death. However, PC supplementation prevented the TNF-alpha-induced DNA fragmentation, cytochrome-c release and caspase-3 activity in control and CD hepatocytes. In conclusion, IL-6 ameliorated the mitochondria lipid disturbance in hepatocytes isolated from steatotic animals. Furthermore, PC is identified as a new survival agent that reverses several TNFalpha-inducible responses that are likely to promote steatosis and necrosis.

The IL-6/sIL-6R complex as a novel target for therapeutic approaches.

IL-6 plays a pivotal role in immune responses and certain oncologic conditions. The intense investigation of its biological activity and function led to the discovery of two different IL-6-driven signalling pathways. Binding to the membrane-bound IL-6 receptor (mIL-6R, CD126) causes the recruitment of two gp130 co-receptor molecules (CD130) and the activation of intracellular signalling cascades via gp130. Although this classical pathway is mainly limited to hepatocytes, neutrophils, monocytes/macrophages and certain other leukocyte populations, which express IL-6R on their surface, an alternative mechanism has also been described. Proteolytic cleavage of the mIL-6R protein or translation from alternatively spliced mRNA leads to the generation of a soluble form of the IL-6R (sIL-6R), which is likewise able to bind to IL-6. The resulting IL-6/sIL-6R complex is also capable of binding to gp130 and inducing intracellular signalling. Through this so-called 'trans-signalling' mechanism, IL-6 is able to stimulate cells that lack an endogenous mIL-6R. High levels of IL-6 and sIL-6R have been reported in several chronic inflammatory and autoimmune diseases as well as in cancer. Preclinical animal disease models have provided strong evidence that specific blockade of IL-6-regulated signalling pathways represents a promising approach for the therapy of these diseases. An optimised variant of the recently described fusion protein sgp30Fc is now heading towards its clinical evaluation.

All-trans retinoic acid modulates radiation-induced proliferation of lung fibroblasts via IL-6/IL-6R system.

Although high-dose thoracic radiotherapy is an effective strategy for some malignancies including lung cancers and malignant lymphomas, it often causes complications of radiation fibrosis. To study the mechanism initiating tissue fibrosis, we investigated irradiation-induced cytokine production from human lung fibroblastic cells and found that IL-6 production was stimulated by irradiation. IL-6 is an autocrine growth factor for human myeloma cells, and retinoic acid is reported to inhibit their growth. Thus we evaluated the effect of all-trans retinoic acid (ATRA) on cell proliferation of lung fibroblasts along with the cytokine/receptor system. Irradiation-dependent stimulation of IL-6 production was correlated with increased NF-kappaB activity, and ATRA reduced this effect. Irradiation also increased the levels of mRNA for IL-6R and gp130, which were blocked by coexisting ATRA. Furthermore, IL-6 stimulated cell proliferation in dose-dependent manner but was overcome by pharmacological concentration of ATRA. These effects of ATRA were inhibited by rottlerin, which suggests ATRA abolished irradiation-induced stimulation through a PKCdelta-dependent pathway. Finally, we demonstrated that IL-6 transcripts in the lung were upregulated at 2 mo after irradiation, and the effect was inhibited by the intraperitoneal administration of ATRA. ATRA is expected to have an advantage for radiotherapy in its antitumor effects, as reported previously, and to prevent radiotherapy-induced pulmonary injury.

[Effects of Chinese herbs for supplementing Shen and strengthening bone on IL-6 mediated myelogenic osteoclasts formation of ovariectomized rats in early stage].

OBJECTIVE: To observe the effect of Chinese herbs for supplementing Shen and strengthening bone (HB) on myelogenic osteoclasts formation, and gene expression of interleukin-6 (IL-6), IL-6 receptor (IL-6R) and gp130 in bone marrow. METHODS: Seventy-two healthy female SD rats of 3 months, were randomly divided into three groups, 24 in the sham-operated group (A), 24 in the ovariectomized group (B) and 24 in the after ovariectomy HB treated group (C). Bone marrow cells of 6 rats from each group were respectively collected and cultured at four time points (2nd, 4th, 6th and 12th weeks after operation). After 6 days of culture, the bone marrow cells were differentiated by Wright-Giemsa stain and TRAP stain, and total RNA in them was extracted by TRIZOL. RESULTS: Beginning from the 2nd week, the osteoclasts formation in Group B was higher than that in Group A (P < 0.05), and IL-6, IL-6R gene expression significantly increased in Group B (P < 0.05 or P < 0.01). These changes reached the peak in the 4th to 6th week, with the level maintained to the 12th week. As for comparison of Group B and C, the above-mentioned changes were significantly weakened in the latter (P < 0.05 or P < 0.01). No significant change of gp130 gene expression revealed in the whole course in either group. CONCLUSION: HB could inhibit the myelogenic osteoclasts formation in ovariectomized rats, this effect may be correlated with, partially at least, its inhibitory effect on the over-expressed IL-6 and IL-6R gene expression in myelocytes after ovariectomy.

A point mutation of Tyr-759 in interleukin 6 family cytokine receptor subunit gp130 causes autoimmune arthritis.

We generated a mouse line in which the src homology 2 domain-bearing protein tyrosine phosphatase (SHP)-2 binding site of gp130, tyrosine 759, was mutated to phenylalanine (gp130(F759/F759)). The gp130(F759/F759) mice developed rheumatoid arthritis (RA)-like joint disease. The disease was accompanied by autoantibody production and accumulated memory/activated T cells and myeloid cells. Before the disease onset, the T cells were hyperresponsive and thymic selection and peripheral clonal deletion were impaired. The inhibitory effect of IL-6 on Fas ligand expression during activation-induced cell death (AICD) was augmented in gp130(F759/F759) T cells in a manner dependent on the tyrosine residues of gp130 required for signal transducer and activator of transcription 3 activation. Finally, we showed that disease development was dependent on lymphocytes. These results provide evidence that a point mutation of a cytokine receptor has the potential to induce autoimmune disease.

Differential expression of various cytokine receptors in the brain after stimulation with LPS in young and old mice.

The effect of lipopolysaccharides (LPS) on the expression of cytokine receptors was examined in the spleen, brain and pituitary gland, and compared in young and old mice. The level of mRNA for various cytokine receptors (IL-1RI, IL-2Ralpha, IL-3Ralpha, IL-6R, TNFalphaR and IFNgammaR) was found to be increased in the spleen of young but not in old mice within 2-6h of stimulation with LPS. Similar enhancement of cytokine receptor mRNA was also observed in the brain after LPS stimulation, but the magnitude varied according to the type of cytokine receptor, the site of brain and the age of the mice. In the hypothalamus, the level of mRNA for IL-1R, IL-3R, IL-6R and IFNgammaR increased in young but not in old mice. Reciprocally, in the cerebral cortex, mRNA for TNFalphaR and IFNgammaR increased in old but not in young mice. In the hippocampus, TNFalphaR mRNA expression, increased in young but not in old mice, and expression of the other cytokine receptors did not change greatly in either. In the pituitary gland, mRNA for IL-6R, TNFalphaR and IFNgammaR increased in both young and old mice, but IL-2Ralpha increased only in young mice.Thus, various cytokines produced by immune cells might directly or indirectly influence brain functions through the various cytokine receptors expressed in the brain. Moreover, interactions between the immune system and the brain at the time of infection would be expected to be different in young and old mice, because cytokine production changes with age, as does the expression of their receptors in the brain.

Effects of repeated stress on expression of interleukin-6 (IL-6) and IL-6 receptor mRNAs in rat hypothalamus and midbrain.

We examined the effects of single and repeated stress on the expression of interleukin-6 (IL-6) and IL-6 receptor (IL-6R) mRNAs in the rat midbrain and hypothalamus using reverse transcriptase-polymerase chain reaction (RT-PCR). Following a single episode of restraint stress for 4 hours (1R) or 4 hours per day on two (2R) or three (3R) consecutive days, the hypothalamus and midbrain were removed immediately and the levels of IL-6 and IL-6R mRNAs in both regions were determined. Regional differences in stress-related changes in mRNA levels were noted. The expression of IL-6 mRNA in the hypothalamus did not change in 1R group but decreased in 2R and 3R groups. The expression of IL-6R mRNA in the same region significantly diminished in all groups. In the midbrain, the expression of IL-6 mRNA increased in 1R group and decreased in 2R and 3R, while the expression of IL-6R mRNA significantly diminished in 1R and 3R groups but was not different from control in 2R group. Our findings indicate that repeated stress in rats produce changes in IL-6 and IL-6R mRNAs in the midbrain and hypothalamus that are different than those of a single stress episode.

Regulation of cytokine expression by an autoreactive B cell clone derived from MRL/MP-lpr/lpr mice.

The B cell line, MRL159.5, was established by somatic hybridization between splenic MRL/MP-lpr/lpr (lpr) mice B cells and 2.52M, a hypoxanthine-aminopterine-thymidine (HAT) medium-sensitive B cell line mutant. It possessed a receptor molecule for mouse erythrocytes treated with bromelain (Br-MRBC) on its surface, likely to be an autoreactive B cell clone specific for Br-MRBC as detected by rosette-forming assay with Br-MRBC. MRL159.5 spontaneously produced IL-6 and secreted IgM, and was induced to augment IgM secretion when treated with Br-MRBC or IL-6. Triggering of CD40 led to an augmentation of IgM secretion as well as IL-6 expression. Blocking the binding of IL-6 to its cellular receptor through the use of inhibitory antibodies inhibited CD40-induced IgM secretion, suggesting a possible autocrine role of IL-6 for CD40-induced differentiation of this B cell hybridoma. Addition of IL-4 or Br-MRBC augmented IL-6 expression as well as IgM secretion by CD40-activated MRL159.5 cells. CD40 also augmented tumour necrosis factor-alpha (TNF-alpha) and granulocyte-macrophage colony-stimulating factor (GM-CSF) expression but resulted in decreased IL-10 expression. Furthermore, under conditions where IL-6 expression was augmented, IL-6R alpha (gp80) expression was down-regulated, suggesting a negative feedback mechanism of an IL-6 autocrine loop in this hybridoma. These results demonstrate a role by which T cell-dependent activation through CD40 regulates an IL-6 autocrine loop, controlling differentiation of autoreactive B cells in autoimmune disease.