The effect of clindamycin (CLI) combined with autovaquone (ATO) was examined in a murine model of... more The effect of clindamycin (CLI) combined with autovaquone (ATO) was examined in a murine model of acute toxoplasmosis. Swiss Webster mice intraperitoneally infected with 10 2 or 10 4 tachyzoites of the RH strain of Toxoplasma gondii were perorally treated with either drug alone (for ATO, 5, 25, 50, or 100 mg/kg of body weight/day; for CLI, 25, 50, or 400 mg/kg/day) or both combined (for ATO plus CLI, respectively, 5 plus 25, 25 plus 25, 25 plus 50, 50 plus 50, or 100 plus 400 mg/kg/day) starting with day 1 for 14 days. Survival was monitored during 7 weeks. Residual infection was assessed by a bioassay of representative 4-week survivors and by parasite DNA detection by PCR for representative 7-week survivors. An effect of treatment was shown in all treatment groups compared to untreated control mice ( P = 0.0000). Among mice infected with 10 2 parasites, ATO and CLI at any dose combination protected significantly more animals than ATO alone ( P = 0.0000), but compared to CLI alone, ...
Tolerogenic dendritic cells (tolDCs) are assessed as immunomodulatory adjuvants to regulate autoi... more Tolerogenic dendritic cells (tolDCs) are assessed as immunomodulatory adjuvants to regulate autoimmunity. The underlying gene expression endorsing their regulatory features remains ill-defined. Using deep mRNA sequencing, we compared transcriptomes of 1,25-dihydroxyvitaminD3/dexametasone-modulated tolDCs with that of non-modulated mature inflammatory DCs (mDCs). Differentially expressed genes controlled cellular interactions, metabolic pathways and endorse tolDCs with the capacity to regulate cell activation through nutrient and signal deprivation, collectively gearing tolDCs into tolerogenic immune regulators. Gene expression differences correlated with protein expression, designating low CD86 and high CD52 on the cell surface as superior discriminators between tolDCs and mDCs. Of 37 candidate genes conferring risk to developing type 1 diabetes (T1D), 11 genes differentially expressed in tolDCs and mDCs regulated immune response and antigen-presenting activity. Differential-express...
Identification of epitopes that are recognized by diabetogenic T cells and cause selective beta c... more Identification of epitopes that are recognized by diabetogenic T cells and cause selective beta cell destruction in type 1 diabetes (T1D) has focused on peptides originating from native beta cell proteins. Translational errors represent a major potential source of antigenic peptides to which central immune tolerance is lacking. Here, we describe an alternative open reading frame within human insulin mRNA encoding a highly immunogenic polypeptide that is targeted by T cells in T1D patients. We show that cytotoxic T cells directed against the N-terminal peptide of this nonconventional product are present in the circulation of individuals diagnosed with T1D, and we provide direct evidence that such CD8(+) T cells are capable of killing human beta cells and thereby may be diabetogenic. This study reveals a new source of nonconventional polypeptides that act as self-epitopes in clinical autoimmune disease.
Type 1 diabetes (T1D) is an autoimmune disease in which a T-cell-mediated attack destroys the ins... more Type 1 diabetes (T1D) is an autoimmune disease in which a T-cell-mediated attack destroys the insulin-producing cells of the pancreatic islets. Despite insulin supplementation severe complications ask for novel treatments that aim at cure or delay of the onset of the disease. In spontaneous animal models for diabetes like the nonobese diabetic (NOD) mouse, distinct steps in the pathogenesis of the disease can be distinguished. In the past 10 years it became evident that DC and macrophages play an important role in all three phases of the pathogenesis of T1D. In phase 1, dendritic cells (DC) and macrophages accumulate at the islet edges. In phase 2, DC and macrophages are involved in the activation of autoreactive T cells that accumulate in the pancreas. In the third phase the islets are invaded by macrophages, DC and NK cells followed by the destruction of the beta-cells. Recent data suggest a role for a new member of the DC family: the plasmacytoid DC (pDC). pDC have been found to induce tolerance in experimental models of asthma. Several studies in humans and the NOD mouse support a similar role for pDC in diabetes. Mechanisms found to be involved in tolerance induction by pDC are inhibition of effector T cells, induction of regulatory T cells, production of cytokines and indoleamine 2,3-dioxygenase (IDO). The exact mechanism of tolerance induction by pDC in diabetes remains to be established but the intrinsic tolerogenic properties of pDC provide a promising, yet underestimated target for therapeutic intervention.
Macrophages are potent regulators of both innate and adaptive immunity. They play a central role ... more Macrophages are potent regulators of both innate and adaptive immunity. They play a central role in the development of autoimmune diabetes and are among the first cells to appear in peri-islet infiltrates of NOD mice that spontaneously develop diabetes. Since efficient adhesion and migration are crucial for proper macrophage trafficking, we examined the migration and fibronectin (FN) adhesion capacity of NOD macrophages, as well as the regulation and expression of the FN receptors alpha4beta1 and alpha5beta1. When compared to macrophages from control strains, resident NOD macrophages showed a reduced ability to adhere to and migrate on FN, a delayed clearance following peritoneal inflammation, and substantially lower expression levels of the alpha4beta1 integrin alpha chain, CD49d. NOD bone marrow-derived macrophages were specifically defective in the LPS-induced increase in CD49d expression. Moreover, the mitogen-activated protein kinase extracellular signal-regulated kinase-1/2 negatively regulated macrophage CD49d expression and strongly suppressed its expression in NOD macrophages. The data presented herein indicate that the LPS-activated signaling cascade plays a critical role in CD49d expression of macrophages. Mature NOD macrophages are characterized by decreased CD49d expression and show defective CD49d-mediated adhesion to FN.
The accumulation of macrophages (MΦ) and dendritic cells (DC) in the pancreas plays a crucial rol... more The accumulation of macrophages (MΦ) and dendritic cells (DC) in the pancreas plays a crucial role in the pathogenesis of autoimmune diabetes. We studied the recruitment of monocytes, MΦ and DC to sites of inflammation, ie the peritoneal cavity and a ...
The non-obese diabetic (NOD) mouse is a widely used animal model for the study of human diabetes.... more The non-obese diabetic (NOD) mouse is a widely used animal model for the study of human diabetes. The lymphocytic (peri-)insulitis is preceded by an early accumulation of dendritic cells (DC) around the islets of Langerhans. This DC accumulation is thought to derive from an influx of monocytes attracted by pro-inflammatory chemokines. Besides chemokines, extracellular matrix (ECM) proteins play an important role in the accumulation of leukocytes in tissues. We studied the expression of the chemokines CCL2, CCL5, CXCL10, CCL19 and CCL21 over time in pancreases of NOD and control mice by ELISA on pancreas lysates as well as by immunohistochemistry. In addition, we studied the adhesive capacity of bone marrow-derived DC (BMDC) to ECM components. DC in the NOD pancreas accumulated at sites with an intense expression of fibronectin. In vitro, NOD BMDC showed increased fibronectin adhesion and increased VLA-5 expression. At the time of early DC accumulation (<10 wk), the lymphoid tissue-related chemokines CCL19 and CCL21 were increased. Our findings support the view that the early accumulation of DC around the NOD islets is not the consequence of an enhanced attraction of precursors and immature DC by pro-inflammatory chemokines. It rather might be the consequence of an aberrantly enhanced adhesion and retention of NOD DC.
The effect of clindamycin (CLI) combined with autovaquone (ATO) was examined in a murine model of... more The effect of clindamycin (CLI) combined with autovaquone (ATO) was examined in a murine model of acute toxoplasmosis. Swiss Webster mice intraperitoneally infected with 10 2 or 10 4 tachyzoites of the RH strain of Toxoplasma gondii were perorally treated with either drug alone (for ATO, 5, 25, 50, or 100 mg/kg of body weight/day; for CLI, 25, 50, or 400 mg/kg/day) or both combined (for ATO plus CLI, respectively, 5 plus 25, 25 plus 25, 25 plus 50, 50 plus 50, or 100 plus 400 mg/kg/day) starting with day 1 for 14 days. Survival was monitored during 7 weeks. Residual infection was assessed by a bioassay of representative 4-week survivors and by parasite DNA detection by PCR for representative 7-week survivors. An effect of treatment was shown in all treatment groups compared to untreated control mice ( P = 0.0000). Among mice infected with 10 2 parasites, ATO and CLI at any dose combination protected significantly more animals than ATO alone ( P = 0.0000), but compared to CLI alone, ...
Tolerogenic dendritic cells (tolDCs) are assessed as immunomodulatory adjuvants to regulate autoi... more Tolerogenic dendritic cells (tolDCs) are assessed as immunomodulatory adjuvants to regulate autoimmunity. The underlying gene expression endorsing their regulatory features remains ill-defined. Using deep mRNA sequencing, we compared transcriptomes of 1,25-dihydroxyvitaminD3/dexametasone-modulated tolDCs with that of non-modulated mature inflammatory DCs (mDCs). Differentially expressed genes controlled cellular interactions, metabolic pathways and endorse tolDCs with the capacity to regulate cell activation through nutrient and signal deprivation, collectively gearing tolDCs into tolerogenic immune regulators. Gene expression differences correlated with protein expression, designating low CD86 and high CD52 on the cell surface as superior discriminators between tolDCs and mDCs. Of 37 candidate genes conferring risk to developing type 1 diabetes (T1D), 11 genes differentially expressed in tolDCs and mDCs regulated immune response and antigen-presenting activity. Differential-express...
Identification of epitopes that are recognized by diabetogenic T cells and cause selective beta c... more Identification of epitopes that are recognized by diabetogenic T cells and cause selective beta cell destruction in type 1 diabetes (T1D) has focused on peptides originating from native beta cell proteins. Translational errors represent a major potential source of antigenic peptides to which central immune tolerance is lacking. Here, we describe an alternative open reading frame within human insulin mRNA encoding a highly immunogenic polypeptide that is targeted by T cells in T1D patients. We show that cytotoxic T cells directed against the N-terminal peptide of this nonconventional product are present in the circulation of individuals diagnosed with T1D, and we provide direct evidence that such CD8(+) T cells are capable of killing human beta cells and thereby may be diabetogenic. This study reveals a new source of nonconventional polypeptides that act as self-epitopes in clinical autoimmune disease.
Type 1 diabetes (T1D) is an autoimmune disease in which a T-cell-mediated attack destroys the ins... more Type 1 diabetes (T1D) is an autoimmune disease in which a T-cell-mediated attack destroys the insulin-producing cells of the pancreatic islets. Despite insulin supplementation severe complications ask for novel treatments that aim at cure or delay of the onset of the disease. In spontaneous animal models for diabetes like the nonobese diabetic (NOD) mouse, distinct steps in the pathogenesis of the disease can be distinguished. In the past 10 years it became evident that DC and macrophages play an important role in all three phases of the pathogenesis of T1D. In phase 1, dendritic cells (DC) and macrophages accumulate at the islet edges. In phase 2, DC and macrophages are involved in the activation of autoreactive T cells that accumulate in the pancreas. In the third phase the islets are invaded by macrophages, DC and NK cells followed by the destruction of the beta-cells. Recent data suggest a role for a new member of the DC family: the plasmacytoid DC (pDC). pDC have been found to induce tolerance in experimental models of asthma. Several studies in humans and the NOD mouse support a similar role for pDC in diabetes. Mechanisms found to be involved in tolerance induction by pDC are inhibition of effector T cells, induction of regulatory T cells, production of cytokines and indoleamine 2,3-dioxygenase (IDO). The exact mechanism of tolerance induction by pDC in diabetes remains to be established but the intrinsic tolerogenic properties of pDC provide a promising, yet underestimated target for therapeutic intervention.
Macrophages are potent regulators of both innate and adaptive immunity. They play a central role ... more Macrophages are potent regulators of both innate and adaptive immunity. They play a central role in the development of autoimmune diabetes and are among the first cells to appear in peri-islet infiltrates of NOD mice that spontaneously develop diabetes. Since efficient adhesion and migration are crucial for proper macrophage trafficking, we examined the migration and fibronectin (FN) adhesion capacity of NOD macrophages, as well as the regulation and expression of the FN receptors alpha4beta1 and alpha5beta1. When compared to macrophages from control strains, resident NOD macrophages showed a reduced ability to adhere to and migrate on FN, a delayed clearance following peritoneal inflammation, and substantially lower expression levels of the alpha4beta1 integrin alpha chain, CD49d. NOD bone marrow-derived macrophages were specifically defective in the LPS-induced increase in CD49d expression. Moreover, the mitogen-activated protein kinase extracellular signal-regulated kinase-1/2 negatively regulated macrophage CD49d expression and strongly suppressed its expression in NOD macrophages. The data presented herein indicate that the LPS-activated signaling cascade plays a critical role in CD49d expression of macrophages. Mature NOD macrophages are characterized by decreased CD49d expression and show defective CD49d-mediated adhesion to FN.
The accumulation of macrophages (MΦ) and dendritic cells (DC) in the pancreas plays a crucial rol... more The accumulation of macrophages (MΦ) and dendritic cells (DC) in the pancreas plays a crucial role in the pathogenesis of autoimmune diabetes. We studied the recruitment of monocytes, MΦ and DC to sites of inflammation, ie the peritoneal cavity and a ...
The non-obese diabetic (NOD) mouse is a widely used animal model for the study of human diabetes.... more The non-obese diabetic (NOD) mouse is a widely used animal model for the study of human diabetes. The lymphocytic (peri-)insulitis is preceded by an early accumulation of dendritic cells (DC) around the islets of Langerhans. This DC accumulation is thought to derive from an influx of monocytes attracted by pro-inflammatory chemokines. Besides chemokines, extracellular matrix (ECM) proteins play an important role in the accumulation of leukocytes in tissues. We studied the expression of the chemokines CCL2, CCL5, CXCL10, CCL19 and CCL21 over time in pancreases of NOD and control mice by ELISA on pancreas lysates as well as by immunohistochemistry. In addition, we studied the adhesive capacity of bone marrow-derived DC (BMDC) to ECM components. DC in the NOD pancreas accumulated at sites with an intense expression of fibronectin. In vitro, NOD BMDC showed increased fibronectin adhesion and increased VLA-5 expression. At the time of early DC accumulation (<10 wk), the lymphoid tissue-related chemokines CCL19 and CCL21 were increased. Our findings support the view that the early accumulation of DC around the NOD islets is not the consequence of an enhanced attraction of precursors and immature DC by pro-inflammatory chemokines. It rather might be the consequence of an aberrantly enhanced adhesion and retention of NOD DC.
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Papers by Tanja Nikolic