Inoculation of lymphocytes from young mice prevents progression of age-related hearing loss in a senescence-associated mouse model.

Despite the increase in age-related hearing loss (ARHL) prevalence owing to increased population aging, preventive measures against ARHL have not yet been established. The immune system becomes one of the most dysfunctional systems upon aging, and immunosenescence greatly affects homeostasis and promotes systemic aging along with chronic inflammation and oxidative stress. This study aimed to determine whether immuno-rejuvenation procedures can prevent ARHL and have clinical applications as well as to analyze the communication mechanisms between the systemic immune system and the cochlea using a murine model. Lymphocytes from young mice inhibited the progression of ARHL. The method of cryopreserving these lymphocytes and inoculating them at the onset of ARHL suggests their clinical application. Mice that were administered this treatment not only maintained auditory threshold but also avoided spinal ganglion degeneration, cellular immune aging, and nitric oxide production, which causes age-related tissue damage. These findings coincide with our previous strategies against immunosenescence and neuronal aging. Therefore, the manipulation of systemic immune function may contribute not only to the prevention of ARHL but also to the development of novel anti-aging clinical measures, paving the way to healthy longevity with preserved organ function.

Treg and IL-1 receptor type 2-expressing CD4+ T cell-deleted CD4+ T cell fraction prevents the progression of age-related hearing loss in a mouse model.

We investigated the association between cellular immunity and age-related hearing loss (ARHL) development using three CD4+ T cell fractions, namely, naturally occurring regulatory T cells (Treg), interleukin 1 receptor type 2-expressing T cells (I1R2), and non-Treg non-I1R2 (nTnI) cells, which comprised Treg and I1R2-deleted CD4+ T cells. Inoculation of the nTnI fraction into a ARHL murine model, not only prevented the development of ARHL and the degeneration of spiral ganglion neurons, but also suppressed serum nitric oxide, a source of oxidative stress. Further investigations on CD4+ T cell fractions could provide novel insights into the prevention of aging, including presbycusis.

Mycophenolic acid, the active form of mycophenolate mofetil, interferes with IRF7 nuclear translocation and type I IFN production by plasmacytoid dendritic cells.

BACKGROUND: Both humoral and cellular immune mechanisms are involved in the onset and progression of autoimmune responses in systemic lupus erythematosus (SLE). Plasmacytoid dendritic cells (pDCs) play a central role in the pathogenesis of SLE via the dysregulation of type I interferon (IFN) production; these cells act together with activated myeloid DCs (mDCs) to amplify the vicious pathogenic spiral of autoimmune disorders. Therefore, control of aberrant DC activation in SLE may provide an alternative treatment strategy against this disease. Mycophenolate mofetil (MMF), which has been used to treat lupus nephritis, specifically blocks the proliferation of B and T lymphocytes via inhibition of inosine-5-monophosphate dehydrogenase. Here, we focus on the effects of MMF in targeting DC functions, especially the IFN response of pDCs. METHODS: We isolated human blood pDCs and mDCs by flow cytometry and examined the effect of mycophenolic acid (MPA), which is a metabolic product of MMF, on the toll-like receptor (TLR) ligand response of DC subsets. Additionally, we cultured pDCs with serum from SLE patients in the presence or absence of MPA and then examined the inhibitory function of MPA on SLE serum-induced IFN-α production. RESULTS: We found that treatment with 1-10 µM of MPA (covering the clinical trough plasma concentration range) dose-dependently downregulated the expression of CD80 and CD86 on mDCs (but not pDCs) without inducing apoptosis, in response to R848 or CpG-ODN, respectively. Notably, in pDCs, MPA significantly suppressed IFN-α production with IRF7 nuclear translocation and repressed the AKT activity. In addition, MPA inhibited IL-12 production with STAT4 expression in mDCs. We further identified that MPA had an inhibitory effect on SLE serum-induced IFN-α production by pDCs. CONCLUSIONS: Our data suggest that MPA can interrupt the vicious pathogenic spiral of autoimmune disorders by regulating the function of DC subsets. This work unveiled a novel mechanism for the therapeutic ability of MMF against SLE.

Immunomodulatory drugs suppress Th1-inducing ability of dendritic cells but enhance Th2-mediated allergic responses.

Immunomodulatory drugs (IMiDs), lenalidomide and pomalidomide, are widely used treatments for multiple myeloma; however, they occasionally lead to episodes of itchy skin and rashes. Here, we analyzed the effects of IMiDs on human myeloid dendritic cells (mDCs) as major regulators of Th1 or Th2 responses and the role they play in allergy. We found that lenalidomide and pomalidomide used at clinical concentrations did not affect the survival or CD86 and OX40-ligand expression of blood mDCs in response to lipopolysaccharide (LPS) and thymic stromal lymphopoietin (TSLP) stimulation. Both lenalidomide and pomalidomide dose-dependently inhibited interleukin-12 (IL-12) and TNF production and STAT4 expression, and enhanced IL-10 production in response to LPS. When stimulated with TSLP, both IMiDs significantly enhanced CCL17 production and STAT6 and IRF4 expression and promoted memory Th2-cell responses. In 46 myeloma patients, serum CCL17 levels at the onset of lenalidomide-associated rash were significantly higher than those without rashes during lenalidomide treatment and those before treatment. Furthermore, serum CCL17 levels in patients who achieved a very good partial response (VGPR) were significantly higher compared with a less than VGPR during lenalidomide treatment. The median time to next treatment was significantly longer in lenalidomide-treated patients with rashes than those without. Collectively, IMiDs suppressed the Th1-inducing capacity of DCs, instead promoting a Th2 response. Thus, the lenalidomide-associated rashes might be a result of an allergic response driven by Th2-axis activation. Our findings suggest clinical efficacy and rashes as a side effect of IMiDs are inextricably linked through immunostimulation.

Widespread time-dependent changes in tissue cytokine concentrations in brain regions during the acute phase of endotoxemia in mice.

Sepsis-associated encephalopathy (SAE) is a diffuse brain dysfunction induced by the systemic response to infection in septic patients. In the present study, we modeled SAE by administering lipopolysaccharide (LPS) intraperitoneally to mice at a concentration of 3.0 mg/kg. We investigated regional preferences for cytokine-mediated brain reactions to endotoxemia and at what time point brain inflammation begins, as well as what cytokines are involved in acute brain reactions. Brains were divided into seven parts: cortex (CTX), olfactory system (Olf), hippocampus (Hip), striatum (Str), diencephalon (Die), brain stem (BS), and cerebellum (CBL). In each brain region, we determined the tissue concentrations of 11 cytokines: CCL2, CCL3, CCL11, CXCL1, CXCL2, CXCL9, CXCL10, G-CSF, IL-1ß, IL-6, and TNF-α, in mice injected with LPS or saline, at 1, 4, and 24 h after injection using multiplex cytokine assays. Every brain region responded with the production of multiple cytokines to LPS-induced systemic inflammation during the acute phase (4-24 h) after LPS injection. IL-6, CCL2, CCL3, CXCL1, CXCL2, CXCL9, and TNF-α were "early cytokines" that increased only at 4 h but not at 24 h after LPS injection in most brain regions. CCL11, CXCL10, and G-CSF were "late cytokines" that were elevated up to 24 h after LPS injection in selected brain regions. The regions Olf, Hip, and Die were the most responsive to endotoxemia; these regions produced ten cytokines and continued to produce three "late cytokines" up to 24 h after LPS injection. Str was the least responsive to endotoxemia. The widespread nature of brain cytokine production explains the characteristics of SAE. Further studies on the roles of CCL11, CXCL10, and G-CSF may be especially important in terms of potential prevention of SAE between 4 and 24 h after the onset of sepsis.

The immunomodulatory-drug, lenalidomide, sustains and enhances interferon-α production by human plasmacytoid dendritic cells.

Background: Lenalidomide (LEN), an immunomodulatory drug (IMiD), is currently used for treatment of multiple myeloma (MM). LEN potentiates T cell and natural killer cell functions. However, the cellular and molecular mechanisms underlying the immunomodulatory effects of LEN remain unclear. We focused on the effects of LEN on human plasmacytoid dendritic cells (pDCs), which are the major source of interferon (IFN)-α in the blood and play a central role in innate immune responses. Results: We found that bortezomib, a proteasome inhibitor used to treat MM, killed pDCs but that 0.1-3 µM LEN (covering clinical plasma concentration range) did not affect pDC survival or CD86 expression. Bortezomib inhibited pDC-derived IFN-α production in a dose-dependent fashion, but 0.1-3 µM LEN sustained pDC-derived IFN-α production when stimulated with an optimal concentration of CpG-ODN 2216 (3 µM). In pDCs stimulated with a low concentration of CpG-ODN (0.1 µM), LEN enhanced IFN-α production. These results indicated that LEN, when used at a clinically relevant concentration, can potentially enhance IFN-α production by pDCs. Conclusion: Collectively, our findings unveiled a novel target of LEN and extend the repertoire of the drug's known immunomodulatory effects. These effects may explain the low incidence of herpes zoster viral infection observed during LEN treatment compared with bortezomib treatment. LEN may function as an IMiD affecting a wide array of immune cells, including pDCs, leading to amplification of a positive immune axis able to eliminate MM cells.

Statins can suppress DC-mediated Th2 responses through the repression of OX40-ligand and CCL17 expression.

DCs and epithelial cell-derived thymic stromal lymphopoietin (TSLP) have pivotal roles in allergic inflammation. TSLP stimulates myeloid DCs to express OX40-ligand (OX40L) and CCL17, which trigger and maintain Th2 cell responses. We have previously shown that statins, which are HMG-CoA reductase inhibitors, have the ability to suppress type I IFN production by plasmacytoid DCs. Here, we extended our previous work to examine the immunomodulatory effect of statins on allergic responses, particularly the TSLP-dependent Th2 pathway induced by myeloid DCs. We found that treatment of TSLP-stimulated DCs with either pitavastatin or simvastatin suppressed both the DC-mediated inflammatory Th2 cell differentiation and CRTH2+ CD4+ memory Th2 cell expansion and also repressed the expressions of OX40L and CCL17 by DCs. These inhibitory effects of statins were mimicked by treatment with either a geranylgeranyl-transferase inhibitor or Rho-kinase inhibitor and were counteracted by the addition of mevalonate, suggesting that statins induce geranylgeranylated Rho inactivation through a mevalonate-dependent pathway. We also found that statins inhibited the expressions of phosphorylated STA6 and NF-κB-p50 in TSLP-stimulated DCs. This study identified a specific ability of statins to control DC-mediated Th2 responses, suggesting their therapeutic potential for treating allergic diseases.

Activation of Dendritic Cells in Dry Eye Mouse Model.

Purpose: The immune system plays a major role in the pathogenesis of dry eye diseases (DED), and dendritic cells (DCs) are known to be important initiators of acquired immunity. Thus, the purpose of this study was to determine the contribution of DCs to the development of DED. Methods: Mouse dry eye model was induced by subcutaneous injections of scopolamine and was euthanized at the baseline, and 2, 4, and 7 days postinjection. The activation of the DCs was determined by the mixed leukocyte reaction (MLR), and the number of activated CD86+ DCs in the lymph nodes was determined by flow cytometry. Upregulation of cytokines in the culture supernatant of MLR was determined by ELISA. Results: Significantly increased superficial corneal punctate lesions and decreased number of goblet cells in the conjunctiva were observed in scopolamine-injected mice. The number of activated CD86+ DCs was significantly increased in the cervical lymph nodes but not in the inguinal lymph nodes of the dry eye mice. The stimulatory activity of the DCs derived from the cervical lymph nodes of dry eye mice was significantly higher than that of control mice, and upregulations of IL-17, IL-2, and IL-4 were observed in the culture supernatant of MLR. These results indicate that the DCs of the cervical lymph nodes were activated by the scopolamine injections. Conclusions: Our results indicate that DCs in our dry eye model were sufficiently activated to stimulate the T cells that participate in the onset and progression of DED.

Induction of PIR-A/B+ DCs in the in vitro inflammatory condition and their immunoregulatory function.

BACKGROUND: Dendritic cells (DCs), primary antigen-presenting cells, are now well known as an immunoregulator of many aspects of immune responses including inflammatory bowel diseases (IBDs) such as Crohn's disease and ulcerative colitis. We have reported that PIR-A/Bhigh cDCs (conventional DCs) appeared in dextran sodium sulfate (DSS)-induced colitis and serve as a negative immunoregulator in an animal model of IBD. The immunoregulatory role of PIR-A/B+ cDCs was confirmed in both an in vitro culture system and an in vivo transfer experiment. Here, we have investigated the differentiation process of PIR-A/B+ cDCs in an in vitro inflammatory environment and examined their functions. METHODS: cDCs were isolated from the large intestinal lamina propria from C57BL/6 mice and cultured in an inflammatory environment (IL-1, IL-6, TNFα, and LPS). The appearance of PIR-A/B+ cDCs was determined after 24 h, and the in vitro-induced PIR-A/B+ cDCs were functionally and genetically examined. RESULTS: PIR-A/B+ cDCs were detected after a 24-h culture only in the inflammatory environment, and the cells acted as a negative immunoregulator when examined in an allogenic mixed leukocyte reaction (MLR). The message level of IL-27 was highly upregulated in PIR-A/B+ cDCs, while that of high mobility group box 1 protein (HMGB1) was downregulated in these cells. This was well in accordance with the fact that PIR-A/B+ cDCs showed a suppressive function against activated T cells. We found that PIR-A/B+ cDCs produced IL-27, as verified by an ELISA assay, and that the inhibitory effect by PIR-A/B+ cDCs was, at least partially, due to IL-27. Furthermore, CD85d+ cells, a human counterpart of mouse PIR-A/B+ cDCs, were found in the lamina propria of the colon of the patients with ulcerative colitis, but not in the similar part of the non-inflammatory area of colon specimens from patients with colon cancer. CONCLUSIONS: PIR-A/B+ cDCs induced in an in vitro inflammatory environment model showed a suppressive function against activated T cells by producing an inhibitory cytokine.

Endotoxemia-induced cytokine-mediated responses of hippocampal astrocytes transmitted by cells of the brain-immune interface.

Systemic inflammation shifts the brain microenvironment towards a proinflammatory state. However, how peripheral inflammation mediates changes in the brain remains to be clarified. We aimed to identify hippocampal cells and cytokines that respond to endotoxemia. Mice were intraperitoneally injected with lipopolysaccharide (LPS) or saline, and examined 1, 4, and 24 h after injection. Tissue cytokine concentrations in the spleens and hippocampi were determined by multiplex assays. Another group of mice were studied immunohistologically. Fourteen cytokines showed an increased concentration in the spleen, and 10 showed an increase in the hippocampus after LPS injection. Cytokines increased at 4 h (CCL2, CXCL1, CXCL2, and interleukin-6) were expressed by leptomeningeal stromal cells, choroid plexus stromal cells, choroid plexus epithelial cells, and hippocampal vascular endothelial cells, all of which were located at the brain-immune interface. Receptors for these cytokines were expressed by astrocytic endfeet. Cytokines increased at 24 h (CCL11, CXCL10, and granulocyte-colony stimulating factor) were expressed by astrocytes. Cells of the brain-immune interface therefore respond to endotoxemia with cytokine signals earlier than hippocampal parenchymal cells. In the parenchyma, astrocytes play a key role in responding to signals by using endfeet located in close apposition to the interface cells via cytokine receptors.

Increased recruitment of bone marrow-derived cells into the brain associated with altered brain cytokine profile in senescence-accelerated mice.

Bone marrow-derived cells enter the brain in a non-inflammatory condition through the attachments of choroid plexus and differentiate into ramified myeloid cells. Neurodegenerative conditions may be associated with altered immune-brain interaction. The senescence-accelerated mouse prone 10 (SAMP10) undergoes earlier onset neurodegeneration than C57BL/6 (B6) strain. We hypothesized that the dynamics of immune cells migrating from the bone marrow to the brain is perturbed in SAMP10 mice. We created 4 groups of radiation chimeras by intra-bone marrow-bone marrow transplantation using 2-month-old (2 mo) and 10 mo SAMP10 and B6 mice as recipients with GFP transgenic B6 mice as donors, and analyzed histologically 4 months later. In the [B6 → 10 mo SAMP10] chimeras, more ramified marrow-derived cells populated a larger number of discrete brain regions than the other chimeras, especially in the diencephalon. Multiplex cytokine assays of the diencephalon prepared from non-treated 3 mo and 12 mo SAMP10 and B6 mice revealed that 12 mo SAMP10 mice exhibited higher tissue concentrations of CXCL1, CCL11, G-CSF, CXCL10 and IL-6 than the other groups. Immunohistologically, choroid plexus epithelium and ependyma produced CXCL1, while astrocytic processes in the attachments of choroid plexus expressed CCL11 and G-CSF. The median eminence produced CXCL10, hypothalamic neurons G-CSF and tanycytes CCL11 and G-CSF. These brain cytokine profile changes in 12 mo SAMP10 mice were likely to contribute to acceleration of the dynamics of marrow-derived cells to the diencephalon. Further studies on the functions of ramified marrow-derived myeloid cells would enhance our understanding of the brain-bone marrow interaction.

Fetal thymus graft enables recovery from age-related hearing loss and expansion of CD4-Positive T cells expressing IL-1 receptor type 2 and regulatory T Cells.

BACKGROUND: Accumulating evidence has indicated the relationship between the systemic immune system and the central nervous system including the inner ear. RESULTS: We have shown that age-related developments of T-cell dysfunction, hearing loss, and degeneration of cochlear spiral ganglion (SG) neurons observed in 6-month-old mice were recovered in 12 months old mice which previously given fetal thymus transplants twice. We have also demonstrated that CD4(+) T cells expressing interleukin 1 receptor type 2 (IL-1R2) and naturally occurring regulatory T cells (nTregs), which expanded in aged 12-month-old mice, were reduced in the thymus-grafted mice of the same age. CONCLUSION: It is conceivable that the rejuvenation of systemic immune function by fetal thymus grafts contributes not only to the activation of cellular immunity but also to the decrease of IL-1R2(+) CD4(+) T cells or nTregs, which cells accelerate both age-related hearing loss (AHL) and neurodegeneration of the cochlear neurons. Further studies on the interactions among IL-1R2 expression on CD4(+) T cells, Tregs, and neuronal cells and also on the relationships between fetal thymus grafting and the rejuvenation of systemic immunity should be designed in order to advance towards therapeutic effects on neurosenescence, including AHL.

Platelet-derived RANK ligand enhances CCL17 secretion from dendritic cells mediated by thymic stromal lymphopoietin.

Dendritic cells (DCs) play an integral role in cellular cascade that initiate and maintain Th2 responses in allergy. In this study, we examined the interaction between platelets and DCs to determine the role of platelets in the intervention of immune responses through modulation of DC functions. Blood-purified myeloid DCs, which had been stimulated with thymic stromal lymphopoietin (TSLP-DCs), formed aggregates with activated platelets. TSLP-DC maturation was induced after the interaction with TRAP6-activated platelets as indicated by an increase in the expression of CD86, CD40, and CD83. In addition, production of a Th2 cell-attracting chemokine, CCL17, was clearly upregulated by coculture of TSLP-DCs with TRAP6-activated platelets. We further found that an expression of RANK ligand (RANKL) on platelets was upregulated by the TRAP6 activation, and that, using the neutralizing antibody against RANKL, the platelet-derived RANKL induces the activation of TSLP-DCs. Thus, activated platelets can intervene in adaptive immune responses through induction of functional modulation of TSLP-DCs. Platelets have the ability to enhance the DC-mediated Th2 response and may contribute to the allergic inflammation. In conclusion, our study provides new insights in platelet functions and the possible mechanism of allergic responses that stem from DCs.

IL-33 promotes the induction and maintenance of Th2 immune responses by enhancing the function of OX40 ligand.

BACKGROUND: In Th2 immune responses, TSLP is a key player by induction of OX40-ligand (OX40L) on dendritic cells (DCs), which is the trigger to induce Th2 cell-mediated allergic cascade. Thus, TSLP-DC-OX40L axis might be the principal pathway in the inflammatory cascades in atopic dermatitis and asthma. IL-33, which is produced by epithelial cells, has been implicated in the Th2 immune responses and pathogenesis of the allergic disorders. However, the role of IL-33 in the Th2-polarizing TSLP-DC-OX40L axis still remains largely elusive. We focused on the ability of IL-33 to promote OX40L-mediated Th2 responses. METHODS: Purified human naïve or memory CD4+ T cells were stimulated with recombinant OX40L or TSLP-treated DCs (TSLP-DCs) in the presence of IL-33, and the cytokine production by the primed T cells was examined. We also performed immunohistochemical analyses for the expression of IL-33 in specimens of lymph node and skin from the patients with atopic dermatitis. RESULTS: IL-33 remarkably enhanced TSLP-DCs-driven or OX40L-driven Th2 responses from naïve T cells and the Th2 functional attributes of CRTH2+ CD4+ Th2 memory cells by the increased production of IL-5, IL-9, and IL-13. In addition, IL-33 was expressed in the nuclei of epithelial cells in not only skin lesion but also lymph nodes of the patient with atopic dermatitis, suggesting a specialized role in adaptive T cell-priming phase. CONCLUSIONS: IL-33 works as a positive regulator of TSLP-DC-OX40L axis that initiates and maintains the Th2 cell-mediated inflammatory responses, and therefore, it would be a new therapeutic target for the treatment of allergic disorders.

Immunoregulatory function of PIR-A/B+ DCs in the inflammatory responses of dextran sodium sulfate-induced colitis.

BACKGROUND: Dendritic cells (DCs) may play an important role in forms of inflammatory bowel disease (IBD), such as Crohn's disease and ulcerative colitis. DCs are generally recognized as initiators of acquired immunity and also serve as regulators of both innate and acquired immunity. We used the animal model of colitis induced by dextran sodium sulfate (DSS), and examined whether DCs prepared from the colon show immunoregulatory roles in the termination of DSS-induced colitis. METHODS: C57BL/6 mice exposed to DSS for 5 days developed acute colitis. DCs were isolated from the large intestinal lamina propria, and then analyzed for phenotypical, functional, and genetic data. RESULTS: Only PIR-A/B(low) conventional DCs (cDCs) were detected in the steady state. However, after the treatment of DSS, PIR-A/B(high) cDCs appeared and gradually increased from day 5 to day 7, at which time the DSS-induced colitis was terminated. Then, allogeneic mixed leukocyte reaction (MLR) was performed. The stimulatory activity of PIR-A/B(high) cDCs obtained on day 7 was very low, and the addition of PIR-A/B(high) cDCs suppressed the T cell proliferation in MLR, indicating the immunoregulatory role of PIR-A/B(high) cDCs. The immunoregulatory role of PIR-A/B(high) cDCs was confirmed by the in vivo transfer experiment, showing their therapeutic effect on DSS-induced colitis. The message level of TGFßi was significantly higher in PIR-A/B(high) cDCs, while that of IFN-γ was highly upregulated in PIR-A/B(low) cDCs, being well in accordance with the fact that PIR-A/B(high) cDCs showed a suppressive function against activated T cells. CONCLUSION: PIR-A/B(high) cDCs showed a suppressive function against activated T cells by producing inhibitory cytokines.

IL-33 Promotes the Induction and Maintenance of Th2 Immune Responses by Enhancing the Function of OX40 Ligand.

BACKGROUND: In Th2 immune responses, TSLP is a key player by induction of OX40-ligand (OX40L) on dendritic cells (DCs), which is the trigger to induce Th2 cell-mediated allergic cascade. Thus, TSLP-DC-OX40L axis might be the principal pathway in the inflammatory cascades in atopic dermatitis and asthma. IL-33, which is produced by epithelial cells, has been implicated in the Th2 immune responses and pathogenesis of the allergic disorders. However, the role of IL-33 in the Th2-polarizing TSLP-DC-OX40L axis still remains largely elusive. We focused on the ability of IL-33 to promote OX40L-mediated Th2 responses. METHODS: Purified human naïve or memory CD4+ T cells were stimulated with recombinant OX40L or TSLP- treated DCs (TSLP-DCs) in the presence of IL-33, and the cytokine production by the primed T cells was examined. We also performed immunohistochemical analyses for the expression of IL-33 in specimens of lymph node and skin from the patients with atopic dermatitis. RESULTS: IL-33 remarkably enhanced TSLP-DCs-driven or OX40L-driven Th2 responses from naïve T cells and the Th2 functional attributes of CRTH2+ CD4+ Th2 memory cells by the increased production of IL-5, IL-9, and IL-13. In addition, IL-33 was expressed in the nuclei of epithelial cells in not only skin lesion but also lymph nodes of the patient with atopic dermatitis, suggesting a specialized role in adaptive T cell-priming phase. CONCLUSIONS: IL-33 works as a positive regulator of TSLP-DC-OX40L axis that initiates and maintains the Th2 cell-mediated inflammatory responses, and therefore, it would be a new therapeutic target for the treatment of allergic disorders.

Serum interleukin 6 before and after therapy with tocilizumab is a principal biomarker in patients with rheumatoid arthritis.

OBJECTIVE: Biologic treatments including the humanized anti-interleukin 6 (anti-IL-6) receptor antibody tocilizumab (TCZ) provide therapeutic options for patients with rheumatoid arthritis (RA). We investigated useful biomarkers to predict the responsiveness to TCZ by measurement of serum proinflammatory cytokine concentrations. METHODS: Serum samples were collected from 61 patients with RA before biologic treatment and at 4 weeks after initial administration of either TCZ (n = 32) or infliximab (IFX; n = 29) and from 13 healthy serum donor controls. Disease Activity Score of 28 joints (DAS28) was determined at baseline and after treatment. RESULTS: Although IL-1ß, IL-2, IL-6, IL-17A, IL-17F, interferon-α, and tumor necrosis factor-α (TNF-α) were all increased in sera from patients with RA compared with controls, only the IL-6 level was significantly correlated with DAS28 before treatment. The IL-6 level before treatment was positively correlated with DAS28 after TCZ treatment, and was significantly lower in TCZ-responsive patients (as judged by a post-treatment DAS28 < 3.2) than in TCZ-resistant patients (post-treatment DAS28 ≥ 3.2). DAS28 after TCZ was significantly lower than after administration of IFX in patients with low pretreatment IL-6 (< 51.5 pg/ml, the mean baseline value of IL-6 in all RA patients), but not in those with high pretreatment IL-6. These results indicate that low serum IL-6 is associated with a favorable response to TCZ. CONCLUSION: Although both TNF-α and IL-6 are major targets of therapeutic intervention in RA, baseline serum IL-6 but not baseline TNF-α level is a potential biomarker reflecting disease activity. Measurement of serum IL-6 in RA before treatment may be useful to estimate residual disease activity after TCZ treatment and to predict responsiveness to TCZ treatment.

Selective localization of bone marrow-derived ramified cells in the brain adjacent to the attachments of choroid plexus.

Although the immune system modulates higher functions of the brain under non-inflammatory conditions, how immune cells interact with brain parenchymal cells remains to be determined. Using bone marrow chimeric mice in which the recipients' immune system was reconstituted by marrow cells derived from GFP-transgenic mice by syngeneic intra-bone marrow-bone marrow transplantation (IBM-BMT) and by intravenous (IV)-BMT, we examined the distribution, density and differentiation of donor-derived marrow cells in the brain parenchyma 2 weeks and 1, 4 and 8 months after BMT. Marrow-derived cells started to populate discrete brain regions from 1 to 4 months after BMT, exhibited ramified morphology and expressed Iba-1. The ramified marrow-derived cells were distributed in more brain regions and for a longer time after IBM-BMT than IV-BMT. Most of these discrete regions were adjacent to the attachments of choroid plexus that comprised thinned brain parenchyma consisting of astroglial processes in the narrow channel between the ependyma and pia. These specific portions of astroglial processes expressed fractalkine. In the choroid plexus stroma, not only Iba-1+ myeloid cells but also non-myeloid CXCL12-expressing cells were of bone marrow-origin. Transcripts of fractalkine, CXCL12 and their related molecules such as CX3CR1, ADAM10 and CXCR4 were detected in the tissue consisting of the choroid plexus, the attachments and adjacent brain parenchyma. Thus, bone marrow cells selectively enter the discrete brain regions adjacent to the attachments of choroid plexus and differentiate into ramified myeloid cells. Fractalkine in the attachments of choroid plexus and CXCL12 in the choroid plexus stroma may be involved in these brain-immune interactions.

Fetal thymus graft prevents age-related hearing loss and up regulation of the IL-1 receptor type II gene in CD4(+) T cells.

We found that rejuvenation of the recipient immunity by inoculation of young CD4(+) T cells or a fetal thymus graft led to down regulation of the interleukin 1 receptor type II (IL-1R2) gene in CD4(+) T cells and reduced age-related hearing loss and degeneration of the spiral ganglion in SAMP1 mice, a murine model of human senescence. Our studies on the relationship between age-related systemic immune dysfunctions and neurodegeneration mechanisms open up new avenues of treatment of neurosenescence, including presbycusis, for which there is no effective therapy.

Amelioration of 2,4,6-trinitrobenzene sulfonic acid-induced colitis in mice by immunoregulatory dendritic cells.

BACKGROUND: Dendritic cells (DCs) are widely distributed throughout the lymphoid and nonlymphoid tissues, and are important initiators of acquired immunity. They also serve as regulators by inducing self-tolerance. However, it has not been thoroughly clarified whether DCs are somehow involved in the regulation or treatment of inflammatory bowel diseases. METHODS: We established an ileitis model by transmurally injecting 2,4,6-trinitrobenzene sulfonic acid (TNBS) into the lumen of the ileocolonic junction. The kinetic movement of DCs at the inflammatory sites was analyzed histologically and by flow cytometry, and DCs obtained from the small intestine were analyzed in order to determine the expression of paired immunoglobulin-like receptor-A/B (PIR-A/B) by flow cytometry and quantitative RT-PCR. Furthermore, the regulatory role of DCs was directly determined by a transfer experiment using TNBS-induced colitis model mice. RESULTS: We observed three DC subsets (PIR-A/B(high), PIR-A/B(med), and PIR-A/B(-) DCs) in the conventional DCs (cDCs) from day 3, and the number of PIR-A/B(med) cDCs increased from the time the inflammatory responses ceased (day 7). PIR-A/B(med) cDCs actually migrated to the inflamed colon, and ameliorated the colitis induced by TNBS when transferred to colitis-induced recipients. The colitis was greatly exacerbated when mice had been treated with the indoleamine-pyrrole 2,3-dioxygenase (IDO) inhibitor 1-methyltryptophan (1-mT) at the time PIR-A/B(med) cDCs were transferred, indicating that the therapeutic ability of PIR-A/B(med) cDCs is partially dependent on IDO. CONCLUSION: The PIR-A/B(med) cDCs, which increase in number during the final stages of inflammation, can be used to treat colitis via an IDO-dependent mechanism.