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.

Screen-detected colorectal cancers show improved cancer-specific survival when compared with cancers diagnosed via the 2-week suspected colorectal cancer referral guidelines

AIM

Biennial screening for colorectal cancer using faecal occult blood testing has been shown to reduce the relative risk of mortality from colorectal cancer. The Norwich screening centre commenced screening in July 2006 and so far has diagnosed over 350 patients with colorectal cancer. We compared the stage at diagnosis and cancer-specific mortality and survival in patients diagnosed through screening with a cohort of symptomatic patients with colorectal cancer within the same age range.

METHOD

A comparative analysis was undertaken of all screen-detected colorectal cancer patients diagnosed between July 2006 and December 2010, with an age-matched group of patients diagnosed in the Norfolk and Norwich Hospital through the 2-week suspected colorectal cancer guidelines.

RESULTS

Three hundred and fifty-six cases of colorectal cancer were diagnosed through the screening programme, in patients with an age range of 60-79 years. In the same time period, 292 patients in the same age range were diagnosed with colorectal cancer through the 2-week suspected colorectal cancer pathway. Sixteen patients in the screening group had evidence of metastatic disease at presentation compared with 62 in the symptomatic group (χ(2) , P<0.001). The proportion of T1/T2 and Dukes A cancers was significantly greater in the screening group (χ(2) , P < 0.001). There were 21 colorectal cancer-related deaths in the screening group compared with 66 in the symptomatic group. Survival analysis curves showed significantly better survival in the screening group (log-rank analysis P<0.001).

CONCLUSION

Screening for colorectal cancer identifies cancers at a significantly earlier stage than in symptomatic patients, with subsequent improvement in cancer-specific survival.

Teaching corner: Regional anaesthesia for ophthalmic surgery

Performing safe and effective regional anaesthesia for ophthalmic surgery is an important skill for anaesthetic and ophthalmologic practitioners. Akinetic sharp-needle blocks are generally safe but rare, sight and life threatening complications occur. Sub-Tenon's block using a blunt canula provides akinesa and is a safer alternative but serious complications have been reported. This review provides an introduction to the relevant anatomy, local anaesthetic drugs and commonly used techniques and a practical guide to their safe performance.

Prospective randomized trial of laparoscopic gastrojejunostomy versus duodenal stenting for malignant gastric outflow obstruction

BACKGROUND

We prospectively compared laparoscopic gastrojejunostomy with duodenal stenting as a means of palliating malignant gastric outflow obstruction.

METHODS

A total of 27 patients with malignant gastric outflow obstruction were randomized to either laparoscopic gastrojejunostomy (LGJ) or duodenal stenting (DS) over a 3-year period.

RESULTS

Thirteen patients underwent successful LGJ and 10 had successful DS. Eight patients had complications after LGJ, but none had complications after DS. Patients who underwent LGJ had a significant increase in visual analog pain score at day 1 (p = 0.05), and also had a longer hospital stay compared to those who underwent DS (11.4 vs. 5.2 days, p = 0.02). After DS, patients experienced an improvement in physical health at 1 month as measured using the Short Form-36 (SF-36) questionnaire (p < 0.01). There was no change following LGJ.

CONCLUSION

Duodenal stenting is a safe means of palliating malignant gastric outflow obstruction. It offers significant advantages for patients compared with minimal-access surgery.

Correction of sickle cell disease in transgenic mouse models by gene therapy

Sickle cell disease (SCD) is caused by a single point mutation in the human betaA globin gene that results in the formation of an abnormal hemoglobin [HbS (alpha2betaS2)]. We designed a betaA globin gene variant that prevents HbS polymerization and introduced it into a lentiviral vector we optimized for transfer to hematopoietic stem cells and gene expression in the adult red blood cell lineage. Long-term expression (up to 10 months) was achieved, without preselection, in all transplanted mice with erythroid-specific accumulation of the antisickling protein in up to 52% of total hemoglobin and 99% of circulating red blood cells. In two mouse SCD models, Berkeley and SAD, inhibition of red blood cell dehydration and sickling was achieved with correction of hematological parameters, splenomegaly, and prevention of the characteristic urine concentration defect.

The effect of continuing penicillamine and gold treatment on the course of penicillamine and gold nephropathy

The effect of continuing penicillamine or gold treatment was examined in 53 patients with biopsy proven penicillamine (32) or gold (21) nephropathy. Thirty-two patients stopped penicillamine or gold treatment as soon as proteinuria was detected whilst 21 patients continued treatment for periods of 2-11 months. The 24-hour creatinine clearance and urinary protein excretion were measured serially for a median period of 6 years. No significant differences were observed in the initial or maximum proteinuria, the duration of the proteinuria or in the initial or latest creatinine clearances between the groups of patients. These results indicate that penicillamine or gold treatment may be continued for short periods under close supervision despite moderate proteinuria without causing permanent renal damage. As several alternative non-nephrotoxic agents are available for the treatment of rheumatoid arthritis, continued treatment with penicillamine or gold despite proteinuria is seldom indicated.