Associations between prior healthcare use, time to diagnosis, and clinical outcomes in inflammatory bowel disease: a nationally representative population-based cohort study.

BACKGROUND: Timely diagnosis and treatment of inflammatory bowel disease (IBD) may improve clinical outcomes. OBJECTIVE: Examine associations between time to diagnosis, patterns of prior healthcare use, and clinical outcomes in IBD. DESIGN: Using the Clinical Practice Research Datalink we identified incident cases of Crohn's disease (CD) and ulcerative colitis (UC), diagnosed between January 2003 and May 2016, with a first primary care gastrointestinal consultation during the 3-year period prior to IBD diagnosis. We used multivariable Cox regression to examine the association of primary care consultation frequency (n=1, 2, >2), annual consultation intensity, hospitalisations for gastrointestinal symptoms, and time to diagnosis with a range of key clinical outcomes following diagnosis. RESULTS: We identified 2645 incident IBD cases (CD: 782; UC: 1863). For CD, >2 consultations were associated with intestinal surgery (adjusted HR (aHR)=2.22, 95% CI 1.45 to 3.39) and subsequent CD-related hospitalisation (aHR=1.80, 95% CI 1.29 to 2.50). For UC, >2 consultations were associated with corticosteroid dependency (aHR=1.76, 95% CI 1.28 to 2.41), immunomodulator use (aHR=1.68, 95% CI 1.24 to 2.26), UC-related hospitalisation (aHR=1.43, 95% CI 1.05 to 1.95) and colectomy (aHR=2.01, 95% CI 1.22 to 3.27). For CD, hospitalisation prior to diagnosis was associated with CD-related hospitalisation (aHR=1.30, 95% CI 1.01 to 1.68) and intestinal surgery (aHR=1.71, 95% CI 1.13 to 2.58); for UC, it was associated with immunomodulator use (aHR=1.42, 95% CI 1.11 to 1.81), UC-related hospitalisation (aHR=1.36, 95% CI 1.06 to 1.95) and colectomy (aHR=1.54, 95% CI 1.01 to 2.34). For CD, consultation intensity in the year before diagnosis was associated with CD-related hospitalisation (aHR=1.19, 95% CI 1.12 to 1.28) and intestinal surgery (aHR=1.13, 95% CI 1.03 to 1.23); for UC, it was associated with corticosteroid use (aHR=1.08, 95% CI 1.04 to 1.13), corticosteroid dependency (aHR=1.05, 95% CI 1.00 to 1.11), and UC-related hospitalisation (aHR=1.12, 95% CI 1.03 to 1.21). For CD, time to diagnosis was associated with risk of CD-related hospitalisation (aHR=1.03, 95% CI 1.01 to 1.68); for UC, it was associated with reduced risk of UC-related hospitalisation (aHR=0.83, 95% CI 0.70 to 0.98) and colectomy (aHR=0.59, 95% CI 0.43 to 0.80). CONCLUSION: Electronic records contain valuable information about patterns of healthcare use that can be used to expedite timely diagnosis and identify aggressive forms of IBD.

Impact of antitumour necrosis factor therapy on surgery in inflammatory bowel disease: a population-based study.

OBJECTIVE: It is unclear whether widespread use of biologics is reducing inflammatory bowel disease (IBD) surgical resection rates. We designed a population-based study evaluating the impact of early antitumour necrosis factor (TNF) on surgical resection rates up to 5 years from diagnosis. DESIGN: We evaluated all patients with IBD diagnosed in Cardiff, Wales 2005-2016. The primary measure was the impact of early (within 1 year of diagnosis) sustained (at least 3 months) anti-TNF compared with no therapy on surgical resection rates. Baseline factors were used to balance groups by propensity scores, with inverse probability of treatment weighting (IPTW) methodology and removing immortal time bias. Crohn's disease (CD) and ulcerative colitis (UC) with IBD unclassified (IBD-U) (excluding those with proctitis) were analysed. RESULTS: 1250 patients were studied. For CD, early sustained anti-TNF therapy was associated with a reduced likelihood of resection compared with no treatment (IPTW HR 0.29 (95% CI 0.13 to 0.65), p=0.003). In UC including IBD-U (excluding proctitis), there was an increase in the risk of colectomy for the early sustained anti-TNF group compared with no treatment (IPTW HR 4.6 (95% CI 1.9 to 10), p=0.001). CONCLUSIONS: Early sustained use of anti-TNF therapy is associated with reduced surgical resection rates in CD, but not in UC where there was a paradoxical increased surgery rate. This was because baseline clinical factors were less predictive of colectomy than anti-TNF usage. These data support the use of early introduction of anti-TNF therapy in CD whereas benefit in UC cannot be assessed by this methodology.

Antidepressant medication use in Inflammatory Bowel Disease: a nationally representative population-based study.

BACKGROUND: Despite high rates of depression and anxiety, little is known about the use of antidepressants amongst individuals diagnosed with inflammatory bowel disease (IBD). AIMS: To evaluate temporal trends in the use of antidepressants; rates of antidepressant initiation and adherence of antidepressant use to international guidelines amongst individuals with IBD. METHODS: This is a study of 14,525 incident IBD cases from 2004 to 2016 compared with 58,027 controls matched 1:4 for age and sex from the Clinical Practice Research Datalink. After excluding tricyclic antidepressants, we performed a Cox regression analysis to determine the risk associated with antidepressant use and logistic regression analysis to determine risk associated with antidepressant undertreatment. RESULTS: Antidepressant use amongst individuals with IBD increased by 51% during the 12-year study period, who were 34% more likely to initiate antidepressants in the year after IBD diagnosis compared with controls (aHR:1.34, 95% CI 1.21-1.49). In those with IBD starting antidepressants, 67% received treatment lasting less than the duration recommended in international guidelines, of which 34% were treated for 1 month or less. 18-24 year olds were twice as likely to discontinue treatment within 1 month compared with those aged 40-60 years (aHR:2.03, 95% CI 1.40-2.95). Socioeconomic deprivation was also associated with early treatment discontinuation (aHR:1.40, 95% CI 1.07-1.83). CONCLUSIONS: In the year following IBD diagnosis individuals are significantly more likely to start antidepressants compared with controls, but treatment duration fell short of recommendations in the majority. Better integration of services may benefit individuals with IBD and psychiatric comorbidity.

Stoma Formation in Crohn's Disease and the Likelihood of Antidepressant Use: A Population-Based Cohort Study.

BACKGROUND & AIMS: The impact of a temporary or permanent stoma on mental health in Crohn's Disease (CD) is unknown. The aim was to examine the association between intestinal surgery and stoma formation and subsequent antidepressant medication (ADM) use. METHODS: Using the Clinical Practice Research Datalink, we identified individuals with CD who underwent intestinal surgery between 1998-2018. We excluded individuals with a prescription for an ADM in the 6 months before surgery. Individuals were stratified into three groups: no stoma, temporary stoma, and permanent stoma. We used Kaplan-Meier curves to examine initiation of ADM after intestinal surgery and Cox regression to identify risk factors for ADM use after intestinal surgery. RESULTS: We identified 1,272 cases of CD undergoing their first intestinal surgery. Of these, 871 (68.5%) had no stoma, 191 (15.0%) had a temporary stoma and 210 (16.5%) had a permanent stoma. The 10-year cumulative incidence of ADM use was 26.4%, 33.4% and 37.3% respectively. Individuals with a permanent stoma were 71% more likely to receive an ADM than those with no stoma (HR 1.71, 95% CI 1.20-2.44). Individuals with a temporary stoma reversed within 12 months had a similar likelihood of ADM use to those without stoma formation (HR 0.99, 95% CI 0.64-1.53) whereas temporary stoma formation with late reversal after 12 months was associated with significantly greater likelihood of ADM use (HR 1.85, 95% CI 1.15-2.96). CONCLUSIONS: Permanent stomas and temporary stomas with late reversal surgery are associated with increased ADM use after intestinal surgery, likely associated with increased anxiety and depression.

Association between antidepressant medication use and steroid dependency in patients with ulcerative colitis: a population-based study.

BACKGROUND: Animal studies indicate a potential protective role of antidepressant medication (ADM) in models of colitis but the effect of their use in humans with ulcerative colitis (UC) remains unclear. OBJECTIVE: To study the relationship between ADM use and corticosteroid dependency in UC. DESIGN: Using the Clinical Practice Research Datalink we identified patients diagnosed with UC between 2005 and 2016. We grouped patients according to serotonin selective reuptake inhibitor (SSRI) and tricyclic antidepressant (TCA) exposure in the 3 years following diagnosis: 'continuous users', 'intermittent users' and 'non-users'. We used logistic regression to estimate the adjusted risk of corticosteroid dependency between ADM exposure groups. RESULTS: We identified 6373 patients with UC. Five thousand two hundred and thirty (82%) use no ADMs, 627 (10%) were intermittent SSRI users and 282 (4%) were continuous SSRI users, 246 (4%) were intermittent TCA users and 63 (1%) were continuous TCA users.Corticosteroid dependency was more frequent in continuous SSRI and TCA users compared with non-users (19% vs 24% vs 14%, respectively, χ2 p=0.002). Intermittent SSRI and TCA users had similar risks of developing corticosteroid dependency to non-users (SSRI: OR 1.19, 95% CI 0.95 to 1.50, TCA: OR 1.14, 95% CI 0.78 to 1.66). Continuous users of both SSRIs and TCAs had significantly higher risks of corticosteroid dependency compared with non-users (SSRI: OR 1.62, 95% CI 1.15 to 2.27, TCA: OR 2.02, 95% CI 1.07 to 3.81). CONCLUSIONS: Continuous ADM exposure has no protective effect in routine clinical practice in UC and identifies a population of patients requiring more intensive medical therapy. ADM use is a flag for potentially worse clinical outcomes in UC.

Association of Genetic Variants in NUDT15 With Thiopurine-Induced Myelosuppression in Patients With Inflammatory Bowel Disease.

Importance: Use of thiopurines may be limited by myelosuppression. TPMT pharmacogenetic testing identifies only 25% of at-risk patients of European ancestry. Among patients of East Asian ancestry, NUDT15 variants are associated with thiopurine-induced myelosuppression (TIM). Objective: To identify genetic variants associated with TIM among patients of European ancestry with inflammatory bowel disease (IBD). Design, Setting, and Participants: Case-control study of 491 patients affected by TIM and 679 thiopurine-tolerant unaffected patients who were recruited from 89 international sites between March 2012 and November 2015. Genome-wide association studies (GWAS) and exome-wide association studies (EWAS) were conducted in patients of European ancestry. The replication cohort comprised 73 patients affected by TIM and 840 thiopurine-tolerant unaffected patients. Exposures: Genetic variants associated with TIM. Main Outcomes and Measures: Thiopurine-induced myelosuppression, defined as a decline in absolute white blood cell count to 2.5 × 109/L or less or a decline in absolute neutrophil cell count to 1.0 × 109/L or less leading to a dose reduction or drug withdrawal. Results: Among 1077 patients (398 affected and 679 unaffected; median age at IBD diagnosis, 31.0 years [interquartile range, 21.2 to 44.1 years]; 540 [50%] women; 602 [56%] diagnosed as having Crohn disease), 919 (311 affected and 608 unaffected) were included in the GWAS analysis and 961 (328 affected and 633 unaffected) in the EWAS analysis. The GWAS analysis confirmed association of TPMT (chromosome 6, rs11969064) with TIM (30.5% [95/311] affected vs 16.4% [100/608] unaffected patients; odds ratio [OR], 2.3 [95% CI, 1.7 to 3.1], P = 5.2 × 10-9). The EWAS analysis demonstrated an association with an in-frame deletion in NUDT15 (chromosome 13, rs746071566) and TIM (5.8% [19/328] affected vs 0.2% [1/633] unaffected patients; OR, 38.2 [95% CI, 5.1 to 286.1], P = 1.3 × 10-8), which was replicated in a different cohort (2.7% [2/73] affected vs 0.2% [2/840] unaffected patients; OR, 11.8 [95% CI, 1.6 to 85.0], P = .03). Carriage of any of 3 coding NUDT15 variants was associated with an increased risk (OR, 27.3 [95% CI, 9.3 to 116.7], P = 1.1 × 10-7) of TIM, independent of TPMT genotype and thiopurine dose. Conclusions and Relevance: Among patients of European ancestry with IBD, variants in NUDT15 were associated with increased risk of TIM. These findings suggest that NUDT15 genotyping may be considered prior to initiation of thiopurine therapy; however, further study including additional validation in independent cohorts is required.

Changing nationwide trends in endoscopic, medical and surgical admissions for inflammatory bowel disease: 2003-2013.

BACKGROUND AND STUDY AIMS: In the last decade, there have been major advances in inflammatory bowel disease (IBD) management but their impact on hospital admissions requires evaluation. We aim to investigate nationwide trends in IBD surgical/medical elective and emergency admissions, including endoscopy and cytokine inhibitor infusions, between 2003 and 2013. PATIENTS AND METHODS: We used Hospital Episode Statistics and population data from the UK Office for National Statistics. RESULTS: Age-sex standardised admission rates increased from 76.5 to 202.9/100 000 (p<0.001) and from 69.5 to 149.5/100 000 (p<0.001) for Crohn's disease (CD) and ulcerative colitis (UC) between 2003-2004 and 2012-2013, respectively. Mean length of stay (days) fell significantly for elective (from 2.6 to 0.7 and from 2.0 to 0.7 for CD and UC, respectively) and emergency admissions (from 9.2 to 6.8 and from 10.8 to 7.6 for CD and UC, respectively). Elective lower gastrointestinal (GI) endoscopy rates decreased from 6.3% to 3.7% (p<0.001) and from 18.4% to 17.6% (p=0.002) for CD and UC, respectively. Elective major abdominal surgery rates decreased from 2.8% to 1.0% (p<0.001) and from 4.9 to 2.4 (p=0.010) for CD and UC, respectively, with emergency rates also decreasing significantly for CD. Between 2006-2007 and 2012-2013, elective admission rates for cytokine-inhibitor infusions increased from 11.1 to 57.2/100 000 and from 1.4 to 12.1/100 000 for CD and UC, respectively. CONCLUSIONS: Rising IBD hospital admission rates in the past decade have been driven by an increase in the incidence and prevalence of IBD. Lower GI endoscopy and surgery rates have fallen, while cytokine inhibitor infusion rates have risen. There has been a concurrent shift from emergency care to shorter elective hospital stays. These trends indicate a move towards more elective medical management and may reflect improvements in disease control.

Patients with Endoscopically Visible Polypoid Adenomatous Lesions Within the Extent of Ulcerative Colitis Have an Increased Risk of Colorectal Cancer Despite Endoscopic Resection.

OBJECTIVES: Ulcerative colitis (UC) is associated with an increased risk of colorectal cancer (CRC). Few studies have looked at long-term outcomes of endoscopically visible adenomatous lesions removed by endoscopic resection in these patients. We aimed to assess the risk of developing CRC in UC patients with adenomatous lesions that develop within the segment of colitis compared to the remainder of an ulcerative colitis cohort. METHODS: We identified patients with a confirmed histological diagnosis of UC from 1991 to 2004 and noted outcomes till June 2011. The Kaplan-Meier method was used to estimate cumulative probability of subsequent CRC. Factors associated with risk of CRC were assessed in a Cox proportional hazards model. RESULTS: Twenty-nine of 301 patients with UC had adenomatous lesions noted within the segment of colitis. The crude incidence rate of developing colon cancer in patients with UC was 2.45 (95 % CI 1.06-4.83) per 1000 PYD and in those with UC and polypoid adenomas within the extent of inflammation was 11.07 (95 % CI 3.59-25.83) per 1000 PYD. Adjusted hazards ratio of developing CRC on follow-up in UC patients with polypoid dysplastic adenomatous lesions within the extent of inflammation was 4.0 (95 % CI 1.3-12.4). CONCLUSIONS: The risk of developing CRC is significantly higher in UC patients with polypoid adenomatous lesions, within the extent of inflammation, despite endoscopic resection. Patients and physicians should take the increased risk into consideration during follow-up of these patients.

Diagnostic imaging and radiation exposure in inflammatory bowel disease.

Diagnostic imaging plays a key role in the diagnosis and management of inflammatory bowel disease (IBD). However due to the relapsing nature of IBD, there is growing concern that IBD patients may be exposed to potentially harmful cumulative levels of ionising radiation in their lifetime, increasing malignant potential in a population already at risk. In this review we explore the proportion of IBD patients exposed to high cumulative radiation doses, the risk factors associated with higher radiation exposures, and we compare conventional diagnostic imaging with newer radiation-free imaging techniques used in the evaluation of patients with IBD. While computed tomography (CT) performs well as an imaging modality for IBD, the effective radiation dose is considerably higher than other abdominal imaging modalities. It is increasingly recognised that CT imaging remains responsible for the majority of diagnostic medical radiation to which IBD patients are exposed. Magnetic resonance imaging (MRI) and small intestine contrast enhanced ultrasonography (SICUS) have now emerged as suitable radiation-free alternatives to CT imaging, with comparable diagnostic accuracy. The routine use of MRI and SICUS for the clinical evaluation of patients with known or suspected small bowel Crohn's disease is to be encouraged wherever possible. More provision is needed for out-of-hours radiation-free imaging modalities to reduce the need for CT.

Impact of timing and duration of thiopurine treatment on first perianal surgery in Crohn's disease: UK population-based study (1995-2009).

BACKGROUND: The impact of thiopurine (TP) use on perianal surgery is uncertain. Our aim was to determine trends in perianal surgery and the impact of timing and duration of TPs on the risk of first perianal surgery. METHODS: We identified a population-based cohort of incident cases of Crohn's disease between 1995 and 2009. We used Kaplan-Meier analysis to determine trends in TP usage and first perianal surgery by era of diagnosis: era 1 (1995-2002) and era 2 (2003-2009). We quantified the impact of duration and timing of TPs on the risk of perianal surgery using a Cox regression model. RESULTS: We identified a cohort of 5235 incident cases of Crohn's disease. The 5-year cumulative probability of first perianal surgery decreased from 2.7% to 1.7% between era 1 and era 2, respectively (P = 0.03). TP use for greater than 18 months was associated with a 40% risk reduction for first perianal surgery (hazard ratio: 0.60, 95% confidence interval: 0.39-0.95) and 49% if TPs were used for 2 years or more (hazard ratio: 0.51, 95% confidence interval: 0.32-0.99). There was no demonstrable additional benefit from early TP use within the first year after diagnosis (hazard ratio: 0.85, 95% confidence interval: 0.52-1.40, P = 0.53). CONCLUSIONS: Over the past 15 years, TP use has increased by 50%, whereas perianal surgery rates have decreased by 37% among UK population with Crohn's disease. Sustained use for 18 months was associated with a reduced risk of perianal surgery by almost a half in the first 5 years after diagnosis.

The impact of timing and duration of thiopurine treatment on first intestinal resection in Crohn's disease: national UK population-based study 1989-2010.

OBJECTIVES: The efficacy of thiopurines (TPs) in altering the risk of surgery in Crohn's disease (CD) remains controversial. We evaluated the impact of TP therapy, optimal timing, and duration of TP therapy on first intestinal resection rates using a population-based cohort. METHODS: We constructed a population-based cohort of incident cases of CD between 1989 and 2005. We used the Kaplan-Meier analysis to calculate time trends in TP use and first intestinal resection in three groups defined by time period of diagnosis: 1989-1993, 1994-1999, and 2000-2005 groups A, B, and C, respectively. We quantified impact of duration and timing of TP treatment on likelihood of surgery using Cox regression and propensity score matching. RESULTS: We identified 5,640 eligible patients with CD. The 5-year cumulative probability of TP use increased from 12, 18, to 25% ( P<0.0001) while probability of first intestinal resection decreased from 15, 12 to 9% (P<0.001) in groups A, B, and C, respectively. Patients treated with at least 6 months of TP therapy had a 44% reduction in the risk of surgery (hazards ratio (HR): 0.56; 95% confidence interval (CI): 0.37-0.85) and those receiving at least 12 months of TP therapy had a 69% reduction in the risk of surgery (HR: 0.31; 95% CI: 0.22-0.44). Early treatment (<12 months from diagnosis) vs. late treatment with TP showed no additional benefit in reducing risk of surgery (HR: 0.41; 95% CI: 0.27-0.61 vs. 0.21; 95% CI: 0.13-0.34). CONCLUSIONS: Over the past 20 years, TP use has doubled, whereas intestinal surgery has fallen by one-third among the UK population of Crohn's patients. Prolonged exposure is associated with a reduced likelihood of surgery whereby more than 12 months TP therapy reduces the risk of first intestinal surgery two-fold; however, early initiation of TP treatment offered no apparent additional benefit.

The role of thiopurines in reducing the need for surgical resection in Crohn's disease: a systematic review and meta-analysis.

OBJECTIVES: The thiopurine (TP) analogs azathioprine and mercaptopurine have proven efficacy in inducing and maintaining clinical remission in Crohn's disease (CD). Their impact on the long-term need for surgery is uncertain since studies have reported conflicting results. The aim of this systematic review was to summarize and evaluate evidence of the published literature regarding those studies assessing the impact of TPs on the risk of first surgical resection in CD. METHODS: We searched Medline, EMBASE, CINAHL, and hand searched reference lists of identified articles, without language restrictions in August 2013. RESULTS: Seventeen retrospective observational studies (eight population based, three multicenter, and six referral center) representing 21,632 participants met our inclusion criteria. Of these 10 studies involving 12,586 participants provided data on the hazard ratio (HR) and 95% confidence intervals (CIs) evaluating use of TPs and surgical risk. The combined pooled HR of first intestinal resection with TP use was 0.59 (95% CI 0.48-0.73). CONCLUSIONS: TP use is associated with a 40% lowered risk of surgical resection in patients with CD. Despite significant reductions in rates of surgical resection in patients with CD over the last 5 decades and increasing use of TPs, a large proportion of patients with CD still require resectional surgery.

Preoperative steroid use and risk of postoperative complications in patients with inflammatory bowel disease undergoing abdominal surgery.

CONTEXT: Corticosteroids are the mainstay of medical therapies to induce remission in acute episodes of inflammatory bowel disease (IBD). However, evidence suggests that this may increase the risk of postoperative complications among patients with IBD who go on to have abdominal surgery. OBJECTIVE: To estimate the risk of postoperative complications following abdominal surgery in patients with IBD on steroids at the time of abdominal surgery. DESIGN: Meta-analysis of observational studies. METHODS: We searched medical electronic databases for full journal articles published after 1965 reporting on postoperative complications in patients with IBD undergoing abdominal surgery provided they compared patients treated with steroids with those not on steroids. We hand searched the reference lists of all retrieved articles. Two independent reviewers extracted data from studies meeting the inclusion criteria and any discrepancies were resolved by discussion. We carried out fixed effects meta-analysis, funnel plot and sensitivity analyses. RESULTS: A total of seven observational studies involving 1,532 patients met the inclusion criteria for risk of total complications, and five observational studies involving 1,714 patients met the inclusion criteria for risk of infectious complications. Pooled analysis showed an increased risk of all postoperative complications (OR 1.41, 95% confidence interval 1.07-1.87), as well as an increased risk of postoperative infectious complications (OR 1.68, 95% confidence interval 1.24-2.28) among patients on steroids. Patients who received higher doses of perioperative oral steroids (>40 mg) had a higher risk of total complications (OR 2.04 (95% CI 1.28-3.26). CONCLUSIONS: There is an increased risk of total as well as infectious complications following the use of steroids in patients with IBD.

Acute mesenteric infarction: an important cause of abdominal pain in ulcerative colitis.

We present four cases of acute mesenteric infarction in patients with active ulcerative colitis: one presenting prior to the diagnosis of ulcerative colitis, two at the time of diagnosis, and one many years after the diagnosis had been made. Intestinal ischaemia is an important part of the differential diagnosis in patients with ulcerative colitis presenting with abdominal pain. Conversely, in patients presenting with bloody diarrhoea after mesenteric ischaemia, ulcerative colitis should be considered.

Interleukin-4 and transforming growth factor beta have opposing regulatory effects on gamma interferon-mediated inhibition of Cryptosporidium parvum reproduction.

It was shown previously that enterocytes activated by gamma interferon (IFN-gamma) are efficient effector cells in the killing of Cryptosporidium parvum. How this function is regulated is not clearly understood, but transforming growth factor beta (TGF-beta) and the Th2 regulatory cytokines may play a role. Using an in vitro cell culture system, we investigated how the key regulatory cytokines interleukin-4 (IL-4), IL-10, IL-13, and TGF-beta might modulate the effect of IFN-gamma in inducing resistance to infection in enterocyte cell lines. The results showed that TGF-beta can abolish the inhibitory effect on C. parvum development and that neither IL-13 nor IL-10 influenced the action of IFN-gamma. In contrast, IL-4 cooperated with low concentrations of IFN-gamma (1 and 10 U/ml) to enhance parasite killing. One mechanism that appeared to be involved in the combined activity of IFN-gamma and IL-4 was intracellular Fe(2+) deprivation, but induction of nitric oxide production was not involved. In one cell line, the extents and durations of phosphorylation of STAT1, a transcription factor involved in IFN-gamma signaling, were similar when cells were stimulated with IFN-gamma alone and with IFN-gamma and IL-4 gamma, suggesting that the cooperative effect of the cytokines was not related to STAT1 activation. The effects of the presence of TGF-beta and IL-4 on IFN-gamma function did not appear to involve any alteration in the level of expression of IFN-gamma receptors.

Management of protozoa-related diarrhea in HIV infection.

Protozoa infections are an important cause of chronic diarrhea in patients infected with HIV. The introduction of highly active antiretroviral treatment to the management of HIV in the mid 1990s has led to a dramatic reduction in the incidence of these opportunistic infections in Europe and America. In contrast, in the developing world where such treatments are not readily affordable, protozoa-related diarrhea remains a major cause of morbidity and mortality in HIV-infected individuals. In this review, the optimum investigations required to diagnose these pathogens in HIV-related diarrhea, as well as current treatment options, will be discussed.

The role of cytokines in the pathogenesis of Cryptosporidium infection.

First described in 1912, the importance of the coccidian parasite Cryptosporidium parvum as an enteropathogen in humans was not recognized until the early 1980s, when it was found to be a common opportunistic infection in AIDS. Infection with this organism triggers a complex array of innate and cell-mediated immune responses within the intestinal mucosa. How cytokines and chemokines interact to regulate these responses in order to achieve clearance of the parasite yet preserve the integrity of the intestinal mucosa is still being unravelled. T helper type 1 cytokines, and particularly interferon-gamma, have long been considered to be the main orchestrators of the immune response to this infection, but recent studies suggest that T helper type 2 cytokines may also be involved. In addition, transforming growth factor-beta 1, although having little effect on parasite development, is an important modulator of the immune response and plays a role in protecting the epithelial integrity from the effects of the inflammatory process.