Tissue distribution of a feline AGP related protein (AGPrP) in cats with feline infectious peritonitis (FIP)

Alpha-1-acid glycoprotein (AGP) is an acute-phase protein important in the immune response. It has been shown that AGP levels increase in cats with FIP, but also that some cats resistant to FIP may have transient increases in AGP. During the course of studying AGP, the researchers identified a similar protein called AGPrP. Cats with FIP appear to have decreased levels of AGPrP. It may be that AGPrP plays some role in susceptibility or resistance to FIP. As an acute-phase protein, AGPrP is found distributed throughout various tissues of healthy cats. AGPrP has also been demonstrated in the tissues of cats with FIP, including within the typical granuloma lesions. However, no correlation was seen between AGPrP presence and coronavirus. Further work remains to be done to characterize AGPrP and its role in FIP

CD40/SCD40 imbalance in hemodialysis patients.

We read with great interest the paper by Pawlak et al. [1] recently published in Clinical Biochemistry. The authors demonstrated that the serum levels of soluble CD40 (sCD40), a natural antagonist of CD40/CD40L system, are high in patients on hemodialysis (HD) and are strictly related to renal residual function (RRF). Elevated sCD40 serum levels have been reported in the clinical setting of chronic kidney disease, peritoneal dialysis, and HD and have been related to the deficient response to hepatitis B vaccination found in those patients [2] and [3]. In addition, it has been recently described that, in HD patients, the reduction of sCD40 levels by a treatment with a high permeability dialytic membrane is associated to a significant increase of anti-HBs antibody titer [4]. Therefore, a role for sCD40 in uremic immunodeficiency has been hypothesized and it is currently under investigation. In order to evaluate the CD40/sCD40 balance in HD patients, we performed an observational study comparing CD40 B-cell membrane expression and sCD40 serum levels among HD patients, uremic patients not on HD (UR) and, also, healthy subjects (HS). Fourteen stable patients (mean ± SD; age, 65.1 ± 13.6 years) on regular thrice-weekly bicarbonate HD for at least 6 months were enrolled. Patients affected by conditions influencing the immune response, such as acute infections, active immunological diseases, immunosuppressive therapy, previous transplantation, or history of malignancies, were excluded from the study. Control samples were taken from 7 UR (age, 68.8 ± 8.5 years) and 8 HS (age, 47.9 ± 11.5 years). Blood samples were collected before HD treatment. sCD40 serum levels were measured by an enzyme-linked immunosorbent assay (Bender MedSystems). CD40+ B lymphocytes were defined by CD20 and CD40 cell membrane co-expression, analyzed by flow cytometry using anti-CD20 and anti-CD40 mAbs (BD Biosciences). Demographic factors, RRF, and dialytic adequacy, evaluated by a single-pool urea kinetic model (spKt/V) and Charlson comorbidity index (CI), were recorded. Glomerular filtration rate was estimated by the Modification of Diet in Renal Disease (MDRD) formula (eGFR) [5]. sCD40 serum levels resulted significantly higher in HD than in HS and UR (Table 1). In the group of patients undergoing HD, serum sCD40 concentrations were significantly higher in anuric patients (N = 5) compared to those with RRF (N = 9) (1392.3 ± 633.3 vs. 507.9 ± 290.5, P < 0.05, respectively), whereas they did not correlate with spKt/V and CI. Similarly, in UR patients, serum sCD40 levels were indirectly correlated with eGFR (UR eGFR = 16.5 ± 6.6 mL/min; r2 = 0.93; P = 0.03). Moreover, CD40 B-cell membrane expression was also impaired in UR and HD patients, who presented a significantly lower number of CD20+CD40+ cells, expressed as both absolute number and percentage of total lymphocytes, compared to HS (Table 1). Our data confirm and further reinforce Pawlak's findings, highlighting the fact that uremic patients show an imbalance in the CD40 co-stimulatory pathway. In particular, HD patients present a modified CD40/sCD40 pattern with a lower number of CD40+ B-cells associated to higher sCD40 serum levels, when compared to HS. The clinical impact of this imbalance is still unknown, but it could well explain those humoral and cellular immune dysfunctions described in uremic patients [6] and [7]. The loss of renal function plays a key role in this CD40/sCD40 imbalance, as proven by the relationship between sCD40 serum levels and renal function in both UR and HD patients. However, the influence of other factors, such as biocompatibility of dialytic devices and inflammatory state, cannot be ruled out and should be investigated in larger, specifically designed studies

CD40/SCD40 imbalance in hemodialysis patients.

We read with great interest the paper by Pawlak et al. [1] recently published in Clinical Biochemistry. The authors demonstrated that the serum levels of soluble CD40 (sCD40), a natural antagonist of CD40/CD40L system, are high in patients on hemodialysis (HD) and are strictly related to renal residual function (RRF). Elevated sCD40 serum levels have been reported in the clinical setting of chronic kidney disease, peritoneal dialysis, and HD and have been related to the deficient response to hepatitis B vaccination found in those patients [2] and [3]. In addition, it has been recently described that, in HD patients, the reduction of sCD40 levels by a treatment with a high permeability dialytic membrane is associated to a significant increase of anti-HBs antibody titer [4]. Therefore, a role for sCD40 in uremic immunodeficiency has been hypothesized and it is currently under investigation. In order to evaluate the CD40/sCD40 balance in HD patients, we performed an observational study comparing CD40 B-cell membrane expression and sCD40 serum levels among HD patients, uremic patients not on HD (UR) and, also, healthy subjects (HS). Fourteen stable patients (mean ± SD; age, 65.1 ± 13.6 years) on regular thrice-weekly bicarbonate HD for at least 6 months were enrolled. Patients affected by conditions influencing the immune response, such as acute infections, active immunological diseases, immunosuppressive therapy, previous transplantation, or history of malignancies, were excluded from the study. Control samples were taken from 7 UR (age, 68.8 ± 8.5 years) and 8 HS (age, 47.9 ± 11.5 years). Blood samples were collected before HD treatment. sCD40 serum levels were measured by an enzyme-linked immunosorbent assay (Bender MedSystems). CD40+ B lymphocytes were defined by CD20 and CD40 cell membrane co-expression, analyzed by flow cytometry using anti-CD20 and anti-CD40 mAbs (BD Biosciences). Demographic factors, RRF, and dialytic adequacy, evaluated by a single-pool urea kinetic model (spKt/V) and Charlson comorbidity index (CI), were recorded. Glomerular filtration rate was estimated by the Modification of Diet in Renal Disease (MDRD) formula (eGFR) [5]. sCD40 serum levels resulted significantly higher in HD than in HS and UR (Table 1). In the group of patients undergoing HD, serum sCD40 concentrations were significantly higher in anuric patients (N = 5) compared to those with RRF (N = 9) (1392.3 ± 633.3 vs. 507.9 ± 290.5, P < 0.05, respectively), whereas they did not correlate with spKt/V and CI. Similarly, in UR patients, serum sCD40 levels were indirectly correlated with eGFR (UR eGFR = 16.5 ± 6.6 mL/min; r2 = 0.93; P = 0.03). Moreover, CD40 B-cell membrane expression was also impaired in UR and HD patients, who presented a significantly lower number of CD20+CD40+ cells, expressed as both absolute number and percentage of total lymphocytes, compared to HS (Table 1). Our data confirm and further reinforce Pawlak's findings, highlighting the fact that uremic patients show an imbalance in the CD40 co-stimulatory pathway. In particular, HD patients present a modified CD40/sCD40 pattern with a lower number of CD40+ B-cells associated to higher sCD40 serum levels, when compared to HS. The clinical impact of this imbalance is still unknown, but it could well explain those humoral and cellular immune dysfunctions described in uremic patients [6] and [7]. The loss of renal function plays a key role in this CD40/sCD40 imbalance, as proven by the relationship between sCD40 serum levels and renal function in both UR and HD patients. However, the influence of other factors, such as biocompatibility of dialytic devices and inflammatory state, cannot be ruled out and should be investigated in larger, specifically designed studies

Circadian organization of serum electrolytes in physiological aging

Age-related structural and neurochemical changes occurring in the central nervous system have been related to changes in some rhythmometric parameters. In spite of their clinical importance, only a few studies have investigated the modifications over time of serum electrolytes in senescence. The aim of our study was to evaluate the circadian pattern of serum potassium, chloride, sodium, calcium and phosphorus in 30 clinically healthy elderly subjects, with no cognitive impairment, and to compare the findings with those given by 24 healthy young controls. The subjects were synchronized as regards their daily activities, sleeping/waking habits, time/quality of meals and dietary electrolyte intake. After an overnight fast, samples were taken beginning at 08.00 and every 4 h there-after until 20.00, and every 2 h from 20.00 to 04.00. Both the young and the elderly subjects exhibited statistically significant circadian rhythms for all serum electrolytes considered. Our findings suggest that circadian organization of serum electrolytes is maintained in physiological aging, even though it should be noted that sodium and phosphorus acrophases differed significantly in the two experimental groups

Expression patterns in feline blood and tissues of a1-acid glycoprotein (AGP) and of an AGP-related protein (AGPrP)

\u3b11-Acid glycoprotein (AGP) is an acute-phase protein (APP) that modulates immune responses, probably - at least in humans - owing to the modification of its glycosylation pattern. On this perspective, feline AGP can be a useful comparative model, as it has different concentrations in cats susceptible or resistant to some disease. As a preliminary approach to the study of feline AGP (fAGP) we have purified this protein from feline serum by HPLC using human AGP (hAGP) as a model. Immunoblotting with a polyclonal antibody against fAGP and with a monoclonal antibody against hAGP was performed on serum from healthy cats, from cats exposed to feline coronavirus (FCoV) infection and from cats with purulent inflammations, such as feline infectious peritonitis (FIP), feline immunodeficiency virus (FIV) and feline leukemia virus (FeLV). Immunohistochemistry on tissues from healthy cats and from cats with different diseases (FIP, FIV, FeLV, locally extensive inflammation) was also performed with the same antibodies. Both hAGP and fAGP have been purified to homogenity as determined by SDS-PAGE. fAGP did not react with the anti-hAGP antibody which, in contrast, detected in feline serum a low MW protein that we called fAGP-related protein (fAGPrP). This protein was underexpressed in cats with FeLV and FIP. Both fAGP and fAGPrP were immunohistochemically detected in plasma and hepatocytes with a stronger intensity in cats with FIP and some inflammatory conditions. Moreover, fAGPrP was detected in the cytoplasm of tissue cells, most likely identifiable with plasma cells. These cells were rarely detectable in cats with FIV and FeLV, and numerous in cats with FIP and with locally extensive inflammation. In conclusion, purified fAGP has physicochemical characteristics similar to those of hAGP, but does not cross-react with anti-hAGP antibodies. In contrast, the anti-hAGP detected an AGP-related protein whose blood concentration and tissue distribution was not related to that of fAGP. Moreover, both fAGP and fAGPrP were differently expressed in cats with pathologic conditions compared to controls. Further study of these proteins by analysing their structural characteristics is required

Mechanisms underlying sCD40 production in hemodialysis patients.

CD40 and its ligand (CD40L) regulate several cellular functions, including T and B-cell activation. The soluble form of CD40 (sCD40) antagonizes CD40/CD40L interaction. Patients undergoing hemodialysis (HD) present elevated sCD40 serum levels, which underlying molecular mechanisms are unknown. We studied sCD40 serum and urinary levels, CD40 membrane and gene expression and membrane shedding in HD, uremic not-HD patients (UR) and healthy subjects (N). We found that in HD sCD40 serum levels were higher than UR and N, being significantly elevated in anuric patients, and that sCD40 correlated to renal function in UR subjects, who presented also a reduced sCD40 urinary excretion rate. HD and UR presented reduced CD40 membrane and gene expression. The concentration of TNF-α converting enzyme (TACE), responsible for CD40 cleavage was not different between HD and N. Therefore the reduced renal clearance is the main cause of elevated sCD40 levels in HD. This finding could have relevant clinical implications

Mechanisms underlying sCD40 production in hemodialysis patients

CD40 and its ligand (CD40L) regulate several cellular functions, including T and B-cell activation. The soluble form of CD40 (sCD40) antagonizes CD40/CD40L interaction. Patients undergoing hemodialysis (HD) present elevated sCD40 serum levels, which underlying molecular mechanisms are unknown. We studied sCD40 serum and urinary levels, CD40 membrane and gene expression and membrane shedding in HD, uremic not-HD patients (UR) and healthy subjects (N). We found that in HD sCD40 serum levels were higher than UR and N, being significantly elevated in anuric patients, and that sCD40 correlated to renal function in UR subjects, who presented also a reduced sCD40 urinary excretion rate. HD and UR presented reduced CD40 membrane and gene expression. The concentration of TNF-α converting enzyme (TACE), responsible for CD40 cleavage was not different between HD and N. Therefore the reduced renal clearance is the main cause of elevated sCD40 levels in HD. This finding could have relevant clinical implications