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Biomedical subjects

H D Volk

Publications and source records attributed to H D Volk.

At least 19 recordsLinked to original sources
PubMed2006

Intrarenal gene expression of proinflammatory chemokines and cytokines in chronic proteinuric glomerulopathies.

Proteinuria has been recently shown to be an independent risk factor for the progression of chronic nephropathies, but the actual mechanisms by which urinary protein load damages renal tissue in humans remain unsolved. Using real-time RT-PCR method we evaluated intrarenal mRNA expression of various cytokines and chemokines in patients with biopsy-proven IgA nephropathy (IgAN, n=11), membranous nephropathy (MN, n=6) and focal and segmental glomerulosclerosis (FSGS, n=6) who exhibited proteinuria over 0.5 g/day. There was a significant positive correlation between the proteinuria extent and the intrarenal RANTES (regulated upon activation normal T cell expressed and secreted) mRNA expression in patients with IgAN, a similar trend was also observed in patients with MN and FSGS. There were no clear relationships between the proteinuria and intrarenal mRNA expression of tumor necrosis factor alpha, transforming growth factor beta1 and monocyte chemoattractant peptide-1. There were no differences in the pattern of cytokine mRNA expression between different glomerulopathies. In conclusion, our results support the hypothesis that lymphocytes, macrophages and their products provoke tissue injury in response to proteinuria independently of the nature of renal diseases in man.

Adult↗
PubMed2005

Increased intracranial pressure induces a rapid systemic interleukin-10 release through activation of the sympathetic nervous system.

There is a bi-directional communication between the immune and central nervous system. In this context, it is known that patients with traumatic brain injury suffered from systemic immunodepression and an increased risk to develop infectious complications. We investigated the role of an increased intracranial pressure (ICP) and sympathetic activation on systemic immune changes. A sustained increase in ICP was achieved by inflation of a subdural balloon. At different time points, plasma levels of the anti-inflammatory cytokine, interleukin (IL)-10, were measured. Furthermore, the effect of a sympathetic blockade by co-administration of the beta2-adreoreceptor antagonist, propranolol, was evaluated. Finally, we examined the impact of epinephrine infusion on blood IL-10 levels. We showed that an increase in ICP with activation of the sympathetic nervous system was able to induce systemic release of IL-10. This effect was blocked by administration of the beta2-adreoreceptor antagonist. Furthermore, epinephrine infusion directly induced systemic release of IL-10. Our data suggested that sympathetic activation with release of epinephrine may induce systemic immunodepression with risk of infectious complications in brain-injured patients.

Animals↗
PubMed2005

Allergoid-specific T-cell reaction as a measure of the immunological response to specific immunotherapy (SIT) with a Th1-adjuvanted allergy vaccine.

BACKGROUND: Specific immunotherapy (SIT) is believed to modulate CD4+ T-helper cells. In order to improve safety, SIT vaccines are often formulated with allergoids (chemically modified allergens). Interaction between T-cells and allergoids is necessary to influence cellular cytokine expression. There have been few reports on identification the early cellular effects of SIT. METHOD: Patients allergic to grass and/or mugwort pollen (n= 21) were treated with a 4-shot allergy vaccine (Pollinex Quattro) containing appropriate allergoids (grass/rye and/or mugwort) adsorbed to L-tyrosine plus a Th1 adjuvant, monophosphoryl lipid A (MPL). Fourteen grass-allergic patients served as untreated controls. Using the peripheral blood mononuclear cells of these patients, an optimized lymphocyte transformation test (LTT) was employed to monitor the in vitro proliferative response of T-cells to an allergoid challenge (solubilised Pollinex Quattro) before the first and last injection and then 2 and 20 weeks after the final injection. Control challenges utilised preparations of a similar pollen vaccine without the adjuvant MPL and a tree pollen vaccine with and without MPL. RESULTS: The LTT showed increased LTT stimulation indices (SI) in 17/20 SIT patients when the solublised vaccine preparation was used as a challenge before the last injection and 2 weeks after, in comparison to pre-treatment levels. Twenty weeks after therapy, the SI decreased to baseline level. A vaccine challenge without MPL gave lower SI levels. A challenge of a clinically inappropriate tree allergoid vaccine gave no response, and a nontreated group also showed no response. CONCLUSION: Following a short-course SIT adjuvated with MPL, challenges of allergoids were shown to activate allergen-specific T cells in vitro. There was an additional stimulating effect when the challenge was in combination with MPL. There were no non-specific effects of MPL, shown by the tree allergoid/MPL control. The timing of the response was closely correlated to the treatment course; reactivity fell two weeks after the final injection and 20 weeks later it was at baseline level. Thus an immunological response to SIT was detected after very few injections. This methodology could provide a basis for monitoring the immediate progress of allergy vaccinations.

Adjuvants, Immunologic↗
PubMed2003

Interleukin-10 therapy--review of a new approach.

Interleukin (IL)-10 is an important immunoregulatory cytokine produced by many cell populations. Its main biological function seems to be the limitation and termination of inflammatory responses and the regulation of differentiation and proliferation of several immune cells such as T cells, B cells, natural killer cells, antigen-presenting cells, mast cells, and granulocytes. However, very recent data suggest IL-10 also mediates immunostimulatory properties that help to eliminate infectious and noninfectious particles with limited inflammation. Numerous investigations, including expression analyses in patients, in vitro and animal experiments suggest a major impact of IL-10 in inflammatory, malignant, and autoimmune diseases. So IL-10 overexpression was found in certain tumors as melanoma and several lymphomas and is considered to promote further tumor development. Systemic IL-10 release is a powerful tool of the central nervous system to prevent hyperinflammatory processes by activation of the neuro-endocrine axis following acute stress reactions. In contrast, a relative IL-10 deficiency has been observed and is regarded to be of pathophysiological relevance in certain inflammatory disorders characterized by a type 1 cytokine pattern such as psoriasis. Recombinant human IL-10 has been produced and is currently being tested in clinical trials. This includes rheumatoid arthritis, inflammatory bowel disease, psoriasis, organ transplantation, and chronic hepatitis C. The results are heterogeneous. They give new insight into the immunobiology of IL-10 and suggest that the IL-10/IL-10 receptor system may become a new therapeutic target.

Animals↗
PubMed2002

Immune monitoring of glucocorticoid therapy.

There is a clear medical need to improve the GC therapy because of the individually variable responsiveness to GC. Recently, several well-standardised cell-based assays focussing on monocyte functions (flowcytometric measurement of HLA-DR expression, semiautomatic measurement of ex vivo TNF release capacity) have been introduced into the clinical laboratory. These techniques allow for both the detection immunosuppression and the monitoring of therapeutic efficacy. The measurement of efficacy might be further improved by applying the novel technology of gene expression profiling that is ready for introducing into the diagnostics.

Drug Monitoring↗
PubMed2002

[Immunomodulation in sepsis].

INTRODUCTION: The systemic inflammatory response syndrome is induced by a strong inflammatory reaction which is called sepsis when it is caused by an infection. However, anti-inflammatory therapeutic strategies in septic patients were not successful, indicating a more complex system. It is now clear that systemic hyper-inflammation induces systemic anti- or hypo-inflammation which can lead to total paralysis of the immune system ("immunoparalysis"). METHODS: Several studies were performed to evaluate parameters for describing the patient's immunocompetence. Based on these parameters, pilot trials were initiated to test immunomodulating therapies depending on the patient's immunocompetence. RESULTS: The measurement of monocytic HLA-DR expression, as well as the measurement of ex vivo LPS-induced TNF-a secretion, are suitable to describe the patient's immunocompetence. In addition to classical inflammation markers, the characterization of the inflammatory and infection status is completed by measurement of the plasma cytokines, LBP and PCT. IFN-g or GM-CSF application as well as the removal of inhibitory plasma mediators by hemofiltration/plasmapheresis can reconstitute the immune function in patients with "immunoparalysis". CONCLUSIONS: Immunomodulating therapeutic strategies in septic patients have to orientate on the patient's immunocompetence and inflammatory as well as infectious status: a patient in a hyper-inflammatory phase may need anti-inflammatory therapy whereas a patient in "immunoparalysis" needs immunoreconstitution/immunostimulating therapy.

Adjuvants, Immunologic↗
PubMed2002

Immunomodulatory changes in patients with colorectal cancer.

BACKGROUND AND AIMS: Solid tumors are frequently accompanied by a depressed cellular and humoral immunity. This study analyzed changes these factors in colorectal cancer patients. PATIENTS AND METHODS: We compared cellular (leukocytes, lymphocytes, HLA-DR expression on monocytes) and humoral immune parameters (interleukin-6, interleukin-10, tumor necrosis factor alpha) in 40 patients with colorectal cancer and in 18 healthy controls. RESULTS: Leukocytes were in the normal range in patients and controls. However, tumor patients showed significant lymphopenia in comparison to controls. HLA-DR antigen expression on CD14+ monocytes was reduced in the cancer patients while IL-6 and IL-10 plasma levels were increased. Patients with UICC stage III had IL-6 and IL-10 concentrations were significantly increased as well. CONCLUSIONS: These findings suggest that colorectal tumor establishment and progression results in a malfunction of the immune system, and underline the importance of elucidating in detail the mechanisms of immune modulation in cancer patients.

Case-Control Studies↗
PubMed2002

Differences in immune cell invasion into the cerebrospinal fluid and brain parenchyma during cerebral infusion of interleukin-1beta.

Cytokine-mediated inflammatory cell recruitment into the brain is a critical step in the response to diverse insults, including infection, trauma, and stroke. Hence, continous intra-cerebroventricular infusion of interleukin (IL)-1beta leads to an impressive cell invasion into the cerebrospinal fluid, as well as the brain parenchyma. Neither tumor necrosis factor-alpha nor IL-6 induced any significant cell invasion at all. However, the diverse immune cells (granulocytes, monocytes/macrophages) showed a different time course of invasion. Moreover, there was an association between the number of infiltrating immune cells and the infused IL-1 concentration. By analyzing intra-brain immune events, we demonstrated a time- and dose-dependent induction of intercellular adhesion molecule (ICAM)-1, whereas there were no differences for P-selectin, vascular cell adhesion molecule (VCAM)-1, and monocyte-chemotractant protein (MCP)-1, comparing vehicle and IL-1-infused animals. In conclusion, we assume IL-1beta to be a key cytokine for the granulocyte and monocyte recruitment into the central nervous system after various insults. However, granulocytes anticipate monocyte invasion.

Animals↗
PubMed2002

Cachexia: a therapeutic approach beyond cytokine antagonism.

Cachexia is seen in a number of chronic diseases, and it is always associated with a poor prognosis. Irrespective of etiology, the development of cachexia appears to share a common pathophysiological pathway. This includes induction of proteasome-dependent myofibril-degradation, which is thought to be secondary to stimulation by enhanced levels of pro-inflammatory cytokines. Elevation of tumor necrosis factor-alpha (TNFalpha) and other plasma cytokines has been demonstrated in many conditions associated with cachexia. Despite improved pathophysiological understanding, a specific treatment for cachexia has not yet been established. Whilst direct TNFalpha antagonism has therapeutic appeal, this review will focus on manipulation of downstream pathways and the potential benefits. For example, nuclear factor-kappaB (NF-kappaB) is one of the most important signal transducers of TNFalpha, and drugs targeting this signalling cascade might be useful in the treatment of cachexia. Although the use of some of these substances, for example glucocorticoids, remains controversial, others may prove beneficial in the treatment of this syndrome. The role of other approaches such as proteasome-inhibitors remains to be elucidated. Alternatively, interleukin-10 and other immunosuppressive cytokines may also be able to counterbalance certain features of cachexia.

Cachexia↗
PubMed2001

T cell subsets and in vitro immune regulation in "infectious" transplantation tolerance.

CD4-targeted mAb therapy results in permanent acceptance of cardiac allografts in rat recipients, in conjunction with features of the infectious tolerance pathway. Although CD4(+) T cells play a central role, the actual cellular and molecular tolerogenic mechanisms remain elusive. This study was designed to analyze in vitro alloimmune responses of T lymphocytes from CD4 mAb-treated engrafted hosts. Spleen, but not lymph node, cells lost proliferative response against donor alloantigen in MLR and suppressed test allograft rejection in adoptive transfer studies, suggesting compartmentalization of tolerogenic T cells in transplant recipients. A high dose of exogenous IL-2 restored the allogeneic response of tolerogenic T cells, indicating anergy as a putative mechanism. Vigorous proliferation of the tolerogenic T cells in in vivo MLR supports the existence of alloreactive lymphocytes in tolerogenic T cell repertoire and implies an active operational suppression mechanism. The tolerogenic splenocytes suppressed proliferation of naive splenocytes in vitro, consistent with their in vivo property of dominant immune regulation. Finally, CD45RC(+) but not CD45RC(-) T cells from tolerant hosts were hyporesponsive to alloantigen and suppressed the proliferation of normal T cells in the coculture assay. Thus, nondeletional, anergy-like regulatory mechanisms may operate via CD4(+)CD45RC(+) T cells in the infectious tolerance pathway in transplant recipients.

Animals↗
PubMed2001

Cytotoxic effector molecule gene expression in acute renal allograft rejection: correlation with clinical outcome; histopathology and function of the allograft.

BACKGROUND: Cytotoxic effector molecule expression in human renal allograft biopsies has been closely associated with acute rejection. Here we studied whether intragraft expression of perforin, granzyme B, and Fas ligand correlates with long-term clinical outcome of acute rejection episodes. Furthermore, we examined the relation to histopathology and function of the allograft during rejection. METHODS: Twenty-two human renal biopsies were quantified for mRNA expression of perforin, granzyme B, Fas ligand, and Fas with reverse transcription-polymerase chain reaction. Expression levels were correlated with clinical outcome after 12 months, Banff rejection grades, and allograft function in the course of acute rejection. RESULTS: Only Fas ligand, but not perforin or granzyme B, showed significantly higher up-regulation in seven samples with therapy-resistant acute rejections versus eight samples with therapy-sensitive acute rejection. We found no relation between cytotoxic marker expression and Banff rejection grades or serum creatinine peak levels. CONCLUSIONS: Fas ligand may be useful as an early marker of therapy-resistant acute rejection. Cells that express Fas ligand but not classical soluble cytotoxic molecules might influence clinical outcome of acute rejection episodes.

Acute Disease↗
PubMed2001

Association between Epstein-Barr virus infection and late acute transplant rejection in long-term transplant patients.

Recently we reported about a possible involvement of extrarenal systemic cytomegalovirus (CMV) infection in graft deteriorating immune processes. We now examined whether Epstein-Barr virus (EBV) may also be associated with late renal graft injury. We analyzed the expression of early antigen-, viral capsid antigen-, and a latency-associated EBV-RNA-transcript, which is not translated into protein in peripheral blood mononuclear cells of kidney transplant patients with histologically proven late acute rejection and no signs of CMV or any other infection (A), patients with stable graft function (B), and healthy probands (C). A total of 40% in group A vs. 5 and 0% in groups B and C, respectively, expressed early antigen-mRNA (P<0.05) suggesting an activation of lytic EBV infection. Response to steroid bolus therapy in group A was comparably poor with that observed in CMV-related graft injury. Our data suggest that extrarenal lytic EBV infection may also be involved in the pathogenesis of late graft injury. A controlled ganciclovir trial may prove the significance of our observation.

Acute Disease↗
PubMed2001

CCAAT/enhancer-binding proteins alpha and beta negatively influence the capacity of tumor necrosis factor alpha to up-regulate the human cytomegalovirus IE1/2 enhancer/promoter by nuclear factor kappaB during monocyte differentiation.

Recently we demonstrated that the ability of tumor necrosis factor alpha (TNFalpha) to stimulate the human cytomegalovirus (HCMV) IE1/2 enhancer/promoter activity in myeloid progenitor-like cells decreases when these cells differentiate into promonocytic cells. In addition, TNFalpha stimulation in the progenitor-like cell line HL-60 was shown to be mediated by nuclear factor kappaB (NF-kappaB) activation and its binding to the 18-base pair sequence motifs of the IE1/2 enhancer. We demonstrate here that the cell differentiation-dependent reduction of TNFalpha stimulation is not due to insufficient NF-kappaB activation but correlates with increased synthesis of the monocyte differentiation-associated factors CCAAT/enhancer-binding protein (C/EBP) alpha and beta. Overexpression of C/EBPalpha/beta in HL-60 cells, which normally produce only very small amounts of C/EBP, stimulated the basal activity of the promoter in the absence of NF-kappaB but suppressed the stimulatory effect of TNFalpha. A novel C/EBP-binding site was identified in the IE1/2 enhancer directly downstream of a NF-kappaB site. In order to understand the mechanisms of interaction, we used an IE1/2 promoter mutant that failed to bind C/EBP at this position and several constructs that contained exclusively NF-kappaB- and/or C/EBP-binding sites upstream of the minimal IE1/2 promoter. We could demonstrate that C/EBPalpha/beta interacts with NF-kappaB p65 and displays inhibitory activity even in the absence of direct DNA binding by forming p65-C/EBP-containing protein complexes bound to the NF-kappaB site. Moreover, C/EBP binding to the DNA adjacent to NF-kappaB supports the down-regulatory effect of C/EBPs possibly due to stabilization of a multimeric NF-kappaB-C/EBP complex. Our results show that cell differentiation factors may interfere with TNFalpha-induced human cytomegalovirus gene (re)activation.

Base Sequence↗