Deborah Howarth

Randomised placebo-controlled trial of rituximab (anti-CD20) in active ulcerative colitis

Objective To assess the safety and efficacy of the B lymphocyte (anti-CD20) antibody, rituximab, in the treatment of steroid-resistant moderately active ulcerative colitis (UC). Methods A double-blinded, randomised controlled trial with a 2:1 ratio of treatment:placebo (phase II) was carried out in the setting of a University teaching hospital. The subjects comprised 24 patients with moderately active UC who have either failed to respond to conventional corticosteroid therapy or who have relapsed during corticosteroid withdrawal. Five of 8 placebo-treated patients and 12 of 16 rituximab-treated patients were receiving azathioprine, 6-mercaptopurine or methotrexate. Two infusions of rituximab 1 g in 500 ml of 0.9% saline intravenously over 4 h (n=16) or saline placebo (n=8) were given at 0 and 2 weeks. Patients still receiving corticosteroids on entry (placebo group 7/8; rituximab group 14/16) continued a standard steroid tapering regimen. The primary end point was remission (Mayo score ≤2) at 4 weeks. Secondary end points included response (Mayo score reduced ≥3) at 4 and 12 weeks. Results Mayo score at entry was higher in rituximab-treated patients (mean 9.19; 95% CI 8.31 to 10.06) than for placebo patients (7.63; 6.63 to 8.62, p=0.03). At week 4 only 1/8 placebo-treated patients and 3/16 rituximab-treated patients were in remission (p=1.0), but 8/16 rituximab-treated patients had responded compared with 2/8 placebo-treated patients, with a median reduction in Mayo score of 2.5 (rituximab) compared with 0 (placebo; p=0.07). This response was only maintained to week 12 in 4/16. Mucosal healing was seen at week 4 in 5/16 rituximab-treated patients and 2/8 placebo-teated patients (non-significant). Rituximab was well tolerated, with one chest infection, three mild infusion reactions plus one case of (probably unrelated) non-fatal pulmonary embolism. Conclusions Rituximab has no significant effect on inducing remission in moderately active UC not responding to oral steroids. There was a possible short-term response that was not sustained. Rituximab is well tolerated in UC. Clinical trial number NCT00261118.

Respiratory Syncytial Virus Binds and Undergoes Transcription in Neutrophils From the Blood and Airways of Infants With Severe Bronchiolitis

Background. Neutrophils are the predominant cell in the lung inflammatory infiltrate of infants with respiratory syncytial virus (RSV) bronchiolitis. Although it has previously been shown that neutrophils from both blood and bronchoalveolar lavage (BAL) are activated, little is understood about their role in response to RSV infection. This study investigated whether RSV proteins and mRNA are present in neutrophils from blood and BAL of infected infants. Methods. We obtained blood and BAL samples from 20 infants with severe RSV bronchiolitis and 8 healthy control infants. Neutrophil RSV F, G, and N proteins, RSV N genomic RNA, and messenger RNA (mRNA) were quantified. Results. RSV proteins were found in BAL and blood neutrophils in infants with RSV disease but not in neutrophils from healthy infants. BAL and blood neutrophils from infants with RSV disease, but not those from healthy infants, expressed RSV N genomic RNA, indicating uptake of whole virus; 17 of 20 BAL and 8 of 9 blood neutrophils from patients expressed RSV N mRNA. Conclusions. This work shows, for the first time, the presence of RSV proteins and mRNA transcripts within BAL and blood neutrophils from infants with severe RSV bronchiolitis.

Respiratory syncytial virus infection of airway epithelial cells, in vivo and in vitro, supports pulmonary antibody responses by inducing expression of the B cell differentiation factor BAFF.

Background The mechanisms regulating antibody expression within the human lung during airway infection are largely unknown. In this study, our objectives were to determine if infection with respiratory syncytial virus (RSV) upregulates expression of the B cell differentiation factors A proliferation inducing ligand (APRIL) and B cell activating factor of the TNF family (BAFF), if this is a common feature of viral airway infection, and how this is regulated in human airway epithelial cells. Methods We measured BAFF and APRIL protein expression in bronchoalveolar lavage (BAL) fluid from infants with severe RSV disease, and healthy control children, and in nasopharyngeal aspirates from preschool children with other single respiratory viral infections. We also measured mRNA expression in bronchial brushings from RSV-infected infants, and in RSV-infected paediatric primary airway epithelial cell cultures (pAEC). Beas-2B cell cultures were used to examine mechanisms regulating BAFF expression. Results BAFF protein and mRNA were elevated (in marked contrast with APRIL) in BAL and bronchial brushings, respectively, from RSV-infected infants. BAFF protein was also found in upper airway secretions from children with human metapneumovirus, H1N1, bocavirus, rhinovirus, RSV and Mycoplasma pneumoniae infection. BAFF mRNA and protein were expressed following in vitro RSV infection of both pAEC and Beas-2B cultures, with mRNA expression peaking 12-h postinfection. BAFF induction was blocked by addition of a neutralising anti-interferon-β antibody or palivizumab. Conclusions BAFF, produced through an interferon-β-dependant process, is a consistent feature of airway infection, and suggests a role for the airway epithelia in supporting protective antibody and B cell responses in the lung.

Chemokine binding protein M3 of murine gammaherpesvirus 68 modulates the host response to infection in a natural host.

Murine γ-herpesvirus 68 (MHV-68) infection of Mus musculus-derived strains of mice is an attractive model of γ-herpesvirus infection. Surprisingly, however, ablation of expression of MHV-68 M3, a secreted protein with broad chemokine-binding properties in vitro, has no discernable effect during experimental infection via the respiratory tract. Here we demonstrate that M3 indeed contributes significantly to MHV-68 infection, but only in the context of a natural host, the wood mouse (Apodemus sylvaticus). Specifically, M3 was essential for two features unique to the wood mouse: virus-dependent inducible bronchus-associated lymphoid tissue (iBALT) in the lung and highly organized secondary follicles in the spleen, both predominant sites of latency in these organs. Consequently, lack of M3 resulted in substantially reduced latency in the spleen and lung. In the absence of M3, splenic germinal centers appeared as previously described for MHV-68-infected laboratory strains of mice, further evidence that M3 is not fully functional in the established model host. Finally, analyses of M3s influence on chemokine and cytokine levels within the lungs of infected wood mice were consistent with the known chemokine-binding profile of M3, and revealed additional influences that provide further insight into its role in MHV-68 biology.

Neutrophil TLR4 expression is reduced in the airways of infants with severe bronchiolitis

Background: In respiratory syncytial virus (RSV) bronchiolitis, neutrophils account for >80% of cells recovered from the airways in bronchoalveolar lavage (BAL) fluid. This study investigated neutrophil activation and Toll-like receptor (TLR) expression in the blood and lungs of infants with severe RSV bronchiolitis. Methods: BAL fluid and (blood) samples were collected from 24 (16) preterm and 23 (15) term infants ventilated with RSV bronchiolitis, and 12 (8) control infants. Protein levels and mRNA expression of CD11b, myeloperoxidase (MPO) and TLRs 2, 4, 7, 8 and 9 were measured in neutrophils. Results: Blood neutrophils had more CD11b in preterm and term infants with RSV bronchiolitis than control infants (p<0.025) but similar amounts of MPO. BAL fluid neutrophils from infants with RSV bronchiolitis had greater amounts of CD11b and MPO than blood neutrophils and BAL fluid neutrophils from controls (p<0.01). Blood neutrophils from term infants with RSV bronchiolitis had less total TLR4 protein than preterm infants with RSV bronchiolitis (p = 0.005), and both had less than controls (p<0.04). Total TLR4 for each group was greater in BAL fluid neutrophils than in blood neutrophils. Blood neutrophils from preterm infants with RSV bronchiolitis had greater TLR4 mRNA expression than term infants with RSV bronchiolitis (p = 0.005) who had similar expression to controls (p = 0.625). Conclusions: In infants with severe RSV bronchiolitis, neutrophil activation starts in the blood and progresses as they are recruited into the airways. Total neutrophil TLR4 remains low in both compartments. TLR4 mRNA expression is unimpaired. This suggests that neutrophil TLR4 expression is deficient in these infants, which may explain why they develop severe RSV bronchiolitis.