Tissue-resident alveolar macrophages reduce O3-induced inflammation via MerTK mediated efferocytosis

Lung inflammation, caused by acute exposure to ozone (O3) - one of the six criteria air pollutants - is a significant source of morbidity in susceptible individuals. Alveolar macrophages (AMØs) are the most abundant immune cells in the normal lung and their number increases following O3 exposure. However, the role of AMØs in promoting or limiting O3-induced lung inflammation has not been clearly defined. Here, we used a mouse model of acute O3 exposure, lineage tracing, genetic knockouts, and data from O3-exposed human volunteers to define the role and ontogeny of AMØs during acute O3 exposure. Lineage tracing experiments showed that 12, 24, and 72 h after exposure to O3 (2 ppm) for 3h all AMØs were tissue-resident origin. Similarly, in humans exposed to FA and O3 (200 ppb) for 135 minutes, we did not observe ~21h post-exposure an increase in monocyte-derived AMØs by flow cytometry. Highlighting a role for tissue-resident AMØs, we demonstrate that depletion of tissue-resident AMØs with clodronate-loaded liposomes led to persistence of neutrophils in the alveolar space after O3 exposure, suggesting that impaired neutrophil clearance (i.e., efferocytosis) leads to prolonged lung inflammation. Moreover, depletion of tissue-resident AMØ demonstrated reduced clearance of intratracheally instilled apoptotic Jurkat cells, consistent with reduced efferocytosis. Genetic ablation of MerTK - a key receptor involved in efferocytosis - also resulted in impaired clearance of apoptotic neutrophils followed O3 exposure. Overall, these findings underscore the pivotal role of tissue-resident AMØs in resolving O3-induced inflammation via MerTK-mediated efferocytosis.

Ulcerative colitis in a renal transplant patient with previous Goodpasture disease

A renal transplant was performed in a 6-year-old boy who developed end stage renal disease (ESRD) after presenting with antiglomerular basement membrane (anti-GBM) disease. At 10 years of age he developed ulcerative colitis while being immunosuppressed with cyclosporin, prednisone, and azothioprine. He had a pancolectomy, and at 14 years has no symptoms of ulcerative colitis or anti-GBM disease. HLA typing revealed that he was homozygous for HLA DR2. The co-occurrence of anti-GBM disease and ulcerative colitis has not previously been described. Although there is no known common etiology for these two autoimmune diseases, we propose that the patient's homozygosity at HLA DR2 may have predisposed him to both.

Wegener granulomatosis--an atypical case

An unusual sequence of the clinical manifestations of microvascular disease is described in a 15 year-old girl. She initially presented with acute renal failure caused by a crescentic glomerulonephritis associated with positive tests for MPO-ANCA. Eighteen months later she had pulmonary hemorrhage and respiratory failure. An open lung biopsy showed granulomas that were diagnostic for Wegener granulomatosis. We discuss the diagnostic dilemmas faced in attempts to distinguish infective causes of pulmonary granulomas, such as tuberculosis or fungi, from granulomas associated with vasculitis, in a patient previously treated with immunosuppressive therapy.

Nephrotic syndrome at 5 months: no definitive treatment or complications for 12 years

We describe a patient who developed nephrotic syndrome at 5 months, with extensive glomerular and tubular damage on biopsy. The patient was treated with diuretics and was asymptomatic for a decade despite unremitting proteinuria. A repeat biopsy at 13 years of age showed remarkable healing with histopathological features consistent with "minimal change" nephrotic syndrome. This patient illustrates a favorable clinical outcome, without specific treatment, of nephrotic syndrome of long duration.

Diaphragmatic hernia-exomphalos-hypertelorism syndrome: a new case and further evidence of autosomal recessive inheritance

We describe a male patient with wide anterior fontanel and metopic suture, hypertelorism, down slanting palpebral fissures, bilateral iris coloboma, omphalocele, and bilateral absence of the diaphragm with herniation of abdominal organs causing pulmonary hypoplasia and death. Autopsy also showed intestinal malrotation. All findings in this case are consistent with those described as a newly recognized syndrome by Donnai and Barrow [1993]. Since the parents are first cousins, this case provides further evidence for the previously postulated autosomal recessive inheritance pattern. Follow-up on the patients and families reported by Donnai and Barrow [1993] also supports autosomal recessive inheritance.

3-Year-old phenotypic female with campomelic dysplasia and bilateral gonadoblastoma

The authors report the case of bilateral gonadoblastomas in a phenotypic female, with a 46,XY karyotype, with campomelic dysplasia. Although campomelic dysplasia with gonadal dysgenesis should be expected to contribute to an increased risk of gonadoblastoma, this is the first documented case report of campomelic dysplasia and gonadoblastoma. Phenotypic females with campomelic dysplasia should be karyotyped once the skeletal dysplasia is recognized. phenotypic females with campomelic dysplasia should undergo gonadectomy if their karyotype includes a Y chromosome or fragment.

Chronic active hepatitis in a child with human immunodeficiency virus infection

The pathologic changes in the liver of a child with human immunodeficiency virus infection are described. The liver biopsy specimens show chronic active hepatitis with bile duct damage. To our knowledge, the etiology and pathogenesis of chronic liver disease in children with acquired immunodeficiency syndrome is not known. In this child, chronic active hepatitis is probably related to hepatitis B.