Randomized Trial on the Effect of an Oral Spleen Tyrosine Kinase Inhibitor in the Treatment of IgA Nephropathy

Introduction

We reported increased spleen tyrosine kinase (SYK) expression in kidney biopsies of patients with IgA nephropathy (IgAN) and that inhibition of SYK reduces inflammatory cytokines production from IgA stimulated mesangial cells.

Methods

This study was a double-blind, randomized, placebo-controlled phase 2 trial of fostamatinib (an oral SYK inhibitor) in 76 patients with IgAN. Patients were randomized to receive placebo, fostamatinib at 100 mg or 150 mg twice daily for 24 weeks on top of maximum tolerated dose of renin-angiotensin system inhibitors. The primary end point was reduction of proteinuria. Secondary end points included change from baseline in estimated glomerular filtration rate (eGFR) and kidney histology.

Results

Although we could not detect significant reduction in proteinuria with fostamatinib overall, in a predetermined subgroup analysis, there was a trend for dose-dependent reduction in median proteinuria (from baseline to 24 weeks by 14%, 27%, and 36% in the placebo, fostamatinib 100 mg, and 150 mg groups, respectively) in patients with baseline urinary protein-to-creatinine ratios (UPCR) more than 1000 mg/g. Kidney function (eGFR) remained stable in all groups. Fostamatinib was well-tolerated. Side effects included diarrhea, hypertension, and increased liver enzymes. Thirty-nine patients underwent repeat biopsy showing reductions in SYK staining associated with therapy at low dose (-1.5 vs. 1.7 SYK+ cells/glomerulus in the placebo group, P < 0.05).

Conclusions

There was a trend toward reduction in proteinuria with fostamatinib in a predefined analysis of high risk patients with IgAN despite maximal care, as defined by baseline UPCR greater than 1000 mg/g. Further study may be warranted.

Association and progression of multi-morbidity with Chronic Kidney Disease stage 3a secondary to Type 2 Diabetes Mellitus, grouped by albuminuria status in the multi-ethnic population of Northwest London: A real-world study

INTRODUCTION

The prevalence of Diabetic Kidney Disease (DKD) secondary to Type 2 Diabetes Mellitus (T2DM) is rising worldwide. However, real-world data linking glomerular function and albuminuria to the degree of multi-morbidity is lacking. We thus utilised the Discover dataset, to determine this association.

METHOD

Patients with T2DM diagnosed prior to 1st January 2015 with no available biochemical evidence of CKD were included. Patients subsequently diagnosed and coded for CKD3a in 2015, were grouped by the degree of albuminuria. Baseline and 5-year co-morbidity was determined, as were prescribing practices with regards to prognostically beneficial medication.

RESULTS

We identified 56,261 patients with T2DM, of which 1082 had CKD stage 3a diagnosed in 2015 (224-CKD3aA1,154-CKD3aA2,93-CKD3aA1; 611 patients with CKD3a but no uACR available in 2015 were excluded from follow up). No statistically significant difference was observed in the degree of co-morbidities at baseline. A significant difference in the degree of hypertension, retinopathy, ischaemic heart disease and vascular disease from baseline compared to study end point was observed for all 3 study groups. Comparing co-morbidities developed at study end point, highlighted a statistical difference between CKD3aA1 Vs CKD3aA3 for retinopathy alone and for hypertension and heart failure between CKD3aA2 Vs CKD3aA3. 40.8% of patients with CKD3aA2 or A3 were prescribed Renin Angiotensin Aldosterone inhibitors (RAASi) therapy between June-December 2021. Survival analysis showed 15% of patients with CKD3aA3 developed CKD stage 5 within 5 years of diagnosis.

DISCUSSION

CKD3a secondary to DKD is associated with significant multimorbidity at baseline and 5 years post diagnosis, with CKD3aA3 most strongly associated with CKD progression to CKD 5, heart failure, hypertension and retinopathy compared to CKD3aA1 or CKD3aA2 at 5 years post diagnosis. The lack of uACR testing upon diagnosis and poor prescribing of RAASi, in those with CKD3aA2/A3, raises significant cause for concern.

CONCLUSION

DKD is associated with significant multimorbidity. Significant work is needed to be done to ensure patients undergo testing for uACR, to allow for future risk stratification and ability to be started on prognostically beneficial medication.

A High-Content Screen for Mucin-1-Reducing Compounds Identifies Fostamatinib as a Candidate for Rapid Repurposing for Acute Lung Injury

Drug repurposing has the advantage of identifying potential treatments on a shortened timescale. In response to the pandemic spread of SARS-CoV-2, we took advantage of a high-content screen of 3,713 compounds at different stages of clinical development to identify FDA-approved compounds that reduce mucin-1 (MUC1) protein abundance. Elevated MUC1 levels predict the development of acute lung injury (ALI) and acute respiratory distress syndrome (ARDS) and correlate with poor clinical outcomes. Our screen identifies fostamatinib (R788), an inhibitor of spleen tyrosine kinase (SYK) approved for the treatment of chronic immune thrombocytopenia, as a repurposing candidate for the treatment of ALI. In vivo, fostamatinib reduces MUC1 abundance in lung epithelial cells in a mouse model of ALI. In vitro, SYK inhibition by the active metabolite R406 promotes MUC1 removal from the cell surface. Our work suggests fostamatinib as a repurposing drug candidate for ALI.

A High Content Screen for Mucin-1-Reducing Compounds Identifies Fostamatinib as a Candidate for Rapid Repurposing for Acute Lung Injury during the COVID-19 pandemic

Drug repurposing is the only method capable of delivering treatments on the shortened time-scale required for patients afflicted with lung disease arising from SARS-CoV-2 infection. Mucin-1 (MUC1), a membrane-bound molecule expressed on the apical surfaces of most mucosal epithelial cells, is a biochemical marker whose elevated levels predict the development of acute lung injury (ALI) and respiratory distress syndrome (ARDS), and correlate with poor clinical outcomes. In response to the pandemic spread of SARS-CoV-2, we took advantage of a high content screen of 3,713 compounds at different stages of clinical development to identify FDA-approved compounds that reduce MUC1 protein abundance. Our screen identified Fostamatinib (R788), an inhibitor of spleen tyrosine kinase (SYK) approved for the treatment of chronic immune thrombocytopenia, as a repurposing candidate for the treatment of ALI. In vivo , Fostamatinib reduced MUC1 abundance in lung epithelial cells in a mouse model of ALI. In vitro , SYK inhibition by Fostamatinib promoted MUC1 removal from the cell surface. Our work reveals Fostamatinib as a repurposing drug candidate for ALI and provides the rationale for rapidly standing up clinical trials to test Fostamatinib efficacy in patients with COVID-19 lung injury.

Glomerular protein sieving and implications for renal failure in Fanconi syndrome

BACKGROUND

Glomerular sieving coefficients (GSCs) of proteins have been measured extensively in animals but not humans. We have studied the proteinuria of Fanconi syndrome, a "knock-out" of renal tubular protein reabsorption, to estimate GSCs and detect potential contributors to development of renal failure.

METHODS

Immunoassay of proteins and polypeptides in serum and urine of patients with early Dent's disease (mean GFR = 83 mL/min, range 60 to 101, N = 5), Lowe's syndrome (N = 3), and ADIF (N = 2) were used.

RESULTS

Twenty-one proteins, ranging in mass from insulin (5.1 kD) and parathyroid hormone (PTH; 9.4 kD) to transferrin (78 kD) and intact IgG (160 kD), were present in Fanconi urine at> 6 to 1000-fold normal. A simple model assuming complete "knock-out" of the reuptake of each protein filtered normally by the glomerulus was applied to protein excretion by Dent's patients. GSCs were estimated for 12 plasma proteins, including albumin (7.7 +/- 0.9 x 10-5) and IgG (4.2 +/- 0.28 x 10-5; mean +/- SEM). We calculated the albumin concentration in normal glomerular filtrate to be 3.5 +/- 0.41 mg/L (53 +/- 6.4 nmol/L), consistent with studies in rat and dog.

CONCLUSIONS

To our knowledge, this study provides the first estimates of human in vivo GSCs. Our model explains why tubular proteinuria of Fanconi syndrome includes proteins of mass of albumin and above as well as low-molecular-weight proteins, and further characterizes the endocytic pathway(s) believed defective in these syndromes. High urinary concentrations of potentially bioactive hormones such as PTH, insulin, IGF-1 and the chemokine monocyte chemoattractant protein-1 (MCP-1), were found; their presence in tubular fluid may contribute to the hypercalciuria, interstitial fibrosis, and the progressive renal failure of Fanconi syndromes.

VCAM-1 has a tissue-specific role in mediating interleukin-4-induced eosinophil accumulation in rat models: evidence for a dissociation between endothelial-cell VCAM-1 expression and a functional role in eosinophil migration

Eosinophil accumulation has been associated with the pathogenesis of numerous allergic inflammatory disorders. Despite the great interest in this response, many aspects of eosinophil accumulation remain unknown. This is particularly true with respect to tissue-specific mechanisms that may regulate the accumulation of eosinophils in different organs. This study addressed this issue by investigating and comparing the roles of alpha(4)-integrins and vascular cell adhesion molecule 1 (VCAM-1) adhesion pathways in interleukin 4 (IL-4)-induced eosinophil accumulation in 2 different rat models of inflammation, namely pleural and cutaneous inflammation. Similar to our previous findings in studies in rat skin, locally administered IL-4 induced a time- and dose-dependent accumulation of eosinophils in rat pleural cavities, a response that was associated with generation of the chemokine eotaxin. The IL-4-induced eosinophil accumulation in skin and pleural cavities was totally inhibited by an antirat alpha(4)-integrins monoclonal antibody (mAb) (TA-2). In contrast, whereas an antirat VCAM-1 mAb (5F10) totally blocked the response in skin, IL-4-induced eosinophil accumulation in rat pleural cavities was not affected by VCAM-1 blockade. A radiolabeled mAb technique demonstrated that endothelial-cell VCAM-1 expression was induced in response to IL-4 in both skin and pleural membrane. The results indicate that although endothelial-cell VCAM-1 is present in skin and pleura, a functional role for it in IL-4-induced eosinophil accumulation was evident only in skin. These findings suggest the existence of tissue-specific adhesive mechanisms in regulating leukocyte migration in vivo and demonstrate a dissociation between VCAM-1 expression and eosinophil accumulation.

CD28-B7 blockade prevents the development of experimental autoimmune glomerulonephritis

Experimental autoimmune glomerulonephritis (EAG), an animal model of Goodpasture's disease, can be induced in Wistar Kyoto (WKY) rats by a single injection of rat glomerular basement membrane (GBM) in adjuvant. EAG is characterized by circulating and deposited anti-GBM antibodies, accompanied by focal necrotizing glomerulonephritis with crescent formation. The role of T cells in the pathogenesis of EAG remains unclear. T-cell costimulation is provided by ligation of CD28 with either B7.1 (CD80) or B7.2 (CD86) on antigen-presenting cells, and can be inhibited by a soluble form of CTLA4 (CTLA4-Ig) that binds to both B7.1 and B7.2. We examined the effect of CD28-B7 blockade on the development of EAG using native CTLA4-Ig or mutant CTLA4-Ig (Y100F-Ig), which selectively blocks B7.1. Native CTLA4-Ig treatment ameliorated EAG by several measures, including the levels of circulating anti-GBM antibodies, albuminuria, the deposition of IgG and fibrin in the glomeruli, the severity of glomerular abnormalities, and the numbers of infiltrating T cells and macrophages. Y100F-Ig resulted in a similar reduction in the severity of nephritis, but produced no overall reduction in circulating anti-GBM antibodies, although there was a reduction in IgG2a antibodies. We concluded that CD28-B7 blockade reduced autoantibody production and cellular infiltration of glomeruli, and prevented target organ injury. Our results suggest a key role for B7. 1 in costimulation of Th1-like autoimmune responses in the rat, and show that glomerular injury in EAG is largely dependent on cell-mediated mechanisms.

Type IV phosphodiesterase inhibitor is effective in prevention and treatment of experimental crescentic glomerulonephritis

BACKGROUND

Tumour necrosis factor alpha (TNF-alpha) has an important role in acute glomerular inflammation. Rolipram, a type IV phosphodiesterase inhibitor, has multiple anti-inflammatory effects including inhibition of TNF-alpha synthesis.

METHODS

We investigated the effects of rolipram in prevention and delayed treatment of crescentic glomerulonephritis in Wistar Kyoto rats. Glomerulonephritis was induced by injection of nephrotoxic serum.

RESULTS

In the preventive study, rolipram (6.25 mg/kg i.p. twice daily) was started 2.5 h before injection of nephrotoxic serum. Rolipram reduced the expression of TNF-alpha in glomeruli and renal tubules and abrogated glomerular injury on day 4 (99.7% reduction in albuminuria and 96.4% reduction in fibrin deposition). In the delayed-treatment experiment, rolipram was started 4 days after injection of nephrotoxic serum. Rolipram reduced renal excretion of TNF-alpha by 63% on day 7. TNF-alpha was not detected in the sera of treated or control rats. Delayed treatment was effective in crescentic glomerulonephritis, as shown by reduction in albuminuria by 38.1%, fibrin deposition by 60.8%, and crescent formation by 67% on day 7.

CONCLUSIONS

Rolipram is effective both in prevention and treatment of experimental crescentic glomerulonephritis. This was associated with a reduction of renal production of TNF-alpha.

Development of scarring and renal failure in a rat model of crescentic glomerulonephritis

BACKGROUND

The aim of this study was to develop and characterize a rat model of crescentic glomerulonephritis which progresses to glomerulosclerosis and renal failure.

METHODS

Glomerulonephritis was induced in Wistar Kyoto rats by a single injection of rabbit anti-glomerular basement membrane antiserum. Albuminuria and serum creatinine were monitored. Kidneys were examined, from 2.5 h to 44 days, using light-microscopy and immunohistochemistry. To characterize the glomerular inflammatory infiltrate, glomeruli were digested to single cells and analysed by fluorescence-activated cell sorter (FACS) and by immunohistochemistry on cytospins.

RESULTS

Rats developed albuminuria by 4 days and increased serum creatinine by day 18. Histology showed glomerular fibrinoid necrosis by day 4 and cellular crescents in a mean of 63% of glomeruli by day 11. By 6 weeks, rats had developed renal failure (mean creatinine >300 micromol/l) with 94% of the glomeruli showing glomerulosclerosis. The kidneys were also affected by severe interstitial nephritis and tubular loss. The glomeruli were infiltrated by monocytes/ macrophages (ED1+) and CD8+ (OX8+) cells. FACS analysis showed that CD8+ cells did not express T-cell markers (CD3, TCRalphabeta or TCRgammadelta) or the NK-cell marker (NKR-P1). FACS analysis of peripheral blood mononuclear cells demonstrated a population of monocytes reactive with OX8, and double-labelling of cytospin preparations of glomerular digests showed that a proportion of the CD8+ cells were a subset of ED1+ monocyte/macrophages.

CONCLUSIONS

We have characterized a reproducible model of crescentic glomerulonephritis which rapidly progresses to chronic renal failure with glomerulosclerosis and tubulo-interstitial scarring. This model will be useful for testing new therapeutic approaches in crescentic glomerulonephritis.

Interleukin-4 ameliorates crescentic glomerulonephritis in Wistar Kyoto rats

BACKGROUND

Activated macrophages play a central role in crescentic glomerulonephritis. Interleukin-4 (IL-4) down-regulates many macrophage proinflammatory activities. We therefore studied the effect of IL-4 on glomerular injury in a model of crescentic glomerulonephritis in the Wistar Kyoto rat.

METHODS

Glomerulonephritis was induced by i.v. administration of rabbit antirat glomerular basement membrane antiserum (nephrotoxic serum, NTS). In experiment 1, IL-4 was given from two hours before NTS until day 6. In experiment 2, rats were treated from day 0 to 7 and were then monitored until killed on day 28. In experiment 3, IL-4 was given from day 4 to 7.

RESULTS

Continuous IL-4 treatment (experiment 1) significantly (P = 0.001) reduced proteinuria (3 +/- 1 mg per 24 hr vs. 56 +/- 7), fibrinoid necrosis (0.06 +/- 0.04 quadrants/glomulus vs. 1.2 +/- 0.1), macrophage infiltration (6.7 +/- 2.6 cells/glom vs. 33 +/- 2.5), CD8+ cells (1.5 +/- 0.6 cells/glom vs. 6.2 +/- 1.1), inducible nitric oxide synthase positive cells (0.04 +/- 0.04 cells/glom vs. 3.7 +/- 0.6), proliferating cell nuclear antigen positive cells (3.2 +/- 1 cells/glom vs. 15 +/- 2.3), and glomerular intercellular adhesion molecule-1 expression. Follow-up after seven days of treatment (experiment 2) showed that at four weeks, creatinine clearance was higher in treated rats (1.1 +/- 0.1 ml/min vs. 0.4 +/- 01, P = 0.011), and both glomerular scarring (P = 0.006) and tubular atrophy (P = 0.006) were less. Delayed treatment (experiment 3) reduced proteinuria (41 +/- 5 mg per 24 hr vs. 97 +/- 9, P = 0.004) and fibrinoid necrosis (0.39 +/- 0.05 quadrants/glom vs. 1.6 +/- 0.1, P = 0.004). There was no difference in macrophage infiltration, but inducible nitric oxide synthase positive cells were reduced (0.6 +/- 0.1 cells/glom vs. 1.8 +/- 0.4, P = 0.01) as were ED3+ cells (0.18 +/- 0.06 cells/glom vs. 1.86 +/- 0.21, P = 0.004).

CONCLUSION

In this model of crescentic glomerulonephritis, early IL-4 treatment abolished proteinuria and markedly reduced glomerular inflammation. If treatment was stopped after seven days, there was continuing benefit on glomerular and tubulointerstitial scarring and creatinine clearance at four weeks. If treatment was delayed until inflammation was established, there was still a reduction of injury, but without an alteration of macrophage numbers, suggesting that IL-4 may be acting, in part, to reduce macrophage activation.

Arginase AI is upregulated in acute immune complex-induced inflammation

Previous studies have shown high arginase activity at inflammatory sites. Arginase converts L-arginine to L-ornithine, sharing a common substrate with nitric oxide synthase. It exists as two isoforms, AI and AII. While the function of liver arginase (AI) in ureagenesis has been defined, the role and isoform of arginase in cells without a complete urea cycle are unknown. We therefore determined arginase isoform mRNA expression in glomerular acute immune complex inflammation, and its cultured constituent cells. AI was induced in nephritic glomeruli, and in mesangial cells stimulated with IL-4 and cAMP, and was present in elicited neutrophils and macrophages. AII was constitutively expressed. Our data strongly suggest that AI, thought to be restricted to the liver, accounts for high arginase activity at inflammatory sites where it may limit high output nitric oxide production and generate polyamines and proline essential for cell proliferation and matrix production. This identification of AI in inflamed tissue is an important step for understanding the consequences of increased arginase activity.

Arginase activity is modulated by IL-4 and HOArg in nephritic glomeruli and mesangial cells

Arginase shares a common substrate, L-arginine, with nitric oxide synthase (NOS). Both enzymes are active at inflammatory sites. To understand regulation of arginase and its relationship to nitric oxide (NO) production, we studied effects of NG-hydroxy-L-arginine (HOArg) and interleukin-4 (IL-4) on urea and NO2- synthesis by glomeruli during rat immune glomerulonephritis and compared these with macrophages and glomerular mesangial cells (MC). In nephritic glomeruli, elicited macrophages, and MC stimulated with IL-1 and adenosine 3',5'-cyclic monophosphate agonists, increased arginase and induced NOS activity was found. Urea production was inhibited by HOArg and increased by IL-4. NO inhibition [NG-monomethyl-L-arginine (L-NMMA)] increased arginase activity in nephritic glomeruli and macrophages but not MC. NO2- synthesis was inhibited by L-NMMA and IL-4. It was increased with HOArg under conditions of NO inhibition. In contrast, in normal glomeruli and basal MC, where there was no induced NO synthesis, IL-4 had no effect on arginase activity, whereas HOArg consistently reduced it in glomeruli only. Type II arginase (Arg II) mRNA was detected in normal glomeruli; nephritic glomeruli expressed both Arg I and Arg II mRNAs. This is the first demonstration of arginase modulation in glomeruli and MC and of the expression of arginase isoforms in glomeruli. The differential responses to two endogenous compounds generated by inflammation suggest this may be part of coordinated regulation of arginase and inducible NOS in immune injury, whereby arginase is inhibited during high-output NO production and stimulated with NO suppression. This, together with control of arginase and NOS isoforms, may be important in controlling the balance of inflammatory and repair mechanisms.

Interleukin-4 ameliorates experimental glomerulonephritis and up-regulates glomerular gene expression of IL-1 decoy receptor

Monocytes/macrophages and pro-inflammatory cytokines such as interleukin (IL)-1 are important in the pathogenesis of acute glomerulonephritis. The aim of this study was to examine whether IL-4, a cytokine with anti-inflammatory activity, could modulate glomerular inflammation and reduce injury in vivo. Treatment with recombinant rat IL-4 in a model of anti-glomerular basement membrane (GBM) antibody mediated glomerulonephritis in rats reduced glomerular injury. Albuminuria was less (73% less at day 4) and a lower proportion of glomeruli had capillary thrombi (79% less at day 4). In IL-4 treated rats, there was a moderate reduction in the number of macrophages in the glomeruli and also suppression of pro-inflammatory activities of the macrophages. Northern blot analysis of glomerular RNA showed that treatment with IL-4 up-regulated mRNA levels of type II IL-1 receptor (IL-1RTII). IL-1RTII, also known as IL-1 decoy receptor, may act as a decoy molecule to inhibit the effect of IL-1 beta. To our knowledge, this is the first demonstration of (i) recombinant IL-4 reducing glomerular inflammation in vivo and (ii) a treatment that increases IL-1RTII expression in association with reduction of tissue injury in vivo.

Abrogation of glomerular injury in nephrotoxic nephritis by continuous infusion of interleukin-6

Interleukin-6 (IL-6) has been reported to have pro- and anti-inflammatory effects. It has also been shown to cause mesangial cell proliferation in vitro and has been suggested as a mediator of injury in proliferative nephritis. We have assessed the effects of continuous infusion of human recombinant (hr) IL-6, by osmotic minipump, on the degree of glomerular injury, and on glomerular and interstitial cell proliferation, in the accelerated autologous phase of nephrotoxic nephritis. Two groups of rats were pre-immunized with 1 mg of normal rabbit IgG in Freund's complete adjuvant. One week later, nephritis was induced by an intravenous injection of 1 ml of rabbit nephrotoxic serum. One day before the induction of nephritis, group 1 (N = 9) was subcutaneously implanted with osmotic minipumps filled with 50 micrograms (200 microliters) of IL-6 (equivalent to a dose of 6 micrograms/day), while in group 2 (N = 11) the minipumps were filled with 200 microliters of normal saline. In group 3 (N = 6) normal rats were infused with 50 micrograms of IL-6 alone. The rats were killed seven days after implantation of minipumps. The administered hrIL-6 was detectable in the circulation within the pathophysiological range, and induced a hepatic acute phase response, as assessed by alpha 2-macroglobulin levels. Continuous treatment with IL-6 resulted in a significant reduction in albuminuria (from 195 +/- 37 mg/20 hr to 60 +/- 15 mg/20 hr on day 1, and from 494 +/- 52 mg/20 hr to 238 +/- 30 mg/20 hr on day 7, P < 0.002) and in the prevalence of glomerular capillary thrombosis (from 19 +/- 3% to 5 +/- 1%, P < 0.002). There was also a reduction in macrophage infiltration (ED1 + ve cells from 524 +/- 34 to 466 +/- 14 per 50 glomeruli, P < 0.02) and activation (ED3 + ve cells from 106 +/- 13 to 42 +/- 5 per 50 glomeruli, P < 0.002). Immunohistology showed fewer interstitial Ia + ve cells (OX3 and OX4) in the IL-6 treated group. Similar results were obtained in a second set of experiments in which the IL-6 treatment was extended until day 14. Kidney sections taken from nephritic rats infused with IL-6 showed no increase in glomerular or interstitial cell proliferation when stained with antibodies to proliferating cell nuclear antigen. There was no difference in the deposition of rabbit IgG or rat IgG along the glomerular basement membrane (GBM), and the titer of rat anti-rabbit IgG was similar in the IL-6 and control treated rats. Infusion of IL-6 alone in normal rats had no functional or pathological effects. In conclusion, these results show that IL-6 has powerful anti-inflammatory effects in a rat model of anti-GBM nephritis, and does not induce mesangial cell proliferation in vivo.

Up-regulation of type 1 plasminogen activator inhibitor messenger RNA with thrombotic changes in renal grafts

Small vessel thrombosis is a prominent feature in kidneys undergoing vascular rejection. Type I and type 2 plasminogen activator inhibitors (PAI-1 and PAI-2, respectively) are known to mediate thrombosis. To examine the potential role of PAI-1 and PAI-2 in the mediation of vascular injury, the relationship and the time course of gene expression of PAI-1 and PAI-2 with the thrombotic changes in renal grafts were investigated in an unmodified rejection model in rats. Orthotopic renal transplantation was performed from Lewis to dark agouti (DA) rats and from DA to DA isografts; untreated normal rat kidneys were used as controls. The rats were killed on days 1-9 posttransplantation (n=18 in each allograft and isograft group). The grafts were analyzed by histopathology, in situ mRNA hybridization and Northern blot methods. The results show that PAM mRNA was first detected at day 4, when the thrombotic changes in the grafts were first seen, and that this relationship persisted during the time course observed to day 9. There was no detectable PAI-1 mRNA in the control groups and no PAI-2 in either group. In situ hybridization showed that PAI-1 positive cells were predominantly located in the cortical interstitium, consistent with the distribution of interstitial microthrombi. These results provide experimental evidence that the thrombotic changes in rejecting allografts are associated with the up-regulation of PAI-1 in the donor tissue, whereas PAI-2, from our results, does not seem to influence these changes. The data are consistent with a role for PAI-1 in the pathogenesis of vascular rejection.

Differential expression of macrophage inflammatory protein-2 and monocyte chemoattractant protein-1 in experimental glomerulonephritis

We examined the relation between glomerular expression of chemokines from alpha-subfamily (macrophage inflammatory protein-2, MIP-2) and beta-subfamily (monocyte chemoattractant protein-1, MCP-1) and infiltration of neutrophils and monocytes in antibody mediated glomerulonephritis in rats. In the accelerated model of nephrotoxic nephritis (NTN), glomerular expression of MIP-2 and MCP-1 genes correlated with the sequential migration of neutrophil and monocyte influx, respectively. These relationships were investigated further in the heterologous phase of NTN by applying various treatments known to modulate the severity of injury. Pretreatment with bacterial lipopolysaccharide resulted in greater injury, MIP-2 expression increased 25- to 50-fold, and the glomerular neutrophil count increased two- to fourfold. Both MIP-2 mRNA levels and neutrophil infiltration were reduced by additional pretreatment with IL-6, IL-1 receptor antagonist, soluble IL-1 receptor or soluble TNF receptor (Spearman correlation coefficient r = 0.897, P < 0.005). In the heterologous phase of NTN, different pre-treatments only resulted in trivial changes in MCP-1 expression and monocyte infiltration. In conclusion, glomerular MIP-2 gene expression correlates with neutrophil infiltration both temporally during the evolution of nephritis, and when glomerular injury is modified by treatment. Glomerular MCP-1 gene expression correlates with monocyte influx. The data show chemokines of alpha- and beta-subfamilies co-operative to cause selective and sequential migration of different leukocyte subsets during development of antibody mediated glomerulonephritis.

Modulation of antibody-mediated glomerular injury in vivo by IL-1ra, soluble IL-1 receptor, and soluble TNF receptor

The severity of glomerular injury in the heterologous phase of NTN is dependent on proinflammatory cytokines including TNF alpha and IL-1 beta, and can be enhanced by LPS. We have previously shown that passive immunization against IL-1 beta and TNF partially abrogated the LPS effect in this model. In the present work, we have assessed the effects on glomerular injury of blocking and binding of IL-1 to its receptor by rh IL-1 receptor antagonist (IL-1ra) and by neutralizing IL-1 and TNF with rm soluble IL-1 receptor type1 (sIL-1Rt1) and rh sTNF receptor (sTNFr p55), respectively. Pretreatment with either IL-1ra, sIL-1Rt1, or sTNFr partially abrogated the effects of LPS and reduced albumin excretion from 45 +/- 8, 66 +/- 9, and 101 +/- 17 mg/24 hr at 13 +/- 4 (P < 0.02), 14 +/- 4 (P < 0.001), and 21 +/- 7 mg/24 hr (P < 0.001), respectively. Similarly, these inhibitors reduced the prevalence of glomerular capillary thrombi and the intensity of glomerular neutrophil infiltration. Glomerular thrombosis was reduced from 18 +/- 3%, 28 +/- 5%, and 25 +/- 7% to 3 +/- 2% (P < 0.002), 6 +/- 2% (P < 0.001), and 3 +/- 2 (P < 0.001), respectively, and glomerular neutrophil infiltration was reduced from 46 +/- 3, 54 +/- 2, 59 +/- 8 to 19 +/- 2 (P < 0.001), 25 +/- 2 (P < 0.001), and 28 +/- 2 neutrophils/50 glomeruli in section, respectively. Coadministration of both soluble receptors of IL-1 and TNF caused a further decrease in glomerular injury. The protective effect was also noticed at four hours after induction of nephritis, and even when these inhibitors were administered after the LPS injection and at the same time of induction of nephritis. All three treatments reduced circulating TNF concentration (down to 20%, 34%, and 0%, respectively) but without detectable glomerular TNF gene expression. Glomerular IL-1 beta mRNA levels were also reduced by 41%, 53%, and 67%, respectively, when assessed by densitometric analysis of Northern blots. In contrast, the glomerular expression of IL-1ra was not affected by its exogenous administration but was mildly reduced by sIL-1Rt1 and sTNFr, which demonstrates the potential role for host derived IL-1ra as an endogenous negative feedback mediator in the glomerulus. These results confirm the direct involvement of IL-1 and TNF in LPS-enhanced hNTN and demonstrate the potency of these inhibitors in modulating injury even when administered after LPS and in time of induction of nephritis. They were more specific and effective than passive immunization with polyclonal antibodies, and this demonstrates their potential usefulness in the management of nephritis.

Rat mesangial cells have a selective role in macrophage recruitment and activation

In proliferative glomerulonephritis glomeruli are the target of an inflammatory reaction involving macrophage recruitment and activation. We examined the role of mesangial cells in this process. Supernatants from basal, IL-1, IFN-tau or LPS-stimulated rat mesangial cells (MCS) were tested for chemotactic, colony-stimulating and activation effects on macrophages in vitro. IL-1-stimulated MCS produced a macrophage chemoattractant (p = 0.007 compared with basal MCS) and MCP-1 mRNA was detected in IL-1-stimulated mesangial cells. LPS or IL-1-stimulated MCS produced colony-stimulating activity (LPS p < 0.05, IL-1 p < 0.01, compared with basal MCS or control supernatant, CS). Macrophage activation, assessed by nitric oxide generation, was suppressed. This evidence from functional bioassays supports a selective role for mesangial cells in the control of macrophage-induced glomerular injury, whereby activated mesangial cells participate in the recruitment and proliferation of infiltrating macrophages, and suppresses at least one field of macrophage activation, namely nitric oxide generation.

Glomerular expression of interleukin-1 receptor antagonist and interleukin-1 beta genes in antibody-mediated glomerulonephritis

Interleukin-1 (IL-1) is a powerful proinflammatory cytokine whose function is modulated by a natural IL-1 receptor antagonist (IL-1ra). There are few data about kinetics of in vivo synthesis of IL-1ra at tissue level, except in response to bacterial endotoxin. The purpose of this study was to examine the kinetics of local expression of IL-1ra gene in relation to IL-1 beta gene in a model of anti-glomerular basement membrane antibody-mediated glomerulonephritis. Rats were killed in groups of 5 or 6 at 0, 4, 6, 24, 48, and 96 hours after induction of glomerulonephritis. Messenger RNA for IL-1ra and IL-1 beta was undetectable by Northern blot in normal glomeruli but increased markedly 4 to 6 hours after induction of nephritis. The increase in IL-1ra mRNA was more sustained than that of IL-1 beta mRNA. In situ hybridization showed that IL-1 beta mRNA increased diffusely within glomeruli, while IL-1ra mRNA was expressed more discretely. Expression of these mRNA in noninflamed tissues, spleens and lungs, was different, particularly increase in IL-1ra mRNA was more substantial than that of IL-1 beta. These observations suggest that differential expression of IL-1ra and IL-1 beta might focus inflammation in glomeruli while protecting more distant sites. They also raise the possibility of reducing glomerular injury by therapeutic measures that upregulate glomerular synthesis of IL-1ra while reducing that of IL-1 beta.

Modulation of antibody-mediated glomerular injury in vivo by interleukin-6

We have shown previously that pretreatment with small doses of bacterial lipopolysaccharide (LPS), human recombinant interleukin-1 beta (hrIL-1 beta) and human recombinant tumor necrosis factor-alpha (hrTNF) increase injury in the heterologous phase of nephrotoxic nephritis (NTN). All three pretreatments induce synthesis of interleukin-6 (IL-6) which in some systems down-regulates synthesis of IL-1 and TNF. We have now investigated the influence of IL-6 on injury in both heterologous and autologous phases of NTN in rats. Injection of hrIL-6 in doses sufficient to induce hepatic synthesis of acute phase proteins (assessed by plasma alpha 2-macroglobulin concentration) had no effect on glomerular injury in the heterologous phase of NTN (albuminuria in NTAb alone 9 +/- 6; LPS/NTAb 34 +/- 10 and IL-6/NTAb 2 +/- 1 mg/24 hr, P < 0.001, Wilcoxon test). In contrast, IL-6 pretreatment partially abrogated the effect of LPS on albumin excretion (NTAb 4 +/- 2; LPS/NTAb 85 +/- 11 and IL-6/LPS/NTAb 32 +/- 6 mg/24 hr, P < 0.002), percentage of glomerular capillary thrombi (3 +/- 1%; 39 +/- 8%; and 6 +/- 1%, P < 0.001) and glomerular neutrophil infiltrate (29 +/- 3; 58 +/- 5; and 34 +/- 2 neutrophils/50 glomeruli in section, P < 0.001, respectively) at 24 hours. The effect of IL-6 was also evident four hours after induction of nephritis and was associated with a marked reduction in glomerular concentration of mRNA for IL-1 beta and TNF, without change in that of tubulin. Serum TNF concentrations were also significantly reduced at four hours in IL-6 treated rats.(ABSTRACT TRUNCATED AT 250 WORDS)

Inhaled platelet-activating factor causes pulmonary neutrophil sequestration in normal humans

Inhaled platelet-activating factor (PAF) causes bronchoconstriction and transient peripheral neutropenia in humans. We studied eight normal subjects to investigate whether inhaled PAF caused pulmonary neutrophil sequestration. All subjects received autologous 99mTc-red cells as a blood pool marker, seven received 111In-neutrophils, and one received 111In-platelets. Six subjects inhaled 48 micrograms of PAF. There was immediate pulmonary sequestration of 111In-neutrophils, maximal (218% baseline) at 6 min (p less than 0.001), returning to normal by 3 h. There was no change in circulating platelet count or pulmonary 111In-platelet transit. Methacholine inhalation caused equivalent bronchoconstriction to PAF, but it had no effect on neutrophil count or pulmonary 111In-neutrophil activity. We have demonstrated pulmonary neutrophil, but not platelet, sequestration after PAF. This supports a role for PAF as an inflammatory mediator in humans. This may be a useful model for exploring pulmonary neutrophil kinetics and preinflammatory processes.

Gummatous lesions in men infected with human immunodeficiency virus and syphilis

Two HIV-infected men are reported who developed gummatous lesions more than 12 months after appropriate treatment of presumptive syphilis. In one patient the lesions developed without any change in the VDRL titre. The most likely explanation for these lesions is reactivation of syphilis in the context of HIV infection. As these lesions respond to penicillin, the possible reactivation of appropriately treated syphilis, or even yaws, should now be considered in any ulcerative lesion in HIV infected individuals at risk from treponemal infection.

Aversive effects of subcutaneously injected vasopressin in the rat: independence of the ascending dorsal noradrenergic bundle

The unconditioned stimulus properties of subcutaneously administered arginine vasopressin (AVP) were examined using place and taste conditioning paradigms. Evidence for an aversive effect of the peptide was found, in general agreement with a previous report, although a high dose of AVP (10 micrograms) was required. Also investigated was the possible role of the dorsal noradrenergic bundle (DNAB) in conditioned taste aversion established by AVP. Although the DNAB has been proposed as one of the central pathways through which AVP exerts a facilitatory effect on conditioned behaviour, destruction of this pontine-forebrain projection with 6-hydroxydopamine did not appear to alter the aversiveness of the drug in the present study. These results replicate the finding that AVP can serve as an aversive stimulus but also indicate that the aversive properties of the peptide may prove to be dissociable from its ability to enhance the retention of learned behaviour.