Exosomes in immunoregulation of chronic lung diseases.

Exosomes are nano-sized, membrane-bound vesicles released from cells that transport cargo including DNA, RNA, and proteins, between cells as a form of intercellular communication. In addition to their role in intercellular communication, exosomes are beginning to be appreciated as agents of immunoregulation that can modulate antigen presentation, immune activation, suppression, and surveillance. This article summarizes how these multifaceted functions of exosomes may promote development and/or progression of chronic inflammatory lung diseases including asthma, chronic obstructive pulmonary disease, and pulmonary fibrosis. The potential of exosomes as a novel therapeutic is also discussed.

Autoimmunity caused by disruption of central T cell tolerance. A murine model of drug-induced lupus.

A side effect of therapy with procainamide and numerous other medications is a lupus-like syndrome characterized by autoantibodies directed against denatured DNA and the (H2A-H2B)-DNA subunit of chromatin. We tested the possibility that an effect of lupus-inducing drugs on central T cell tolerance underlies these phenomena. Two intrathymic injections of procainamide-hydroxylamine (PAHA), a reactive metabolite of procainamide, resulted in prompt production of IgM antidenatured DNA antibodies in C57BL/6xDBA/2 F1 mice. Subsequently, IgG antichromatin antibodies began to appear in the serum 3 wk after the second injection and were sustained for several months. Specificity, inhibition and blocking studies demonstrated that the PAHA-induced antibodies showed remarkable specificity to the (H2A-H2B)-DNA complex. No evidence for polyclonal B cell activation could be detected based on enumeration of Ig-secreting B cells and serum Ig levels, suggesting that a clonally restricted autoimmune response was induced by intrathymic PAHA. The IgG isotype of the antichromatin antibodies indicated involvement of T cell help, and proliferative responses of splenocytes to oligonucleosomes increased up to 100-fold. As little as 5 microM PAHA led to a 10-fold T cell proliferative response to chromatin in short term organ culture of neonatal thymi. We suggest that PAHA interferes with self-tolerance mechanisms accompanying T cell maturation in the thymus, resulting in the emergence of chromatin-reactive T cells followed by humoral autoimmunity.

T cell receptor biases and clonal proliferations among lung transplant recipients with obliterative bronchiolitis.

Obliterative bronchiolitis (OB) is the most serious late complication of lung transplantation, but the pathogenesis of this disorder has not been elucidated. We sought evidence that OB is mediated by a cellular immunologic response by characterizing T cell antigen receptor beta-chain variable gene (TCRBV) repertoires in lung allograft recipients. Expression levels of 27 TCRBV among recipients were determined by multiprobe RNase protection assay after PCR amplification. In comparison to recipients with no evidence of rejection (n = 9), the PBL TCRBV repertoires of OB subjects (n = 16) exhibited more frequent expansions (16 vs. 9% of all measured TCRBV, P < 0.02), and the magnitudes of these abnormalities were greater (8.2 +/- 0.8 vs. 4.5 +/- 0.3 SD from mean normal values, P < 0.01). TCRBV sequencing showed these expansions were composed of clonal or oligoclonal populations. Thus, T cell responses in the recipients are marked by highly selective clonal expansions, presumably driven by indirect recognition of a limited number of immunodominant alloantigens. These processes are exaggerated among allograft recipients with OB, implying that cognate immune mechanisms are important in the pathogenesis of the disorder. Furthermore, the prominence of finite, distinct TCR phenotypes raise possibilities for development of novel diagnostic modalities and targeted immunotherapies for OB and other manifestations of chronic allograft rejection.

Reappraisal of the historical selective pressures for the CCR5-Delta32 mutation.

HIV strains are unable to enter macrophages that carry the CCR5-Delta32 deletion; the average frequency of this allele is 10% in European populations. A mathematical model based on the changing demography of Europe from 1000 to 1800 AD demonstrates how plague epidemics, 1347 to 1670, could have provided the selection pressure that raised the frequency of the mutation to the level seen today. It is suggested that the original single mutation appeared over 2500 years ago and that persistent epidemics of a haemorrhagic fever that struck at the early classical civilisations served to force up the frequency to about 5x10(-5) at the time of the Black Death in 1347.

Combining Healthcare-Based and Participatory Approaches to Surveillance: Trends in Diarrheal and Respiratory Conditions Collected by a Mobile Phone System by Community Health Workers in Rural Nepal.

BACKGROUND: Surveillance systems are increasingly relying upon community-based or crowd-sourced data to complement traditional facilities-based data sources. Data collected by community health workers during the routine course of care could combine the early warning power of community-based data collection with the predictability and diagnostic regularity of facility data. These data could inform public health responses to epidemics and spatially-clustered endemic diseases. Here, we analyze data collected on a daily basis by community health workers during the routine course of clinical care in rural Nepal. We evaluate if such community-based surveillance systems can capture temporal trends in diarrheal diseases and acute respiratory infections. METHODS: During the course of their clinical activities from January to December 2013, community health workers recorded healthcare encounters using mobile phones. In parallel, we accessed condition-specific admissions from 2011-2013 in the hospital from which the community health program was based. We compared diarrhea and acute respiratory infection rates from both the hospital and the community, and assigned three categories of local disease activity (low, medium, and high) to each week in each village cluster with categories determined by tertiles. We compared condition-specific mean hospital rates across categories using ANOVA to assess concordance between hospital and community-collected data. RESULTS: There were 2,710 cases of diarrhea and 373 cases of acute respiratory infection reported by community health workers during the one-year study period. At the hospital, the average weekly incidence of diarrhea and acute respiratory infections over the three-year period was 1.8 and 3.9 cases respectively per 1,000 people in each village cluster. In the community, the average weekly rate of diarrhea and acute respiratory infections was 2.7 and 0.5 cases respectively per 1,000 people. Both diarrhea and acute respiratory infections exhibited significant differences between the three categories of disease rate burden (diarrhea p = 0.009, acute respiratory infection p = 0.001) when comparing community health worker-collected rates to hospital rates. CONCLUSION: Community-level data on diarrhea and acute respiratory infections modestly correlated with hospital data for the same condition in each village each week. Our experience suggests that community health worker-collected data on mobile phones may be a feasible adjunct to other community- and healthcare-related data sources for surveillance of such conditions. Such systems are vitally needed in resource-limited settings like rural Nepal.

Interstitial and airspace granulation tissue reactions in lung transplant recipients.

Twenty-three transbronchial and open-lung biopsies from patients who had received a lung allograft displayed fibromyxoid plugs of granulation tissue within airways, airspaces, and the interstitium in a patchy distribution. This granulation tissue-like reaction was identified in three clinicopathologic settings. First, 11 cases occurred with acute lung rejection, of which four cases had been partially treated with steroids for a previous rejection episode. Second, in seven cases the fibromyxoid tissue represented the healing phase of previously diagnosed diffuse alveolar damage resulting from preservation (harvest) injury to the allograft. Third, five cases were related to infection: herpes, Pseudomonas, Serratia, Staphylococcus, and Pneumocystis pneumonias. Although organizing pneumonia-like responses usually suggest an infectious episode, this reaction may be seen as a manifestation of acute lung rejection or ischemic lung injury.

Whooping cough epidemics in London, 1701-1812: infection dynamics, seasonal forcing and the effects of malnutrition.

Time series analysis of the London Bills of Mortality, 1701-1812, reveals that whooping cough appeared as a lethal endemic disease after 1700 with epidemics of progressively increasing amplitude after 1720. The interepidemic period changed from 5 years (1720-1750) to 3 years (1750-1785) before returning to 5 years during 1785-1812. The epidemiology of whooping cough can be described by the mathematics of linearized dynamic systems and the interepidemic interval is determined by population size and susceptibility. The latter was governed by fluctuating levels of malnutrition, which were directly associated with oscillations in the wheat prices. It is suggested that the epidemics were driven in 1720-1785 by fluctuating seasonal temperatures which interacted with oscillations in wheat prices to produce an oscillation in susceptibility, but after 1785 the dynamics escaped from the pattern predicted by mathematical theory and the epidemics were apparently driven only by the wheat prices which generated a regular oscillation in susceptibility. The results emphasize the importance of an adequate nutritive level in combating whooping cough in the Third World today where it remains a lethal disease in children because of immunodeficiency linked to fluctuating and severe malnutrition which is often a consequence of crop cycles.

Clonal characteristics of T cell infiltrates in skin and synovium of patients with psoriatic arthritis.

Psoriasis is a chronic inflammatory skin disease that is often complicated by an inflammatory arthritis. Considerable evidence implicates cellular immune responses in psoriatic skin lesions, but the pathogenesis of the associated arthritis has not been elucidated. We analyzed T cell antigen receptor beta chain variable (TCRbetaV) gene repertoires among peripheral blood lymphocytes, skin and synovium of nine patients with psoriatic arthritis. RNase protection assays were used to quantitate the expression levels of 25 TCRbetaV genes, and CDR3 region sequencing was used to further characterize selected expansions. All patients exhibited significant TCRbetaV biases in the peripheral blood and moreover, all had expansions common to both skin and synovium. CDR3 sequencing demonstrated these expansions frequently consisted of oligo- or monoclonal populations. Although no ubiquitous CDR3 nucleotide sequences were identified, two patients shared identical sequences and several highly homologous amino acid motifs were present in skin and synovium among and between individual patients. Findings of common TCRbetaV expansions in diverse inflammatory sites, among multiple afflicted individuals, suggest that these T cell proliferations are driven by engagements with a limited set of conventional antigens. These findings demonstrate an important role for cognate T cell responses in the pathogenesis of psoriatic arthritis, and further suggest the inciting antigen(s) is identical or homologous between afflicted skin and synovium.

T-cell receptor biases and clonal proliferations in blood and pleural effusions of patients with lung cancer.

We sought evidence that pulmonary carcinomas mediate a cellular immunologic response by analyzing T-cell antigen receptor beta-chain variable gene (TCRBV) repertoires of lymphocytes from peripheral blood (PBL) and malignant pleural effusions (PEL) of five lung cancer patients. Expression levels of 27 TCRBV were quantitated by multiprobe RNase protection assay (RPA), and clonal expansions were identified by sequence enrichment nuclease assay (SENA) and junctional region sequencing. Abnormal TCRBV expansions were identified in all subjects by RPA (mean 6.9 +/- 1.7/patient), and their number closely correlated with elapsed time since initial diagnosis (r = 0.97). SENA, performed in specimens from three patients, confirmed the presence of mono or oligoclonality in 48% of abnormal RPA expansions, and further identified T-cell clones among TCRBV with normal expression levels. The majority of clonal expansions were among PEL, and were nearly equally divided between CD4 and CD8. These data show that T-cell repertoires of lung cancer patients are characterized by marked abnormalities and frequent clonal expansions, most likely representing responses to unique, tumor-specific antigens (TSA). Moreover, this process appears exaggerated among PEL, further suggesting that malignant effusions include local proliferations of tumor reactive T cells. These findings imply the presence of lung cancer TSA capable of eliciting cellular immune responses and raise the possibility that selective immunotherapies can ultimately be developed.

The diagnosis of Wegener's granulomatosis from transbronchial biopsy specimens.

It is widely believed that thoracotomy is necessary to obtain biopsy specimens adequate for the histopathologic demonstration of pulmonary Wegener's granulomatosis (WG). We report five patients with WG who were diagnosed by transbronchial biopsy (TBB). In three cases, a diagnosis of WG was made by TBB alone. In the other two patients, subsequent open lung biopsies confirmed the TBB findings but did not add essential diagnostic information. Our experience suggests TBB may be appropriate as the initial diagnostic procedure in selected cases of suspected WG. This approach requires an understanding of the diverse histologic features of WG and the correlation of clinical and pathologic data.

Nasal continuous positive airway pressure in atelectasis.

Nasal continuous positive airway pressure (CPAP) has been widely and safely used in the treatment of sleep disorders but has not been previously utilized for therapy of pulmonary atelectasis in adults. We observed three patients with significant atelectasis which was refractory to conventional chest physiotherapy. Bronchoscopy was not a viable therapeutic option in any patient. Therapy with continuous nasal CPAP was initiated at 10 to 15 cm H2O. The patients tolerated the therapy well and had prompt resolution of atelectasis. Nasal CPAP may be an effective modality for therapy of pulmonary atelectasis in spontaneously breathing patients, particularly when conventional therapies are not tolerated or are ineffectual.

Pulmonary capillaritis and alveolar hemorrhage. Update on diagnosis and management.

Pulmonary vascular inflammatory disorders may involve all components of the pulmonary vasculature, including capillaries. The principal histopathologic features of pulmonary capillaritis include capillary wall necrosis with infiltration by neutrophils, interstitial erythrocytes, and/or hemosiderin, and interalveolar septal capillary occlusion by fibrin thrombi. Immune complex deposition is variably present. Patients often present clinically with diffuse alveolar hemorrhage, which is characterized by dyspnea and hemoptysis; diffuse, bilateral, alveolar infiltrates on chest radiograph; and anemia. Pulmonary capillaritis has been reported with variable frequency and severity as a manifestation of Wegener's granulomatosis, microscopic polyarteritis, systemic lupus erythematosus, Goodpasture's syndrome, idiopathic pulmonary renal syndrome, Behçet's syndrome, Henoch-Schönlein purpura, IgA nephropathy, antiphospholipid syndrome, progressive systemic sclerosis, and diphenylhydantoin use. In addition to history, physical examination, and routine laboratory studies, certain ancillary laboratory tests, such as antineutrophil cytoplasmic antibodies, antinuclear antibodies, and antiglomerular basement membrane antibodies, may help diagnose an underlying disease. Diagnosis of pulmonary capillaritis can be made by fiberoptic bronchoscopy with transbronchial biopsy, but thoracoscopic biopsy is often employed. Since many disorders can result in pulmonary capillaritis with diffuse alveolar hemorrhage, it is crucial for clinicians and pathologists to work together when attempting to identify an underlying disease. Therapy depends on the disorder that gave rise to the pulmonary capillaritis and usually includes corticosteroids and cyclophosphamide or azathioprine. Since most diseases that result in pulmonary capillaritis are treated with immunosuppression, infection must be excluded aggressively.

Distinguishing between infection, rejection, and the adult respiratory distress syndrome after human lung transplantation.

The adult respiratory distress syndrome, bacterial pneumonia, cytomegalovirus pneumonitis, acute rejection, or a combination thereof were the primary causes of radiographic infiltrates or gas exchange abnormalities that occurred early after lung transplantation. The time of occurrence after transplantation, standard measures of clinical assessment as for nontransplant patients (i.e., vital signs, weight, white blood cell count, sputum, and cultures, etc.), bronchoalveolar lavage, and transbronchial lung biopsy were the primary tools used to analyze these situations. Bacterial pneumonia always occurred after postoperative day 2, acute rejection after postoperative day 5, and cytomegalovirus pneumonitis after postoperative day 16. Although cultures of bronchoalveolar lavage fluid were useful to detect pneumonia caused by bacteria, virus, and fungus, the types of cells recovered by bronchoalveolar lavage were not diagnostic of any type of disorder. Transbronchial lung biopsy was necessary to detect acute rejection and cytomegalovirus pneumonitis. Thus the cause of an early radiographic infiltrate or impairment of gas exchange was almost always reliably determined by using standard tools of clinical assessment, knowledge of the usual temporal sequence of the complications, and judicious use of bronchoalveolar lavage and transbronchial lung biopsy.

Donor cerebral emboli as a cause of acute graft dysfunction in lung transplantation.

Early graft dysfunction in lung transplantation has many causes, most commonly preservation injury. This report details a more unusual cause of graft failure and respiratory decompensation in the early postoperative period donor cerebral emboli occluding segments of the pulmonary arterial tree in the implanted lung allografts of two patients who had received single lung implants from a common donor in whom massive cerebral trauma had been incurred in a motor vehicle accident. The incidence, complications, and clinical manifestations of cerebral emboli are discussed.

Inspiratory timing of heart-lung transplant recipients during progressive hypercapnia.

The relationship between tidal volume (VT) and inspiratory duration (TI) displays biphasic characteristics during progressive hypercapnia in humans: an initial phase in which VT increases while TI remains constant (region I) and a subsequent phase with reciprocal decreases of TI as VT continues to increase (region II). Region II behavior is generally attributed, albeit inferentially, to lung volume-mediated inflation inhibition (Breuer-Hering reflex). To investigate this phenomenon, we compared CO2 responses of 10 heart-lung transplant recipients (HL) with normal pulmonary function tests and 13 normal controls. Despite pulmonary denervation, the HL exhibited region II behavior identical to controls. In four additional HL with pulmonary restriction, there were comparative decreases of the region II slope (P less than 0.05), but the absolute VT where the phase change between regions occurred was indistinguishable from the other groups. We conclude that TI shortening in humans during progressive hypercapnia occurs in the absence of pulmonary reflexes. The consistency of the VT associated with phase changes, despite pulmonary denervation, suggests that the stimulus for this behavior is volume displacement of extra-pulmonary respiratory structures.

Effects of pulmonary restriction on hypercapnic responses of heart-lung transplant recipients.

Previous studies of hypercapnic ventilatory responses (HCVR) in human heart-lung transplant recipients (HLTX) have yielded conflicting results. We compared the HCVR of restricted transplant recipients (HLTX-R) to recipients with normal pulmonary function (HLTX-N), and normal controls (C). HLTX-R exhibited limited tidal volume responses, whereas their frequency responses were essentially identical to those of other subjects. Accordingly, HCVR of HLTX-R (1.45 +/- 0.59 l.min-1.Torr CO2(-1)) were significantly depressed compared with both HLTX-N and C (2.90 +/- 0.55 vs 3.05 +/- 1.23, respectively) (P less than 0.02). Despite undoubtedly greater ventilatory impedances, airway (mouth) occlusion pressure responses (Pm0.1) during hypercarbia of HLTX-R (0.46 +/- 0.28 cmH2O) were similar to those of C (0.43 +/- 0.20) and paradoxically blunted compared with HLTX-N (0.83 +/- 0.36) (P less than 0.02). We conclude that pulmonary reflexes are superfluous for maintenance of HCVR in HLTX with normal respiratory mechanics, whereas the presence of moderate restriction results in profound depression of CO2 responses among these subjects.

Infant mortality and famine: a study in historical epidemiology in northern England.

OBJECTIVE: To examine whether periodic variations in annual infant mortality were associated with malnutrition and the poor quality of the food supply available to the community. DESIGN: Retrospective study of historical epidemiology of infant mortality by time series analysis and family reconstitution of parish registers of burials and baptisms. SETTING: Penrith, Cumbria, England, 1557-1812. SUBJECTS: A total of 17,500 births during 1557-1812. RESULTS: This community in the Eden Valley, Cumbria, close to the Scottish borders, was living under marginal conditions with high mortality and low fertility. Clear oscillations in infant mortality synchronise with the oscillations in the wheat price index which is regarded as a measure of the availability of food to the community, and to pregnant and nursing mothers in particular. Input-output analysis showed that the relationship between the wheat price index (input) and infant mortality (output) was highly significant (p < 0.001). Events during the famine of 1623 have been analysed in detail: high wheat prices during pregnancy caused subsequent severe infant mortality but did not have indirect effects on the subsequent mortality of the surviving children over the age of 1 year. Non-stationary oscillations in neonatal and post neonatal mortality were strongly coherent (p < 0.001) with the wheat price index throughout the period. CONCLUSIONS: Infant mortality is particularly sensitive to famine and also to the quality of the food supply available to pregnant and nursing mothers. The lags between neonatal and post-neonatal mortalities and wheat prices, together with the analysis of the famine of 1623, support the hypothesis that neonatal mortality was related to malnutrition in pregnancy whereas post-neonatal mortality was primarily directly dependent on exogenous causes in the first year of life.

Mechanisms and management of respiratory failure.

Management of respiratory failure is a complex endeavor that requires consideration of diverse etiologies and pathophysiology. Future investigation may lead to specific pharmacologic interventions of greater efficacy. In the meantime, careful attention to basic tenets of pathophysiology, supportive care, and reversal of underlying pulmonary insults is the foundation of successful therapy.