Basak Kayhan

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 β. No expression of the inflammatory cytokine IFN-γ 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 β 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.

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-α, and interferon-γ expression was modulated by GA, whereas the regulatory anti-inflammatory transforming growth factor-β 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.

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

Abstract 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 Crohns 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‐&agr;, and transforming growth factor‐&bgr;. 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‐&agr; secretion. In addition, it induced a beneficial secretion of transforming growth factor‐&bgr;. 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.

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 αβ TCR+ lymphocytes and their phenotype analysis were not significantly different to those of healthy controls, the percentage of pan γδ 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.

Immune Response in the Liver under Conditions of Infection, Malignancy, and Transplantation

The liver is the largest solid organ in the body and commands a large blood supply that is rich in bacterial products, environment toxins, and food antigens, which are repeatedly scanned by cells within the liver. In addition, the regenerative capability of liver tissue makes it unique in comparison to other internal organs. In contrast to these unlike properties, the liver is one of the most common sites for metastatic diseases; it supports chronic viral infections caused by hepatitis B and C and can also promote tolerance against external antigens in animal models. Furthermore, liver transplantation often requires less immunosuppression compared to kidney and other solid organ transplantations. Despite these properties, the study of liver immunology remains in its infancy, and many questions remain unanswered. In that special issue, authors try to find answers in various subjects about immune response in liver under the approach of infection, malignancy, and transplantation.

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‐γ) and mouse monoclonal antibodies specific for human IFN‐γ [anti‐hIFN‐γ mAb (CAy‐IFNγ38)] respectively. An intact IgG‐free preparation of Fab plus various Fc fragments was prepared from papain‐digested CAy‐IFNγ38. 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 Freunds 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.