Sickle Cell Disease—Pulmonary Complications and a Proinflammatory State?

Acute chest syndrome in sickle cell anaemia: higher serum levels of interleukin-8 and highly sensitive C-reactive proteins are associated with impaired lung function

BACKGROUND

Sickle cell anaemia (SCA) is a chronic inflammatory disorder with multiple organ manifestations including acute and long-term pulmonary dysfunction.

AIMS/OBJECTIVES

To assess lung function of children with SCA and determine the possible role of acute chest syndrome (ACS), serum inflammatory cytokines, highly sensitive C-reactive protein (hs-CRP), leucocytes and 25-hydroxyvitamin D on the development of impaired lung function.

SUBJECTS AND METHODS

Lung function of 76 children with SCA was determined by spirometer and classified into normal or impaired. Sociodemographic, clinical, haematological, biochemical and immunological data of the two groups were compared by univariate and multivariate analyses.

RESULTS

Fifty (65.8%) patients had impaired lung function, comprising of 30.3%, 3.9% and 31.6% with restrictive, obstructive and mixed disease patterns, respectively. Children with previous ACS were 3.6 times more likely to have impaired lung function than those without ACS (82.1% vs 56.3%, p = 0.02, OR 3.6, 95% CI 1.2-10.8). Interleukin (IL)-8 and hs-CRP were significantly higher in patients with impaired lung function (p = 0.02 and <0.001, respectively). Using logistic regression, previous ACS (OR 5.8, 95% CI 1.1-5.8, p = 0.03) and higher serum IL-8 levels (OR 3.0, 95% CI 1.0-8.0, p = 0.02) independently predicted the presence of abnormal lung function.

CONCLUSIONS

Lung dysfunction, predominantly restrictive pattern, is common in SCA and is associated with previous ACS and alterations in immunological markers, especially serum IL-8 and hs-CRP.

ABBREVIATIONS

ACS: acute chest syndrome; CBT: chronic blood transfusion; ELISA: enzyme-linked immunosorbent assay; FEV₁: forced expiratory volume in 1 s; FVC: forced vital capacity; HPLC: high-density liquid chromatography; hs-CRP: highly sensitive C-reactive proteins; HU: hydroxyurea; IL: Interleukin; PEFR: peak expiratory flow rate; SEM: standard error of the mean; TLC: total lung capacity; 25-OHD: 25-hydroxyvitamin D; VOC: vaso-occlusive crisis; WGH: Wesley Guild Hospital.

Função pulmonar em portadores de anemia falciforme

OBJETIVO: Avaliar a função ventilatória por meio de espirometria, em escolares e adolescentes com anemia falciforme (AF), relacionando os achados a parâmetros clínicos e hematológicos. MÉTODOS: Foram avaliados portadores de AF de ambos os gêneros, a partir dos dez anos, clinicamente estáveis, sem intercorrências agudas, que foram submetidos à espirometria e avaliados quanto à saturação transcutânea de oxigênio, níveis de hemoglobina e contagem de leucócitos. Verificou-se a associação de alterações à espirometria com as características demográficas, clínicas e laboratoriais dos pacientes analisados. Para a análise estatística, aplicou-se o teste do qui-quadrado e o teste t para amostras não pareadas, sendo significante p<0,05. RESULTADOS: Foram estudados 51 pacientes e, em 40 (78%), identificou-se comprometimento do perfil espirométrico, do quais 20 (50%) apresentaram distúrbio ventilatório misto ou combinado, 13 (33%) mostraram perfil restritivo clássico e sete (18%), distúrbio ventilatório obstrutivo. Dos sete, em cinco (71%) observou-se resposta broncodilatadora positiva. A contagem total de leucócitos associou-se à função pulmonar alterada. O volume expiratório forçado no primeiro segundo sem broncodilatador, a capacidade vital forçada antes e após broncodilatador e o fluxo expiratório forçado entre 25 e 75% da capacidade vital forçada após broncodilatador foram significativamente menores nos pacientes com relato de internação hospitalar prévia por doença pulmonar aguda. CONCLUSÕES: A maioria dos pacientes apresentou alteração da função pulmonar, predominando o padrão misto ou combinado, seguido pelo restritivo clássico. Presença de leucocitose, na ausência de intercorrências agudas, associou-se a comprometimento de função pulmonar.

Histopathology of experimentally induced asthma in a murine model of sickle cell disease

Asthma is a comorbid condition associated with increased rates of pain, acute chest syndrome, and premature death in human sickle cell disease (SCD). We developed an experimental asthma model in SCD and control mice expressing either normal human or murine hemoglobin to determine its effect on mortality and lung pathology. To induce lung inflammation, experimental mice were sensitized to ovalbumin (OVA) by subcutaneous OVA implantation (Sen), allowed 2 weeks to recover, and then divided into 2 groups, each receiving over a subsequent 10-day period the same dosage of aerosolized OVA but 2 different levels of exposure: 15 minutes (LoSen) and 30 minutes (HiSen). During recovery, 10% of SCD mice died compared with no deaths in control mice. An additional 30% of HiSen SCD mice died during aerosolization compared with 10% in LoSen SCD. Histologic indices of lung inflammation (eg, eosinophil recruitment, airway and vessel wall thickening, and immunoreactive TGFbeta and fsp-1) and bronchial alveolar lavage fluid eosinophil peroxidase activity differentially increased in sensitized mice compared with unsensitized mice. Our findings indicate SCD mice with experimentally induced asthma are more susceptible to death and pulmonary inflammation compared with control mice, suggesting that asthma contributes significantly to morbidity and mortality in SCD.

Tuberculosis in adult patients with sickle cell disease

OBJECTIVE

Although infection, in particular pulmonary infection, is a common complication of sickle cell disease (SCD) and although SCD is frequent in populations where the prevalence of tuberculosis is high, the relationship between the two diseases has never been studied. We conducted a study to assess the epidemiological and clinical pattern of tuberculosis in adult patients with SCD.

METHODS

We retrospectively reviewed the cases of tuberculosis reported within our cohort of 457 SCD patients from January 1998 to April 2006 in the adult sickle cell center of Hôpital Tenon, Paris, France.

RESULTS

We identified 12 cases of tuberculosis, 8 men and 4 women. There were 7 lymph node lesions, 3 pulmonary lesions and 2 vertebral lesions. The incidence of pulmonary and extrapulmonary tuberculosis was respectively of 82 and 246 cases per 100,000, to compare with an expected incidence of 184 cases, and 65 cases per 100,000. Three of the patients with lymph node tuberculosis were asymptomatic. No case of multi-organ involvement was seen. No other cause of immunodepression than the functional asplenia was found. All the patients showed clinical improvement under treatment.

CONCLUSIONS

In SCD patients, lymph node tuberculosis appears to have a higher incidence than that in an epidemiologically comparable population, and has a rather indolent presentation and a favourable outcome. Pulmonary tuberculosis seems to be less frequent than expected.

Vascular growth and remodeling in compensatory lung growth following right lobectomy

Studies in animal models have shown that, following lobectomy (LBX), there is compensatory growth in the remaining lung. The vascular growth response following right LBX (R-LBX) is poorly understood. To test the hypothesis that arterial growth and remodeling occur in response to LBX, in proportion to the amount of right lung tissue removed, two (24% of lung mass; R-LBX2 group) or three right lobes (52% of lung mass; R-LBX3 group) were removed via thoracotomy from adult rats. Sham control animals underwent thoracotomy only. Arteriograms were generated 3 wk after surgery. The areas of the left lung arteriogram, arterial branching, length of arterial branches, arterial density, and arterial-to-alveolar ratios were measured. To determine whether R-LBX causes vascular remodeling and pulmonary hypertension, muscularization of arterioles and right ventricular hypertrophy were assessed. Lung weight and volume indexes were greater in R-LBX3. Arterial area of the left lung increased 26% in R-LBX2 and 47% in R-LBX3. The length of large arteries increased in R-LBX3 and to a lesser extent in R-LBX2. The ratio of distal pulmonary arteries to alveoli was similar after R-LBX2 compared with sham but was 30% lower in R-LBX3. Muscularization of arterioles increased after R-LBX3, but not in R-LBX2. Right ventricular hypertrophy increased 50-70% in R-LBX3, but not in R-LBX2. Whereas removal of three right lung lobes induced arterial growth in the left lungs of adult rats, which was proportionate to the number of lobes removed, the ratio of distal pulmonary arteries to alveoli was not normal, and vascular remodeling and pulmonary hypertension developed.