Genome-wide association study for resistance in bread wheat (Triticum aestivum L.) to stripe rust (Puccinia striiformis f. sp. tritici) races in Argentina

BACKGROUND

Wheat stripe rust, caused by Puccinia striiformis f. sp. tritici (Pst), is one of the most devastating diseases of the wheat crop. It causes significant reductions in both grain yield and grain quality. In recent years, new and more virulent races have overcome many of the known resistance genes in Argentinian germplasm. In order to identify loci conferring resistance to the local races of Pst for effective utilization in future breeding programs, a genome-wide association study (GWAS) was performed using a collection of 245 bread wheat lines genotyped with 90 K SNPs.

RESULTS

To search for adult plant resistance (APR) the panel was evaluated for disease severity (DS) and area under disease progress curve (AUDPC) in field trials during two years under natural infection conditions. To look for seedling or all-stage resistance (ASR) the panel was evaluated to determine infection type (IT) under greenhouse conditions against two prevalent races in Argentina. The phenotypic data showed that the panel possessed enough genetic variability for searching for sources of resistance to Pst. Significant correlations between years were observed for Pst response in the field and high heritability values were found for DS (H² = 0.89) and AUDPC (H² = 0.93). Based on GWAS, eight markers associated with Pst resistance (FDR < 0.01) were identified, of these, five were associated with ASR (on chromosomes 1B, 2A, 3A and 5B) and three with APR (on chromosomes 3B and 7A). These markers explained between 2% and 32.62% of the phenotypic variation. Five of the markers corresponded with previously reported Yr genes/QTL, while the other three (QYr.Bce.1B.sd.1, QYr.Bce.3A.sd and QYr.Bce.3B.APR.2) might be novel resistance loci.

CONCLUSION

Our results revealed high genetic variation for resistance to Argentinian stripe rust races in the germplasm used here. It constitutes a very promising step towards the improvement of Pst resistance of bread wheat in Argentina. Also, the identification of new resistance loci would represent a substantial advance for diversifying the current set of resistance genes and to advance in the improvement of the durable resistance to the disease.

Reductions in perceived stress following Transcendental Meditation practice are associated with increased brain regional connectivity at rest

Transcendental Meditation (TM) is defined as a mental process of transcending using a silent mantra. Previous work showed that relatively brief period of TM practice leads to decreases in stress and anxiety. However, whether these changes are subserved by specific morpho-functional brain modifications (as observed in other meditation techniques) is still unclear. Using a longitudinal design, we combined psychometric questionnaires, structural and resting-state functional magnetic resonance imaging (RS-fMRI) to investigate the potential brain modifications underlying the psychological effects of TM. The final sample included 19 naïve subjects instructed to complete two daily 20-min TM sessions, and 15 volunteers in the control group. Both groups were evaluated at recruitment (T0) and after 3 months (T1). At T1, only meditators showed a decrease in perceived anxiety and stress (t₍₁₈₎ = 2.53, p = 0.02), which correlated negatively with T1-T0 changes in functional connectivity among posterior cingulate cortex (PCC), precuneus and left superior parietal lobule. Additionally, TM practice was associated with increased connectivity between PCC and right insula, likely reflecting changes in interoceptive awareness. No structural changes were observed in meditators or control subjects. These preliminary findings indicate that beneficial effects of TM may be mediated by functional brain changes that take place after a short practice period of 3 months.

CD4+ T helper cells and regulatory T cells in active lupus nephritis: an imbalance towards a predominant Th1 response?

The objective of this study was to evaluate the frequency of CD4⁺ T cell subsets in peripheral blood mononuclear cells (PBMC), urine and renal tissue from patients with lupus nephritis (LN). PBMC and urinary cells were collected from 17 patients with active LN, 20 disease controls (DC) with primary glomerulonephritis and 10 healthy controls (HC) and were analysed by flow cytometry with markers for T helper type 1 (Th1), Th2, Th17 and regulatory T cells (T_reg ) cells. T cell subsets were assessed by immunohistochemistry from LN biopsy specimens from 12 LN patients. T cell subtypes in PBMC were re-evaluated at 6 months of therapy. CD4⁺ T cells were decreased in PBMC in LN compared with DC and HC (P = 0·0001). No differences were observed in urinary CD4⁺ T cell subsets between LN and DC. The frequency of urinary Th17 cells was higher in patients with non-proliferative than in proliferative LN (P = 0·041). CD3⁺ and T-box 21 ( Tbet+) cells were found in glomeruli and interstitium of LN patients, while forkhead box protein 3 (FoxP3), retinoid-related orphan receptor gamma (ROR-γ) and GATA binding protein 3 (GATA-3) were present only in glomeruli. Th1 cells in PBMC were correlated negatively with urinary Th1 cells (Rho = -0·531; P = 0·028) and with T_bet in renal interstitium (Rho = -0·782; P = 0·004). At 6 months, LN patients showed an increase in Th17 cells in PBMC. In conclusion, the inverse association between Th1 cells from PBMC and urinary/renal tissue indicate a role for Th1 in LN pathophysiology. Urinary Th17 cells were associated with less severe LN, and Th17 increased in PBMC during therapy. Urinary CD4⁺ T cells were not different between LN and DC.

IgA nephropathy in Brazil: apropos of 600 cases

IgA nephropathy (IgAN) is th e commonest primary glomerular disease worldwide. Studies on its prevalence in Brazil are however scarce. Databases and clinical records from 10 reference centres were retrospectively reviewed. Clinical and laboratory features at the moment of the biopsy were retrieved (age, gender, presence of hematuria, serum creatinine [mg/dL], proteinuria [g/24 h]). Renal biopsy findings were classified according to Haas single grade classification scheme and the Oxford Classification of IgAN. 600 cases of IgAN were identified, of which 568 (94.7 %) were on native kidneys. Male to female ratio was 1.24:1. Patients averaged 32.76 ± 15.12 years old (range 4–89, median 32). Proteinuria and hematuria were observed, respectively in 56.63 and 72.29 % of patients. The association of both these findings occurred in 37.95 % of the cases. Serum creatinine averaged 1.65 ± 0.67 mg/dL (median 1.5 mg/dL) at diagnosis. Segmental sclerosis and mesangial hypercellularity were the main glomerular findings (47.6 and 46.2 %) The commonest combination by Oxford Classification of IgAN, was M0 E0 S0 T0 (22.4 %). Chronic tubulo-interstitial lesions with an extension wider than 25 % of the renal cortex could be identified in 32.2 % of the cases. Tubular atrophy and interstitial fibrosis were more strongly associated with higher 24-h proteinuria and serum creatinine levels. Segmental sclerosis (S1) showed a stronger tendency of association with the presence of tubulo-interstitial lesions (T1 and T2) than other glomerular variables. To the best of our knowledge this is the largest series of IgAN in Brazil. It depicts the main biopsy findings and their possible clinical correlates. Our set of data is comparable to previous reports.

Glomerular damage as a predictor of renal allograft loss

Interstitial fibrosis and tubular atrophy (IF/TA) are the most common cause of renal graft failure. Chronic transplant glomerulopathy (CTG) is present in approximately 1.5-3.0% of all renal grafts. We retrospectively studied the contribution of CTG and recurrent post-transplant glomerulopathies (RGN) to graft loss. We analyzed 123 patients with chronic renal allograft dysfunction and divided them into three groups: CTG (N = 37), RGN (N = 21), and IF/TA (N = 65). Demographic data were analyzed and the variables related to graft function identified by statistical methods. CTG had a significantly lower allograft survival than IF/TA. In a multivariate analysis, protective factors for allograft outcomes were: use of angiotensin-converting enzyme inhibitor (ACEI; hazard ratio (HR) = 0.12, P = 0.001), mycophenolate mofetil (MMF; HR = 0.17, P = 0.026), hepatitis C virus (HR = 7.29, P = 0.003), delayed graft function (HR = 5.32, P = 0.016), serum creatinine > or =1.5 mg/dL at the 1st year post-transplant (HR = 0.20, P = 0.011), and proteinuria > or =0.5 g/24 h at the 1st year post-transplant (HR = 0.14, P = 0.004). The presence of glomerular damage is a risk factor for allograft loss (HR = 4.55, P = 0.015). The presence of some degree of chronic glomerular damage in addition to the diagnosis of IF/TA was the most important risk factor associated with allograft loss since it could indicate chronic active antibody-mediated rejection. ACEI and MMF were associated with better outcomes, indicating that they might improve graft survival.

Synergistic effect of mycophenolate mofetil and angiotensin-converting enzyme inhibitor in patients with chronic allograft nephropathy

Experimental data and few clinical non-randomized studies have shown that inhibition of the renin-angiotensin system by angiotensin-converting enzyme (ACE) associated or not with the use of mycophenolate mofetil (MMF) could delay or even halt the progression of chronic allograft nephropathy (CAN). In this retrospective historical study, we investigated whether ACE inhibition (ACEI) associated or not with the use of MMF has the same effect in humans as in experimental studies and what factors are associated with a clinical response. A total of 160 transplant patients with biopsy-proven CAN were enrolled. Eighty-one of them were on ACE therapy (G1) and 80 on ACEI_free therapy (G2). Patients were further stratified for the use of MMF. G1 patients showed a marked decrease in proteinuria and stabilized serum creatinine with time. Five-year graft survival after CAN diagnosis was more frequent in G1 (86.9 vs 67.7%; P < 0.05). In patients on ACEI-free therapy, the use of MMF was associated with better graft survival. The use of ACEI therapy protected 79% of the patients against graft loss (OR = 0.079, 95%CI = 0.015-0.426; P = 0.003). ACEI and MMF or the use of MMF alone after CAN diagnosis conferred protection against graft loss. This finding is well correlated with experimental studies in which ACEI and MMF interrupt the progression of chronic allograft dysfunction and injury. The use of ACEI alone or in combination with MMF significantly reduced proteinuria and stabilized serum creatinine, consequently improving renal allograft survival.

Improved renal function after kidney transplantation is associated with heme oxygenase-1 polymorphism

Heme oxygenase-1 (HO-1) has a microsatellite polymorphism based on the number of guanosine-thymidine nucleotide repeats (GT) repeats that regulates expression levels and could have an impact on organ survival post-injury. We correlated HO-1 polymorphism with renal graft function. The HO-1 gene was sequenced (N = 181), and the allelic repeats were divided into subclasses: short repeats (S) (<27 repeats) and long repeats (L) (>/=27 repeats). A total of 47.5% of the donors carried the S allele. The allograft function was statistically improved six months, two and three yr after transplantation in patients receiving kidneys from donors with an S allele. For the recipients carrying the S allele (50.3%), the allograft function was also better throughout the follow-up, but reached statistical significance only three yr after transplantation (p = 0.04). Considering only those patients who had chronic allograft nephropathy (CAN; 74 of 181), allograft function was also better in donors and in recipients carrying the S allele, two and three yr after transplantation (p = 0.03). Recipients of kidney transplantation from donors carrying the S allele presented better function even in the presence of CAN.

Contribution of CD4+ T cells to the early mechanisms of ischemia- reperfusion injury in a mouse model of acute renal failure

Renal ischemia-reperfusion (IR) injury is the major cause of acute renal failure in native and transplanted kidneys. Mononuclear leukocytes have been reported in renal tissue as part of the innate and adaptive responses triggered by IR. We investigated the participation of CD4+ T lymphocytes in the pathogenesis of renal IR injury. Male mice (C57BL/6, 8 to 12 weeks old) were submitted to 45 min of ischemia by renal pedicle clamping followed by reperfusion. We evaluated the role of CD4+ T cells using a monoclonal depleting antibody against CD4 (GK1.5, 50 micro, ip), and class II-major histocompatibility complex molecule knockout mice. Both CD4-depleted groups showed a marked improvement in renal function compared to the ischemic group, despite the fact that GK1.5 mAb treatment promoted a profound CD4 depletion (to less than 5% compared to normal controls) only within the first 24 h after IR. CD4-depleted groups presented a significant improvement in 5-day survival (84 vs 80 vs 39%; antibody treated, knockout mice and non-depleted groups, respectively) and also a significant reduction in the tubular necrosis area with an early tubular regeneration pattern. The peak of CD4-positive cell infiltration occurred on day 2, coinciding with the high expression of betaC mRNA and increased urea levels. CD4 depletion did not alter the CD11b infiltrate or the IFN-gamma and granzyme-B mRNA expression in renal tissue. These data indicate that a CD4+ subset of T lymphocytes may be implicated as key mediators of very early inflammatory responses after renal IR injury and that targeting CD4+ T lymphocytes may yield novel therapies.

Exploratory calcineurin inhibitor-free regimens in living-related kidney transplant recipients

Chronic allograft nephropathy is among the major causes of graft loss even in low-risk kidney transplant recipients and correlates with acute nephrotoxic events during the first year post-transplant. Therefore, calcineurin inhibitor-free regimens may improve patient and graft survival among recipients of living-related kidney transplants. To confirm this hypothesis, we evaluated the efficacy and safety of two calcineurin inhibitor-free regimens in 92 low-risk recipients of one-haplotype living-related kidney transplants. Immunosuppression consisted of tacrolimus, azathioprine and prednisone (group I, GI, N = 38), 2 doses of daclizumab, mycophenolate mofetil (MMF), and prednisone (GII, N = 33) and 2 doses of daclizumab, MMF, sirolimus and prednisone (GIII, N = 21). At 12 months, treatment failure (biopsy-confirmed acute rejection, graft loss or death) was higher in GII compared to GIII and GI (54.5 vs 24.0 vs 13.1%, P < 0.01, respectively). In patients of black ethnicity the incidence of acute rejection was 25 vs 83.3 vs 20% (P = 0.055), respectively. Patient and graft survival was comparable. There were no differences in mean creatinine or calculated creatinine clearance at 12 months. Overall incidence of post-transplant diabetes mellitus (3.3%) and cytomegalovirus disease (4.3%) was similar in all groups. Further development of effective calcineurin inhibitor-free regimens should exclude patients of black ethnicity and may need full-induction therapy, perhaps with depleting agents, and concentration-controlled use of sirolimus and MMF.

Impact of Therapeutic Changes on Renal Graft Survival With Posttransplant Glomerulonephritis

INTRODUCTION

Posttransplant glomerulonephritis (GN) is the third cause of graft loss after 1 year of transplant follow-up; few approaches have been efficient in reversing this outcome. The aim of this study was to evaluate whether the modification of the immunosuppressive therapy for treating posttransplant GN had an impact on allograft survival.

PATIENTS AND METHODS

Forty-nine patients who underwent renal transplantation and developed posttransplant GN were divided into two groups: group 1, 22 patients with modified immunosuppressive treatment (72.3%, pulse of methylprednisolone; 13.6%, high-dose oral corticosteroid), and group 2, where it was maintained. Additionally, the impact of the concomitant use of drugs that promote the renin-angiotensin-aldosterone system blockade (RAASB) was analyzed in terms of graft survival.

RESULTS

We established the diagnosis of GN at 17.9 months (range, 0.57 to 153.4) after transplantation, when serum creatinine (Cr) was 2.2 mg/dL (range, 0.8 to 12.5) and proteinuria 3.2 g/L (range, 0.2 to 24.2). Graft survivals at 1 and 3 years after diagnosis were 69.2% and 52.9%, respectively. The patients of group 1 showed a lower prevalence of graft loss (27.2% versus 48.1%, P = .40) and better survival at the end of 1 year (73.2% versus 60.4%) and 3 years (62.5% versus 38.0%, P = .26), but the differences were not significant. RAASB showed a positive impact on survival at the end of 3 years in both groups: for group 1, 83.8% with RAASB, 41.4% without RAASB; and for group 2, 75% with RAASB and 14.8% without RAASB (P < .001).

CONCLUSION

Although treatment of posttransplant GN with modification of immunosuppression seemed to improve graft survival in the first 3 years after diagnosis, RAASB improved this effect.

Conversion from azathioprine to mycophenolate mofetil followed by calcineurin inhibitor minimization or elimination in patients with chronic allograft dysfunction

The purpose of this study was to evaluate the effects of the conversion from azathioprine (AZA) to mycophenolate mofetil (MMF) followed by calcineurin inhibitor (CNI) elimination or minimization in patients with progressive chronic allograft dysfunction (CAD).

METHODS

Between November 6, 1999 and February 12, 2003, 169 patients receiving CNI/AZA/prednisone (153 CsA; 14 tacrolimus) were included in this study. Demographics, immunosuppression, graft function, hematology, and biochemistry were obtained before (-6, -3, and -1 month) and 1, 3, 6, 9 and 12 months after and at last follow-up visit after conversion.

RESULTS

Mean age was 34 +/- 12 years, 66% males, 51% Caucasian, and 72% living allograft recipients. Mean follow-up times before and after conversion were 32.4 and 19.4 months; 10 patients completed 3 years of follow-up. CNI elimination was performed in 39% and minimization in 61% of patients. Overall there was significantly improved graft function at 1 year after conversion (2.6 +/- 1.0 vs 2.1 +/- 0.6 mg/dL, P = .038). The slopes of the regression lines of 1/Cr vs time were significantly improved from preconversion to after conversion (-0.026 vs +0.007 mg(-1)/dL per day(-1), P = .001). There was a significant decrease in mean systolic (141 +/- 21 vs 135 +/- 22 mm Hg, P = .015) and diastolic (89 +/- 15 vs 84 +/- 14 mm Hg, P = .005) blood pressure values at 1 year. There were four episodes of acute rejection (Banff IA) treated with steroids. Three years after conversion, patient and graft survivals were 95% and 79%, respectively. One patient developed posttransplant lymphoproliferative disease.

CONCLUSION

Among patients with CAD, conversion from AZA to MMF followed by CNI minimization or elimination was a safe and effective strategy to preserve or improve graft function.

Beneficial effect of N-acetyl-cysteine on renal injury triggered by ischemia and reperfusion

Reactive oxygen species are critical mediators of the early phase of ischemic (IR) injury. The contribution of antioxidants, such as N-acetyl-cysteine (NAC), in ameliorating the parenchymal lesions, inflammatory parameters, and functional variables in renal IR is still controversial. We studied the effect of NAC administration on renal injury induced by IR. Mice were subjected to renal pedicle occlusion and subsequent reperfusion for 24 or 120 hours. NAC was administered prior to surgery at two concentrations (40 or 300 mg/kg, i.p.). Renal function and acute tubular necrosis were assessed, as well as immune phenotyping of infiltrating cells, by flow cytometry. At 40 mg/dL of NAC, we did not observe any significant improvement in renal function (1.85 +/- 0.43 md/dL, P = .367) or tissue architecture (% of ATN: 2.51 +/- 0.27 mm, P = .852) compared to the controls (1.87 +/- 0.43 mg/dL and 3.12 +/- 0.34 mm, respectively). However, animals that received 300 mg/dL of NAC showed lower serum creatinine values (24 hours: 1.25 +/- 0.54 mg/dL) compared to controls (P = .009) and less extensive acute tubular necrosis (1.54 +/- 0.12 vs, P < .05). Treatment with 300 mg/dL of NAC decreased renal dendritic cell infiltration. The protective effect of NAC was better observed at high concentrations and early times.

Synthesis and immunological activity of a branched peptide carrying the T-cell epitope of gp43, the major exocellular antigen of Paracoccidioides brasiliensis

The 43 kDa glycoprotein (gp43) of Paracoccidioides brasiliensis is the major diagnostic antigen of paracoccidioidomycosis (PCM), a prevalent fungal infection in South America. A 15-mer sequence from gp43, denominated P10, induced T-CD4+ T helper 1 cellular immune responses in mice of three different haplotypes and protected against intratracheal challenge by a virulent isolate of P. brasiliensis. In an attempt to improve delivery of P10, a promiscuous antigen also presented by human leucocyte antigen-DR alleles, aiming at immunotherapy, we synthesized a multiple antigen peptide with the protective T-cell epitope expressed in a tetravalent 13-mer analog of P10 (M10). M10 induced specific lymph node cell proliferation in mice preimmunized with peptides in complete Freund's adjuvant (CFA). In addition, M10 immunization without CFA significantly protected intratracheally infected mice. We conclude that M10 is a candidate for an anti-PCM vaccine. In this report we describe: (1) the synthesis of M10; (2) the induction of M10-elicited T-cell response and (3) in vivo protection of mice immunized with M10 and challenged by a virulent strain of P. brasiliensis.

Effect of antibodies to intercellular adhesion molecule type 1 on the protection of distant organs during reperfusion syndrome in rats

We investigated kidney and lung alterations caused by intercellular adhesion molecule type 1 (ICAM-1) blockade after ischemia and reperfusion of hind limb skeletal muscles. Rats were submitted to ligature of the infrarenal aorta for 6 h. The animals were randomized into three groups of 6 rats each: group I, sacrificed after ischemia; group II, reperfusion for 24 h, and group III, reperfusion for 24 h after receiving monoclonal anti-ICAM-1 antibodies. At the end of the experiment, blood samples were collected for creatinine, lactate dehydrogenase, creatine phosphokinase, potassium, pH and leukocyte counts. Samples were taken from the muscles of the hind limbs and from the kidneys and lungs for histological analysis and measurement of the neutrophil infiltrate by myeloperoxidase staining. The groups did not differ significantly with regard to the laboratory tests. There were no major histological alterations in the kidneys. An intense neutrophil infiltrate in the lungs, similar in all groups, was detected. Myeloperoxidase determination showed that after reperfusion there was significantly less retention of polymorphonuclear neutrophils in the muscles (352 +/- 70 vs 1451 +/- 235 x 10(2) neutrophils/mg; P<0.01) and in the kidneys (526 +/- 89 vs 852 +/- 73 10(2) neutrophils/mg; P<0.01) of the animals that received anti-ICAM-1 before perfusion compared to the group that did not. The use of anti-ICAM-1 antibodies in this experimental model minimized neutrophil influx, thus reducing the inflammatory process, in the muscles and kidneys after ischemia and reperfusion of the hind limbs.

Abnormal Expression of MDM2 in Prostate Carcinoma

Mutation of p53 is rare in localized prostate carcinoma. The oncoprotein MDM2, whose gene has a response element for p53, promotes the degradation of p53 protein and inhibits its transcriptional activation of genes related to cell cycle arrest and apoptosis, constituting a negative feedback control. We studied p53 and MDM2 expression by immunohistochemistry and looked for mutations in p53 exons 5 to 8 by polymerase chain reaction-single strand conformational polymorphism in 118 patients submitted to radical prostatectomy for localized prostate cancer. In 28 cases, we studied cell proliferation by immunohistochemistry, using antibody for Ki-67, and apoptosis by the deoxynucleotidyl transferase mediated dUTP biotin nick end labeling technique. Although no p53 mutations were found, p53 protein was detected in 31.4% of the cases, and these cases had higher Gleason scores (P = .03) and more advanced tumor stages (P = .02). MDM2 was overexpressed in 40.7% of the cases, and these cases had greater tumor volumes (P = .001). Tumors that were positive for both p53 and MDM2 were larger (P = .003) and of more advanced stage (P = .03). Within the 28-case subset, the proliferative index was higher among MDM2-positive tumors (P = .046), and the apoptotic index was lower among p53-positive tumors (P = .01). We conclude that, although p53 mutation is a rare event in prostate carcinogenesis, the detection of p53 protein by immunohistochemistry is common and is associated with decreased apoptosis and increased histologic grade and tumor stage. We also conclude that the overexpression of MDM2 has a role in prostate carcinogenesis, being frequently detected and associated with increased cell proliferation and tumor volume. Finally, we propose that the MDM2-positive/p53-positive phenotype identifies prostate cancers with aggressive behavior.

DNA-based vaccination against murine paracoccidioidomycosis using the gp43 gene from paracoccidioides brasiliensis

Gp43, the major 43-kDa antigenic glycoprotein of Paracoccidioides brasiliensis, or its 15-amino acid inner peptide (P10), induces a T-CD4(+), Th1 cellular immune response which protects BALB/c mice from intratracheal infection by virulent yeast forms. We investigated whether DNA vaccination using the gp43 gene could elicit protective immunity against P. brasiliensis. Animals immunised intramuscularly (i.m.) or intradermally (i.d.) with plasmid DNA containing the gp43 gene induced a specific, long lasting humoral and cellular immune response. A mixed Th1/Th2 cellular immune response in DNA-immunized mice was modulated in vivo by IFN-gamma and was protective in BALB/c mice. A significant decrease in the lung colony forming units (CFUs) and reduced, or no dissemination to the spleen and liver of immunised mice were observed.

Influence of cholecalciferol (vitamin D3) on the course of experimental systemic lupus erythematosus in F1 (NZBxW) mice

The course of systemic lupus erythematosus (SLE), an autoimmune disease, is markedly affected by hormones such as estrogen and prolactin. It is well known that heavy exposure to sunlight has deleterious effects on SLE, triggering episodes of the disease. Classical explanations for this occurrence suggest that UV radiation damages DNA, which becomes immunogenic, or induces exposure of the Ro antigen in keratinocytes. In recent years, it has been shown that vitamin D3 has important effects on the immune system. Thus, we proposed an alternative hypothesis, suggesting that UV radiation, by promoting vitamin D3 synthesis, could be a factor aggravating the course of SLE after exposure to sunlight. To test this hypothesis, we injected F1(NZBxW) mice, which are prone to developing SLE, with vitamin D3, and we demonstrated a worsening of the histopathological findings in the kidney.

Laminin-binding epitope on gp43 from Paracoccidioides brasiliensis is recognized by a monoclonal antibody raised against Staphylococcus aureus laminin receptor

Adhesion is regarded as an important step in the pathogenesis of several microorganisms. Thus, the ability to recognize extracellular matrix proteins, such as laminin or fibronectin, has been correlated with invasiveness. Studying the already characterized laminin-binding protein of Paracoccidioides brasiliensis, the 43 kDa glycoprotein (gp43), we evaluated whether MAb 1.H12, raised against the laminin-binding protein from Staphylococcus aureus, cross-reacts with that fungal protein. By immunoblot analysis we show that MAb 1.H12 recognizes gp43. This interaction is able to inhibit the laminin-mediated adhesion to epithelial cells as well as the P. brasiliensis infection in vivo. Moreover, through immunoenzymatic assays, we show that MAb 1.H12 recognizes gp43 in solid phase and that this interaction is partially inhibited by the addition of anti-gp43 MAbs. These results show that MAb 1.H12 recognizes the gp43, suggesting the presence of an epitope similar to those found in the other laminin-binding proteins from phylogenetically very distant cells. These findings reinforce the possibility of evolutionary conservation of such epitopes.

Monoclonal antibodies against the 43,000 Da glycoprotein from Paracoccidioides brasiliensis modulate laminin-mediated fungal adhesion to epithelial cells and pathogenesis

The surface glycoprotein gp43, a highly immunogenic component of Paracoccidioides brasiliensis, is used in the serodiagnosis of paracoccidioidomycosis (PCM) and has recently been shown to specifically bind the extracellular matrix protein laminin. Binding to laminin induces the increased adhesion of the fungus to epithelial cells; a hamster testicle infection model has shown that the gp43-dependent binding of fungal cells to laminin enhances their pathogenicity in vivo. We report on the production and characterization of 12 monoclonal antibodies against the gp43 that recognize peptide sequences in the molecule detecting at least three different epitopes as well as different isoforms of this antigen. MAbs interfered in the fungal pathogenicity in vivo either by inhibiting or enhancing granuloma formation and tissue destruction. Results suggest that P. brasiliensis propagules may start infection in man by strongly adhering to human lung cells. Thus, laminin-mediated fungal adhesion to human lung carcinoma (A549) cells was much more intense than to Madin-Darby canine kidney cells (MDCK), indicating differences in binding affinity. Subsequent growth of fungi bound to the lung cells could induce the granulomatous inflammatory reaction characteristic of PCM. Both steps are greatly stimulated by laminin binding in infective cells expressing gp43.

Paracoccidioides brasiliensis-gp43 used as paracoccidioidin

A purified glycoprotein of 43,000 daltons from Paracoccidioides brasiliensis (gp43) was tested as paracoccidioidin in delayed-type hypersensitivity (DTH) tests in both experimental animals (guinea pig and mice) and patients with paracoccidioidomycosis (PCM). The gp43 paracoccidioidin was compared with the traditional Fava Netto antigen (AgFN). In guinea pigs, the intradermal injection of 2 micrograms of gp43 showed a similar response to those obtained with AgFN, showing in histological sections a population of lymphoid cells that participate in DTH. In mice, gp43 at a dose of 3.75 micrograms showed positive DTH response. The use of gp43 as paracoccidioidin in humans showed that this molecule can be used to evaluate the DTH response in patients with PCM. Of 25 PCM patients studied, 48% were positive to gp43 while only 28% were positive to AgFN; 12 PCM patients were completely anergic to both antigens. Considering only those 13 PCM patients who were responsive to gp43 and/or to AgFN, 92.3% reacted against gp43 and 53.8% reacted against AgFN (P < 0.05). Gp43 skin test responses (13.67 +/- 9.56 mm) were significantly larger than those obtained with AgFN (8.43 +/- 3.69 mm). Immunohistochemical study of the human skin showed a perivascular inflammatory response constituted predominantly by T lymphocytes, macrophages and polymorphonuclear leukocytes.

Binding of Paracoccidioides brasiliensis to laminin through surface glycoprotein gp43 leads to enhancement of fungal pathogenesis

Extracellular matrix protein laminin binds specifically to yeast forms of Paracoccidioides brasiliensis and enhances adhesion of the fungus to the surface of epithelial Madin-Darby canine kidney cells in vitro. Immunoblotting of fungal extracts showed that the gp43 glycoprotein is responsible for adhesion. This was confirmed by binding assays using purified gp43, with a Kd of 3.7 nM. The coating of P. brasiliensis yeast forms with laminin before injection into hamster testicles enhanced the fungus virulence, resulting in a faster and more severe granulomatous disease. These results indicate that interaction of fungi with extracellular matrix elements may constitute a basis for the evolution of fungal infection toward regional spreading and dissemination.

Toxic dilatation of the colon in Chagas' disease

Toxic megacolon occurs in colitis of differing aetiology. This report describes 15 patients with chagasic megacolon with this complication. The clinical signs and symptoms in all patients were pain and progressive abdominal distension accompanied by fever, severe toxaemia and shock. Seven patients developed this clinical pattern after manual removal of faeces. The remaining patients had pain and abdominal distension followed by signs of severe toxaemia when first examined. Nine patients underwent total colectomy with ileostomy (one death), four partial colectomy (all died) and two received medical treatment (both died). At autopsy, three of the four patients undergoing partial colectomy had residual colitis and enteritis. The surgical procedure of choice for this complication of chagasic megacolon is total colectomy.

Pulmonary paracoccidioidomycosis in immunized mice

Paracoccidioidomycosis was induced in immunized (IM) and non-immunized (NI) mice. The histopathology, the number of fungi in the lungs, the cellular (footpad test--FPT and macrophage inhibition factor assay--MIF) and humoral (immunodiffusion test) immune response were investigated serially post-infection. In the IM mice, at days 1 and 3, there was intense and predominant macrophagic-lymphocytic alveolitis with loose granulomatous reaction; at day 30, inflammation was mild. In the NI group, up to day 3, the lesions were focal; later there was formation of extensive epithelioid granuloma. The number of fungi in IM mice were always smaller than those of NI group. Immunization alone induced positive FPT and MIF indices with low titer of antibody. After infection, there was a significant decrease of the FPT indices in the IM group, which we interpreted as desensitization due to trapping of sensitized lymphocytes in the lungs. In conclusion, (1) The lesional pattern of pulmonary paracoccidioidomycosis in IM mice was similar to that of a hypersensitivity pneumonitis. This reaction was probably effective in reducing the extension of the infection and decrease the number of fungi. (2) In this model, pulmonary resistance against P. brasiliensis seems to be related to local and systemic delayed-type hypersensitivity reaction.

Protective effect of prior immunization on ocular paracoccidioidomycosis in guinea pigs

The present study reproduced the experimental model of ocular paracoccidioidomycosis in guinea pigs, by the intracardiac inoculation of yeast-forms of P. brasiliensis. Ocular involvement was observed in 80% of the infected animals. The uvea, ciliary body, choroid, iris, lids and the conjunctiva were the structures most commonly affected. To protect the animals against the infection, an immunization protocol was standardized utilizing a P. brasiliensis soluble antigen in Freund's complete adjuvant, administered weekly, during 3 weeks, by the subcutaneous route. Two weeks later, previously immunized guinea pigs were challenged by the intracardiac route with yeast-forms of P. brasiliensis (vaccinated group). When compared with a control group (infection in the absence of prior immunization), the vaccinated animals developed higher levels of anti-P. brasiliensis cellular and humoral immune response and a three times lower frequency of ocular involvement (85.7% vs 28.5%). In addition, the ocular lesions were significantly more localized and contained less fungal cells. The data demonstrated that the subcutaneous immunization was effective in decreasing the frequency and extent of ocular lesions, as well as in blocking fungal multiplication.

A comparative study of the immunoantigenicity of eight Paracoccidioides brasiliensis isolates

Para se detectar diferenças imuno-antigênicas entre 8 amostras de P. brasiliensis isoladas de diferentes áreas endêmicas (Botucatu: Pb 1, 2 e 3; São Paulo: Pb: 18, 192 e 265; Venezuela: Pb 9 e 73), esutdaram-se: 1. A reatividade antigênica de cada amostra nas reações de imunofluorescência indireta (II) e de imunodifusão dupla em gel de agar (ID) contra painel de 20 soros controles positivos para paracoccidioidomicose; 2. A capacidade de induzir resposta imune humoral (medida por imunodifusão) e celular (medida pelo teste de coxim plantar) em camundongos imunizados com an-tígenos de cada amostra. Observamos: 1. As amostras Pb 265 e Pb 9 mostraram-se mais reativas na II; 2. Os antígenos das amostras Pb 192 e Pb 73 foram significativamente mais reativas na ID; 3. Estes dados demonstram diferenças de antigenicidade entre estas amostras; 4. A amostra Pb 18 mostrou baixo poder indutor de resposta imune celular e alta capacidade de indução de resposta imune humoral em camundongos imunizados, revelando dissociação de sua imunogenicidade. Estas diferenças podem indicar a existência de cepas distintas do fungo ou refletir modificações do parasita no hospedeiro ou du rante seu cultivo.

Paracoccidioidomycosis: a comparative study of the evolutionary serologic, clinical and radiologic results for patients treated with ketoconazole or amphotericin B plus sulfonamides

A comparative study of two groups of patients with paracoccidioidomycosis was carried out with the objective of comparing the evolutionary serologic, clinical and radiologic results after 6, 12, 15 and 18 months of treatment with ketoconazole (22 patients) or amphotericin B plus sulfonamides (32 patients). The serologic data analyzed as a whole showed a tendency to sharper drops in antibody titers in the patients treated with ketoconazole. Clinically patients treated with ketoconazole fared better but the differences were not statistically significant. No statistical difference was detected between groups in terms of the results of radiologic evolution.

Correlation between cell-mediated immunity and clinical forms of paracoccidioidomycosis

Cellular immune response to specific and non-specific stimulants was investigated, both in vivo and in vitro, in 29 healthy controls and in 53 previously untreated patients with the chronic isolated organic form (CIOF), the chronic mixed form (CMF) and the acute progressive form (APF) of paracoccidioidomycosis. The study included skin tests to Paracoccidioides brasiliensis antigen (PbAg) and phytohaemagglutinin (PHA), DNCB sensitization, determination of T lymphocytes and complement rosette-forming cells, lymphocyte transformation and leucocyte migration inhibition tests using PbAg and PHA. Patients displayed staggered cutaneous response to PHA and to PbAg, with marked decrease in intensity in the APF group. DNCB sensitization test and proliferative response of lymphocytes to PHA and PbAg were severely depressed in most of the patients. Leucocyte migration inhibition indices to PbAg were highly positive, while response to PHA was slightly decreased regardless of the clinical form. The number of T lymphocytes was reduced in most of patients and in them the number of complement-rosette forming cells was normal. The distribution of patients according to a suppression index, based in the results of the tests employed, revealed a tendency towards an increased degree of cellular immunosuppression from the least severe (CIOF) to the most severe (APF) clinical form of the disease. On the whole, the present study demonstrated a gamut of immunological reactivity in paracoccidioidomycosis.

Indirect fluorescent test for detection of anti-Paracoccidioides brasiliensis antibodies using coated bentonite particles as antigen

An indirect fluorescent test was developed for detecting antibodies to Paracoccidioides brasiliensis using bentonite particles as antigen (Bent-IF). The bentonite particles were coated with P. brasiliensis polysaccharide antigen and tested with sera from paracoccidioidomycosis patients (36 sera), normal blood donors (32 sera) and patients with non-mycotic diseases (29 sera). The titres given by the positive sera were compared with those of complement fixation (CF), immunodiffusion (ID) and immunofluorescent test using yeast forms of the fungus as antigen (conventional-IF). All normal blood donors' sera gave a negative Bent-IF, conventional-IF, ID and CF tests. All paracoccidioidomycosis sera were reactive in conventional-IF and gave concordant results in Bent-IF. There was no correlation between CF and Bent-IF titres. 27.6% of sera from patients with non-mycotic diseases gave weak titres in both IF-tests. The present data indicate that the Bent-IF is a sensitive and simple serodiagnostic technique comparable with the conventional P. brasiliensis antibody test.

[Retrospective study in hepatic biopsies, of hepatitis B surface antigen by the orcein method and indirect immunofluorescence methods]

A retrospective study of the HBsAg was done in 56 liver biopsies of children less than 12 year-old and 78 biopsies of adults. The study was performed by orcein stain and indirect immunofluorescent method. In 23 of the adults patients, the serological detection of HBsAg and antibodies (HbsAb) was determined by reverse passive haemagglutination technique. The adults patients' histological dianosis were variable and included acute or chronic hepatitis (20.5%) and cirrhosis (24.4%). Orcein was positive in 7 and IFI in 6 cases; 5 biopsies were positive by both methods. The highest incidence of HBsAg was seen in active cirrhosis (75%), including two cases of alcoholic cirrhosis. In the 23 serologically studied patients, 15 cases were HBsAg negative and 3 were HBsAg positive both in the liver and serum; only 2 cases showed discrepancy between these results. Three patients were HBsAb positive and HBsAg negative both in the liver and serum. All children biopsies were HBsAg negative. Among these patients, 26.8% had acute or chronic hepatitis and 10.7% cirrhosis. Serological and tissue techniques for HBsAg and HbsAb detection have different sensitivity. This should be kept in mind when studying the incidence of hepatitis B virus related to liver diseases.

A comparison of the hematogenous cell infiltrate evoked by lymphokine injection with that of delayed hypersensitivity reactions

Lymphokine preparations of high potency obtained by in vitro assay were employed in vivo to determine whether they could produce inflammatory responses showing a cellular infiltrate that qualitatively or quantitatively resembled responses of delayed hypersensitivity. Hematogenous cell infiltrates in guinea pig skin were characterized in terms of the number and types of participating cells following intradermal injection of either lymphokines or an antigen (PPD) to which the animals exhibited delayed hypersensitivity. The dose of lymphokine or PPD per skin test site was selected on the basis of comparable ability to enhance vascular permeability. Delayed hypersensitivity responses showed, as expected, a persistent mononuclear cell exudate both in dermis and subcutis, but most notable in the dermis, during the 24 hours following antigen injection. In contrast, the response to lymphokine over the same period was characteristically neutrophilic and principally in the subcutis. There was no pronounced mononuclear cell infiltrate at any time throughout the reaction to lymphokine. It is concluded that preformed lymphokine produces a pattern of increased vascular permeability appropriate to a mediator of delayed hypersensitivity reactions, provided there is sustained secretion of this material. The ability of lymphokine to cause carbon labeling of dermal capillaries is also pertinent to a mediator of delayed hypersensitivity. The absence of significant mononuclear cell accumulation suggests that the in vitro chemotactic activity of lymphokine toward mononuclear cells may be more important for retention of mononuclear cells in the extravascular connective tissue space than for their selective accumulation.

Use of 125I-labelled albumin for the detection and measurement of delayed-hypersensitivity reactions in the mouse

Accumulation of 125I-labelled albumin in the mouse hind foot has been used to measure reactions of delayed hypersensitivity in the mouse. The assay is technically simple and permits use of groups of 10 or more animals. Its sensitivity and reproducibility have been demonstrated by comparing sensitized with non-sensitized animals in two antigen systems (P.P.D. and an extract of Trypanosoma cruzi).

Technical modification of indirect immunofluorescent antibody test using filter paper blood eluates

An indirect immunofluorescence test using small discs (0.4 cm in diameter) cut from blood smears on filter paper is described. Discs plus three drops of phosphate-buffered saline are laid on antigenic areas on slides, which are then incubated. During incubation, eluted antibodies react with antigen. The method was tested with 10 eluates from healthy persons and with 30 eluates from three groups of 10 patients with Chagas’ disease, schistosomiasis <i>Mansoni </i>and South American blastomycosis, respectively. Sera from the same blood samples were tested also by conventional indirect immunofluorescence tests. Both tests gave similar results. The method proposed is useful as a rapid qualitative screening test when dealing with a large number of samples.