Both biofilm cytotoxicity and monocytes' adhesion may be used as estimators of enterococcal virulence.

Our study aimed to identify markers of enterococci's virulence potential by evaluating the properties of strains of different sites of isolation. Enterococcal strains were isolated as commensals from faeces and as invasive strains from the urine and blood of patients from the University Clinical Centre, Gdansk, Poland. Changes in monocytes' susceptibility to the cytotoxic activity of isolates of different origins and their adherence to biofilm were evaluated using a flow cytometer. The bacterial protein profile was estimated by matrix assisted laser desorption ionization-time of flight mass spectrometer. The cytotoxicity of biofilm and monocytes' adherence to it were the most accurate factors in predicting the prevalence of the strain in the specific niche. Additionally, a bacterial protein with mass-to-charge ratio (m/z) 5000 was found to be responsible for the increased bacterial cytotoxicity, while monocytes' decreased adherence to biofilm was linked with the presence of proteins either with m/z 3330 or 2435. The results illustrate that monocytes' reaction when exposed to the bacterial biofilm can be used as an estimator of pathogens' virulence potential. The observed differences in monocytes' response are explainable by the bacterial proteins' profile. Additionally, the results indicate that the features of both bacteria and monocytes impact the outcome of the infection.

Longevity, Centenarians and Modified Cellular Proteodynamics.

We have shown before that at least one intracellular proteolytic system seems to be at least as abundant in the peripheral blood lymphocytes of centenarians as in the same cells of young individuals (with the cells of the elderly population showing a significant dip compared to both young and centenarian cohorts). Despite scarce published data, in this review, we tried to answer the question how do different types of cells of longevous people-nonagenarians to (semi)supercentenarians-maintain the quality and quantity of their structural and functional proteins? Specifically, we asked if more robust proteodynamics participate in longevity. We hypothesized that at least some factors controlling the maintenance of cellular proteomes in centenarians will remain at the "young" level (just performing better than in the average elderly). In our quest, we considered multiple aspects of cellular protein maintenance (proteodynamics), including the quality of transcribed DNA, its epigenetic changes, fidelity and quantitative features of transcription of both mRNA and noncoding RNAs, the process of translation, posttranslational modifications leading to maturation and functionalization of nascent proteins, and, finally, multiple facets of the process of elimination of misfolded, aggregated, and otherwise dysfunctional proteins (autophagy). We also included the status of mitochondria, especially production of ATP necessary for protein synthesis and maintenance. We found that with the exception of the latter and of chaperone function, practically all of the considered aspects did show better performance in centenarians than in the average elderly, and most of them approached the levels/activities seen in the cells of young individuals.

Emerging cellular senescence-centric understanding of immunological aging and its potential modulation through dietary bioactive components.

Immunological aging is strongly associated with the observable deleterious effects of human aging. Our understanding of the causes, effects, and therapeutics of aging immune cells has long been considered within the sole purview of immunosenescence. However, it is being progressively realized that immunosenescence may not be the only determinant of immunological aging. The cellular senescence-centric theory of aging proposes a more fundamental and specific role of immune cells in regulating senescent cell (SC) burden in aging tissues that has augmented the notion of senescence immunotherapy. Now, in addition, several emerging studies are suggesting that cellular senescence itself may be prevalent in aging immune cells, and that senescent immune cells exhibiting characteristic markers of cellular senescence, similar to non-leucocyte cells, could be among the key drivers of various facets of physiological aging. The present review integrates the current knowledge related to immunosenescence and cellular senescence in immune cells per se, and aims at providing a cohesive overview of these two phenomena and their significance in immunity and aging. We present evidence and rationalize that understanding the extent and impact of cellular senescence in immune cells vis-à-vis immunosenescence is necessary for truly comprehending the notion of an 'aged immune cell'. In addition, we also discuss the emerging significance of dietary factors such as phytochemicals, probiotic bacteria, fatty acids, and micronutrients as possible modulators of immunosenescence and cellular senescence. Evidence and opportunities related to nutritional bioactive components and immunological aging have been deliberated to augment potential nutrition-oriented immunotherapy during aging.

Ageing-resembling phenotype of long-term allogeneic hematopoietic cells recipients compared to their donors.

BACKGROUND: Ageing is a complex phenomenon that leads to decreased proliferative activity, loss of function of the cells, and cellular senescence. Senescence of the immune system exacerbates individual's immune response, both humoral and cellular but increases the frequency of infections. We hypothesized that physiological ageing of adaptive immune system occurs in recipients of allogeneic hematopoietic cells transplant (allo-HCT) at faster rate when compared to their respective donors since the small number of donor cells undergo immense proliferative stress restoring recipients hematopoiesis. We compared molecular characterizations of ageing between recipients and donors of allo-HCT: telomeric length and immunophenotypic changes in main lymphocyte subsets - CD4+, CD8+, CD19+, CD56+. RESULTS: Median telomeric length (TL) of CD8+ lymphocytes was significantly longer in donors compared to recipients (on average 2,1 kb and 1,7 kb respectively, p = 0,02). Similar trends were observed for CD4+ and CD19+ although the results did not reach statistical significance. We have also found trends in the immunophenotype between recipients and donors in the subpopulations of CD4+ (naïve and effector memory), CD8+ Eomes+ and B-lymphocytes (B1 and B2). Lower infection risk recipients had also a significantly greater percentage of NK cells (22,3%) than high-risk patients (9,3%) p = 0,04. CONCLUSION: Our data do not support the initial hypothesis of accelerated aging in the long term all-HCT recipients with the exception of the recipients lymphocytes (mainly CD8+) which present some molecular features, characteristic for physiological ageing (telomeric shortening, immunophenotype) when compared to their respective donors. However, a history of lower infection numbers in HCT recipients seems to be associated with increased percentage of NK cells. The history of GVHD seems not to affect the rate of ageing. Therefore, it is safe to conclude that the observed subtle differences between recipients' and donors' cells result mainly from the proliferative stress in the early period after allo-HCT and the difference between hosts' and recipients' microenvironments.

The integration of inflammaging in age-related diseases.

Aging is characterized by a morpho-functional adaptation, variably affecting major physiological systems, depending on a complex interaction between genetic, environmental and stochastic factors. This dynamic interaction drives an age-related remodelling of a number of pathways/systems, providing the chance to reach the extreme limit of human life in healthy state which is reflected in the ever-increasing number of centenarians. This conceptualization implies that aging process per se and the development of the most common age-related diseases (ARD) are somewhat separate but must share somehow common set of basic biological mechanisms. One of the features that characterize both processes is the development and progression of an inflammatory state named inflammaging. Notably, inflammaging is characterized by a peculiar presentation, being a chronic, systemic, low grade and therefore for a long time subclinical, inflammatory process. For these reasons, even if the rate of progression of inflammaging is currently recognized as the main force driving aging and one of the main risk factors for clinical morbidity and mortality in the elderly, current knowledge on the causal agents are still incomplete and the "clinical evaluation" of inflammaging has not yet been standardized. Even if a number of biomarkers of inflammaging have been identified, their analysis is not recommended as part of the routine evaluation of elderly patients. This review will aim to describe the concept of inflammaging within several other concepts such as the definition of aging per se and how we integrate it in the context of ARD.

Hyperactivation of monocytes and macrophages in MCI patients contributes to the progression of Alzheimer's disease.

BACKGROUND: Alzheimer's disease (AD) is the most common neurodegenerative disease ultimately manifesting as clinical dementia. Despite considerable effort and ample experimental data, the role of neuroinflammation related to systemic inflammation is still unsettled. While the implication of microglia is well recognized, the exact contribution of peripheral monocytes/macrophages is still largely unknown, especially concerning their role in the various stages of AD. OBJECTIVES: AD develops over decades and its clinical manifestation is preceded by subjective memory complaints (SMC) and mild cognitive impairment (MCI); thus, the question arises how the peripheral innate immune response changes with the progression of the disease. Therefore, to further investigate the roles of monocytes/macrophages in the progression of AD we assessed their phenotypes and functions in patients at SMC, MCI and AD stages and compared them with cognitively healthy controls. We also conceptualised an idealised mathematical model to explain the functionality of monocytes/macrophages along the progression of the disease. RESULTS: We show that there are distinct phenotypic and functional changes in monocyte and macrophage populations as the disease progresses. Higher free radical production upon stimulation could already be observed for the monocytes of SMC patients. The most striking results show that activation of peripheral monocytes (hyperactivation) is the strongest in the MCI group, at the prodromal stage of the disease. Monocytes exhibit significantly increased chemotaxis, free radical production, and cytokine production in response to TLR2 and TLR4 stimulation. CONCLUSION: Our data suggest that the peripheral innate immune system is activated during the progression from SMC through MCI to AD, with the highest levels of activation being in MCI subjects and the lowest in AD patients. Some of these parameters may be used as biomarkers, but more holistic immune studies are needed to find the best period of the disease for clinical intervention.

The dual role of the immune system in the course of COVID-19. The fatal impact of the aging immune system.

COVID-19 is a highly contagious respiratory disease caused by the novel coronavirus SARS-CoV-2. Since October 2020 the second wave of the pandemic has been observed around the world, as pathogen specific herd immunity has not been built yet. Moreover, the current, more contagious pathogen carrying the D614G mutation has become the globally dominant form of SARS-CoV-2. In this article we present the current state of knowledge on the impact of ACE2 and the reninangiotensin system (RAS) and the innate immune system on different outcomes of COVID-19. Especially, we point out the dual role of the immune system and ACE2 in pathogenesis of the disease. Namely, at the initial stage of the infection anti-viral activity of innate immunity is responsible for inhibition of SARS-CoV-2 replication. On the other hand, a dysregulated immune response may cause the detrimental hyperinflammation ("cytokine storm") responsible for the severe course of the disease. Concomitantly, we analyse the roles of ACE2 in both facilitation of infection and abrogation of its effects, as the major cellular entry receptor for SARS-CoV-2 and an important enzyme responsible for tissue protection, respectively. Finally, we discuss the dominant impact of aging on the fatal outcome of COVID-19.

Constipation and the Quality of Life in Conservatively Treated Chronic Kidney Disease Patients: A Cross-sectional Study.

Background: Constipation is a common gastrointestinal disorder that in general population is associated with worse health-related quality of life (HRQoL). The epidemiology of constipation has not been reliably determined in conservatively-treated CKD patients. We aimed to determine the prevalence of constipation and constipation-related symptoms in conservatively-treated CKD patients, to find factors associated with their altered prevalence ratio (PR), and to verify the associations between constipation and HRQoL. Methods: In this cross-sectional study, 111 conservatively-treated CKD outpatients fulfilled questionnaires that included questions addressing HRQoL (SF-36v2®), constipation-related symptoms (The Patient Assessment of Constipation-Symptoms questionnaire), the Bristol stool form scale (BSFS), Rome III criteria of functional constipation (FC), and frequency of bowel movement (BM). Results: Depending on the used definition, the prevalence of constipation was 6.6-28.9%. Diuretics and paracetamol were independently associated with increased PR of BSFS-diagnosed constipation (PR 2.86, 95% CI 1.28-6.37, P = 0.01) and FC (PR 2.67, 95% CI 1.07-6.64, P = 0.035), respectively. The most commonly reported symptoms were bloating (50.9%) and straining to pass a BM (42.7%). Abdominal discomfort (37.3%) was independently associated with worse scores in all analyzed HRQoL domains. In multiple regressions, FC and having <7 BM/week, but not BSFS-diagnosed constipation, were associated with lower scores in several HRQoL domains. Conclusions: Constipation and related symptoms are prevalent in CKD patients. FC and decreased frequency of defecation, but not BSFS-diagnosed constipation, are associated with worse assessment of HRQoL in conservatively-treated CKD patients.

The role of Lactobacillus plantarum 299v in supporting treatment of selected diseases.

Alterations in composition of human gut microbiome can lead to its dysbiosis. It is associated with gastrointestinal side effects during anti-cancer treatment, antibiotics administration, or infectious agents. There are studies confirming positive effect of consuming Lactobacillus plantarum 299v on intestinal microflora. This review summarizes the current knowledge about the role of L. plantarum 299v in supporting treatment of selected diseases, such as cancer, irritable bowel syndrome (IBS), and Clostridium difficile infection. The immunomodulating properties of L. plantarum 299v include an increase in the level of anti-inflammatory cytokines, which reduce the risk of cancer and improve the efficacy of regimens. The intake of L. plantarum 299v provides benefits for IBS patients, mainly due to normalization of stool and relief of abdominal pain, which significantly improves the quality of life of IBS patients. In addition, the intake of L. plantarum 299v prevents C. difficile-associated diarrhea among patients receiving antibiotic treatment. Due to the limited possibilities of treating these diseases and numerous complications of cancer treatment, there is a need for new therapeutic strategies. The administration of L. plantarum 299v seems to be useful in these cases.

Does HIV infection contribute to increased beta-amyloid synthesis and plaque formation leading to neurodegeneration and Alzheimer's disease?

HIV infection in the combination antiretroviral therapy (cART) era has become a chronic disease with a life expectancy almost identical to those free from this infection. Concomitantly, chronic diseases such as neurodegenerative diseases have emerged as serious clinical problems. HIV-induced cognitive changes, although clinically very diverse are collectively called HIV-associated neurocognitive disorder (HAND). HAND, which until the introduction of cART manifested clinically as a subcortical disorder, is now considered primarily cognitive disorder, which makes it similar to diseases like Alzheimer's (AD) and Parkinson's disease (PD). The pathogenesis involves either the direct effects of the virus or the effect of viral proteins such as Tat, Ggp120, and Nef. These proteins are either capable of destroying neurons directly by inducing neurotoxic mediators or by initiating neuroinflammation by microglia and astrocytes. Recently, it has become recognized that HIV infection is associated with increased production of the beta-amyloid peptide (Aß) which is a characteristic of AD. Moreover, amyloid plaques have also been demonstrated in the brains of patients suffering from HAND. Thus, the question arises whether this production of Aß indicates that HAND may lead to AD or it is a form of AD or this increase in Aß production is only a bystander effect. It has also been discovered that APP in HIV and its metabolic product Aß in AD manifest antiviral innate immune peptide characteristics. This review attempts to bring together studies linking amyloid precursor protein (APP) and Aß production in HIV infection and their possible impact on the course of HAND and AD. These data indicate that human defense mechanisms in HAND and AD are trying to contain microorganisms by antimicrobial peptides, however by employing different means. Future studies will, no doubt, uncover the relationship between HAND and AD and, hopefully, reveal novel treatment possibilities.

Immunological aspects of autoimmune thyroid disease - Complex interplay between cells and cytokines.

Autoimmune thyroid disease (ATD) is a chronic autoimmune thyroiditis with a complex pathogenesis including environmental factors, genetic background and immune system actions. Despite the large-scale research and discovery of new subpopulations of lymphocytes, cytokines, chemokines and their functions in the human body, the ethiology of ATD in many aspects remains a mystery. This article tries to summarize mostly the immunological aspects of this disease, including the roles of different cells types (dendritic cells, B cells, CD4+ and CD8+ T cells, NK cells and regulatory T cells) and of different cytokines (secreted by Th1/Th2/Th17/Th22 lymphocyte subpopulations and other, including the IL-23 and CXCL10). We describe the role of immunological abnormalities in the ATD pathogenesis and show that for some cells and cytokines their respective roles are not clear, and bi-directional action is possible. Finally, we propose a network of interactions between the immune cells and thyrocytes in the course of ATD.

Human Inflammaging.

Human aging is a very complex process that occurs in an intricate biological and physiological setting. Many changes occur with aging and among the most important are changes in immune reactivity associated with cell differentiation stages and the phenomenon of inflammaging, understood as subclinical inflammatory readiness, manifested by elevated levels of proinflammatory factors. It was stated for a long time that this tandem occurs in parallel or eventually sequentially. However, recent evidence points to the fact that, as both originate from chronic antigen stimulation, they mutually drive each other. In this context, inflammaging is considered the basis of most age-related diseases (ARD). In this review concerning human inflammaging, we argue that inflammatory diseases develop during whole life as a diverted (excessive) normal immune reaction to specific stressors. Thus, inflammaging may not be the cause of these diseases; however, it can be the trigger of clinical manifestation of ARD. In this context, the best intervention should aim to regulate the balance between pro- and anti-inflammatory signals and the more appropriate reaction to chronic stimulations to avoid/delay the appearance of associated diseases.

T cells in IgA nephropathy: role in pathogenesis, clinical significance and potential therapeutic target.

BACKGROUND: Immunoglobulin A nephropathy (IgAN), the most frequent cause of primary glomerulonephritis worldwide, is an autoimmune disease with complex pathogenesis. In this review, we focus on T cells and summarize knowledge about their involvement in pathophysiology and treatment of IgAN METHODS: We reviewed the literature for (1) alterations of T cell subpopulations in IgAN, (2) experimental and clinical proofs for T cells' participation in IgAN pathogenesis, (3) clinical correlations with T cell-associated alterations, and (4) influence of drugs used in IgAN therapy on T cell subpopulations. RESULTS: We found that IgAN is characterized by higher proportions of circulatory Th2, Tfh, Th17, Th22 and γδ T cells, but lower Th1 and Treg cells. We discuss genetic and epigenetic makeup that may contribute to this immunological phenotype. We found that Th2, Th17 and Tfh-type interleukins contribute to elevated synthesis of galactose-deficient IgA1 (Gd-IgA1) and that the production of anti-Gd-IgA1 autoantibodies may be stimulated by Tfh cells. We described the roles of Th2, Th17, Th22 and Treg cells in the renal injury and summarized correlations between T cell-associated alterations and clinical features of IgAN (proteinuria, reduced GFR, hematuria). We detailed the impact of immunosuppressive drugs on T cell subpopulations and found that the majority of drugs have nonoptimal influence on T cells in IgAN patients. CONCLUSIONS: T cells play an important role in IgAN pathogenesis and are correlated with its clinical severity. Clinical trials with the drugs targeting the reported alterations of the T-cell compartment are highly desirable.

Lactulose: Patient- and dose-dependent prebiotic properties in humans.

Lactulose is a disaccharide used in clinical practice since 1957 and has since been tested in the treatment of many human disorders, including chronic constipation, hepatic encephalopathy, and chronic kidney disease. Its mode of action is based on the lactulose fermentation by intestinal microbiota. Based on in silico, in vitro and in vivo studies we comprehensively review here the impact of lactulose on human gut/fecal and vaginal microbiota composition and both fecal and blood metabolomes. However, both in vitro and in vivo studies summarized in this review have revealed that the effects of lactulose on human microbiota composition are both patient- and dose-dependent. This highlights the need of heterogeneity indication in clinical trials.

Heterogeneity of the cytokinome in undifferentiated arthritis progressing to rheumatoid arthritis and its change in the course of therapy. Move toward personalized medicine.

OBJECTIVES: To conduct a comprehensive analysis of cytokine concentrations in sera and mononuclear cell supernatants in order to examine inter- and intra-individual cytokine variations in undifferentiated arthritis progressing to rheumatoid arthritis and healthy control groups. METHODS: Patients with UA (undifferentiated arthritis) developing RA (rheumatoid arthritis) (UA→RA) (n=16) and healthy controls (n=16) were enrolled into the study. UA→RA patients were followed up for six months since the final RA diagnosis. Cytokines IFN-γ, IL-10, TNF, IL-17A, IL-6, IL-1ß, IL-2 in sera and mononuclear cell supernatants in 72h and 120h culture variants with- and without anti-CD3 stimulations were assayed using flow cytometric bead array. RESULTS: The cytokine profile of UA→RA differs from the healthy individual cytokine profile. It is possible to observe specific cytokine pattern characterizing each patient, which alters during course of disease. Specifically, we can distinguish three UA→RA cohorts: the group of patients susceptible to the therapy, characterized by the drop of cytokine levels between 1st and 3rd visit with visible decrease of cytokines in 2nd visit and then secondary slighter increase in 3rd visit; the group of patients refractory or clinically worsening on the therapy, characterized by the highest cytokine levels at 2nd visit with secondary decrease in 3rd visit; and the group of patients with variable responses to the therapy without any specific common cytokine pattern. The cytokine patterns in supernatants of PBMC stimulated anti-CD3 for 72h and 120h are very similar. CONCLUSIONS: The personal profile including multiplexed cytokine patterns in serum and supernatant may be potentially used for optimization of therapy introduction and monitoring.

Phenotype, proliferation and apoptosis of B lymphocytes in hemodialysis patients treated with recombinant human erythropoietin.

One of the major causes of disorders of the immune response in patients undergoing hemodialysis (HD) is weaker activity of their helper T lymphocytes (Th cells), mainly reduced proliferative capacity associated with decreased expression of key surface antigens. Since cooperation between Th and B lymphocytes is essential for B cell function, changes in Th cell phenotype and ability to proliferate or produce cytokines could directly translate into an impaired humoral response. Therefore, we investigated the T cell-dependent activity of B cells in HD patients focusing mainly on their proliferative kinetics, susceptibility to apoptosis and the ability to produce antibodies. Since our previous studies have shown the beneficial effects of recombinant human erythropoietin (rhEPO) on T lymphocytes, we also investigated the in vivo and in vitro influence of rhEPO on B cells. Our results show that B lymphocytes of HD patients, especially of those who are not treated with rhEPO, have reduced proliferative capacity in vitro, reflected in low number of cell divisions, decreased percentage of proliferating cells and an increased susceptibility to apoptosis. They are also characterized by impaired ability to produce immunoglobulins. We have found no significant changes in the expression of key antigens of B lymphocytes with the exception of IL-10R. Furthermore, we demonstrated a time- and health status-dependent impact of rhEPO on patient's B cells. Our results show possible mechanisms responsible for the deficiency of humoral responses in HD patients which, at least partially, can be modulated through the supplementation with rhEPO.

Homeostatic 'bystander' proliferation of human peripheral blood B cells in response to polyclonal T-cell stimulation in vitro.

The mechanisms of maintenance of adequate numbers of B lymphocytes and of protective levels of immunoglobulins in the absence of antigenic (re)stimulation remain not fully understood. Meanwhile, our results presented here show that both peripheral blood naive and memory B cells can be activated strongly and non-specifically (in a mitogen-like fashion) in 5-day in vitro cultures of anti-CD3- or concanavalin A (Con A)-stimulated peripheral blood mononuclear cells of healthy people. This polyclonal, bystander activation of the B cells includes multiple divisions of most of them (assessed here by the flow cytometric technique of dividing cell tracking) and significant antibody [immunoglobulin M (IgM) and IgG] secretion. Observed proliferation of the CD19(+) B cells depends on contact with stimulated T helper (Th) cells (via CD40-CD40L interaction) and on the response of B cells to secreted interleukins IL-5, IL-10 and IL-4, and is correlated with the levels of these Th-derived molecules, while it does not involve the ligation of the BCR/CD19 complex. We suggest that the effect might reflect the situation occurring in vivo as the homeostatic proliferation of otherwise non-stimulated, peripheral B lymphocytes, providing an always ready pool for efficient antibody production to any new (or cognate) antigen challenge.

The Role of Immunosenescence in the Development of Age-Related Diseases.

Aging is a complex phenomenon leading to numerous changes in the physiological systems of the body. One of the most important changes, called immunosenescence, occurs in the immune system. Immunosenescence covers changes in the innate and the adaptive immune systems and is associated with a low-grade inflammation called inflammaging. Aging, likely via inflammaging, is also associated with the emergence of chronic diseases including cardiovascular and neurodegenerative diseases, cancer, and diabetes mellitus type 2. The origin of this inflammaging is not known with certainty, but several concurrent contributing factors have been suggested, such as aging-associated changes in the innate and adaptive immune response, chronic antigenic stimulation, the appearance of endogenous macromolecular changes, and the presence of senescent cells exhibiting a senescence-associated secretory phenotype. A better understanding of the multiple biological phenomena leading to these diseases via the immunosenescence associated with inflammaging provides a powerful target for interventions to increase the healthspan of elderly subjects.

Dexamethasone-dependent modulation of cyclic GMP synthesis in podocytes.

Podocytes may be direct target for glucocorticoid therapy in glomerular proteinuric disease. Permeability of podocytes largely depends on their capacity to migrate which involves the contractile apparatus in their foot processes. In this study, we examined the effect of synthetic glucocorticoid dexamethasone (DEX) on the ability of podocytes to produce cyclic guanosine monophosphate (cGMP) in the presence of vasoactive factors, atrial natriuretic peptide (ANP), nitric oxide (NO), and angiotensin II (Ang II). We investigated also the effects of cGMP and DEX on podocyte motility. Primary rat podocytes and immortalized mouse podocytes were pretreated with 1 µM DEX for 4 or 24 h. Glomerular hypertension was mimicked by subjecting the cells to mechanical stress. Total and subcellular cGMP levels were determined in podocytes incubated with 0.1 µM ANP, 1 µM S-nitroso-N-acetyl penicillamine (SNAP), and 1 µM Ang II. Cell motility was estimated by a wound-healing assay. The ANP-dependent production of cGMP increased after 4 h exposition to DEX, but was attenuated after 24 h. Adversely, a 24-h pretreatment with DEX augmented the NO-dependent cGMP synthesis. Ang II suppressed the ANP-dependent cGMP production and the effect was enhanced by DEX in mechanical stress conditions. Mechanical stress reduced total cGMP production in the presence of all stimulators, whereas extracellular to total cGMP ratio increased. 8-Br cGMP enhanced podocyte migration which was accompanied by F-actin disassembly. In the presence of DEX these effects were prevented. We conclude that DEX modulates the production of cGMP in podocytes stimulated with vasoactive factors such as Ang II, ANP, and NO, and the effect is time-dependent. cGMP increases podocyte motility, which is prevented by DEX. This mechanism may account for the antiproteinuric effect of glucocorticoids.

Influence of hemodialysis on circulating CD4(low)CD25 (high) regulatory T cells in end-stage renal disease patients.

OBJECTIVE: Immunodeficiency of end-stage renal disease (ESRD) is caused by several factors including uremic toxins and biocompatibility reactions due to the repeated hemodialysis (HD) procedure. It has also been suggested that poor T cell responses could be associated with the increased number of regulatory T cells (Tregs) which are necessary to limit the function of activated T cells. The aim of the study was to determine the proportion of CD4(+)CD25(+) cells (activated T cells) to CD4(low)CD25(high) cells (Tregs) within the CD4(+) population in ESRD patients. PATIENTS AND METHODS: Two groups of ESRD patients, predialysis patients treated conservatively and patients undergoing hemodialysis (HD), as well as healthy controls were included in the study. Percentages of activated and regulatory T cells were determined ex vivo with flow cytometry based on the expression of CD4 and CD25 antigens. RESULTS AND CONCLUSIONS: HD patients showed an increased percentage of CD4(+)CD25(+) cells when compared with healthy controls, while there was no difference in the percentage of CD4(low)CD25(high) cells between the patient groups. In our opinion, the repeated hemodialysis procedure significantly disturbs the balance between activated T cells and regulatory T cells in ESRD patients. Lack of Treg mobilization and chronic stimulation of T cells may contribute to the immune deficiency observed in these patients.