Prevalence of metabolic dysfunction-associated steatotic liver disease in the Middle East and North Africa

BACKGROUND AND AIMS

Metabolic dysfunction-associated steatotic liver disease (MASLD), formerly known as nonalcoholic fatty liver disease (NAFLD), is common and closely associated with type 2 diabetes (T2D). We assessed the prevalence of NAFLD/MASLD in the general population and among patients with T2D in the Middle East and North Africa (MENA) region.

METHODS

We searched PubMed and Embase for English-language articles published between 1990 and 2023 according to PRISMA. Each country's NAFLD/MASLD prevalence in the general population and in T2D patients was predicted by using a multivariable meta regression model. Input data were extracted from our systematic review, GBD and NCD Risk Factor Collaboration. Confidence intervals were constructed by using prediction intervals with the delta method.

RESULTS

Meta-analytic pooling estimated the prevalence of NAFLD/MASLD as 39.43% in the general population and 68.71% among T2D patients. NAFLD/MASLD prevalence has increased from 35.42% (2008-2016) to 46.20% (2017-2020). Using GBD-2019 dataset, it was predicted that there are 141.51 million cases of NAFLD/MASLD in the MENA region. The highest number of NAFLD/MASLD cases were expected in Egypt (25.71 million), followed by Türkiye (23.33 million) and Iran (19.85 million). Estimated NAFLD prevalence exceeded 40% in 10 of 21 countries with the top countries being Kuwait (45.37%), Egypt (45.0%), Qatar (44.4%), and Jordan (43.3%). Furthermore, it was predicted that there are 24.96 million cases of NAFLD/MASLD with T2D in the MENA region.

CONCLUSIONS

In the MENA region, prevalence of NAFLD/MASLD is very high and growing, necessitating an urgent need for regional public policy to deal with this growing burden.

An International Survey of Genitourinary and Renal Pathologists Regarding Evaluation of the Non-Neoplastic Parenchyma in Kidney Cancer Specimens

Increasing survivorship in kidney cancer patients has shifted treatment strategies to optimize renal function preservation. In 2010, the College of American Pathologists (CAP) updated their synoptic reporting guidelines for tumor nephrectomies to require evaluation of the nonneoplastic kidney parenchyma. We conducted this study to understand current practice behaviors regarding the evaluation of the nonneoplastic kidney parenchyma in tumor nephrectomy specimens. We emailed a 14-item multiple-choice survey to members of the Renal Pathology Society and Genitourinary Pathology Society. We also emailed a 12-item survey to program and associate program directors of American pathology residencies to assess the current state of renal pathology education. Ninety-eight genitourinary and 104 renal pathologists responded to the survey on the nonneoplastic kidney parenchyma. Ninety-five percent of respondents who examine tumor nephrectomies reported evaluating the nonneoplastic kidney parenchyma. Seventy-five percent of genitourinary pathologists and 67% of renal pathologists use synoptic reporting, and 81% use the CAP protocol. Thirty-nine percent of respondents report always contacting the clinician when they find evidence of medical renal disease. Forty-two program leaders responded to our renal pathology education survey, and 64% of them have a mandatory renal pathology rotation that on average lasts about 2 to 4 weeks. The majority of pathologists examine the nonneoplastic kidney parenchyma of tumor nephrectomies and frequently report incidences of new medical renal disease directly to clinicians, but there remains room for improvement and educational gaps during residency training. Further efforts to standardize both this evaluation and renal pathology education will improve patient care.

The Global Epidemiology of Nonalcoholic Fatty Liver Disease and Nonalcoholic Steatohepatitis Among Patients With Type 2 Diabetes

BACKGROUND & AIMS

Nonalcoholic fatty liver disease (NAFLD), now known as metabolic dysfunction associated steatotic liver disease (MASLD), is closely associated with type 2 diabetes (T2D). Our aim was to estimate the most recent global prevalence of NAFLD/MASLD, nonalcoholic steatohepatitis (NASH), now known as metabolic dysfunction associated steatohepatitis (MASH), advanced fibrosis, and mortality among patients with T2D.

METHODS

We systematically searched PubMed and Ovid MEDLINE for terms including NAFLD, NASH, and T2D published in 1990-2023 according to PRISMA. The meta-analysis was conducted using a random-effects model. Assessment of bias risk used the Joanna Briggs Institute appraisal tool.

RESULTS

From 3134 studies included in the initial search, 123 studies (N = 2,224,144 patients with T2D) were eligible. Another 12 studies (N = 2733 T2D patients with liver biopsy) were eligible for histologic assessments. The global pooled prevalence of NAFLD/MASLD among patients with T2D was 65.33% (95% confidence interval, 62.35%-68.18%). This prevalence increased from 55.86% (42.38%-68.53%) in 1990-2004 to 68.81% (63.41%-73.74%) in 2016-2021 (P = .073). The highest NAFLD/MASLD prevalence among T2D patients was observed in Eastern Europe (80.62%, 75.72%-84.73%), followed by the Middle East (71.24%, 62.22%-78.84%), and was lowest in Africa (53.10%, 26.05%-78.44%). Among patients with liver biopsy data, the global pooled prevalence of NASH/MASH, significant fibrosis, and advanced fibrosis was 66.44% (56.61%-75.02%), 40.78% (24.24%-59.70%), and 15.49% (6.99%-30.99%), respectively. The pooled all-cause mortality was 16.79 per 1000 person-years (PY) (10.64-26.40), 4.19 per 1000 PY (1.34-7.05) for cardiac-specific mortality; 6.10 per 1000 PY (0.78-4.88) for extrahepatic cancer-specific mortality; and 2.15 per 1000 PY (0.00-2.21) for liver-specific mortality.

CONCLUSIONS

The prevalence of NAFLD/MASLD among T2D is high and growing. The majority of NAFLD/MASLD patients with T2D have NASH/MASH, and a significant proportion have advanced fibrosis.

Evidence for an association of serum microanalytes and myofascial pain syndrome

BACKGROUND

Myofascial Pain Syndrome (MPS) is a common pain disorder. Diagnostic criteria include physical findings which are often unreliable or not universally accepted. A precise biosignature may improve diagnosis and treatment effectiveness. The purpose of this study was to assess whether microanalytic assays significantly correlate with characteristic clinical findings in people with MPS.

METHODS

This descriptive, prospective study included 38 participants (25 women) with greater than 3 months of myofascial pain in the upper trapezius. Assessments were performed at a university laboratory. The main outcome measures were the Beighton Index, shoulder range of motion, strength asymmetries and microanalytes: DHEA, Kynurenine, VEGF, interleukins (IL-1b, IL-2, IL-4, IL-5, IL-7, IL-8, IL-13), growth factors (IGF-1, IGF2, G-CSF, GM-CSF), MCP-1, MIP-1b, BDNF, Dopamine, Noradrenaline, NPY, and Acetylcholine. Mann-Whitney test and Spearman's multivariate correlation were applied for all variables. The Spearman's analysis results were used to generate a standard correlation matrix and heat map matrix.

RESULTS

Mean age of participants was 32 years (20-61). Eight (21%) had widespread pain (Widespread Pain Index ≥ 7). Thirteen (34%) had MPS for 1-3 years, 14 (37%) 3-10 years, and 11 (29%) for > 10 years. The following showed strong correlations: IL1b,2,4,5,7,8; GM-CSF and IL 2,4,5,7; between DHEA and BDNF and between BDNF and Kynurenine, NPY and acetylcholine. The heat map analysis demonstrated strong correlations between the Beighton Index and IL 5,7, GM-CSF, DHEA. Asymmetries of shoulder and cervical spine motion and strength associated with select microanalytes.

CONCLUSION

Cytokine levels significantly correlate with selected clinical assessments. This indirectly suggests possible biological relevance for understanding MPS. Correlations among some cytokine clusters; and DHEA, BDNF kynurenine, NPY, and acetylcholine may act together in MPS. These findings should be further investigated for confirmation that link these microanalytes with select clinical findings in people with MPS.

Review article: the epidemiologic burden of non-alcoholic fatty liver disease across the world

BACKGROUND

The prevalence of non-alcoholic fatty liver disease (NAFLD) is increasing in parallel with obesity and type 2 diabetes.

AIM

To review the global epidemiology of NAFLD METHODS: We retrieved articles from PubMed using search terms of NAFLD, epidemiology, prevalence, incidence, and comorbidities.

RESULTS

Over 250 articles were reviewed. In 2016, the global NAFLD prevalence was 25%; this increased to >30% in 2019. Prevalence in Asia, Latin America and Middle East-North Africa (MENA) was 30.8%, 34.5% and 42.6%, respectively. Prevalence increased with age. Although prevalence was higher in men, prevalence in post-menopausal women was similar. NAFLD prevalence was higher in certain subpopulations, especially among the obese and those with metabolic syndrome (MS). However, the prevalence of lean NAFLD was 11.2%. The global prevalence of non-alcoholic steatohepatitis (NASH) is estimated between 2% and 6% in the general population. Approximately 7% of patients with NAFLD have advanced fibrosis; rates were between 21% and 50% among patients with NASH. Overall mortality related to NAFLD was 15-20 per 1000 person-years, and increased substantially in patients with NASH, especially in those with components of MS. Recent data suggest mortality/morbidity from NAFLD is increasing globally but NAFLD awareness remains low among patients and healthcare providers.

CONCLUSIONS

NAFLD poses a global public health problem with a very high disease burden in Asia, MENA and Latin America. Research is needed to better quantify the full impact of NAFLD and to develop strategies to improve awareness and risk stratification.

POS0256 CLINICAL PREDICTORS OF ATTENUATED ANTIBODY RESPONSE TO PRIMARY SARS-CoV-2 VACCINATION IN A LARGE PROSPECTIVE STUDY OF PATIENTS WITH RHEUMATIC AND MUSCULOSKELETAL DISEASES

Background

An attenuated humoral response to SARS-CoV-2 vaccination has been observed in some patients with rheumatic and musculoskeletal diseases (RMD) (1). We sought to identify clinical factors associated with poor humoral response following primary (two-dose mRNA or single adenoviral vector dose) SARS-COV-2 vaccination in patients with RMD on immunosuppression.

Objectives

To identify clinical predictors of an attenuated antibody response to primary SARS-CoV-2 vaccination in RMD patients on immunosuppression.

Methods

We included patients ≥18 years old with RMD on immunosuppression who received either two-dose mRNA or single dose Janssen/Johnson and Johnson (J&J) vaccination. Demographics, diagnoses, and therapeutic regimens were collected via participant report; those with prior COVID-19 infection were excluded. One month after vaccination, participants underwent SARS-CoV-2 antibody testing on the semi-quantitative Roche Elecsys anti-SARS-CoV-2 S enzyme immunoassay, which measures antibody to the SARS-CoV-2 S-receptor binding domain (RBD) protein (ceiling >250U/mL later expanded to >2500U/mL). Associations were evaluated using Fisher’s exact and Wilcoxon rank sum tests. Logistic regression analyses were performed to evaluate for clinical factors associated with antibody response. We adapted survival methods to address right-truncation of titers; this methodology was used to calculate medians. Participants provided informed consent electronically and the study was approved by the local Institutional Review Board.

Results

We studied 1138 RMD participants on immunosuppression; most were female (93%) and white (91%) (Table 1). One-hundred and fifteen (10%) had anti-RBD response in the negative range at a median (IQR) of 29 days (28-34) following completion of vaccine series. A greater proportion of participants with negative response were non-white, received J&J vaccine, reported use of mycophenolate, rituximab, or glucocorticoids. Antibody response differed by immunosuppressive regimen, with those receiving rituximab having poorest response (Figure 1). Use of mycophenolate (aOR 9.92, p=0.001), rituximab (aOR 56.99, p=0.001), glucocorticoids (aOR 2.99, p=0.001) or receipt of J&J (aOR 3.13, p=0.039) were associated with negative antibody response.

Table 1.

Clinical characteristics stratified by anti-SARS-CoV-2 RBD response

Negative (n=115)*Positive (n=1023)*p-value†Age,median(IQR)49(42, 58)47(37, 58)0.07Female sex,no.(%)108(94%)952(93%)0.78Non-white,no.(%)16(13.9%)83(8.1%)0.04Diagnosis,no.(%)Inflammatory arthritis22(19.1%)469(45.8%)<0.01SLE27(23.5%)193(18.9%)0.27Sjὅgren’s syndrome5(4.3%)46(4.5%)0.53Myositis13(11.3%)49(4.8%)<0.01Systemic sclerosis2(1.7%)9(0.9%)0.55Vasculitis12(10.4%)16(1.6%)<0.01Overlap connective tissue disease¶34(29.5%)24(23.6%)0.65  Vaccine,no.(%) Pfizer/BioNTech66(57.4%)548(53.6%)0.01Moderna38(33.0%)438(42.8%)J&J11(9.6%)37(3.6%)Non-biologic in regimen89(77.4%)725(70.9%)0.52Biologic in regimen84(73.0%)570(55.7%)0.01 Mycophenolate**56(48.7%)120(11.7%)<0.01 Rituximab54(47.0%)29(2.8%)<0.01 Glucocorticoid**61(53.0%)284(27.8%)<0.01Withheld immunosuppression18(21.2%)260(39.6%)<0.01

* Negative defined as anti-RBD titer <0.8 U/mL.

† Comparisons between negative and positive groups.

¶ Denotes a combination of two or more of the above conditions

** Mycophenolate: mycophenolic acid and mycophenolate mofetil. Corticosteroid: prednisone and prednisone equivalents

Figure 1.

Conclusion

Use of mycophenolate, glucocorticoids, rituximab and receipt of J&J vaccine were the strongest predictors of an attenuated antibody response to primary SARS-CoV-2 vaccination; these data support use of an additional primary dose in RMD patients.

References

[1]Deepak P, Kim W, Paley MA, et al. Effect of Immunosuppression on the Immunogenicity of mRNA Vaccines to SARS-CoV-2: A Prospective Cohort Study. Ann Intern Med. 2021.

Acknowledgements

We would like to acknowledge the contributions of: Brian J. Boyarsky MD, PhD, Jake A. Ruddy BS, and Jacqueline M. Garonzik-Wang MD PhD.

Disclosure of Interests

Caoilfhionn Connolly: None declared, Teresa Po-Yu Chiang: None declared, Mayan Teles: None declared, Sarah Frey: None declared, Jennifer Alejo: None declared, Allan Massie: None declared, Lisa Christopher Stine Consultant of: Janssen, Boehringer-Ingelheim, Mallinckrodt, EMD-Serono, Allogene, and ArgenX., William Werbel: None declared, Dorry Segev Speakers bureau: Sanofi, Novartis, CSL Behring, Jazz Pharmaceuticals, Veloxis, Mallincrodt, Thermo Fisher Scientific, Regeneron, and Astra-Zeneca, Consultant of: Sanofi, Novartis, CSL Behring, Jazz Pharmaceuticals, Veloxis, Mallincrodt, Thermo Fisher Scientific, Regeneron, and Astra-Zeneca, Julie Paik: None declared

Intraosseous Administration of 23.4% NaCl for Treatment of Intracranial Hypertension

BACKGROUND/OBJECTIVE

Prompt treatment of acute intracranial hypertension is vital to preserving neurological function and frequently includes administration of 23.4% NaCl. However, 23.4% NaCl administration requires central venous catheterization that can delay treatment. Intraosseous catheterization is an alternative route of venous access that may result in more rapid administration of 23.4% NaCl.

METHODS

Single-center retrospective analysis of 76 consecutive patients, between January 2015 and January 2018, with clinical signs of intracranial hypertension received 23.4% NaCl through either central venous catheter or intraosseous access.

RESULTS

Intraosseous cannulation was successful on the first attempt in 97% of patients. No immediate untoward effects were seen with intraosseous cannulation. Time to treatment with 23.4% NaCl was significantly shorter in patients with intraosseous access compared to central venous catheter (p < 0.0001).

CONCLUSIONS

Intraosseous cannulation resulted in more rapid administration of 23.4% NaCl with no immediate serious complications. Further investigations to identify the clinical benefits and safety of hypertonic medication administration via intraosseous cannulation are warranted.

Mortality Risk Detected by Atherosclerotic Cardiovascular Disease Score in Patients With Nonalcoholic Fatty Liver Disease

Cardiovascular diseases (CVDs) are the leading cause of mortality in patients with nonalcoholic fatty liver disease (NAFLD). Our aim was to assess the association of atherosclerotic cardiovascular disease (ASCVD) risk scores with overall and cardiac-specific mortality among patients with NAFLD. We used the National Health and Nutrition Examination Survey III with the National Death Index-linked mortality files. NAFLD was defined by ultrasound as presence of steatosis in the absence of secondary causes of liver disease. High risk for CVD was defined as a 10-year ASCVD score ≥7.5%. Hazard ratios (HRs) and population-attributable fractions (PAFs) of high risk for CVD were calculated. Among 1,262 subjects with NAFLD (47.9% men; 41.2% white; mean age, 56.3 years), the prevalence of high risk for CVD was 55.9% and 4.8% had advanced fibrosis. After a median follow-up of 17.7 years, 482 subjects (38.2%) died of overall causes, of whom 382 (79.3%) had a high risk for CVD. The unadjusted overall and cardiac-specific mortality were higher for patients with NAFLD who had a high risk for CVD compared to subjects with NAFLD with a low risk for CVD (57.3% vs. 16.8% for overall mortality; 16.4% vs. 3.5% for cardiovascular mortality). After controlling for risk factors associated with mortality, high risk for CVD was associated with a 42% higher overall mortality rate (adjusted HR [aHR], 1.42; 95% confidence interval [CI], 1.05-1.91) and twice the risk of cardiovascular mortality (aHR, 2.02; 95% CI, 1.12-3.65). Adjusted PAFs were 11.4% for overall mortality and 44.9% for cardiovascular mortality. Conclusion: Among patients with NAFLD, ASCVD score ≥7.5% was associated with a higher risk of overall and cardiac-specific mortality.

Prevalence and long-term outcomes of non-alcoholic fatty liver disease among elderly individuals from the United States

Background

The prevalence and outcomes of non-alcoholic fatty liver disease (NAFLD) among elderly have not been well described. Our aim was to assess the prevalence, risk factors and mortality of NAFLD in individuals older than 60 years.

Methods

The data from the Third National Health and Nutrition Examination Survey with linked mortality files were utilized. NAFLD was defined by United States Fatty Liver Index in the absence of other causes of liver disease. Cox proportional hazards models were used to assess all-cause and cardiovascular (CV) mortality. All analyses were performed using SAS software.

Results

Three thousand two hundred seventy-one NHANES-III participants were included. The prevalence rates from NAFLD were 40.3% (95% CI: 37.2–43.5%) and 39.2% (95% CI: 34.4–44.0%) among 60–74 and > 74 years old. Among aged 60–74, the risks for 5-year and 10-year all-cause mortality were associated with presence of NAFLD [adjusted hazard ratios: 1.60 (95% CI: 1.24–1.96) for 5-year and 1.22 (95%CI: 1.01–1.49) for 10-year]. CV mortality were higher in this group were (aHR: 2.12 (95% CI: 1.20–3.75) for 5-year and 1.06 (95%CI: 0.73–1.52) for 10-year]. In contrast, in individuals > 74 years old, diagnosis of NAFLD was not associated with all-cause or CVD mortality.

Conclusions

NAFLD is common among elderly population. Although NAFLD is associated with increased risk of mortality for 60–74-year-old individuals, this risk was not increased in those older than 74 years.

Electronic supplementary material

The online version of this article (10.1186/s12876-019-0972-6) contains supplementary material, which is available to authorized users.

Prevalence and outcomes of non-alcoholic fatty liver disease (NAFLD) among Asian American adults in the United States

BACKGROUND & AIMS

Non-alcoholic fatty liver disease (NAFLD) affects about 25% of the general population worldwide. Although epidemiology of NAFLD is well studied in the United States, there is paucity of data for the Asian Americans. Our aim was to assess the prevalence and risk factors for NAFLD among Asian Americans.

METHODS

We utilized NHANES data for 2011-2016. We defined NAFLD using recently derived US-FLI. Relative risks (RRs) and population attributable fractions (PAFs) of metabolic components on atherosclerotic cardiovascular disease (ASCVD) and advanced fibrosis were calculated for Asian Americans, and these rates were compared to non-Hispanic whites.

RESULTS

NAFLD prevalence was 18.3% among Asian Americans and 28.4% among non-Hispanic whites. Asian Americans with NAFLD had lower BMI and waist circumference than non-Hispanic whites with NAFLD and were less likely to have metabolic syndrome, cardiovascular disease (CVD), chronic obstructive pulmonary disease, cancer and incident ASCVD (P < 0.05). Hyperlipidaemia had the highest attributable fraction (76.6%) for risk of ASCVD among Asian Americans with NAFLD, followed by diabetes (24.0%), current smoking (9.2%), and obesity (3.7%). Advanced fibrosis in Asian American with NAFLD was independently associated with presence of type 2 diabetes (RR = 2.70, 95% CI: 1.00-7.27).

CONCLUSIONS

Asian Americans have lower prevalence of NAFLD than non-Hispanic whites. However, Asian Americans with NAFLD have similar risk factors for advanced fibrosis and ASCVD than non-Hispanic Whites.

Chronic kidney disease is independently associated with increased mortality in patients with nonalcoholic fatty liver disease

BACKGROUND & AIMS

Nonalcoholic fatty liver disease and chronic kidney disease share similar pathophysiologic features. Our aim was to assess the association between different stages of chronic kidney disease and mortality in patients with nonalcoholic fatty liver disease.

METHODS

Third National Health and Nutrition Examination Survey-linked mortality files were utilized. Nonalcoholic fatty liver disease was diagnosed by hepatic ultrasound and chronic kidney disease was defined according to the Kidney Disease Improving Global outcomes guideline. Multivariable Cox proportional hazard model was used to assess the effect of chronic kidney disease on overall and cardiovascular mortality.

RESULTS

Total cohort included 11 695 adult participants; mean age 43.3 years, 48.4% male, 76.4% white, 18.6% had nonalcoholic fatty liver disease and 9.3% had chronic kidney disease. 5.6% had diabetes, 21.3% had hypertension, 4.3% had cardiovascular disease. Compared to subjects without chronic kidney disease or nonalcoholic fatty liver disease, nonalcoholic fatty liver disease patients with chronic kidney disease were more likely to be older, had less income, and higher prevalence of comorbidities (all P < 0.001). Prevalence of chronic kidney disease among nonalcoholic fatty liver disease cohort was 11.31%. Compared to non-nonalcoholic fatty liver disease group, patients with nonalcoholic fatty liver disease had higher rates of stage 1, 2 and 3a chronic kidney disease, but similar rates for stage 3b, 4 and 5. Mortality rate was 18.5% in 17 years. Among nonalcoholic fatty liver disease cohort, the presence of chronic kidney disease stages 2-3a (HR = 2.31, 95% CI: 1.70-3.15) and stages 3b-5 (HR = 4.83, 95% CI: 2.40-9.71) were independently associated with increased overall mortality.

CONCLUSIONS

Among patients with nonalcoholic fatty liver disease, moderate to advanced stages of chronic kidney disease are associated with overall mortality. Identification of chronic kidney disease in nonalcoholic fatty liver disease has important prognostic implications.

Impact of hepatitis C virus and insurance coverage on mortality

OBJECTIVES

To assess the association of payer status and mortality in hepatitis C virus (HCV)-infected patients.

STUDY DESIGN

For this retrospective observational study, we used the National Health and Nutrition Examination Survey from 2000 to 2010. Adults with complete data on medical questionnaires, HCV RNA, insurance types, and mortality follow-ups were included.

METHODS

We used Cox proportional hazards models to evaluate independent associations of insurance type with mortality in HCV-infected individuals. These models were rerun in the subset of HCV-positive subjects to determine the association of insurance type with mortality. The data used in this study predated the implementation of the Affordable Care Act.

RESULTS

Among 19,452 eligible participants, 311 (1.4%) were HCV positive. HCV-positive patients were older, were more likely to be non-Hispanic black and male, and had higher prevalence of hypertension (all P <.001). HCV-positive patients were also less likely to have private insurance and more likely to be covered by Medicaid or be uninsured relative to HCV-negative patients (P <.001). Among HCV-positive patients, after adjustment for confounders, those with Medicaid coverage had an increased risk of mortality compared with those with private insurance (hazard ratio [HR], 6.31; 95% CI, 1.22-29.94) and uninsured individuals (HR, 8.83; 95% CI, 1.56-49.99).

CONCLUSIONS

Patients who have HCV are more likely to be uninsured or covered by Medicaid. HCV-positive patients with Medicaid have an increased mortality risk compared with those with private insurance. Given the high burden of HCV infection and adverse prognosis among individuals covered by Medicaid, policy makers must prioritize funding and supporting Medicaid programs.

Burden of Primary Biliary Cholangitis Among Inpatient Population in the United States

Primary biliary cholangitis (PBC) is an autoimmune liver disease that can lead to cirrhosis and liver failure. Our aim was to assess the recent trends in the mortality rates and health care utilization of patients with PBC seen in the inpatient setting in the United States. We used the National (Nationwide) Inpatient Sample data (2005‐2014). The study population included adults with PBC, using International Classification of Diseases, Ninth Revision codes. Trends in PBC‐related discharges, total charges, length of stay (LoS), and in‐hospital mortality were evaluated. Hierarchical generalized linear models were performed for determining predictors of mortality and total hospital charges. Between the study years of 2005 and 2014, a total of 22,665 hospitalized cases with PBC were identified (mean age 63 years; 84% female, 76% white). The number of PBC‐related discharges increased from 3.24 per 100,000 in 2005 to 3.68 per 100,000 in 2014, with an average annual increase of 1.4% (95% confidence interval [CI]: 0.4%‐2.4%). Fifty‐seven percent had Medicare as their primary payer, 37% had cirrhosis, and 1.3% had hepatocellular carcinoma. Between 2005 and 2014, the average total charges for PBC increased from $53,901 to $57,613 (annual percent change [APC], 1.7%; 95% CI: −0.2%‐3.5%), LoS decreased from 6.9 days to 5.4 days (APC, −2.2%; 95% CI: −3.2% to −1.1%), and mortality rate decreased from 3.8% to 2.8% (APC, −5.4%; 95% CI: −8.4% to −2.4%). Multivariable analysis revealed that ascites were independently associated with increased risk of in‐hospital mortality (odds ratio: 1.77; 95% CI: 1.50‐2.08), increased charge (percent change: 22.5%; 95% CI: 18.6%‐26.7%), and increased LoS (percent change: 29.7%; 95% CI: 25.7%‐33.9%). Conclusion: The number of PBC cases has increased in recent years. Mortality and LoS have decreased, and the total charges have remained the same.

Patients With Lean Nonalcoholic Fatty Liver Disease Are Metabolically Abnormal and Have a Higher Risk for Mortality

IN BRIEF Nonalcoholic fatty liver disease (NAFLD) is an increasingly recognized and common cause of chronic liver disease worldwide. Although most patients with NAFLD are obese, a smaller group of NAFLD patients are lean. This study explored the long-term outcomes of lean patients with NAFLD in the United States. Compared to lean individuals without NAFLD, lean people with NAFLD were significantly more likely to be older and male and had higher comorbidities (i.e., diabetes, hyperlipidemia, hypertension, metabolic syndrome, chronic kidney disease, and cardiovascular disease). The presence of NAFLD in lean individuals was independently associated with increased risk of all-cause and cardiovascular mortality.

Prevalence of Nonalcoholic Fatty Liver Disease in the Female Population

There is a paucity of recent data about the epidemiology and long‐term outcomes of nonalcoholic fatty liver disease (NAFLD) in the female population. Our aim was to assess the prevalence, risk factors, and mortality of NAFLD in female adults of the United States. Data from the National Health and Nutrition Examination Survey (NHANES) III and NHANES 1999‐2014 were used. NAFLD status was determined by the U.S. Fatty Liver Index (US‐FLI) in the absence of other liver diseases and excessive alcohol consumption. The prevalence rates, risk factors, and 5‐year all‐cause and cardiovascular mortality were determined in women with NAFLD. The most recent prevalence of NAFLD among female adults (2007‐2014) in the United States was 24.4% (95% confidence interval [CI], 22.48‐26.33). Prevalence was higher among women >44 years of age and those with body mass index ≥30 kg/m². In addition, the average age of the female population with NAFLD has decreased over time. The fully adjusted odds ratios in women with NAFLD compared to those without NAFLD were 1.48 (95% CI, 1.20‐1.82) for cardiovascular disease (CVD), 1.89 (95% CI, 1.42‐2.52) for atherosclerotic cardiovascular disease (ASCVD) score ≥7.5%, and 1.76 (95% CI, 1.37‐2.25) for either CVD or ASCVD ≥7.5%. The 5‐year mortality for female adults with NAFLD was significantly higher than for those without NAFLD (adjusted hazard ratio, 1.48; 95% CI, 1.07‐2.05). Among women with NAFLD, those with ASCVD ≥7.5% had significantly higher 5‐year all‐cause mortality and CVD mortality. Conclusion: The prevalence of NAFLD in female NHANES participants from the United States has continued over recent years. In the female population with NAFLD, ASCVD ≥7.5% is an independent predictor of overall and cardiac‐specific mortality.

NAFLD is growing in the female population in the U.S. NAFLD is associated with metabolic risk factors and increases the risk of CVD and mortality. Detection of NAFLD in females consider a serious risk threat that needs to be addressed to potentially improve their long‐term outcomes.

Among Patients With NAFLD, Treatment of Dyslipidemia Does Not Reduce Cardiovascular Mortality

Dyslipidemia is one of the common risk factors for NAFLD and is associated with cardiovascular (CV) mortality, which is the most common cause of death in NAFLD. Lipid-lowering agents (LLAs) are used to reduce CV events in the general population. Our aim was to assess whether the use of LLAs in patients with NAFLD can reduce the risk of CV mortality. We used the third National Health and Nutrition Examination Survey mortality linked files. Mortality was determined from the National Death Index records through 2011. NAFLD was diagnosed by ultrasound after exclusion of other causes of liver disease. After inclusion and exclusion, the cohort consisted of 2,566 patients with NAFLD (45.8% < 45 years of age, 52.8% male, 75.4% white). Those who were taking LLAs were more likely to be older, non-Hispanic white, and had significantly higher rates of diabetes mellitus (DM), hyperlipidemia, hypertension, metabolic syndrome, and history of CV disease (CVD) (all P< 0.01). In our multivariate analysis, DM was an independent predictor of overall mortality (adjusted hazard ratio [aHR]: 1.79 [95% confidence interval (CI): 1.40-2.30]) and CV mortality (aHR: 1.89 [95% CI: 1.08-3.30]). History of CVD was associated with both overall (aHR: 2.03 [95% CI: 1.57-2.63]) and CV mortality (aHR: 3.69 [95% CI: 2.23-6.08]). In contrast, the use of statins and other LLAs was not associated with reduction in overall (aHR = 0.95 [95% CI: 0.37-2.44] and aHR = 1.43 [95% CI: 0.99-2.07]) and CV mortality (aHR = 1.20 [95% CI: 0.26-5.54] and aHR = 1.63 [95% CI: 0.70-3.76]). Conclusion: The use of statins and other LLAs did not reduce the increased risk of overall or CV mortality in NAFLD.

Impaired insulin-receptor autophosphorylation is an early defect in fat-fed, insulin-resistant rats

High-fat feeding results in impaired insulin signaling in skeletal muscle, but the role of the insulin receptor (IR) remains controversial. In the present study, female Fischer 344 rats were fed diets either low in fat [low fat, complex carbohydrate (LFCC)] or high in fat and sucrose (HFS). Insulin-stimulated skeletal muscle glucose transport, measured in purified sarcolemmal vesicles, was lower in rats consuming the HFS diet for 2 and 8 wk compared with LFCC controls (72.9 +/- 3.5, 67.6 +/- 3.5, and 86.1 +/- 3.5 pmol x mg(-1) x 15 s(-1), respectively; P < 0.05). Muscle IR content was unchanged in 2-wk HFS animals but was 50% lower in the 8-wk HFS group (P < 0.001). However, compared with LFCC, insulin-stimulated IR autophosphorylation was 26% lower in 2-wk HFS and 40% lower in 8-wk HFS animals (P < 0.005). Total muscle content of the proposed IR inhibitors cytokine tumor necrosis factor-alpha and membrane glycoprotein PC-1 was not significantly changed in HFS animals at either 2 or 8 wk. These results demonstrate that high-fat feeding induces insulin resistance in muscle concomitant with a diminished IR signaling capacity, although the mechanism remains unknown.

Expression and characterization of a murine enzyme able to cleave beta-carotene. The formation of retinoids

Because animals are not able to synthesize retinoids de novo, ultimately they must derive them from dietary provitamin A carotenoids through a process known as carotene cleavage. The enzyme responsible for catalyzing carotene cleavage (beta-carotene 15,15'-dioxygenase) has been characterized primarily in rat intestinal scrapings. Using a recently reported cDNA sequence for a carotene cleavage enzyme from Drosophila, we identified a cDNA encoding a mouse homolog of this enzyme. When the cDNA was expressed in either Escherichia coli or Chinese hamster ovary cells, expression conferred upon bacterial and Chinese hamster ovary cell homogenates the ability to cleave beta-carotene to retinal. Several lines of evidence obtained upon kinetic analyses of the recombinant enzyme suggested that carotene cleavage enzyme interacts with other proteins present within cell or tissue homogenates. This was confirmed by pull-down experiments upon incubation of recombinant enzyme with tissue 12,000 x g supernatants. Matrix-assisted laser desorption ionization-mass spectrometry analysis of pulled-down proteins indicates that an atypical testis-specific isoform of lactate dehydrogenase associates with recombinant carotene cleavage enzyme. mRNA transcripts for the carotene cleavage enzyme were detected by reverse transcription-polymerase chain reaction in mouse testes, liver, kidney, and intestine. In situ hybridization studies demonstrated that carotene cleavage enzyme is expressed prominently in maternal tissue surrounding the embryo but not in embryonic tissues at 7.5 and 8.5 days postcoitus. This work offers new insights for understanding the biochemistry of carotene cleavage to retinoids.

9-cis-retinoids: biosynthesis of 9-cis-retinoic acid

Retinoids function through conformational alterations of ligand-dependent nuclear transcription factors, the retinoic acid receptors, and retinoid X receptors. 9-cis-Retinoic acid is a known biological ligand for retinoid X receptors, but its synthesis pathway in vivo is largely unknown. Recently, we identified a cis-retinol dehydrogenase (cRDH) that oxidizes 9-cis-retinol to 9-cis-retinal. Since both the expression of cRDH mRNA and its substrate are found in liver, we studied 9-cis-retinol metabolism and 9-cis-retinoic acid biosynthesis in two hepatic-derived cell types, Hep G2 hepatoma cells and HSC-T6 stellate cells. Both cell lines accumulate similar amounts of 9-cis-retinol provided in the medium. However, Hep G2 cells preferentially incorporate all-trans-retinol when equimolar concentrations of all-trans- and 9-cis-retinol were provided. In contrast, HSC-T6 cells did not exhibit a preference between all-trans- and 9-cis-retinol under the same conditions. Esterification of 9-cis-retinol occurred in both cell types, likely by acyl-CoA:retinol acyltransferase and lecithin:retinol acyltransferase. In vitro enzyme assays demonstrated that both cell types can hydrolyze 9-cis-retinyl esters via retinyl ester hydrolase(s). In Hep G2 cells, 9-cis-retinoic acid synthesis was strongly inhibited by high concentrations of 9-cis-retinol, which may explain the low levels of 9-cis-retinol in liver of mice. Cell homogenates of Hep G2 can convert all-trans-retinol to 9-cis-retinal, suggesting that the free form of all-trans-retinol may be used as a source for 9-cis-retinol and, thus, 9-cis-retinoic acid synthesis. Our studies provide the basis for identification of additional pathways for the generation of 9-cis-retinoic acid in specialized tissues.

Mutational analysis of the Streptococcus pneumoniae bimodular class A penicillin-binding proteins

One group of penicillin target enzymes, the class A high-molecular-weight penicillin-binding proteins (PBPs), are bimodular enzymes. In addition to a central penicillin-binding-transpeptidase domain, they contain an N-terminal putative glycosyltransferase domain. Mutations in the genes for each of the three Streptococcus pneumoniae class A PBPs, PBP1a, PBP1b, and PBP2a, were isolated by insertion duplication mutagenesis within the glycosyltransferase domain, documenting that their function is not essential for cellular growth in the laboratory. PBP1b PBP2a and PBP1a PBP1b double mutants could also be isolated, and both showed defects in positioning of the septum. Attempts to obtain a PBP2a PBP1a double mutant failed. All mutants with a disrupted pbp2a gene showed higher sensitivity to moenomycin, an antibiotic known to inhibit PBP-associated glycosyltransferase activity, indicating that PBP2a is the primary target for glycosyltransferase inhibitors in S. pneumoniae.

A putative monofunctional glycosyltransferase is expressed in Ralstonia eutropha

A gene, mgt, encoding a protein homologous to the N-terminal module of class A high-molecular-mass penicillin-binding proteins was identified in Ralstonia eutropha. By using specific antibodies, the corresponding Mgt protein was detected in association with the membrane, confirming that the N-terminal hydrophobic segment functioned as a membrane anchor. A derivative in which the hydrophobic sequence was deleted was overexpressed as a maltose-binding fusion protein in Escherichia coli. Cleavage of the product resulted in substantial amounts of soluble Mgt derivative, indicating that folding occurs independently on other proteins or on homologous domains of penicillin-binding proteins.

A novel resistance mechanism against beta-lactams in Streptococcus pneumoniae involves CpoA, a putative glycosyltransferase

Piperacillin resistance in Streptococcus pneumoniae was mediated by mutations in a novel gene, cpoA, that also confer transformation deficiency and a decrease in penicillin-binding protein la. cpoA is part of an operon located downstream of the primary sigma factor of S. pneumoniae. The deduced protein, CpoA, and the peptide encoded by the adjacent 3' open reading frame contained domains homologous to glycosyltransferases of procaryotes and eucaryotes that act on membrane-associated substrates, such as enzymes functioning in lipopolysaccharide core biosynthesis of gram-negative bacteria, RodD of Bacillus subtilis, which is involved in teichoic acid biosynthesis, and the human PIG-A protein, which is required for early steps of glycosylphosphatidylinositol anchor biosynthesis. This suggests that the cpo operon has a similar function related to cell surface components.

Factors influencing pulmonary venous flow velocity patterns in mitral regurgitation: an in vitro study

OBJECTIVES

The aim of this study was to investigate factors affecting pulmonary venous flow patterns in mitral regurgitation.

BACKGROUND

Although pulmonary venous flow velocity patterns have been reported to be helpful in assessing the severity of mitral regurgitation, the influence of regurgitant jet direction, pulmonary venous location and left atrial pressures on pulmonary venous flow patterns has yet to be clarified.

METHODS

The mitral regurgitant jet was produced by a pulsatile piston pump at 10, 30 and 40 ml/beat through a circular orifice, whereas the pulmonary venous flow was driven by gravity. Four different patterns of pulmonary venous flow and mitral regurgitation were examined. The V wave pressure was set at 10, 30 and 50 mm Hg and pulmonary venous flow velocity at 30 cm/s. Color and pulsed Doppler recordings were obtained with a VingMed 800 scanner interfaced with a computer facilitating digital analysis.

RESULTS

The decrease in the velocity time integral of pulmonary venous flow was more prominent for any given volume of mitral regurgitation at higher left atrial pressure. When the mitral regurgitant jet was directed toward the pulmonary vein, a more prominent decrease in the velocity time integral was seen, especially for severe mitral regurgitation (40 ml) with high left atrial pressure (95% vs. 55%, p < 0.001); and the time to peak deceleration of forward flow was significantly shorter (485 vs. 523 ms, respectively, p < 0.01). Also, two different types (laminar and turbulent) of reversed pulmonary venous flow were observed.

CONCLUSIONS

Multiple factors, including jet direction, mitral regurgitant volume and left atrial pressure, determine the effect of mitral regurgitation on pulmonary venous flow velocity patterns.

Effects of pulmonary venous flow direction on mitral regurgitation jet area as imaged by color Doppler flow mapping. An in vitro study

BACKGROUND

Although the effects of adjacent walls and left atrial pressure on mitral regurgitation (MR) jet area imaged by color Doppler have been examined, few data exist regarding the influence of pulmonary venous (PV) filling flow on regurgitant jets. Therefore, we designed a left atrial model to examine the relation between PV flow direction and MR jet area.

METHODS AND RESULTS

The left atrial chamber (7.6 cm in diameter) was built with a PV inflow (1.0 cm in diameter) and mitral valve regurgitant orifice in the same plane. The MR jet was simulated as fixed in volume and velocity (3.5 m/s) and directed with a pulsatile pump into the left atrial model. PV flow with a constant velocity (30 cm/s) was driven by gravity (83 cm H2O). With left atrial mean pressure at either 10, 30, or 50 mm Hg, four flow patterns were examined: (1) PV flow away from the mitral valve, MR jet toward the pulmonary vein; (2) PV flow toward the mitral valve, MR jet toward the pulmonary vein; (3) PV flow away from the mitral valve, MR jet away from the pulmonary vein; and (4) PV flow toward the mitral valve, MR jet away from the pulmonary vein. MR color Doppler images were recorded with a 3.5-mHz frequency transducer and at 7-kHz pulse repetition frequency. For each condition, we compared jet area, length, and width of the MR signal. MR jet areas for conditions 3 and 4 were larger at 10 mm Hg than at 30 or 50 mm Hg left atrial pressure. Especially at the lower pressures, PV flow diminished the MR jet area in condition 4 compared with that in condition 3, such that MR jets were smaller in condition 4. In conditions 1 and 2, the jets were imaged at an oblique angle and were smaller than in conditions 3 and 4 (P < .001), but they were not significantly different from each other as imaged.

CONCLUSIONS

In this model, factors including the direction of PV flow, the direction of MR as relates to the angle of interrogation, and the level of left atrial pressure influenced the size of MR jets. The effect of PV flow direction was diminished by increased left atrial pressure. PV flow directed away from the mitral valve was associated with larger MR jets than when PV flow was directed toward it (condition 4), probably because of jet distortion and flattening.

Inactivation of nitric oxide synthase after prolonged incubation of mouse macrophages with IFN-gamma and bacterial lipopolysaccharide

Large amounts of nitric oxide (NO) are produced by the inducible isoform of NO synthase (iNOS) in many cell types once the iNOS gene is transcriptionally activated. In primary mouse peritoneal macrophages elicited by thioglycolate broth, expression of iNOS follows treatment with IFN-gamma and is synergistically increased by the addition of bacterial LPS. Expression of iNOS is suppressible at transcriptional and translational levels by certain cytokines and microbial products. The present study describes a novel form of inactivation of iNOS that is post-translational and nondegradative. Mouse peritoneal macrophages cultured in the presence of IFN-gamma alone or IFN-gamma plus LPS rapidly depleted the medium of L-arginine, a substrate for iNOS, and stopped producing NO. Repletion of L-arginine permitted cells treated with IFN-gamma alone to resume NO production for at least 5 days, leading to the release of more NO than macrophages were previously believed capable of generating. L-Arginine repletion also boosted NO production by macrophages cultured for up to 2 to 3 days in the presence of IFN-gamma plus LPS, but thereafter, iNOS was inactive in these cells whether or not L-arginine was repleted. Activity of iNOS could be restored by adding both L-arginine and fresh IFN-gamma with or without LPS, likely reflecting the synthesis of new enzyme. However, the inactivation of iNOS seen late in culture with a single application of IFN-gamma plus LPS could be attributed neither to loss of iNOS protein nor to its autoinactivation by NO. Thus, LPS, a co-inducer of iNOS, causes macrophages to inactivate iNOS about 3 days after the onset of its induction. The mechanism, which remains to be identified, is novel for iNOS, in that it decreases neither its amount nor its apparent molecular mass.

Inactivation of nitric oxide synthase after prolonged incubation of mouse macrophages with IFN-gamma and bacterial lipopolysaccharide

Large amounts of nitric oxide (NO) are produced by the inducible isoform of NO synthase (iNOS) in many cell types once the iNOS gene is transcriptionally activated. In primary mouse peritoneal macrophages elicited by thioglycolate broth, expression of iNOS follows treatment with IFN-gamma and is synergistically increased by the addition of bacterial LPS. Expression of iNOS is suppressible at transcriptional and translational levels by certain cytokines and microbial products. The present study describes a novel form of inactivation of iNOS that is post-translational and nondegradative. Mouse peritoneal macrophages cultured in the presence of IFN-gamma alone or IFN-gamma plus LPS rapidly depleted the medium of L-arginine, a substrate for iNOS, and stopped producing NO. Repletion of L-arginine permitted cells treated with IFN-gamma alone to resume NO production for at least 5 days, leading to the release of more NO than macrophages were previously believed capable of generating. L-Arginine repletion also boosted NO production by macrophages cultured for up to 2 to 3 days in the presence of IFN-gamma plus LPS, but thereafter, iNOS was inactive in these cells whether or not L-arginine was repleted. Activity of iNOS could be restored by adding both L-arginine and fresh IFN-gamma with or without LPS, likely reflecting the synthesis of new enzyme. However, the inactivation of iNOS seen late in culture with a single application of IFN-gamma plus LPS could be attributed neither to loss of iNOS protein nor to its autoinactivation by NO. Thus, LPS, a co-inducer of iNOS, causes macrophages to inactivate iNOS about 3 days after the onset of its induction. The mechanism, which remains to be identified, is novel for iNOS, in that it decreases neither its amount nor its apparent molecular mass.

Mechanism of suppression of nitric oxide synthase expression by interleukin-4 in primary mouse macrophages

Nitric oxide (NO) contributes to the antitumor, antimicrobial, and immunosuppressive activity of macrophages. An inducible form of NO synthase (iNOS) is responsible for high output generation of nitric oxide by macrophages after stimulation with cytokines and/or lipopolysaccharide (LPS). In the present study, we demonstrate that interleukin 4 (IL-4) suppressed production of NO by primary mouse peritoneal macrophages exposed to IFN-gamma with or without LPS, even while synergizing with IFN-gamma to increase the secretion of TNF-alpha. Suppression of NO production was paralleled by decreases in iNOS enzyme activity and iNOS antigen. IL-4 did not inhibit induction of iNOS mRNA 4-6 h after exposure to IFN-gamma, but strongly reduced iNOS mRNA at later times of stimulation (24-72 h), without increasing its turnover. The conditions for maximal suppression of iNOS expression by IL-4 and the mechanisms of suppression differed from those determined in parallel for transforming growth-factor-beta as described elsewhere. These results illustrate the diversity of phenotypes of macrophages deactivated by different cytokines, and demonstrate that IL-4 has the potential to reduce one component of the anti-tumor, antimicrobial, and immunosuppressive activities of macrophages.

Effects of adjacent surfaces of different shapes on regurgitant jet sizes: an in vitro study using color Doppler imaging and laser-illuminated dye visualization

OBJECTIVES

The present study was designed to estimate the influence of different-shaped adjacent surfaces on regurgitant jets as assessed by color Doppler imaging and laser-illuminated dye optical visualization.

BACKGROUND

Because color Doppler techniques provide real-time two-dimensional imaging of flow, the evaluation of valvular regurgitation by analysis of variance-encoded regurgitant jets by this method has been widely used in clinical studies. However, recent studies have demonstrated that color Doppler jet sizes are affected not only by several hemodynamic factors and instrument settings but also by the interaction between jets and adjacent wall surfaces. In clinical conditions, jets may interact with adjacent walls of variable shapes that might have different effects on the jet size.

METHODS

An in vitro model was constructed consisting of a rigid, optically clear receiving chamber that had no outlet resistance and had a pulsatile pump ejecting through 1.5, 2.3 and 3.1 mm2 inflow orifices into the chamber. The surfaces were flat or smoothly and equally curved, convex and concave aluminum positioned at 0, 2 and 4 mm from and to the side of the inflow orifices. The pump was run with stroke volumes from 0.5 to 3.0 ml and with a pulse frequency of 70 beats/min. The echocardiographic and laser beams were aimed at the inflow orifice imaging jets perpendicular to the surfaces (vertical view) through the central plane of the jet flows. Maximal jet areas were measured by both color Doppler techniques and laser-illuminated dye visualization.

RESULTS

Color Doppler study showed fair correlation between the jet areas and the stroke volumes (r = 0.83 to 0.99), but the jet sizes under different surface conditions were variable. All the surface jet areas at a jet-surface distance of 0 and 2 mm were smaller than free jet areas at the same stroke volume for both flat and convex surfaces (p < 0.001). Flow constraint by the concave surface resulted in the smallest jet areas (p < 0.001). The color Doppler jet areas on the curved surfaces were significantly smaller than the laser-illuminated dye visualization jet areas (p < 0.01 to 0.0001). However, at intermediate jet-surface distances (4 mm and sometimes 2 mm with higher velocity flows), jet interaction with the flat and especially with the convex surface resulted in larger jets. This effect was most pronounced on dye fluorescence studies because flow around these jets consisted mainly of low velocity vortical events with only partial surface adherence and these low velocity swirling flows were not well imaged by color Doppler technique.

CONCLUSIONS

Our study suggests that the different-shaped adjacent surfaces with different degrees of flow alterations resulted in variable decreases in jet size and that color Doppler imaging could not encode and image the angled and low velocity swirling events well when jets flowed along the curved surfaces. These effects need to be taken into account when interpreting color Doppler images.

Mechanisms of suppression of macrophage nitric oxide release by transforming growth factor beta

Activated mouse peritoneal macrophages produce nitric oxide (NO) via a nitric oxide synthase that is inducible by interferon gamma (IFN-gamma): iNOS. We have studied the mechanisms by which transforming growth factor beta 1 (TGF-beta) suppresses IFN-gamma-stimulated NO production. TGF-beta treatment reduced iNOS specific activity and iNOS protein in both cytosolic and particulate fractions as assessed by Western blot with monospecific anti-iNOS immunoglobulin G. TGF-beta reduced iNOS mRNA without affecting the transcription of iNOS by decreasing iNOS mRNA stability. Even after iNOS was already expressed, TGF-beta reduced the amount of iNOS protein. This was due to reduction of iNOS mRNA translation and increased degradation of iNOS protein. The potency of TGF-beta as a deactivator of NO production (50% inhibitory concentration, 5.6 +/- 2 pM) may reflect its ability to suppress iNOS expression by three distinct mechanisms: decreased stability and translation of iNOS mRNA, and increased degradation of iNOS protein. This is the first evidence that iNOS is subject to other than transcriptional regulation.

Traces of bacterial lipopolysaccharide suppress IFN-gamma-induced nitric oxide synthase gene expression in primary mouse macrophages

A nitric oxide synthase (iNOS) inducible by cytokines and microbial products contributes to the cytotoxic and antimicrobial activity of mouse macrophages. Bacterial LPS interacts synergistically with IFN-gamma to induce iNOS when both stimuli are added together. In contrast, we show here that pre-exposure of peritoneal macrophages to low concentrations of LPS suppresses the induction of iNOS when IFN-gamma is added subsequently. Suppression required pretreatment with LPS for at least 8 h and was optimal with LPS concentrations in the range of 50 to 200 pg/ml. Suppression was exerted by smooth and rough forms of LPS from Escherichia coli and by lipid A from Salmonella minnesota, but not by a biologically inactive lipid A from Rhodobacter sphaeorides. Suppression of nitrite accumulation and iNOS enzyme activity by prior exposure of macrophages to LPS could be explained by their markedly decreased content of iNOS protein, as revealed by immunoblot with monospecific anti-iNOS IgG. Messenger RNA for iNOS was affected in a biphasic manner by pretreatment with LPS. Five hours after addition of IFN-gamma, iNOS mRNA levels were unaltered or even enhanced by pretreatment with LPS, but by 24 to 48 h, expression of iNOS mRNA was inhibited strongly enough to account for the reduced levels of iNOS protein. Suppression by LPS did not appear to be mediated by endogenous prostaglandins, transforming growth factor-beta, or TNF-alpha, even though pretreatment with exogenous TNF-alpha was also suppressive. These findings suggest that preactivation of pathways normally contributing to synergistic induction of iNOS may deplete macrophages of factors needed for its expression. Regulation of iNOS in vivo may depend on the relative tempo with which the inflammatory and immune responses evolve.

Traces of bacterial lipopolysaccharide suppress IFN-gamma-induced nitric oxide synthase gene expression in primary mouse macrophages

A nitric oxide synthase (iNOS) inducible by cytokines and microbial products contributes to the cytotoxic and antimicrobial activity of mouse macrophages. Bacterial LPS interacts synergistically with IFN-gamma to induce iNOS when both stimuli are added together. In contrast, we show here that pre-exposure of peritoneal macrophages to low concentrations of LPS suppresses the induction of iNOS when IFN-gamma is added subsequently. Suppression required pretreatment with LPS for at least 8 h and was optimal with LPS concentrations in the range of 50 to 200 pg/ml. Suppression was exerted by smooth and rough forms of LPS from Escherichia coli and by lipid A from Salmonella minnesota, but not by a biologically inactive lipid A from Rhodobacter sphaeorides. Suppression of nitrite accumulation and iNOS enzyme activity by prior exposure of macrophages to LPS could be explained by their markedly decreased content of iNOS protein, as revealed by immunoblot with monospecific anti-iNOS IgG. Messenger RNA for iNOS was affected in a biphasic manner by pretreatment with LPS. Five hours after addition of IFN-gamma, iNOS mRNA levels were unaltered or even enhanced by pretreatment with LPS, but by 24 to 48 h, expression of iNOS mRNA was inhibited strongly enough to account for the reduced levels of iNOS protein. Suppression by LPS did not appear to be mediated by endogenous prostaglandins, transforming growth factor-beta, or TNF-alpha, even though pretreatment with exogenous TNF-alpha was also suppressive. These findings suggest that preactivation of pathways normally contributing to synergistic induction of iNOS may deplete macrophages of factors needed for its expression. Regulation of iNOS in vivo may depend on the relative tempo with which the inflammatory and immune responses evolve.

Contrasting mechanisms for suppression of macrophage cytokine release by transforming growth factor-beta and interleukin-10

Transforming growth factor (TGF)-beta and interleukin (IL)-10 inhibited lipopolysaccharide (LPS)-induced macrophage production of the inflammatory cytokines tumor necrosis factor-alpha (TNF), IL-1 alpha, and IL-1 beta by contrasting post-transcriptional mechanisms. TGF-beta acted slowly and late, as it required 12-16 h to exert a suppressive effect, and inhibited TNF production even when added 6 h after LPS. TGF-beta affected neither the level of TNF mRNA, the release of preformed TNF nor the degradation of TNF. Thus, TGF-beta appeared to inhibit translation of TNF mRNA. IL-10 not only suppressed TNF release to a 25-fold greater extent than TGF-beta, but also inhibited release of IL-1. In contrast to TGF-beta, IL-10 acted on an early step in cytokine production, its effect being maximal 3 h after addition of LPS. Unlike TGF-beta, IL-10 markedly suppressed TNF, IL-1 alpha, and IL-1 beta mRNA levels. However, this was accomplished without suppressing transcription of the corresponding genes. Moreover, cycloheximide antagonized the IL-10-dependent reduction in cytokine mRNA levels. Thus, IL-10 may induce a ribonuclease active on cytokine transcripts or may induce a protein that enhances the susceptibility of TNF, IL-1 alpha, and IL-1 beta mRNAs to ribonucleolytic action. We conclude that IL-10 and TGF-beta induce different phenotypes of macrophage deactivation, and deactivate macrophages by different mechanisms: IL-10 promotes degradation of cytokine mRNA, while TGF-beta primarily suppresses translation.