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Alejandro Martín-Malo

Publications and source records attributed to Alejandro Martín-Malo.

12 recordsLinked to original sources
PubMed2006

On-line hemodiafiltration reduces the proinflammatory CD14+CD16+ monocyte-derived dendritic cells: A prospective, crossover study.

It is not known whether high convective transport may have a role in modulating the chronic inflammation of hemodialysis (HD) patients. The aim of this study was to evaluate the effect of on-line hemodiafiltration (OL-HDF) on proinflammatory peripheral monocytes: Percentage of CD14+CD16+ cells and their telomere length and spontaneous or bacterial DNA-induced production of cytokines (TNF-alpha and IL-6). In a prospective, crossover study, 31 patients who were on high-flux HD (HF-HD) were evaluated. Patients underwent the following sequence of treatments (4 mo each): HF-HD (basal), OL-HDF (period 1), HF-HD (period 2), OL-HDF (period 3), and HF-HD (period 4). The dialysis characteristics were similar in the two modalities; the only difference was a higher convective transport in the OL-HDF than in the HF-HD. All patients who were on OL-HDF periods showed a significantly lower number of CD14+CD16+ cells than on HF-HD (18.5 +/- 2.3 basal versus 13.6 +/- 2.9 period 1 and 13.9 +/- 2.3 period 3; P = 0.001). By contrast, HF-HD restored the number of CD14+CD16+ cells to the basal values (19.2 +/- 2.8 and 18.6 +/- 1.4, periods 2 and 4, respectively; NS). During OL-HDF periods, the reduction of CD14+CD16+ was paralleled by a decreased number of short telomere cells. Spontaneous or bacterial DNA-induced production of cytokines (TNF-alpha and IL-6) was increased in HF-HD as compared with OL-HDF. In conclusion, these results demonstrate that as compared with HF-HD, OL-HDF markedly reduces the number of proinflammatory CD14+CD16+ cells and the production of TNF-alpha and IL-6. Future studies are needed to assess the possible therapeutic effect of convective transport on chronic inflammation that is associated with HD.

Adult↗
PubMed2006

Microinflammation in hemodialysis is related to a preactivated subset of monocytes.

Increased percentage of monocytes with low CD14 expression and that co-express CD16 (CD14+/CD16+) have been reported in hemodialysis (HD) patients. We sought to determine whether CD14+/CD16+ monocytes in HD therapy are sensibilized cells to a proinflammatory activity. Cells from 32 HD patients, and from 9 Systemic Lupus Erythematosus (SLE), 9 individuals with human immunodeficiency virus (HIV)-1- and 15 healthy controls were studied. Cells were analyzed by means of flow cytometry for CD14/CD16 expression and immune function (cytokine, chemokines, and sialoadhesin expression), and phagocytosis. Increased percentage of CD14+/CD16+ monocytes was observed in HD patients. Compared with CD14++ monocytes, the CD14+/CD16+ monocytes exhibited increased expression of proinflammatory cytokines and markers of differentiated cells. In addition, these monocytes showed an increased phagocytic activity. Similarly, CD14+/CD16+ monocytes from SLE and HIV patients showed increased inflammatory activity as compared with CD14++ cells. These results support that CD14+/CD16+ monocytes from HD patients evidence characteristics of primed prestimulated proinflammatory cells, similar to data observed in SLE and HIV.

Adult↗
PubMed2005

Calcium-sensing receptor expression and parathyroid hormone secretion in hyperplastic parathyroid glands from humans.

In uremic patients, severe parathyroid hyperplasia is associated with reduced parathyroid calcium-sensing receptor (CaR) expression. Thus, in these patients, a high serum Ca concentration may be required to inhibit parathyroid hormone (PTH) secretion. This study compares the magnitude of reduction in CaR expression and the degree of the abnormality in Ca-regulated PTH release in vitro. A total of 50 glands from 23 hemodialysis patients with refractory hyperparathyroidism were studied. Tissue slices were incubated in vitro to evaluate (1) the PTH secretory output in a normal Ca concentration (1.25 mM) and (2) the PTH secretory response to high (1.5 mM) and low (0.6 mM) Ca concentration. Tissue aliquots were processed for determination of CaRmRNA expression. The results showed that, corrected for DNA, parathyroid tissue with lowest CaR expression secreted more PTH than that with relatively high CaR expression (146 +/- 23 versus 60 +/- 2 pg/microg DNA; P < 0.01). Furthermore, glands with low CaR expression demonstrated a blunted PTH secretory response to both the inhibitory effect of high Ca and the stimulatory effect of low Ca. The study also showed that the larger the gland, the lower the CaRmRNA expression. Thus, large parathyroid glands produce a large amount of PTH not only as a result of the increased gland size but also because the parathyroid tissue secretory output is increased. These abnormalities in PTH regulation are related to low CaR expression.

Female↗
PubMed2005

Lymphocyte apoptosis: role of uremia and permeability of dialysis membrane.

BACKGROUND: Uremia is associated to host defense mechanism disorders. Lymphocyte apoptosis, which may cause alteration of the immune system, is increased in uremic patients. The aim of the present study was to determine if, in addition to uremia, dialysis membranes with different biocompatibility and permeability have an effect on lymphocyte apoptosis. METHODS: Cell apoptosis and Fas expression were assessed using flow cytometry in four groups of patients: (1) uremic non-dialyzed (Non-D) patients; (2) hemodialysis (HD) patients on hemophan; (3) low-flux polysulfone, and (4) high-flux polysulfone membrane. Ten healthy volunteers were used as controls. RESULTS: At baseline, lymphocytes from patients on hemophan showed an increase in apoptosis (18.4 +/- 6.9%) as compared with Non-D (7.2 +/- 2.8%; p < 0.001), low-flux (6.4 +/- 2.4%; p < 0.001), high-flux (2.6 +/- 1.2%; p < 0.001) and controls (2.0 +/- 1.0%; p < 0.001). Fas expression was similar in lymphocytes from Non-D and hemophan dialyzed patients (40.5 +/- 5% vs. 40.4 +/- 6%), and in both groups it was greater than low-flux (30%+/-7%; p < 0.001), high-flux (11 +/- 4%; p < 0.001) and controls (12.6 +/- 3%; p < 0.001). When lymphocytes were cultured for 48 h, apoptosis was similar in Non-D and hemophan (27.0 +/- 4.3% vs. 27.1 +/- 6.9%); apoptosis of lymphocyte from patients on low-flux (14.1 +/- 3.5%) was greater than on high-flux polysulfone membrane (7.0 +/- 2.0%; p < 0.001). CONCLUSION: These findings suggest that in dialysis patients lymphocyte apoptosis is influenced not only by the biocompatibility but also by the permeability of the dialysis membrane.

Adult↗
PubMed2005

Stress-induced premature senescence in mononuclear cells from patients on long-term hemodialysis.

BACKGROUND: Repeatedly stimulated mononuclear cells may become senescent prematurely as a result of frequent activation-induced replication. In hemodialysis patients, mononuclear cells are activated repeatedly with each hemodialysis procedure. Characteristics of senescent mononuclear cells include telomere length shortening, increased p53 expression, CD14dim/CD16bright expression, and interleukin overproduction. METHODS: Peripheral mononuclear cells from 15 hemodialysis patients and 15 age-matched controls were evaluated. Telomere length was assessed by means of fluorescence in situ hybridization in flow cytometry. Expression of p53, CD14/CD16, and intracellular cytokine production (interleukin-1beta [IL-1beta], IL-6, and IL-4) was evaluated by means of flow cytometry using specific antibodies. RESULTS: Features of senescence were found in a subpopulation of mononuclear cells: (1) accelerated telomere shortening, (2) increased p53 expression, (3) CD14dim/CD16bright expression, and (4) cytokine overproduction (IL-1beta, IL-6, and IL-4). Telomere length shortening was present in 40% +/- 6% of cells from hemodialysis patients compared with less than 5% from age-matched controls. Percentage of cells with short telomeres correlated positively with serum C-reactive protein level, which reflects inflammation. p53 expression was increased in mononuclear cells from hemodialysis patients. Mononuclear cells from hemodialysis patients with decreased telomere length mainly showed the CD14dim/CD16bright phenotype; conversely, cells with normal telomeres presented the CD14bright/CD16dim phenotype. Finally, mononuclear cells from hemodialysis patients, but not controls, spontaneously produced the proinflammatory cytokines IL-1beta and IL-6. CONCLUSION: This study shows the presence of a prematurely senescent subpopulation of peripheral mononuclear cells in hemodialysis patients. These senescent cells probably result from repeated activation and may have a pathophysiological role in the chronic inflammation described in hemodialysis patients.

Adult↗
PubMed2005

Replicative senescence in patients with chronic kidney failure.

BACKGROUND: Chronic activation of immunocompetent cells may lead to stress-induced premature senescence (SIPS); these senescent cells are characterized by a decrease in telomere length. The present study evaluates SIPS in circulating immunocompetent cells from predialysis patients, patients on hemodialysis, and in renal transplant patients with normal renal function. METHODS: Determination of telomere length by flow-fluorescence in situ hybridization (FISH), expression of surface molecules, and evaluation of apoptosis was performed by flow cytometry. RESULTS: In uremic predialysis patients, we observed a subpopulation of lymphocytes with short telomeres. However, in this population of patients we did not observe SIPS mononuclear cells. In hemodialysis patients, we found a subpopulation of SIPS mononuclear cells that also showed phenotypic changes of proinflammatory activity. Finally, transplant patients with normal renal function also exhibited a subpopulation of SIPS lymphocytes, which can be attributed to chronic lymphocyte activation induced by the major histocompatibility complex. CONCLUSION: In chronic kidney disease patients, immunocompetent cells undergo SIPS, a process associated with chronic cell activation and induced by numerous stimuli including uremia, hemodialysis membranes, and bacterial products. Because SIPS immunocompetent cells are activated cells with proinflammatory features and live longer in peripheral blood, it is likely that SIPS cells contribute significantly to the chronic inflammatory state of patients with advanced renal failure.

Apoptosis↗
PubMed2004

The imbalance in the ratio of Th1 and Th2 helper lymphocytes in uraemia is mediated by an increased apoptosis of Th1 subset.

BACKGROUND: In uraemia there is a reduction in the total number of T lymphocytes and an imbalance in the ratio of Th1/Th2 T-helper (Th) lymphocytes. A higher rate of apoptosis in T lymphocytes has been reported in haemodialysis patients. The aims of the present study were to assess the Th1/Th2 pattern in uraemia and to evaluate whether a relative increase in Th1 apoptosis may explain the Th1/Th2 imbalance observed in uraemic patients. METHODS: Seventeen non-dialysed uraemic patients were evaluated; eight healthy volunteers served as controls. Intracellular interferon-gamma (IFN-gamma) and interleukin-4 (IL-4) were measured by direct intracellular immunofluorescence and flow cytometry. Apoptosis was determined by flow cytometry using annexin V or TUNEL. Mechanisms of apoptosis were assessed by determination of Fas and Bcl-2 expression. RESULTS: Cell production of cytokines is significantly higher in uraemic patients than in controls. In addition, in uraemic patients only 5.1+/-2.1% of the T lymphocytes contained IFN-gamma (Th1 cells) while 61.9 +/- 14.8% contained IL-4 (Th2 cells) (P < 0.0001). The percentage of apoptosis was 29.6 +/- 6.3% and 4.7 +/- 1.6% in Th1 and Th2 lymphocytes, respectively (P < 0.001). Fas expression was higher in Th1 than in Th2 cells and the expression of Bcl-2 was lower in Th1 than in Th2 cells. The apoptosis induced by anti-Fas antibodies was similar in both types of lymphocytes. CONCLUSIONS: In uraemia there is a reduction in the proportion of Th1 lymphocytes due to a higher rate of apoptosis in this subset of lymphocytes. Th1 from uraemic patients show a higher expression of Fas and a lower expression of Bcl-2 than Th2. This makes uraemic Th1 cells more susceptible to apoptosis. The Th1/Th2 imbalance may contribute to alterations in cellular immunity observed in chronic kidney disease patients.

Adult↗
PubMed2002

Cell apoptosis and hemodialysis-induced inflammation.

Hemodialysis patients exhibit a defective immune response leading to an increased susceptibility of infections and neoplasms. Far from being helpful, dialytic therapy per se also may be responsible for this acquired immunodeficiency. Dialysis membranes and bacterial products present in dialysis water may trigger and even perpetuate an abnormal mononuclear cell activation. Upon contact with cellulosic dialysis membranes, monocytes display an increased expression of surface markers of cell activation, such as adhesion molecules CD18, CD49, CD54 and the lipopolysaccharide (LPS) ligand (CD14). Moreover, proinflammatory cytokines as IL-1beta and TNF-alpha are released both in vivo and in vitro when monocytes are exposed to cellulosic membranes. Of special interest is the fact that end-stage renal disease patients undergoing hemodialysis exhibit an increased mononuclear cell apoptosis. This apoptosis is directly related to the degree of biocompatibility of the dialysis membrane. Apoptosis is activated when monocytes enter in contact with the cellulosic dialysis membrane through cell surface receptors linked to G-proteins. In early steps of apoptosis signaling, pertussis toxin-sensitive G proteins are coupled to protein kinase C (PKC)-dependent phosphorylative mechanisms. Furthermore, recent evidence support that the execution phase of apoptosis is mediated by a caspase-3 dependent pathway. Finally, very recent available data support that monocytes subjected to repeated activation suffer a process of accelerated senescence, as demonstrated by the senescent phenotype (CD14 and CD32) expressed and their shortened telomeric length. This senescent profile may generage a defective cellular response in acute stress situations, explaining (at least in part) the altered immune response observed in hemodialysis patients.

Acute-Phase Reaction↗
PubMed2002

Caspase-3-dependent pathway mediates apoptosis of human mononuclear cells induced by cellulosic haemodialysis membranes.

BACKGROUND: Mononuclear cells from patients dialysed with cellulosic membranes undergo rapid apoptosis in vitro. The aim of the present study was to determine whether the apoptosis associated with cellulosic haemodialysis membrane shares similar features with the spontaneous apoptosis described in normal monocytes. Thus, we determined whether apoptosis is dependent on caspase-3 activity and is inhibited by lipopolysaccharide (LPS), which are two features of spontaneous apoptosis in normal monocytes. METHODS: We examined mononuclear cells from healthy subjects and from 14 end-stage renal failure patients on haemodialysis with cellulosic membranes (n=7) and non-cellulosic membranes (n=7). Isolated mononuclear cells were cultured for 48 h. To determine the effect of haemodialysis membrane exposure on caspase-3 activity, on mononuclear apoptosis, or both, cells from healthy subjects were cultured in mini-dialysers with the same membrane types that were used in the haemodialysis patients. Caspase-3 active form was determined by flow cytometric analysis using anti-human-active caspase-3 antibodies. The effect of LPS and Ac-DEVD-CHO, a specific inhibitor of active caspase-3, was also evaluated. Cell apoptosis was assessed by the terminal deoxynucleotidyl transferase (TdT)-mediated dUTP nick-end labelling method. RESULTS: After 48 h of culture, the percentage of mononuclear cells expressing the active form of caspase-3 was greater in patients dialysed with cellulosic membranes than in patients using non-cellulosic membranes and in healthy subjects. This increase in caspase-3 activity was associated with a high rate of apoptosis, which was prevented by Ac-DEVD-CHO, an inhibitor of caspase-3 activity. LPS decreased both apoptosis and caspase-3 activity in mononuclear cells from patients dialysed with cellulosic membranes. Finally, in cells from healthy subjects, both caspase-3 activation and apoptosis were induced after incubation with cellulosic membranes. In contrast, the active form of caspase-3 was not increased in cells cultured with non-cellulosic membranes and was significantly lower than with cellulosic membranes. CONCLUSION: These findings suggest that the apoptosis of mononuclear cells induced by cellulosic haemodialysis membranes occurs through a pathway that is similar to the spontaneous apoptosis of normal monocytes. They additionally suggest that LPS regulates the proteolytic activation of caspase-3.

Adult↗
PubMed2000

Effect of uremia and dialysis modality on mononuclear cell apoptosis.

The aim of this study was to evaluate the effect of both uremia itself and hemodialysis (HD) membranes on the induction of apoptosis. Four groups of subjects were evaluated: 21 nondialyzed (Non-D) patients, 10 continuous ambulatory peritoneal dialysis (CAPD) patients, and 53 HD patients who were on hemophan, cuprophan, cellulose acetate, AN69, and polysulfone; control subjects were nine healthy volunteers. Circulating mononuclear cells were obtained before dialysis and cultured for 48 h. Mean percentage of apoptosis was analyzed by a FACScan flow cytometer using Annexin V-FITC. Cell apoptosis was increased in Non-D patients (11.5 +/- 5.5%) compared with control subjects (2.1 +/- 0.7%, P < 0.001) and CAPD patients (7. 0 +/- 5.8%, P < 0.05). In patients on HD with cuprophan, apoptosis was higher than in control subjects and Non-D and CAPD patients. In Non-D patients, apoptosis was inversely correlated with renal creatinine clearance (r = -0.62, P = 0.003). Cell apoptosis was higher in hemophan than the other HD membranes. In seven patients on hemophan, switching to polysulfone resulted in decreased apoptosis (P < 0.01). Mononuclear cell circulation through mini-dialyzers made of different types of membranes (cuprophan, hemophan, cellulose acetate, AN69, and polysulfone) prouced a significant increase in apoptosis. However, there was a marked difference in the percentage of apoptosis induced by these five membranes, being significantly increased in hemophan and cuprohan compared with the other three membranes. Similar results were obtained when whole blood from healthy donors was circulated through the mini-dialyzers, showing that mononuclear cell apoptosis was increased in hemophan and cuprophan compared with polysulfone. In conclusion, uremia and membrane characteristics may independently affect the mononuclear cell apoptosis.

Adult↗