Chronic liver fibrosis induction in aging causes significant ultra-structural deterioration in liver and alteration on immune response gene expressions in liver-spleen axis.

The relationship between damage to the liver and spleen by aging and the immune response status in these two organs, which are anatomically and immunologically interconnected, is unknown. The authors investigated the histopathological, ultrastructural, and immunological effects of aging in young and aged fibrotic mice by using an experimental model. Four groups were planned, with 10 mice in each experimental group. The levels of fibrosis and ultrastructural destruction in the liver were determined by α-SMA staining and TEM analysis. Expression levels of immunity genes (Il2, Il4, Il6, Il10, Il12, Il17, Tnf, Ifng, Tgfb1, Gata3, Rorc, Tbx21, Foxp3, Ccl2, Ccr2, Cxcr3, Pf4, Cxcl10) were carried out by qRT-PCR. While structural disorders were detected in the mitochondria of aged healthy group, cellular destruction in the fibrosis-induced elderly group was at a dramatic level. Fibrosis induction in aged mice caused an elevation in the expression of chemokines (CCl2, CXCL10, CCR2) and cytokine (IL-17a) genes that induce autoinflammatory response in the liver. Unlike the cellular pathology and genes activated in fibrosis in youth and the natural occurrence of fibrosis with aging, induction of fibrosis during aging causes deterioration in the liver and expression of genes responsible for autoimmunity in both the liver and spleen.

Is hepatitis-B immunization effective during chronic liver fibrosis? Investigation of secretory and cellular immune responses on an experimental model.

OBJECTIVE: Adults with end-stage of chronic liver diseases have lower antibody titers after hepatitis-B vaccination. We have less amount of knowledge about the effect of non-viral cause chronic liver fibrosis on vaccination. In this study, we investigated the effect of non-viral chronic liver fibrosis on hepatitis B vaccine and the effect of tetanous toxoid co-administration at the level of humoral and cellular immune responses in an experimental model. METHODS: Hepatitis B vaccine was administered either alone or in combination with tetanus toxoid in thioacetamide-induced fibrotic BALB/c mice. Fibrosis level was determined by Knodell scoring. Anti-HBsAg, biochemical parameters, inflammatory (IL-1ß, TNF-α), and anti-inflammatory (IL-10) cytokine levels were investigated in serum samples by automated systems and ELISA; respectively. Frequencies of activated lymphocytes were determined in flow cytometer. RESULTS: Antibody titers significantly decreased after immunization of fibrotic mice. However, co-administration of toxoid significantly elevated antibody titer. The percentage of CD19+CD69+ B lymphocytes was found to be lower in vaccinated fibrotic group compared to vaccinated naive group. Simultaneous administration of toxoid significantly increased the frequencies of CD4+ and CD8+ T cells expressing CD69 and CD127. Interestingly, CD19+CD5+CD1high Breg cells were significantly reduced in the group vaccinated with hepatitis B vaccine and toxoid, simultaneously. The reduction in Breg percentage did not expose a significant decrease in the level of IL-10. CONCLUSION: Non-viral chronic liver fibrosis causes a reduction on specific antibody level after vaccination. Reduction on Breg cell frequency may have an effect on elevation of antibody level after co-administration of tetanus toxoid.

Histological and biochemical effects of dexmedetomidine on liver during an inflammatory bowel disease.

Inflammation in the liver is an extraintestinal manifestation that is frequently seen during inflammatory bowel diseases (IBD). The authors investigated histopathologycal, ultrastructural and antioxidant effects of dexmedetomidine (Dex) on liver during trinitrobenzene sulfonic acid (TNBS)-induced inflammatory bowel disease. Thirty-two BALB/c mice were divided (n = 8) as follows: control; Dex (dexmedetomidine) (30 µg/kg) for 6 days; TNBS 150 µL, TNBS + ethanol (50% w/v) intrarectally; TNBS + Dex. The histopathological and ultrastructural changes were evaluated. The levels of malondialdehyde (MDA), activity of antioxidant enzymes (GPx and SOD) were measured in liver tissue. Induction of colitis induced histopathological and ultrastructural changes of damage in liver. Those changes were markedly reduced in the TNBS + Dex group and that reduction was even significant in comparison to the TNBS group. MDA levels were significantly higher in the TNBS group and dexmedetomidine significantly elevated SOD levels in the TNBS + Dex group. These results suggest that the administration of dexmedetomidine reduces the histopathological and ultrastructural damage and increases the defense capacity against oxidative damage on liver in this IBD mice model.

Dexmedetomidine ameliorates TNBS-induced colitis by inducing immunomodulator effect.

BACKGROUND: Since sedatives are often administered to immune-compromised and critically ill patients, our understanding of immunomodulation by sedation will be critical. Dexmedetomidine, a selective α2-adrenergic receptor agonist, is often used for sedation and analgesia especially in intensive care units. There are conflicting and little data concerning both the effect and the mechanism of dexmedetomidine on immune response. In our study, we aimed to investigate the effect of dexmedetomidine on immune system at two different doses (5 µg.kg(-1) and 30 µg.kg(-1)) during inflammatory bowel disease by using an experimental model, which resembles both systemic and local inflammation. METHODS: The effect of dexmedetomidine on the course of inflammatory bowel disease was investigated by measuring macroscopic and microscopic parameters. We investigated pro-inflammatory Th1, Th2, and Th17 cytokine levels in serum samples to analyze systemic immune response. Following this, local immune response was investigated by measuring cytokine levels in the presence of dexmedetomidine in spleen cell culture. RESULTS: Dexmedetomidine administration led to amelioration of all disease associated pathological manifestations. According to our in vitro and in vivo results, dexmedetomidine shows anti-inflammatory effect by increasing IL-4 and IL-10 levels responsible from anti-inflammatory response via Th2 pathway. Moreover, we showed for the first time in the study that dexmedetomidine administration reduces IL-23, which is responsible from initiation of inflammatory response via Th17 pathway. CONCLUSIONS: Dexmedetomidine can have beneficial effect on preoperative or postoperative inflammatory bowel disease patients in intensive care units by down-regulating inflammatory immune response not only in systemic circulation but also in tissue-specific manner.

Influence of Lipoxin-A4 Treatment on Cytokine, Chemokine Genes Expression, and Phenotypic Distribution of Lymphocyte Subsets During Experimental Liver Fibrosis.

OBJECTIVE: Lipoxins are anti-inflammatory, pro-resolving molecules that are secreted by immune cells such as neutrophils and macrophages. Lipoxins are a metabolite of the arachidonic acid pathway that resolve inflammation in fibrotic liver by producing several anti-inflammatory molecules. In this study, phenotypic distribution activation markers of lymphocytes in the spleen and expression levels of chemokines (chemokine (C-X-C motif) receptor 3, chemokine (C-X-C motif) ligand 10) cytokines (interferon gamma, tumor necrosis factor alpha, interleukin-6, interleukin-10) in the liver of lipoxin A4-treated fibrotic mice were investigated. MATERIALS AND METHODS: Liver fibrosis was induced in BALB/c mice by thioacetamide administration. Lipoxin A4 was administered during last 2 weeks of induction. Fibrosis level was determined by using Knodell scoring. Lymphocytes were identified by flow-cytometry. Expression levels of genes were measured by quantitative real time polymerase chain reaction in liver homogenates. RESULTS: Lipoxin A4 treatment caused an elevation of T-lymphocyte percentage in the spleen. Interestingly, administration of lipoxin A4 significantly reduced B-lymphocyte population in spleen of fibrotic group. CD8+ cytotoxic T cell frequency significantly reduced in thioacetamide-induced mice; however, lipoxin A4 administration increased that percentage significantly. Lipoxin A4 treatment significantly reduced frequency of activated (CD8+CD69+) cytotoxic T cells. Expression levels of chemokines significantly reduced in the liver after lipoxin A4 treatment. While expression levels of interferon gamma, tumor necrosis factor alpha, and interleukin-6 significantly reduced in the liver after lipoxin A4 treatment, an anti-inflammatory cytokine interleukin-10 expression was almost at similar levels in all experimental groups. CONCLUSION: Lipoxin A4 performs its anti-inflammatory effect by reducing the frequency of activated T cells and expression levels of chemokines cytokines responsible from inflammatory immune response in the liver.

The effect of atorvastatin and its role on systemic cytokine network in treatment of acute experimental colitis.

Inflammatory bowel diseases are characterized by disabilities in gastrointestinal system and defects in mucosal immune system. Statins are 3-hydroxy-3-methyl glutaryl coenzyme A reductase inhibitor and are used to treat hypercholesterolemia in patients with coronary artery and atherosclerotic diseases. Recent studies have demonstrated that statins have immunomodulatory role by effecting different pathways in immune system. In this study, we investigated the effect of atorvastatin and its mechanism on systemic immune response in treatment of trinitrobenzene sulfonic acid (TNBS)-induced colitis mice. We observed that atorvastatin significantly suppressed the severity of TNBS-induced colitis in BALB/c mice. This was manifested in reduced rectal bleeding, decrease in colon length, reduction of histological damage, and improved survival. Concurrently, we investigated the immunomodulatory role of atorvastatin on systemic immune system. We investigated the proinflammatory (IL-1α, IL-6, TNF-α), Th1 (IFN-γ, IL-2), Th2 (IL-4, IL-5, IL-10), and Th17 (IL-17, IL-23) cytokine levels in serum samples of colitis and atorvastatin-administered mice. We discovered that administration of atorvastatin significantly down-regulates systemic TNF-α level and Th17 cytokine levels. Furthermore, atorvastatin treatment switches Th1 type T-cell response toward/to Th2 (IL-4, IL-10) type response.

Neuroprotective effects of the new Na channel blocker rs100642 in global ischemic brain injury.

INTRODUCTION: RS100642, a mexiletine analogue, is a novel sodium channel blocker with neuroprotective and antioxidant activities. The protectivity of RS100642, which has been shown against focal cerebral ischemia, was investigated in global cerebral ischemia in this study. MATERIAL AND METHODS: Global cerebral ischemia was induced for five minutes in adult male Wistar Albino rats via the 4-vessel occlusion method. Intravenous administration of 1 mg/kg RS100642 following reperfusion for 30 min (RS100642 group) was compared with a sham treatment group (ischemia group) and nonischemized group (control) histologically based on morphology and caspase-3 immunohistochemistry, and biochemically based both on measurement of oxidative stress including malondialdehyde (MDA) levels, superoxide dismutase (SOD), glutathione peroxidase (GPx) and catalase (CAT) activities and on assessment of apoptosis including caspase-3 and -8 activities and tumor necrosis factor α (TNF-α) levels at the end of 6 h. RESULTS: While the RS100642 group had significantly lower MDA levels and higher SOD activities than the sham treatment group (p < 0.05), GPx and CAT activities of the RS100642 and sham treatment groups were similar (p > 0.05) and significantly lower than those of the controls (p < 0.05). Necrosis and caspase-3 activity and immunoreactivity in the RS100642 group were significantly lower than those in the sham treatment group (p < 0.05), while there was no significant difference between groups regarding caspase-8 and TNF-α (p > 0.05). CONCLUSIONS: Na+ channel blockade by RS100642 has remarkable neuroprotective effects following global brain ischemia/reperfusion damage. Further research is required to determine the optimum dose and time of administration.

The relationship between caspase-1 related inflammasome expression and serum inflammatory cytokine levels during acute brucellosis.

OBJECTIVE: Brucellosis is a zoonotic disease caused by Brucella in domestic and wild animals. It also causes systemic diseases with the involvement of different parts of the human body. An efficient innate immune response is crucial to cure brucellosis with optimum antibiotic treatment. The inflammasomes are innate immune system receptors and sensors that regulate the activation of cysteine-dependent aspartate specific protease-1 (caspase-1) and caspase-1-induced cell death process known as pyroptosis. The aim of the present study was to investigate the expression levels of CASPASE-1 and associated inflammasomes AIM2, NLRP3, and NLRC4 to analyze their relationship with the inflammatory cytokine interleukin (IL)-1ß, IL-18, and interferon-gamma (IFN-γ) in peripheral blood samples of patients with acute brucellosis with healthy controls. METHODS: Peripheral blood samples were obtained from 20 healthy volunteers and 20 patients with acute brucellosis. RNA and serum samples were isolated to examine the expression levels of AIM2, NLRP3, NLRC4, and CASPASE-1 by real-time polymerase chain reaction, and IL-1ß, IL-18, and IFN-γ were measured by enzyme-linked immunosorbent assay. RESULTS: In the acute brucellosis group, AIM2 and NLRC4 expressions were significantly higher than in healthy volunteers. A significant increase on caspase-1 expression in patients with acute brucellosis was not observed. Serum IL-18 and IFN-γ levels were significantly higher in patients with acute brucellosis than in healthy controls. CONCLUSION: Caspase-1-related inflammasomes are sufficiently activated to induce the secretion of cytokines, such as IFN-γ and IL-18, to induce cellular immune response. Caspase-1 activation level should be investigated at different periods of disease in a group with high number of patients to understand the role of pyroptosis and caspase-1 in brucellosis.

A bioactive product lipoxin A4 attenuates liver fibrosis in an experimental model by regulating immune response and modulating the expression of regeneration genes.

BACKGROUND/AIMS: Lipoxin A4 (LXA4), an anti-inflammatory lipid mediator, regulates leukocyte cellular activity and activates gene transcription. The therapeutic effect of LXA4 on liver fibrosis and its mechanism on the immune system are largely unknown. Because the regenerative capacity of hepatocytes in acute and chronic liver failure models of mouse increases by silencing MKK4, we aimed to investigate the effect of parenteral administration of LXA4 on the genes responsible for regeneration of liver, namely MKK4, MKK7, and ATF2, and visualize the therapeutic effects in an experimental model. MATERIALS AND METHODS: Fibrosis was induced in mice by administration of thioacetamide (TAA). LXA4 was administered during the last two weeks of fibrosis induction. The fibrosis level was measured by Knodell scoring. The liver function was measured by analyzing serum ALT, AST, and AP levels. Expression levels of genes responsible for liver fibrosis (TGF-α) and cell regeneration (MKK4, MKK7, and ATF2) have been measured by RT-PCR analysis. Inflammatory and anti-inflammatory cytokine levels were measured in serum samples and liver homogenates by Enzyme Linked Immunosorbent Assay (ELISA). Ultrathin sections were examined using a transmission electron microscope and analyzed. RESULTS: We observed significant healing in liver of the LXA4-treated group, histologically. This finding was in parallel with reduction of serum ALT, AST, but not AP levels. TGF-α and MKK4 expressions were significantly reduced in the LXA4-treated group. Administration of LXA4 caused significant elevation of IL-10 in systemic circulation; however, that elevation was not detected in liver homogenates. Nevertheless, significant reductions in TNF-α and IL-17 have been observed. CONCLUSION: The anti-inflammatory effect of LXA4 maintains the regenerative capacity of liver during fibrosis in an experimental liver fibrosis model. LXA4 may be therapeutically beneficial in liver fibrosis.

The effect of exercise induced weight-loss on myokines and adipokines in overweight sedentary females: steps-aerobics vs. jogging-walking exercises.

BACKGROUND: The objectives of this study were to verify effects of step-aerobic exercise (SAE) and jogging-walking exercise (JWE) program on myokines and adipokines levels in overweight sedentary females. METHODS: Volunteer subjects (N.=25) were assigned to two exercise groups: steps aerobics and jogging-walking. The exercise program given to them was for five days a week and for twelve weeks period. Serum samples were collected from venous blood before and immediately after Cardio-Respiratory Fitness Test (CRF) by Bruce protocol and stored at -80 °C until they were assayed before 12 weeks exercise program. After 12-weeks training program this procedure was repeated. Serum TNF-α, IL-6, IL-15, IL-17, IL-18, leptin, resistin and adiponectin levels were assayed by ELISA. RESULTS: Leptin and IL-15 levels were increased whereas resistin levels were decreased after CRF Test in JWE training group following 12-weeks exercise program. TNF-α, IL-15 and IL-18 levels were higher and leptin levels were lower in SAE group than JWE group after 12-weeks exercise period. However, both SAE and JWE did not lead to significant change in serum levels of IL-17, IL-6 and adiponectin levels. CONCLUSIONS: This study has added to existing knowledge that both SAE and JWE may cause weight loss especially in fat mass. But, the effect of SAE and JWE on myokines and adipokines levels may be the different. Further studies are needed to find out clinical importance of these findings.

Therapeutic effect of the immunomodulator glatiramer acetate on trinitrobenzene sulfonic acid-induced experimental colitis.

Inflammatory bowel diseases are characterized by detrimental immune reactivity in the gut and imbalance between proinflammatory and antiinflammatory reactivity. In an attempt to downregulate inflammatory bowel disease, we tested whether the immunomodulator glatiramer acetate (GA; Copaxone, copolymer 1), an approved drug for the treatment of multiple sclerosis, can ameliorate trinitrobenzene sulfonic acid (TNBS)-induced colitis, a murine model that resembles human Crohn's disease. Experimental colitis was induced by rectal instillation of TNBS in 3 mice strains: BALB/c, SJL/J, and (SJL/JXBALB/c)F1, and its severity was evaluated by gross colon injury, histologic damage, body weight, and survival rate. We studied the effect of GA on all these parameters as well as on lymphocyte reactivity manifested by proliferation and secretion of tumor necrosis factor-alpha, and transforming growth factor-beta. GA treatment significantly suppressed the various manifestations of TNBS-induced colitis as demonstrated by substantial reduction in the macroscopic colonic damage, preservation of the microscopic colonic structure, reduced weight loss, and improved long-term survival, in GA treated mice compared with untreated mice. The parenteral route was more effective than the oral route. GA suppressed the proliferation of local mesenteric lymphocytes to syngeneic colon extract and the detrimental tumor necrosis factor-alpha secretion. In addition, it induced a beneficial secretion of transforming growth factor-beta. The ability of GA to effectively modulate the clinical manifestations and the detrimental immune response involved in experimental colitis warrants further studies to determine the clinical efficacy of GA in the treatment of human inflammatory bowel diseases.

Histopathological, Ultrastructural and Apoptotic Changes in Diabetic Rat Placenta.

BACKGROUND: The exchange of substances between mother and fetus via the placenta plays a vital role during development. A number of developmental disorders in the fetus and placenta are observed during diabetic pregnancies. Diabetes, together with placental apoptosis, can lead to developmental and functional disorders. AIMS: Histological, ultrastructural and apoptotic changes were investigated in the placenta of streptozotocin (STZ) induced diabetic rats. STUDY DESIGN: Animal experimentation. METHODS: In this study, a total of 12 female Wistar Albino rats (control (n=6) and diabetic (n=6)) were used. Rats in the diabetic group, following the administration of a single dose of STZ, showed blood glucose levels higher than 200 mg/dL after 72 hours. When pregnancy was detected after the rats were bred, two pieces of placenta and the fetuses were collected on the 20(th) day of pregnancy by cesarean incision under ketamine/ xylazine anesthesia from in four rats from the control and diabetic groups. Placenta tissues were processed for light microscopy and transmission electron microscopy (TEM). Hematoxylin-eosin (HE) and periodic acid Schiff-diastase (PAS-D) staining for light microscopic and caspase-3 staining for immunohistochemical investigations were performed for each placenta. Electron microscopy was performed on thin sections contrasted with uranyl acetate and lead nitrate. RESULTS: Weight gain in the placenta and fetuses of diabetic rats and thinning of the decidual layer, thickening of the hemal membrane, apoptotic bodies, congestion in intervillous spaces, increased PAS-D staining in decidual cells and caspase-3 immunoreactivity were observed in the diabetic group. After the ultrastructural examination, the apoptotic appearance of the nuclei of trophoblastic cells, edema and intracytoplasmic vacuolization, glycogen accumulation, dilation of the endoplasmic reticulum and myelin figures were observed. In addition, capillary basement membrane thickening, capillary endothelial cells chromatin condensation in the nucleus and corrugation of the nucleus were found. CONCLUSION: Diabetes causes histomorphometric, ultrastructural and apoptotic changes in rat placenta.

Glatiramer acetate (Copaxone) regulates nitric oxide and related cytokine secretion in experimental autoimmune encephalomyelitis.

Nitric oxide (NO) is an important mediator involved in the pathogenesis of experimental autoimmune encephalomyelitis (EAE) and multiple sclerosis (MS). We examined the effect of glatiramer acetate (GA), an agent with suppressing effect on EAE and of therapeutic value for the treatment of MS, on the secretion of NO, as well as of the NO regulating cytokines. We observed that induction of EAE leads to 4-fold elevation in NO secretion and that treatment of the EAE mice by GA indeed leads to a significant reduction in the NO secretion by the splenocytes in response to the encephalitogen. A parallel decrease was observed in the secretion of the NO inducing cytokine IL-1beta. On the other hand, the secretion level of NO modulating cytokines IL-10 and IL-13 was significantly augmented. The correlation between these findings and the therapeutic effect of GA is discussed.

Analysis of peripheral blood lymphocyte phenotypes and Th1/Th2 cytokines profile in the systemic immune responses of Helicobacter pylori infected individuals.

H. pylori elicits specific humoral and cellular immune responses in the mucosal immune system. However, the type and extent of T lymphocyte response in the systemic immune system is not clear for H. pylori positive patients. In this study, peripheral blood T lymphocyte phenotypes and serum Th1/Th2 based cytokines of 32 H. pylori positive patients were analyzed and compared to those of healthy controls. While alphabeta TCR(+) lymphocytes and their phenotype analysis were not significantly different to those of healthy controls, the percentage of pan gammadelta TCR(+) lymphocytes was up to 2.4 times greater in the H. pylori positive group then in healthy controls. Furthermore, significant increases in IL-10 concentrations in serum samples of H. pylori patients indicated that their immune systems had switched toward a Th2 type immune response. The correlation between phenotype and type of T cell response in the peripheral blood during H. pylori infection is discussed.

A replication-deficient murine gamma-herpesvirus blocked in late viral gene expression can establish latency and elicit protective cellular immunity.

The human gamma-herpesviruses, EBV and Kaposi's sarcoma-associated herpesvirus, are widely disseminated and are associated with the onset of a variety of malignancies. Thus, the development of prophylactic and therapeutic vaccination strategies is an important goal. The experimental mouse gamma-herpesvirus, gammaHV68 (or MHV-68), has provided an in vivo model for studying immune control of these persistent viruses. In the current studies, we have examined infectivity, immunogenicity, and protective efficacy following infection with a replication-deficient gammaHV68 blocked in late viral gene expression, ORF31STOP. The data show that ORF31STOP was able to latently infect B cells. However, the anatomical site and persistence of the infection depended on the route of inoculation, implicating a role for viral replication in viral spread but not the infectivity per se. Furthermore, i.p. infection with ORF31STOP elicited strong cellular immunity but a non-neutralizing Ab response. In contrast, intranasal infection was poorly immunogenic. Consistent with this, mice infected i.p. had enhanced control of both the lytic and latent viral loads following challenge with wild-type gammaHV68, whereas intranasal infected mice were not protected. These data provide important insight into mechanisms of infection and protective immunity for the gamma-herpesviruses and demonstrate the utility of replication-deficient mutant viruses in direct testing of "proof of principal" vaccination strategies.

Immunomodulatory therapeutic effect of glatiramer acetate on several murine models of inflammatory bowel disease.

Inflammatory bowel disease (IBD) is characterized by detrimental immune reactivity in the gut and imbalance between proinflammatory and anti-inflammatory reactivity. In an attempt to down-regulate colitis, we investigated the effect of the immunomodulator glatiramer acetate (GA, Copaxone, copolymer 1) on two murine models of IBD, chemically induced and spontaneous. Acute experimental colitis of different levels of severity was induced in C57BL/6 mice by dextran sulfate sodium (DSS) administered orally at different concentrations and frequencies. It was manifested in weight loss, intestinal bleeding, and diarrhea, as well as by macroscopic and microscopic colon damage. GA treatment led to amelioration of all of these pathological manifestations, resulting in improved long-term survival. Moreover, even when colitis was induced by three cycles of DSS in this highly susceptible mouse strain, as well as in BALB/c mice that exhibit a chronic disease pattern, a substantial reduction in disease activity and mortality was obtained. GA treatment induced a beneficial effect also in a spontaneous model of colitis developed in the C3H/HeJBir IL-10-deficient mice. The detrimental proinflammatory response manifested by proliferation, tumor necrosis factor-alpha, and interferon-gamma expression was modulated by GA, whereas the regulatory anti-inflammatory transforming growth factor-beta and IL-10 cytokines response was elevated. This was demonstrated on the level of protein secretion in splenocytes and local mesenteric lymphocytes in response to syngeneic colon extract and in the overall response to anti-CD3, as well as on the level of mRNA expression in the colon.

Infection of dendritic cells by a gamma2-herpesvirus induces functional modulation.

The murine gamma-herpesvirus-68 (gammaHV68) establishes viral latency in dendritic cells (DCs). In the present study, we examined the specific consequences of DC infection by gammaHV68, both in vivo and in vitro. Ex vivo analysis of infected mice showed that the virus colonizes respiratory DCs very early after infection and that all subsets of splenic DCs analyzed are viral targets. We have developed and characterized an in vitro model of gammaHV68 infection of DCs. Using this model, we demonstrated that viral infection neither induces full DC maturation nor interferes with exogenous activation, which is assessed by cell surface phenotypic changes. However, whereas gammaHV68 infection alone failed to elicit cytokine secretion, IL-10 secretion of exogenously activated DCs was enhanced. Furthermore, gammaHV68-infected DCs efficiently stimulated virus-specific T cell hybridomas but failed to induce alloreactive stimulation of normal T cells. These data indicate that viral infection doesn't interfere with Ag processing and presentation but does interfere with the ability of DCs to activate T cells. The inhibition of T cell activation was partially reversed by blocking IL-10. Analysis of infected mice shows elevated levels of IL-10 expression in DCs and that lack of endogenous IL-10 is associated with decreased gammaHV68 long-term latency. Taken together, these observations indicate that gamma2-herpesvirus infection of DCs is a mechanism of viral immune evasion, partially mediated by IL-10.

Fc-dependent monoclonal IgG1-mediated suppression of antibody response.

It has been known for a long time that passively administered antibodies (Abs) or immune complexes regulate the immune response to their specific antigen (Ag). IgG may sometimes suppress the humoral immune response against soluble antigens. The exact mechanism behind this phenomenon has not been understood yet and the requirement for the Fc part is still a matter of controversy. The present study was undertaken to clarify whether there is a true IgG-mediated Fc-dependent suppression of the immune response. Antigen and monoclonal antibody (mAb) used in this study were recombinant human interferon gamma (r-hIFN-gamma) and mouse monoclonal antibodies specific for human IFN-gamma [anti-hIFN-gamma mAb (CAy-IFNgamma38)] respectively. An intact IgG-free preparation of Fab plus various Fc fragments was prepared from papain-digested CAy-IFNgamma38. Ag/IgG and Ag/Fab complexes were prepared at various molar ratios. Keeping the Ag doses constant, mice were immunized either with Ag, Ag/IgG or Ag/Fab complexes. Primary immunization and the boosting were performed with the samples in complete and incomplete Freund's adjuvants respectively. Specific antibody levels were measured by an ELISA. Immunization performed with Ag/Fab complexes even at a molar ratio of 1:1.36 did not result in marked suppression of the response when compared to that of Ag only-immunization. In contrast, Ag/IgG complexes resulted in nearly 90% suppression of the antibody response. Our observations suggest that Fc part of IgG molecule plays a crucial role in suppression of the in vivo antibody response against the Ag when complexed with intact IgG.

Glatiramer acetate-specific T cells in the brain express T helper 2/3 cytokines and brain-derived neurotrophic factor in situ.

The ability of a remedy to modulate the pathological process in the target organ is crucial for its therapeutic activity. Glatiramer acetate (GA, Copaxone, Copolymer 1), a drug approved for the treatment of multiple sclerosis, induces regulatory T helper 2/3 cells that penetrate the CNS. Here we investigated whether these GA-specific T cells can function as suppressor cells with therapeutic potential in the target organ by in situ expression of T helper 2/3 cytokines and neurotrophic factors. GA-specific cells and their in situ expression were detected on the level of whole-brain tissue by using a two-stage double-labeling system: (i) labeling of the GA-specific T cells, followed by their adoptive transfer, and (ii) detection of the secreted factors in the brain by immunohistological methods. GA-specific T cells in the CNS demonstrated intense expression of the brain-derived neurotrophic factor and of two antiinflammatory cytokines, IL-10 and transforming growth factor beta. No expression of the inflammatory cytokine IFN-gamma was observed. This pattern of expression was manifested in brains of normal and experimental autoimmune encephalomyelitis-induced mice to which GA-specific cells were adoptively transferred, but not in control mice. Furthermore, infiltration of GA-induced cells to the brain resulted in bystander expression of IL-10 and transforming growth factor beta by resident astrocytes and microglia. The ability of infiltrating GA-specific cells to express antiinflammatory cytokines and neurotrophic factor in the organ in which the pathological processes occur correlates directly with the therapeutic activity of GA in experimental autoimmune encephalomyelitis/multiple sclerosis.