Circulating autoantibodies as serological markers in the differential diagnosis of pulmonary renal syndrome

Autoantibodies against laminin-521 are pathogenic in anti-glomerular basement membrane disease

Anti-glomerular basement membrane (anti-GBM) disease is an organ-specific autoimmune disorder characterized by autoantibodies against GBM components. Evidence from human inherited kidney diseases and animal models suggests that the α, β, and γ chains of laminin-521 are all essential for maintaining the glomerular filtration barrier. We previously demonstrated that laminin-521 is a novel autoantigen within the GBM and that autoantibodies to laminin-521 are present in about one-third of patients. In the present study, we investigated the pathogenicity of autoantibodies against laminin-521 with clinical and animal studies. Herein, a rare case of anti-GBM disease was reported with circulating autoantibodies binding to laminin-521 but not to the NC1 domains of α1-α5(IV) collagen. Immunoblot identified circulating IgG from this patient bound laminin α5 and γ1 chains. A decrease in antibody levels was associated with improved clinical presentation after plasmapheresis and immunosuppressive treatments. Furthermore, immunization with laminin-521 in female Wistar-Kyoto rats induced crescentic glomerulonephritis with linear IgG deposits along the GBM, complement activation along with infiltration of T cells and macrophages. Lung hemorrhage occurred in 75.0% of the rats and was identified by the presence of erythrocyte infiltrates and hemosiderin-laden macrophages in the lung tissue. Sera and kidney-eluted antibodies from rats immunized with laminin-521 demonstrated specific IgG binding to laminin-521 but not to human α3(IV)NC1, while the opposite was observed in human α3(IV)NC1-immunized rats. Thus, our patient data and animal studies imply a possible independent pathogenic role of autoantibodies against laminin-521 in the development of anti-GBM disease.

Pulmonary renal syndrome: a clinical review

The term "pulmonary renal syndrome" describes a clinical syndrome which is characterised by the presence of both diffuse alveolar haemorrhage and glomerulonephritis. It encompasses a group of diseases with distinctive clinical and radiological manifestations, as well as different pathophysiological processes. The most common diseases implicated are anti-neutrophil cytoplasm antibodies (ANCA)-positive small vessel vasculitis and anti-glomerular basement membrane (anti-GBM) disease. Prompt recognition is required as respiratory failure and end-stage renal failure can rapidly occur. Treatment includes a combination of glucocorticoids, immunosuppression, plasmapheresis and supportive measures. The use of targeted treatments has significantly reduced mortality. Thus, an understanding of pulmonary renal syndrome is essential for the respiratory physician.

The presentation, etiologies, pathophysiology, and treatment of pulmonary renal syndrome: A review of the literature

Pulmonary renal syndrome (PRS) is a constellation of different disorders that cause both rapidly progressive glomerulonephritis and diffuse alveolar hemorrhage. While antineutrophil cytoplasmic antibody associated vasculitis and anti-glomerular basement membrane disease are the predominant causes of PRS, numerous other mechanisms have been shown to cause this syndrome, including thrombotic microangiopathies, drug exposures, and infections, among others. This syndrome has high morbidity and mortality, and early diagnosis and treatment is imperative to improve outcomes. Treatment generally involves glucocorticoids and immunosuppressive agents, but treatment targeted to the underlying disorder can improve outcomes and mitigate side effects. Familiarity with the wide range of possible causes of PRS can aid the clinician in workup, diagnosis and early initiation of treatment. This review provides a summary of the clinical presentation, etiologies, pathophysiology, and treatment of PRS.

Gender dimension in cardio-pulmonary continuum

Cardio-pulmonary diseases, which were once regarded as a man's illness, have been one of the leading causes of morbidity and mortality for both men and women in many countries in recent years. Both gender and sex influence the functional and structural changes in the human body and therefore play an important role in disease clinical manifestation, treatment choice, and/or response to treatment and prognosis of health outcomes. The gender dimension integrates sex and gender analysis in health sciences and medical research, however, it is still relatively overlooked suggesting the need for empowerment in the medical research community. Latest advances in the field of cardiovascular research have provided supportive evidence that the application of biological variables of sex has led to the understanding that heart disease in females may have different pathophysiology compared to males, particularly in younger adults. It has also resulted in new diagnostic techniques and a better understanding of symptomatology, while gender analysis has informed more appropriate risk stratification and prevention strategies. The existing knowledge in the pulmonary field shows the higher prevalence of pulmonary disorders among females, however, the role of gender as a socio-cultural construct has yet to be explored for the implementation of targeted interventions. The purpose of this review is to introduce the concept of gender dimension and its importance for the cardiopulmonary continuum with a focus on shared pathophysiology and disease presentation in addition to interrelation with chronic kidney disease. The review presents basic knowledge of what gender dimension means, and the application of sex and gender aspects in cardiovascular medicine with a specific focus on early pulmonary development, pulmonary hypertension, and chronic obstructive pulmonary disease (COPD). Early vascular aging and inflammation have been presented as a potential pathophysiological link, with further interactions between the cardiopulmonary continuum and chronic kidney disease. Finally, implications for potential future research have been provided to increase the impact of gender dimension on research excellence that would add value to everybody, foster toward precision medicine and ultimately improve human health.

Amino acid sequence homology between thyroid autoantigens and central nervous system proteins: Implications for the steroid-responsive encephalopathy associated with autoimmune thyroiditis

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Alpha-enolase, aldehyde reductase-I and dimethylargininase-I are SREAT autoantigens.

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Molecular mimicry between thyroid and CNS autoantigens is hypothesized in SREAT.

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Homology with TSH-R, Tg and TPO exists for 6, 27 and 47 of 46,809 CNS-proteins.

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The above homologies are often in epitope-containing parts of thyroid autoantigens.

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Most of the above proteins are expressed in CNS regions which are altered in SREAT.

A few patients with Hashimoto’s thyroiditis or Graves’ disease develop a multiform syndrome of the central nervous system (CNS) termed Hashimoto’s encephalopathy or steroid-responsive encephalopathy associated with autoimmune thyroid disease (HE/SREAT). They have high levels of thyroid autoantibodies (TgAb, TPOAb and/or TSH-R-Ab) in blood and cerebrospinal fluid. Autoantibodies against alpha-enolase, aldehyde reductase-I (AKRIA) and/or dimethylargininase-I (DDAHI), proteins expressed in the CNS among other tissues, were detected in the blood and, when searched, in the cerebrospinal fluid of HE/SREAT patients. Recently, we reported that alpha-enolase, AKRIA and DDAHI share local sequence homology with each of the three autoantigens (TgAb, TPOAb, TSH-R-Ab), often in epitope-containing segments of the thyroid autoantigens. We hypothesized that there might be additional CNS-expressed proteins homologous to thyroid autoantigens, possibly overlapping known epitopes of the thyroid autoantigens. We used bioinformatic methods to address this hypothesis.

Six, 27 and 47 of 46,809 CNS-expressed proteins share homology with TSH-R, Tg and TPO, respectively. The homologous regions often contain epitopes, and some match regions of thyroid autoantigens which have homology with alpha-enolase, AKRIA and/or DDAHI. Several of the aforementioned proteins are present in CNS areas that show abnormalities at neuroimaging in HE/SREAT patients. Furthermore, autoantibodies against some of the said six, 27 and 47 proteins were reported to be associated with a number of autoimmune diseases.

Not only we validated our hypothesis, but we think that such a variety of potential CNS targets for thyroid Ab against epitopes contained in regions that have local homology with CNS proteins may explain the polymorphic phenotypes of HE/SREAT. Only when elevated amounts of these Ab are synthesized and trespass the blood-brain barrier, HE/SREAT appears. This might explain why HE/SREAT is so relatively rare.

Accuracy of Anti-GBM Antibodies in Diagnosing Anti-Glomerular Basement Membrane Disease: A Systematic Review and Meta-Analysis

BACKGROUND

The sensitivity and specificity of anti-glomerular basement membrane (GBM) antibodies have not been systematically analyzed. In this systematic review, we aimed to evaluate the diagnostic accuracy of anti-GBM antibodies for anti-GBM disease.

SUMMARY

Potential studies were searched using MEDLINE, Embase, the Cochrane Library, and the International Clinical Trials Registry Platform based on the index test and target condition. The inclusion criteria were prospective or retrospective cohort studies or case-control studies assessing the sensitivity and specificity of anti-GBM antibodies, and the reference standard was clinical diagnosis including biopsy results. The exclusion criteria were review articles, case reports, animal studies, and in vitro studies. Quality assessment was conducted based on the Quality Assessment of Diagnostic Accuracy Studies-2. The pooled estimates of sensitivity and specificity were calculated using a bivariate random-effects model. The overall quality was evaluated using the Grades of Recommendation, Assessment, Development, and Evaluation. Six studies (1,691 patients) and 11 index tests were included in our systematic review. A high risk of bias and concerns regarding the applicability of patient selection were noted because of the case-control design in 67% of the included studies. The pooled sensitivity and specificity were 93% (95% CI: 84-97%) and 97% (95% CI: 94-99%), respectively. The certainty of evidence was low because of the high risk of bias and indirectness. Key Messages: Anti-GBM antibodies may exhibit high sensitivity and specificity in the diagnosis of anti-GBM disease. Further cohort studies are needed to confirm their precise diagnostic accuracy and compare diagnostic accuracies among different immunoassays.

[Interactions between lung and kidney in the critically ill]

Interactions between lung and kidney can significantly affect the course of acute diseases, a phenomenon that was first observed in the 1950s by describing pulmonary dysfunction in uremic patients. From animal experiments there is ample evidence for remote lung injury following acute kidney injury (AKI), with an increased risk for the development of pulmonary edema and acute respiratory distress syndrome (ARDS). Coincident ARDS and AKI are associated with higher rates of intubation and mechanical ventilation, significantly prolonged weaning from mechanical ventilation and increased mortality. On the other hand, acute lung diseases and mechanical ventilation can promote the development of AKI and are associated with increased mortality when AKI is also present. These bidirectional interactions may include hemodynamic adverse effects during mechanical ventilation or volume overload as well as the release or decreased clearance and metabolism of proinflammatory mediators (e.g., interleukin-6 and tumor necrosis factor-α), which may induce and aggravate distant organ injury. The aim of this work is to examine the interactions between lung and the kidney in critically ill patients, as well as discuss potential preventive approaches.

Small vessel vasculitis of the lung

Interstitial Lung Disease Program, National Jewish Medical and Research Center, Division of Pulmonary Sciences and Critical Care Medicine, University of Colorado Health Sciences Center, Denver, Colorado, USA The diagnosis and management of SVV remains one of the most challenging clinical scenarios encountered by a clinician. Careful attention to detail and a thorough knowledge of the specific disorders, their therapies, and complications thereof is required to optimally care for these patients. The recent completion of a number of randomized, controlled, multicenter clinical trials has greatly improved our knowledge base and ability to care for vasculitis patient. The next decade holds even more promise.

A Rare Clinical Course of Seronegative Pulmonary-Renal Syndrome

Purpose. Pulmonary-renal syndrome (PRS) is characterized by diffuse alveolar hemorrhage and rapidly progressive glomerulonephritis mainly due to autoimmune etiologies. Seronegative PRS is a challenging entity to the clinician, since early diagnosis may be missed leading to delayed appropriate treatment. Materials and Methods. We present the clinical course of a 77-year-old patient who was admitted under the suspected diagnosis of pneumogenic sepsis and septic renal failure with fever, dyspnea, and elevated CRP levels. The diagnosis of pulmonary-renal syndrome was initially missed because of the absence of autoantibodies in all serological findings. Results. Despite delayed initiation of immunosuppressive therapy and a prolonged period of dialysis and extracorporeal membrane oxygenation the patient recovered well and was released to a rehabilitation center with nearly normalized creatinine levels. The diagnosis of PRS was established by renal biopsy. Conclusion. This case illustrates the important differential diagnosis of seronegative pulmonary-renal syndrome in patients with pulmonary and renal impairment.

Pulmonary-Renal Syndrome with Negative ANCAs and Anti-GBM Antibody

We report the case of a 76-year-old woman who was referred to our hospital for a gradually worsening cough and renal dysfunction. Although pneumonia was initially suspected, imaging findings of the lungs revealed diffuse alveolar hemorrhage at a later date. Renal failure developed and hemodiafiltration was performed on the 9th day. Rapidly progressive glomerulonephritis with crescent formation was diagnosed by renal biopsy. This case presentation has important clinical implications because uncategorizable pulmonary-renal syndrome (PRS) without the presence of ANCAs and anti-GBM antibody is extremely rare and has high rates of morbidity and mortality. No treatment has been established.

Pulmonary renal vasculitis syndromes

The term pulmonary renal vasculitis syndrome describes a clinical syndrome of diffuse alveolar haemorrhage (DAH) complicating acute glomerulonephritis that often heralds severe, life-threatening systemic vasculitis requiring urgent, aggressive therapy. "Anti-neutrophil cytoplasmic antibody (ANCA) associated vasculitis" and glomerular basement membrane ("Goodpasture's") disease are the commonest causes but other pathologies including systemic lupus erythematosus and the anti-phospholipid syndrome are also implicated. Such patients hence present most commonly to rheumatologists and nephrologists but usually require input from a number of specialties, respiratory and critical care medicine in particular. Such care is typically provided in specialist centres able to offer plasma exchange and experience in the use of immunosuppressants. We review clinical features, advances in therapy and understanding of pathophysiology.

A Case Report of Pulmonary-Renal Syndrome Treated With Continuous Hemodiafiltration and Hemodialysis

This case describes a 40-year-old man complaining of general malaise, dyspnea with hemoptysis and anuria. Laboratory data indicated renal failure and the presence of systemic inflammation. His chest radiograph and computed tomography showed bilateral diffuse interstitial alveolar infiltration. These findings indicated acute deterioration of chronic renal dysfunction complicated by interstitial pneumonitis. He initially received daily conventional hemodialysis (HD), an antibiotic and oxygen therapy. However, his renal and pulmonary function continued to deteriorate. Antineutrophil cytoplasm antibodies against myeloperoxidase (MPO-ANCA) and antibodies against proteinase 3 (PR3-ANCA) were negative. We suspected that his pulmonary-renal syndrome was caused by ANCA-negative vasculitis. We applied mechanical ventilation, pulsed methylprednisolone therapy and continuous hemodiafiltration (CHDF) combined with HD. PaO(2)/FiO(2) ratio and mean pulmonary arterial pressure gradually improved after initiation of CHDF. He was finally separated from mechanical ventilation after 44 days in the hospital. He is currently alive with the support of conventional HD.

[Pulmonary-renal syndrome]

Pulmonary-renal syndrome is a potentially life-threatening disorder, characterized by diffuse alveolar hemorrhage on the basis of pulmonary capillaritis in conjunction with rapidly progressive glomerulonephritis. Pulmonary-renal syndrome can originate from various systemic autoimmune diseases. ANCA-associated vasculitides account for approximately 60%, Goodpasture's Syndrome for approximately 20% of the cases. Fulminant pulmonary capillaritis can result in acute respiratory failure, more subtle courses are only detected by bronchoalveolar lavage. Renal biopsy displays extracapillary proliferating glomerulonephritis and renal immunohistology facilitates detection of the underlying systemic disease. By accelerating the diagnosis of the specific underlying disease, autoantibody testing fosters rapid initiation of treatment and thereby significantly improved the prognosis of pulmonary-renal syndrome. Intense immunosuppression with cyclophosphamide and glucocorticoids, augmented by plasmapheresis in the event of Goodpastures' syndrome, is the mainstay of therapy. Supportive measures as temporary ventilation and hemodialysis have further reduced mortality.

Coexistence of Anti-Glomerular Basement Membrane Antibodies and Myeloperoxidase-ANCAs in Crescentic Glomerulonephritis

BACKGROUND

In a substantial proportion of patients with crescentic glomerulonephritis (CGN), both anti-glomerular basement membrane (GBM) antibodies and antineutrophil cytoplasmic antibodies (ANCAs) with specificity for myeloperoxidase (MPO-ANCA) are detected. In the present study, we questioned whether histological and clinical features of patients with both ANCA and anti-GBM antibodies differ from those of patients with either ANCA or anti-GBM alone.

METHODS

We reviewed the Limburg renal biopsy registry (1978 to 2003; n = 1,373) for cases of CGN. The presence of linear fluorescence on renal biopsy and the presence of ANCA and/or anti-GBM antibodies were measured. Subsequently, we assessed patient characteristics and follow-up and compared histological findings among the different groups.

RESULTS

We identified 46 MPO-ANCA-positive, 10 double-positive, and 13 anti-GBM-positive patients. Mean ages were 63, 64, and 52 years (P = 0.04), and serum creatinine levels were 5.0, 10.3, and 9.6 mg/dL (445, 910, and 850 micromol/L), respectively (P = 0.01). Granulomatous periglomerular inflammation was found in either MPO-ANCA- or double-positive patients, but not in anti-GBM-positive patients with CGN without MPO-ANCAs. Patient survival among the 3 groups was different, although not statistically significant (log rank P = 0.17, with 75%, 79%, and 100% alive at 1 year, respectively). Renal survival analysis showed significant differences among the 3 groups (P = 0.04, with 65%, 10%, and 15% off dialysis therapy at 1 year, respectively).

CONCLUSION

In patients with both anti-GBM antibodies and MPO-ANCAs, histological findings differ from those of patients with anti-GBM antibodies only. However, renal survival in these patients is not better than that in anti-GBM-positive patients and is worse compared with patients with MPO-ANCAs only.

ANCA and anti-GBM antibodies in diagnosis and follow-up of vasculitic disease

In the last decade, serological detection of anti-neutrophil cytoplasmic antibodies (ANCA) and of anti-glomerular basement membrane (GBM) antibodies has tremendously facilitated the diagnosis of small vessel vasculitides. Once diagnosed, these diseases have proven to be treatable. However, in contrast to anti-GBM disease, ANCA-associated vasculitides are chronic diseases with a high relapse rate. Since morbidity in ANCA-associated vasculitides is dictated by the frequency and severity of relapses, much health benefit would be achieved if a relapse could be prevented or early treatment started. Increases in ANCA titers and persistently high ANCA levels indicate a high risk of relapse and warrant clinical evaluation of the patient for signs of relapse. This review will focus on the value of ANCA and anti-GBM antibody testing in diagnosis and on the importance of these tests in follow-up of disease.

Pulmonary-renal vasculitic disorders: differential diagnosis and management

Pulmonary-renal syndrome (PRS) is a combination of diffuse pulmonary hemorrhage and glomerulonephritis. Pulmonary-renal syndrome is not a single entity and is caused by a variety of conditions, including Goodpasturés syndrome associated with autoantibodies to the glomerular and alveolar basement membranes, various forms of primary systemic vasculitis associated with serum positivity for antineutrophil cytoplasmic antibodies (ANCA), cryoglobulinemia, systemic lupus erythematosus, systemic sclerosis, antiphospholipid syndrome, environmental factors, and drugs. The majority of cases of PRS are associated with ANCAs. The antigen target in Goodpasturés syndrome is the alpha-3 chain of type IV collagen. The antigen target in PRS associated with systemic vasculitis is proteinase-3 and myeloperoxidase. Pulmonary-renal syndrome has been observed from the first to the ninth decade of life. The widespread adoption of serologic testing performed in an appropriate clinical context hopefully will limit diagnostic delay. The goals of treatment in PRS are to remove the circulating antibodies, to stop further production of autoantibodies, and to remove any antigen that stimulates antibody production. Treatment is based on plasmapheresis, steroids, and cyclophosphamide; however, infections are frequent contributors to death, and less toxic alternatives may improve outcome and prognosis resulting in a long-term survival. The degree of renal function and the percent of crescents on renal biopsy are better predictors of outcome. Renal transplantation can be safely carried out in PRS.

Autoantibodies in vasculitis

Before the mid-1980s the only autoantibody widely used to assist in diagnosing vasculitic disease was IgG antibody to the alpha(3) domain of the noncollagenous part of type IV collagen (anti-glomerular basement membrane). Since that time, antineutrophil cytoplasmic antibodies (ANCAs) directed at the azurophilic granule proteins proteinase-3 and myeloperoxidase have been established as clinically useful autoantibodies to support a diagnosis of Wegener's granulomatosis, microscopic polyangiitis, Churg-Strauss syndrome and limited forms of these primary, small vessel necrotizing and often granulomatous vasculitides. The establishment of standardized methods for identifying those antibodies was needed before they could be used in clinical practice. The levels of both types of ANCAs tend to increase in parallel with the degree of clinical disease activity, and they decrease with successful immunosuppressive therapy. More than one assay may have to be used to discover imminent exacerbations in proteinase-3-ANCA associated syndromes. Although autoantibodies to endothelial cells may be important players in the pathogenesis of several vasculitic conditions, they have not gained clinical popularity because of lack of standardized detection methods.

Vasculitis: Wegener granulomatosis, Churg-Strauss syndrome, microscopic polyangiitis, polyarteritis nodosa, and Takayasu arteritis

Identification, diagnosis, and management of the primary vasculitides and their attendant complications is a challenging task for the critical care physician. However, with appropriate therapy, the morbidity and mortality of these diseases can be markedly improved and allow the individual patient to return to their previous functional state.

Pulmonary renal syndrome: a 4-year, single-center experience

Pulmonary renal syndrome (PRS), defined as a combination of diffuse pulmonary hemorrhage and glomerulonephritis (GN), represents a severe syndrome for which minimal outcome data are available in the literature. We present a retrospective study of 14 consecutive patients from 1996 to 2000. Mean patient age was 65 +/- 2.1 (SEM) years, and 7 patients were women. At presentation, Po(2) on air was 6.0 +/- 0.5 kPa, and creatinine level was 554 +/- 70 micromol/L. Thirteen patients had systemic vasculitis, and 1 patient had systemic lupus erythematosus (SLE). Five patients were cytoplasmic antineutrophil cytoplasmic autoantibody (C-ANCA) positive, and 7 patients were perinuclear ANCA (P-ANCA) positive; 2 of the latter patients also were positive for anti-glomerular basement membrane antibodies. Renal biopsy was performed in 10 patients. Histological examination showed membranous GN in the patient with SLE and segmental necrotizing crescentic GN in the other 9 patients examined. Twelve of 14 patients were initially dialysis dependent, and 8 of 14 patients required ventilatory support. All patients were treated with corticosteroids, 8 of 14 patients were administered intravenous methylprednisolone, 13 of 14 patients were administered daily cyclophosphamide, and 12 of 14 patients underwent plasma exchange. Patients were followed up for 22 +/- 9 months. Early reduction in cyclophosphamide dosage was required in 9 patients for neutropenia. Seven patients were alive at the end of follow-up, but 5 patients (36%) died in the first month. Of the survivors, 85% and 67% were alive after 1 and 2 years of completed follow-up: 83% and 75% of these survivors were dialysis independent, respectively. Five relapses were seen in 4 patients. One patient died of progressive pulmonary fibrosis. Sepsis was a major factor in 6 of 7 deaths. This patient group was older than those previously reported. Findings confirm previous suggestions that PRS requiring intensive care treatment has high mortality, and early survivors have good 1- and 2-year outcomes. Cyclophosphamide-associated neutropenia and infection were frequent contributors to death, and less toxic alternatives may improve outcome in PRS.

Clinical use of serological tests for antineutrophil cytoplasmic antibodies. What do the studies say?

Trustworthy and clinically useful laboratory test results depend on high quality laboratory knowledge and performance and on close collaboration with experienced clinicians. Just like a diagnosis can only be made by contrasting it to a number of differential diagnoses, a prototype autoantibody profile can only be recognized if autoantibodies that partially mimic the former are just as well-known. In antineutrophil cytoplasmic antibody (ANCA)-associated small vessel vasculitides the characteristic autoantibody profile can only be demonstrated by use of at least two different methodologies and an assay-specific cut-off selection that clearly distinguishes between strongly positive and disease control low positive to negative values. Local serum banks containing samples from patients with well-characterized chronic immunoinflammatory diseases and ANCA-associated vasculitides are needed for such important studies whether in-house or commercial assays are used.

Diffuse alveolar hemorrhage syndromes

Diffuse alveolar hemorrhage (DAH) is a rare yet serious and frequently life-threatening complication of a variety of conditions. DAH may result from coagulation disorders, inhaled toxins, or infections. Most cases of DAH are caused by capillaritis associated with systemic autoimmune diseases such as antineutrophil cytoplasmic antibodies-associated vasculitis, anti-glomerular basement membrane disease, and systemic lupus erythematosus. Early recognition is crucial, because the prompt institution of supportive measures and immunosuppressive therapy is required for survival. Our understanding of DAH and its management is largely empiric and based on small case series and individual reports, many dating back more than one decade. To provide the practicing specialist with a rational diagnostic and management approach to the patient with DAH, this review summarizes the most recent publications and salient information derived from older publications.

Pulmonary renal syndrome in childhood: a report of twenty-one cases and a review of the literature

In adults, the term specific pulmonary renal syndrome describes disorders with pulmonary and glomerular manifestations and includes Wegener's granulomatosis, Goodpasture disease, and systemic lupus erythematosus. Nonspecific pulmonary renal syndrome refers to either pulmonary disease complicating glomerular disease, or glomerular diseases following pulmonary disease. Since little is known regarding pulmonary renal syndrome in childhood, we reviewed the charts of 21 pediatric patients with pulmonary renal syndromes treated by the Department of Pediatrics, University of Bern between 1991 and 1998; we also reviewed the pediatric literature that deals with specific pulmonary renal syndromes. Specific pulmonary renal syndrome was noted in 3 children with systemic vasculitis (Wegener granulomatosis, N = 2; microscopic polyangiitis, N = 1) and 2 with systemic lupus erythematosus. Nonspecific pulmonary renal syndrome was observed in 12 patients with pulmonary edema (N = 9), pulmonary thromboembolism (N = 2), and pulmonary infection (N = 1) complicating the course of a glomerular disease, and in 4 children with a pulmonary disease followed by a glomerular disease. Review of the literature disclosed 52 cases of specific pulmonary renal syndrome other than systemic lupus erythematosus: Wegener granulomatosis (N = 28), Goodpasture disease (N = 13), and Henoch-Schönlein purpura (N = 11). In addition, hemolytic uremic syndrome complicated pneumococcal pneumonia in 32 cases. We conclude that pulmonary renal syndromes need to be looked for in childhood. Apart from Wegener granulomatosis, Goodpasture disease, and systemic lupus erythematosus, Henoch-Schönlein purpura and hemolytic-uremic syndrome occasionally have both pulmonary and renal features.

Nonresolving or slowly resolving pneumonia

Given the variability in rate of radiographic resolution, it remains controversial to decide when to initiate an invasive diagnostic work-up for nonresolving or slowly resolving pulmonary infiltrates. In immunocompetent patients who present with classical features of CAP (i.e., fever, chills, productive cough, new pulmonary infiltrate), clinical response to therapy is the most important determinant for further diagnostic studies. Within the first few days, persistence or even progression of infiltrates on chest radiographs is not unusual. Defervescence, diminished symptoms, and resolution of leukocytosis strongly support a response to antibiotic therapy, even when chest radiographic abnormalities persist. In this context, observation alone is reasonable, and invasive procedures can be deferred. Serial radiographs and clinical examinations dictate subsequent evaluation. In contrast, when clinical improvement has not occurred and chest radiographs are unchanged or worse, a more aggressive approach is warranted. In this setting, we advise fiberoptic bronchoscopy with BAL and appropriate cultures for bacteria, legionella, fungi, and mycobacteria. When endobronchial anatomy is normal and there is no purulence to suggest infection, TBBs should be done to exclude noninfectious causes (discussed earlier) or infections attributable to mycobacteria or fungi. An aggressive approach is also warranted in patients who are clinically stable or improving when the rate of radiographic resolution is delayed. As discussed earlier, what constitutes excessive delay is controversial, and depends upon the acuity of illness, specific pathogen, extent of involvement (i.e., lobar versus multilobar), comorbidities, and diverse host factors. Stable infiltrates even 2 to 4 weeks after institution of antibiotic therapy does not mandate intervention provided patients are improving clinically. Invasive techniques can also be deferred when unequivocal, albeit incomplete, radiographic resolution can be demonstrated. Lack of at least partial radiographic resolution by 6 weeks, even in asymptomatic patients, however, deserves consideration of alternative causes (e.g., endobronchial obstructing lesions, or noninfectious causes). Fiberoptic bronchoscopy with BAL and TBBs has minimal morbidity and is the preferred initial invasive procedure for detecting endobronchial lesions or substantiating noninfectious causes. The yield of bronchoscopy depends on demographics, radiographic features, and pre-test likelihood. In the absence of specific risk factors, the incidence of obstructing lesions (e.g., bronchogenic carcinomas, bronchial adenomas, obstructive foreign body) is low. Bronchogenic carcinoma is rare in nonsmoking, young (< 50 years) patients but is a legitimate consideration in older patients with a history of tobacco abuse. Non-neoplastic causes (e.g., pulmonary vasculitis, hypersensitivity pneumonia, etc.) should be considered when specific features are present (e.g., hematuria, appropriate epidemiologic exposures). Ancillary serologic tests or biopsies of extrapulmonary sites are invaluable in some cases. In rare instances, surgical (open or VATS) biopsy is necessary to diagnose refractory or non-resolving "pneumonias."

The pulmonary-renal syndrome: a poorly understood clinicopathologic condition

The co-existence of pulmonary hemorrhage and glomerulonephritis delineates a severe syndrome, often underestimated, resulting from several diseases and frequently associated with serum positivity for antineutrophil cytoplasmic antibodies (ANCA) or antiglomerular basement membrane (GBM) antibodies. The most common illness presenting as pulmonary-renal syndrome is systemic vasculitis. Moreover, the idiopathic pulmonary-renal syndrome is a distinctive clinicopathologic entity with different pathogenetic mechanisms. Tissue immunofluorescence studies are fundamental in distinguishing anti-GBM antibody-mediated forms from immune-complex-mediated and ANCA-associated forms. The type of glomerular or alveolar immunologic injury is the main factor determining the outcome and thus the prognosis of the pulmonary-renal syndrome. Development and improvement of appropriate serologic detection techniques have given reliable and early guidance for diagnosing these cases.

Alternative therapies for vasculitis and proliferative nephritides: the role of cyclic AMP elevating agents

Cytoprotection by E-prostaglandins, working by elevation of intracellular cyclic AMP, is a natural physiological mechanism. When agents that elevate cAMP are used in pharmacological regimens they have potent anti-inflammatory effects that could be used to good effect as adjuncts for the control of vasculitides/nephritides.