Longitudinal myelin content measures of slowly expanding lesions using 7T MRI in multiple sclerosis

BACKGROUND AND PURPOSE

Slowly expanding lesions (SELs) are thought to represent a subset of chronic active lesions and have been associated with clinical disability, severity, and disease progression. The purpose of this study was to characterize SELs using advanced magnetic resonance imaging (MRI) measures related to myelin and neurite density on 7 Tesla (T) MRI.

METHODS

The study design was retrospective, longitudinal, observational cohort with multiple sclerosis (n = 15). Magnetom 7T scanner was used to acquire magnetization-prepared 2 rapid acquisition gradient echo and advanced MRI including visualization of short transverse relaxation time component (ViSTa) for myelin, quantitative magnetization transfer (qMT) for myelin, and neurite orientation dispersion density imaging (NODDI). SELs were defined as lesions showing ≥12% of growth over 12 months on serial MRI. Comparisons of quantitative measures in SELs and non-SELs were performed at baseline and over time. Statistical analyses included two-sample t-test, analysis of variance, and mixed-effects linear model for MRI metrics between lesion types.

RESULTS

A total of 1075 lesions were evaluated. Two hundred twenty-four lesions (21%) were SELs, and 216 (96%) of the SELs were black holes. At baseline, compared to non-SELs, SELs showed significantly lower ViSTa (1.38 vs. 1.53, p < .001) and qMT (2.47 vs. 2.97, p < .001) but not in NODDI measures (p > .27). Longitudinally, only ViSTa showed a greater loss when comparing SEL and non-SEL (p = .03).

CONCLUSIONS

SELs have a lower myelin content relative to non-SELs without a difference in neurite measures. SELs showed a longitudinal decrease in apparent myelin water fraction reflecting greater tissue injury.

The relationship between cognition, education, and employment in multiple sclerosis patients

Background

Processing speed decline is a common manifestation of multiple sclerosis (MS). The processing speed test (PST) is a validated electronic cognitive assessment based on the Symbol–Digit Modalities Test, which is routinely administered as part of the multi-institutional Multiple Sclerosis Partners Advancing Technology and Health Solutions (MS PATHS) initiative. The longitudinal relationship between education, processing speed, and employment is unclear.

Objectives

Determine the longitudinal impact of educational attainment on processing speed and employment.

Methods

MS PATHS data through March 2020 were analyzed. Repeat PST assessments at 1, 2, and 3 years were classified as improved, worsened, or stable. Linear regression was used to evaluate the relationship between education and baseline PST performance and logistic regression was used to determine the odds of PST worsening by educational attainment. Employment outcomes were analyzed by PST status and educational level.

Results

There were 13,732 patients analyzed. Education impacted baseline PST scores, but had a limited effect on PST performance over time. Education was protective with respect to employment in the setting of both PST worsening and improvement.

Conclusion

Greater education results in better baseline processing speed and is protective with respect to employment status. Its impact on processing speed over time is marginal.

Assessing Access to Five Types of Insurance by People with Multiple Sclerosis Using a Cross-sectional Online Survey

Background

Many individuals with multiple sclerosis (MS) depart the workforce prematurely. In the United States, access to insurance, including health, disability income, long-term care, and life insurance, is largely employment-based or purchased from earnings. Many individuals we see in the clinic experience financial hardship because of a lack of insurance, even if working. We sought to determine the proportion of workers who are financially protected through insurance coverage and the sources of this coverage in a large sample.

Methods

We developed an online survey and opened it to individuals aged 18 to 65 years registered with the North American Research Committee on Multiple Sclerosis, iConquerMS, or the National Multiple Sclerosis Society Minority Advisory Council. Data collected included demographic and disease characteristics, current information about each insurance type (coverage vs no coverage), and when the current insurance policies were obtained relative to MS diagnosis.

Results

Of 2507 survey respondents, 82.9% were female, 3.8% Hispanic/Latino, and 91.2% White. The mean ± SD age was 53.5 ± 8.5 years and disease duration was 16.4 ± 8.5 years after diagnosis. The most frequently held insurance types were health (96.3%) and life (58.8%). Only 9.7% of respondents had long-term care insurance. Except for life insurance, most current policies were obtained after MS diagnosis.

Conclusions

Individuals with MS might not prioritize the possible short- and long-term benefits of these types of insurance. Health care providers can direct patients to nonprofit agencies that educate about of these insurance types and emphasize that others with MS have obtained these insurance types after their diagnosis.

Clinical features and outcomes of COVID-19 despite SARS-CoV-2 vaccination in people with multiple sclerosis

BACKGROUND

Several studies have demonstrated reduced serological response to vaccines in patients treated with anti-CD20 agents. However, limited data exist surrounding the clinical effect of disease modifying therapy (DMT) use on vaccine efficacy.

OBJECTIVES

To investigate breakthrough coronavirus disease 2019 (COVID-19) in vaccinated people with multiple sclerosis (PwMS) on DMT.

METHODS

PwMS on DMT diagnosed with COVID-19 after full vaccination were identified from an existing Cleveland Clinic COVID-19 registry, supplemented by provider-identified cases. Demographics, disease history, DMTs, comorbidities, exposures, vaccination status, and COVID-19 outcomes were confirmed by review of the electronic medical record.

RESULTS

Thirteen (3.8%) of 344 fully vaccinated people with multiple sclerosis on disease modifying therapy were diagnosed with COVID-19 after vaccination. Ten patients (76.9%) were on an anti-CD20 therapy, the remaining 3 (23.1%) on fingolimod. Only 2 patients (15.4%), both on anti-CD20 therapy, required hospitalization and steroid treatment. Neither required Intensive Care Unit admission.

CONCLUSION

Patients treated with anti-CD20 agents and sphingosine 1-phosphate receptor modulators may still be at risk for COVID-19 despite vaccination. While still at risk for hospitalization, intubation and death from COVID-19 appear rare. Larger studies analyzing how this may differ in the setting of emerging variants are needed.

Symptomatic and restorative therapies in neuromyelitis optica spectrum disorders

Neuromyelitis optica spectrum disorders (NMOSD) are a group of autoimmune inflammatory conditions that primarily target the optic nerves, spinal cord, brainstem, and occasionally the cerebrum. NMOSD is characterized by recurrent attacks of visual, motor, and/or sensory dysfunction that often result in severe neurological deficits. In recent years, there has been a significant progress in relapse treatment and prevention but the residual disability per attack remains high. Although symptomatic and restorative research has been limited in NMOSD, some therapeutic approaches can be inferred from published case series and evidence from multiple sclerosis literature. In this review, we will discuss established and emerging therapeutic options for symptomatic treatment and restoration of function in NMOSD. We highlight NMOSD-specific considerations and identify potential areas for future research. The review covers pharmacologic, non-pharmacologic, and neuromodulatory approaches to neuropathic pain, tonic spasms, muscle tone abnormalities, sphincter dysfunction, motor and visual impairment, fatigue, sleep disorders, and neuropsychological symptoms. In addition, we briefly discuss remyelinating agents and mesenchymal stem cell transplantation in NMOSD.

Obtaining Patient Priorities in a Multiple Sclerosis Comprehensive Care Center: Beyond Patient-Reported Outcomes

Background:

In order to provide patient center care, our multiple sclerosis (MS) clinic assesses patient concerns before clinical encounters, first by asking the optional qualitative question “What is the most important thing you what your health-care provider to know today” (most important concern of the patient [MIPC]) and then completing quantitative patient-reported outcome measures (PROMs) including Quality of Life in Neurological Disorders (Neuro-QoL). Both sets of questions are designed to facilitate encounters that address patients’ values and preferences.

Objective:

Determine whether the qualitative MIPC responses provided unique information not included in PROMs or clinical assessments.

Methods:

We randomly selected 400 first-time MIPC responders and 400 first-time MIPC nonresponders from 2788 participants in our database. We categorized MIPC responses by content and number of unique concerns and appended them to the Neuro-QoL framework. Nonresponders were compared to those who provided 1 and 2 or more responses.

Results:

Several MIPCs MS symptoms categories were added to the Neuro-QoL Physical domain. Most important concern of the patients work and cost-of-care categories were added to the Social Domain. Domains regarding treatment satisfaction and disease management were added. Two hundred thirty (58%) MIPC respondents reported 1 concern, 140 (35%) expressed 2 to 6 concerns, and 30 (7%) reported MS-unrelated concerns and not analyzed. Physical symptoms were the most common MIPC (69.9%). Respondents with more concerns were more likely African American, lacked private insurance, and worse disability.

Conclusions:

Importantly, MIPC responders described idiosyncratic symptoms, disease management, and social concerns not included in the PROMS, suggesting the MIPC question offered patients a unique opportunity to share specific concerns with their providers.

Achieving effective patient and public involvement in international clinical trials in neurology

There is a growing need for patient and public involvement (PPI) to inform the way that research is developed and performed. International randomized controlled trials are particularly likely to benefit from PPI, but guidance is lacking on how or when it should be incorporated. In this article, we describe the PPI process that occurred during the design and initiation of an international treatment clinical trial in MS. PPI was incorporated using a structured approach, aiming to minimize bias and achieve equivalence in study design, implementation, and interpretation. Methods included PPI representation within the study research team, and the use of focus groups, analyzed using thematic framework analysis. We report the outcomes of PPI and make recommendations on its use in other neurology clinical trials. By sharing our model for PPI, we aim to maximize effectiveness of future public involvement and to allow its effect to be better evaluated.

Is Obesity Related to Processing Speed Impairment in Patients with Multiple Sclerosis: Results of a Large-Scale, Multicenter Study

Background

Obesity is linked to greater physical disability and increased comorbidities among patients with multiple sclerosis (MS). Its contribution to cognition in this group is unclear. This observational study examines the link between obesity and processing speed in a large sample of patients with MS (PwMS).

Methods

As part of routine clinical care at our center, PwMS completed the Processing Speed Test (PST), an electronic implementation of the Symbol Digit Modalities Test (SDMT). Height and weight were used to calculate body mass index (BMI). Bivariate correlations were conducted to examine the association between PST and BMI in the group overall and in subgroups based on demographic and clinical variables. A one-way ANOVA examined differences in PST by BMI categories (normal weight, overweight, obese).

Results

The sample included 8,713 patients. No association between PST and BMI was found in the entire sample (r = .01), nor within subgroups based on demographic and disease variables. No difference in PST score was found between BMI categories.

Conclusions

No association between BMI and processing speed was found among PwMS regardless of demographic or disease-specific patient characteristics.

Serum neurofilament light chain concentration in a phase 1/2 trial of autologous mesenchymal stem cell transplantation

Background

Serum neurofilament light chain concentration is a proposed biomarker of axonal injury in multiple sclerosis. Mesenchymal stem cells have anti-inflammatory and repair-promoting activities, making them of interest for potential multiple sclerosis treatment.

Objectives

The purpose of this study was to assess correlation of serum neurofilament light chain concentration and measures of multiple sclerosis disease activity/severity, longitudinal stability of serum neurofilament light chain concentration, and treatment effect of mesenchymal stem cell transplantation on serum neurofilament light chain concentration.

Methods

Twenty-four multiple sclerosis patients underwent intravenous infusion of autologous mesenchymal stem cells. Clinical assessments, serum collection, and brain magnetic resonance imaging were performed at months -1, 0 (transplant), 1, 3, and 6. Matched control serum was collected once (n = 10). Serum neurofilament light chain concentration was measured by single-molecule array. Serum neurofilament light chain concentration correlations with disease measures were analyzed by Spearman correlations and linear mixed effect models. Pre-post transplant serum neurofilament light chain concentration was compared by Wilcoxon signed rank testing.

Results

There were significant (p<0.01) correlations between serum neurofilament light chain concentration and gadolinium-enhancing lesion number (rho = 0.55) and volume (rho = 0.65), and new/enlarging T2 lesions (rho = 0.65). Patients without disease activity had lower fluctuation in serum neurofilament light chain concentration (p = 0.01). Mean pre- versus post-treatment serum neurofilament light chain concentration values were not significantly different.

Conclusions

Serum neurofilament light chain concentration correlated with magnetic resonance imaging measures of disease activity cross sectionally and longitudinally, and was stable in patients without disease activity. There was no clear treatment effect of mesenchymal stem cell transplantation on serum neurofilament light chain concentration.

Tuberculosis screening in multiple sclerosis: effect of disease-modifying therapies and lymphopenia on the prevalence of indeterminate TB screening results in the clinical setting

Background

Tuberculosis screening is recommended in multiple sclerosis patients starting certain disease-modifying therapies. Disease-modifying therapies may affect interferon-gamma release assay results.

Objective

To determine the effects of multiple sclerosis disease-modifying therapies on interferon-gamma release assay results.

Methods

Indeterminate interferon-gamma release assay results among multiple sclerosis patients were compared across disease-modifying therapies by Fisher's exact test. Logistic regression evaluated the effects of lymphopenia on interferon-gamma release assay results.

Results

A total of 1058 patients underwent interferon-gamma release assay: 2.0% (21) positive, 6.1% (65) indeterminate, with 59.4% (628) on disease-modifying therapies. Results were significantly different across disease-modifying therapies (P = 0.002). Absolute lymphocyte count less than 0.5 k/μL had 9.39 times (95% confidence interval 5.2-17.0) increased odds of indeterminate interferon-gamma release assay results.

Conclusions

Disease-modifying therapies affecting lymphocytes had a higher risk of indeterminate interferon-gamma release assay results.

Collaborative International Research in Clinical and Longitudinal Experience Study in NMOSD

Objective

To develop a resource of systematically collected, longitudinal clinical data and biospecimens for assisting in the investigation into neuromyelitis optica spectrum disorder (NMOSD) epidemiology, pathogenesis, and treatment.

Methods

To illustrate its research-enabling purpose, epidemiologic patterns and disease phenotypes were assessed among enrolled subjects, including age at disease onset, annualized relapse rate (ARR), and time between the first and second attacks.

Results

As of December 2017, the Collaborative International Research in Clinical and Longitudinal Experience Study (CIRCLES) had enrolled more than 1,000 participants, of whom 77.5% of the NMOSD cases and 71.7% of the controls continue in active follow-up. Consanguineous relatives of patients with NMOSD represented 43.6% of the control cohort. Of the 599 active cases with complete data, 84% were female, and 76% were anti-AQP4 seropositive. The majority were white/Caucasian (52.6%), whereas blacks/African Americans accounted for 23.5%, Hispanics/Latinos 12.4%, and Asians accounted for 9.0%. The median age at disease onset was 38.4 years, with a median ARR of 0.5. Seropositive cases were older at disease onset, more likely to be black/African American or Hispanic/Latino, and more likely to be female.

Conclusions

Collectively, the CIRCLES experience to date demonstrates this study to be a useful and readily accessible resource to facilitate accelerating solutions for patients with NMOSD.

Exploratory MRI measures after intravenous autologous culture-expanded mesenchymal stem cell transplantation in multiple sclerosis

Background

Mesenchymal stem cells (MSC) have immunomodulatory and neuro-protective properties and are being studied for treatment of multiple sclerosis (MS). Tractography-based diffusion tensor imaging (DTI), cortical thickness (Cth) and T2 lesion volume (T2LV) can provide insight into treatment effects.

Objective

The objective of this study was to analyse the effects of MSC transplantation in MS on exploratory MRI measures.

Methods

MRIs were obtained from 24 MS patients from a phase 1 open-label study of autologous MSC transplantation. DTI metrics were obtained in lesions and normal-appearing white matter motor tracts (NAWM). T2LV and Cth were derived. Longitudinal evolution of MRI outcomes were modelled using linear mixed effects. Pearson’s correlation was calculated between MRI and clinical measures.

Results

Lesional radial diffusivity (RD) and axial diffusivity (AD) decreased pre-transplant and showed no changes post-transplant. There were mixed trends in NAWM RD and AD pre/post-transplant. Transplantation stabilized T2LV growth. NAWM RD and AD correlated with Cth, T2LV and with leg and arm function but not with cognition. Lesional DTI demonstrated similar but less robust correlations.

Conclusions

Microstructural tissue integrity is altered in MS. DTI changes pre-transplant may be influenced by concomitant lesion accrual. Contributor to DTI stabilization post-transplant is multifactorial. DTI of major motor tracts correlated well with clinical measures, highlighting its sensitivity to clinically meaningful changes.

Modulators of Redox Metabolism in Head and Neck Cancer

SIGNIFICANCE

Head and neck squamous cell cancer (HNSCC) is a complex disease characterized by high genetic and metabolic heterogeneity. Radiation therapy (RT) alone or combined with systemic chemotherapy is widely used for treatment of HNSCC as definitive treatment or as adjuvant treatment after surgery. Antibodies against epidermal growth factor receptor are used in definitive or palliative treatment. Recent Advances: Emerging targeted therapies against other proteins of interest as well as programmed cell death protein 1 and programmed death-ligand 1 immunotherapies are being explored in clinical trials.

CRITICAL ISSUES

The disease heterogeneity, invasiveness, and resistance to standard of care RT or chemoradiation therapy continue to constitute significant roadblocks for treatment and patients' quality of life (QOL) despite improvements in treatment modality and the emergence of new therapies over the past two decades.

FUTURE DIRECTIONS

As reviewed here, alterations in redox metabolism occur at all stages of HNSCC management, providing opportunities for improved prevention, early detection, response to therapies, and QOL. Bioinformatics and computational systems biology approaches are key to integrate redox effects with multiomics data from cells and clinical specimens and to identify redox modifiers or modifiable target proteins to achieve improved clinical outcomes. Antioxid. Redox Signal.

Pilot trial of intravenous autologous culture-expanded mesenchymal stem cell transplantation in multiple sclerosis

BACKGROUND

Mesenchymal stem cells (MSCs) exhibit immunomodulatory, tissue-protective, and repair-promoting properties in vitro and in animals. Clinical trials in several human conditions support the safety and efficacy of MSC transplantation. Published experience in multiple sclerosis (MS) is modest.

OBJECTIVE

To assess feasibility, safety, and tolerability and explore efficacy of autologous MSC transplantation in MS.

METHODS

Participants with relapsing-remitting multiple sclerosis (RRMS) or secondary progressive multiple sclerosis (SPMS), Expanded Disability Status Scale score 3.0-6.5, disease activity or progression in the prior 2 years, and optic nerve involvement were enrolled. Bone-marrow-derived MSCs were culture-expanded and then cryopreserved. After confirming fulfillment of release criteria, 1-2 × 106 MSCs/kg were thawed and administered IV.

RESULTS

In all, 24 of 26 screened patients were infused: 16 women and 8 men, 10 RRMS and 14 SPMS, mean age 46.5, mean Expanded Disability Status Scale score 5.2, 25% with gadolinium-enhancing magnetic resonance imaging (MRI) lesions. Mean cell dosage (requiring 1-3 passages) was 1.9 × 106 MSCs/kg (range, 1.5-2.0) with post-thaw viability uniformly ⩾95%. Cell infusion was tolerated well without treatment-related severe or serious adverse events, or evidence of disease activation.

CONCLUSION

Autologous MSC transplantation in MS appears feasible, safe, and well tolerated. Future trials to assess efficacy more definitively are warranted.

Feasibility of mesenchymal stem cell culture expansion for a phase I clinical trial in multiple sclerosis

Background

Multiple sclerosis is an inflammatory, neurodegenerative disease of the central nervous system for which therapeutic mesenchymal stem cell transplantation is under study. Published experience of culture-expanding multiple sclerosis patients' mesenchymal stem cells for clinical trials is limited.

Objective

To determine the feasibility of culture-expanding multiple sclerosis patients' mesenchymal stem cells for clinical use.

Methods

In a phase I trial, autologous, bone marrow-derived mesenchymal stem cells were isolated from 25 trial participants with multiple sclerosis and eight matched controls, and culture-expanded to a target single dose of 1-2 × 10⁶ cells/kg. Viability, cell product identity and sterility were assessed prior to infusion. Cytogenetic stability was assessed by single nucleotide polymorphism analysis of mesenchymal stem cells from 18 multiple sclerosis patients and five controls.

Results

One patient failed screening. Mesenchymal stem cell culture expansion was successful for 24 of 25 multiple sclerosis patients and six of eight controls. The target dose was achieved in 16-62 days, requiring two to three cell passages. Growth rate and culture success did not correlate with demographic or multiple sclerosis disease characteristics. Cytogenetic studies identified changes on one chromosome of one control (4.3%) after extended time in culture.

Conclusion

Culture expansion of mesenchymal stem cells from multiple sclerosis patients as donors is feasible. However, culture time should be minimized for cell products designated for therapeutic administration.

CNS disease diminishes the therapeutic functionality of bone marrow mesenchymal stem cells

Mesenchymal stem cells (MSCs) have emerged as a potentially powerful cellular therapy for autoimmune diseases including multiple sclerosis (MS). Based on their success in treating animal models of MS like experimental autoimmune encephalomyelitis (EAE), MSCs have moved rapidly into clinical trials for MS. The majority of these trials use autologous MSCs derived from MS patients, although it remains unclear how CNS disease may affect these cells. Here, we report that bone marrow MSCs derived from EAE mice lack therapeutic efficacy compared to naïve MSCs in their ability to ameliorate EAE. Treatment with conditioned medium from EAE-MSCs also fails to modulate EAE, and EAE-MSCs secrete higher levels of many pro-inflammatory cytokines compared to naïve MSCs. Similarly, MSCs derived from MS patients have less therapeutic efficacy than naïve MSCs in treating EAE and secrete higher levels of some of the same pro-inflammatory cytokines. Thus diseases like EAE and MS diminish the therapeutic functionality of bone marrow MSCs, prompting reevaluation about the ongoing use of autologous MSCs as a treatment for MS.

Human Mesenchymal Stem Cells Impact Th17 and Th1 Responses Through a Prostaglandin E2 and Myeloid-Dependent Mechanism

: Human mesenchymal stem cells (hMSCs) are being increasingly pursued as potential therapies for immune-mediated conditions, including multiple sclerosis. Although they can suppress human Th1 responses, they reportedly can reciprocally enhance human Th17 responses. Here, we investigated the mechanisms underlying the capacity of hMSCs to modulate human Th1 and Th17 responses. Human adult bone marrow-derived MSCs were isolated, and their purity and differentiation capacity were confirmed. Human venous peripheral blood mononuclear cells (PBMC) were activated, alone, together with hMSC, or in the presence of hMSC-derived supernatants (sups). Cytokine expression by CD4+ T-cell subsets (intracellular staining by fluorescence-activated cell sorting) and secreted cytokines (enzyme-linked immunosorbent assay) were then quantified. The contribution of prostaglandin E2 (PGE2) as well as of myeloid cells to the hMSC-mediated regulation of T-cell responses was investigated by selective depletion of PGE2 from the hMSC sups (anti-PGE2 beads) and by the selective removal of CD14+ cells from the PBMC (magnetic-activated cell sorting separation). Human MSC-secreted products could reciprocally induce interleukin-17 expression while decreasing interferon-γ expression by human CD4+ T cells, both in coculture and through soluble products. Pre-exposure of hMSCs to IL-1β accentuated their capacity to reciprocally regulate Th1 and Th17 responses. Human MSCs secreted high levels of PGE2, which correlated with their capacity to regulate the T-cell responses. Selective removal of PGE2 from the hMSC supernatants abrogated the impact of hMSC on the T cells. Selective removal of CD14+ cells from the PBMCs also limited the capacity of hMSC-secreted PGE2 to affect T-cell responses. Our discovery of a novel PGE2-dependent and myeloid cell-mediated mechanism by which human MSCs can reciprocally induce human Th17 while suppressing Th1 responses has implications for the use of, as well as monitoring of, MSCs as a potential therapeutic for patients with multiple sclerosis and other immune-mediated diseases.

SIGNIFICANCE

Although animal studies have generated a growing interest in the anti-inflammatory potential of mesenchymal stem cells (MSCs) for the treatment of autoimmune diseases, MSCs possess the capacity to both limit and promote immune responses. Yet relatively little is known about human-MSC modulation of human disease-implicated T-cell responses, or the mechanisms underlying such modulation. The current study reveals a novel prostaglandin E2-dependent and myeloid cell-mediated mechanism by which human MSCs can reciprocally regulate human Th17 and Th1 responses, with implications for the use of MSCs as a potential therapeutic for patients with multiple sclerosis and other immune-mediated diseases.

Effects of meditation on pain and quality of life in multiple sclerosis and peripheral neuropathy: a pilot study

The objective of this study was to determine whether meditation affects pain and quality of life in people with multiple sclerosis (MS) and peripheral neuropathy (PN). A total of 22 patients (10 with MS, 12 with PN) participated in a weekly meditation class over a 2-month period. A total of 18 controls (7 with MS, 11 with PN) received standard care. Primary outcome assessments were based on the 36-item Short Form Health Status Survey (SF-36) and a visual analogue scale (VAS) for pain at baseline and at 2 months. Secondary outcome measures included the Neuropathy Impairment Score (NIS) for PN patients and the Patient-Determined Disease Steps (PDDS) questionnaire and 5-item Modified Fatigue Impact Scale (MFIS-5) for MS patients. After 2 months, study participants who practiced meditation reported an improvement in pain on the VAS (P = .035 combined group), summed physical health scores on the SF-36 (P = .011 MS, P = .014 PN), summed mental health scores (P = .02 combined group), vitality (P = .005 combined group), and physical role (P = .003 combined group). A significant improvement was also observed for bodily pain (P = .031) in MS patients. In contrast, no significant differences before and after the intervention were observed for controls. Regarding the secondary measure of fatigue, improved scores for the cognitive and psychosocial components of the MFIS were noted in MS patients in the intervention group (P = .037, P = .032). No statistically significant changes were observed in the NIS for PN patients or in PDDS scores for MS patients. Meditation may be helpful in reducing pain and improving quality of life in patients with MS and PN. The lack of changes seen in mobility (MS) and sensorimotor deficits (PN) suggests that meditation may not affect the overall clinical course.

Germline and somatic cancer-associated mutations in the ATP-binding motifs of PTEN influence its subcellular localization and tumor suppressive function

Germline and somatic PTEN mutations are found in Cowden syndrome (CS) and multiple sporadic malignancies, respectively. PTEN function appears to be modulated by subcellular compartmentalization, and mislocalization may affect function. We have shown that cellular ATP levels affect nuclear PTEN levels. Here, we examined the ATP-binding capabilities of PTEN and functional consequences, relevant to cancer-associated mutations. PTEN mutation analysis of CS patients and sporadic colorectal carcinomas and comparative aminoacid analysis were utilized to identify mutations in ATP-binding motifs. The ability of wild-type (WT) or mutant PTEN to bind ATP was assessed by ATP–agarose-binding assays. Subcellular fractionation, western blotting, confocal microscopy and growth assays were used to determine relative nuclear-cytoplasmic localization and function. Somatic colorectal carcinoma-derived PTEN missense mutations were associated with nuclear mislocalization. These mutations altered cellular proliferation, apoptosis and anchorage-dependent growth. Examination of PTEN's amino acid sequence revealed these mutations resided in previously undescribed ATP-binding motifs (c.60–73; c.122–136). In contrast to WT PTEN, both cancer-associated somatic and germline-derived PTEN missense mutations, which lie within the ATP-binding motifs, result in mutant PTEN that does not bind ATP efficiently. We also show that CS patients with germline ATP-binding motif-mutations had nuclear PTEN mislocalization. Of four unrelated patients with functional germline ATP-binding domain mutations, all three female patients had breast cancers. Germline and somatic mutations within PTEN's ATP-binding domain play important pathogenic roles in both heritable and sporadic carcinogenesis by PTEN nuclear mislocalization resulting in altered signaling and growth. Manipulation of ATP may represent novel therapies in tumors with such PTEN alterations.

ATP modulates PTEN subcellular localization in multiple cancer cell lines

The tumour suppressor gene PTEN plays an important somatic role in both hereditary and sporadic breast carcinogenesis. While the role of PTEN's lipid phosphatase activity, as a negative regulator of the cytoplasmic phosphatidylinositol-3-kinase/Akt pathway is well known, it is now well established that PTEN exists and functions in the nucleus. Multiple mechanisms of regulating PTEN's subcellular localization have been reported. However none are ubiquitous across multiple cancer cell lines and tissue types. We show here that adenosine triphosphate (ATP) regulates PTEN subcellular localization in a variety of different cancer cell lines, including those derived from breast, colon and thyroid carcinomas. Cells deficient in ATP show an increased level of nuclear PTEN protein. This increase in PTEN is reversed when cells are supplemented with ATP, ADP or AMP. In contrast, the addition of the non-hydrolyzable analogue ATPgammaS, did not reverse nuclear PTEN protein levels in all the cell types tested. To our knowledge, this is the first report that describes a regulation of PTEN subcellular localization that is not specific to one cell line or tissue type, but appears to be common across a variety of cell lineages.

The nuclear affairs of PTEN

PTEN encodes a major tumor-suppressor protein that is a dual-specificity phosphatase. Inactivation of PTEN has been shown to be involved in heritable and sporadic cancers. Mutation or deletion of PTEN, historically the most commonly identified mechanisms of inactivation of tumor suppressors, is found only in the minority of sporadic non-cultured primary cancers, which indicates that there might be other, novel mechanisms of inactivation. Despite the absence of a classic nuclear localization signal, PTEN enters the nucleus by several mechanisms, including simple diffusion, active shuttling, cytoplasmic-localization-signal-dependent export and monoubiquitylation-dependent import. Cytoplasmic PTEN has a well-known role as a negative regulator of the PI3K/AKT pathway; however, it is becoming clear that cytosolic PTEN is not the same as nuclear PTEN. Nuclear PTEN plays a role in chromosome stability, DNA repair, cell cycle arrest and cellular stability. The balance between these functions is an important factor in determining whether a cell remains benign or becomes neoplastic.

Regulation of the PTEN promoter by statins and SREBP

Germline mutations in the tumor-suppressor gene PTEN predispose to heritable breast cancer. The transcription factor peroxisome proliferator-activated receptor-gamma (PPARgamma) has also been implicated as a tumor suppressor pertinent to a range of neoplasias, including breast cancer. We previously demonstrated that lovastatin may signal through PPARgamma and directly upregulate PTEN expression at the transcriptional level. In our current study, we show that simvastatin, pravastatin and fluvastatin can induce PTEN expression in a dose-dependent manner. This resulted from an increase in PTEN mRNA indicating transcriptional upregulation. In addition, we observed, for the first time, that upregulation of sterol response element-binding protein (SREBP), known to induce PPARgamma expression, can increase PTEN expression. Using reporter assays, we observed that both the statins and SREBP could specifically induce PPARgamma-mediated transcription. However, the statins do not appear to signal through SREBP. Furthermore, our results indicate that SREBP utilizes PPARgamma's transcriptional activity to induce PTEN transcription, whereas the statins signal through PPARgamma's protein activity to upregulate PTEN expression. Overall, our observations suggest that statins signal through another transcription factor, in a PPARgamma-dependent manner, which in turn induces PTEN transcription. We, therefore, studied the full-length PTEN promoter through serial deletion reporter assays and electromobility shift assays and identified a region between -854 and -791 that binds an as-yet-unidentified transcription factor, through which the statins induce PTEN expression. Since PTEN is constitutively active, our data indicate it may be worthwhile to examine statin and SREBP stimulation as mechanisms to increase PTEN expression for therapeutic and preventative strategies in cancer, diabetes mellitus and cardiovascular disease.

Tyk2 tyrosine kinase expression is required for the maintenance of mitochondrial respiration in primary pro-B lymphocytes

Tyk2, a member of the Jak family of protein tyrosine kinases, is critical for the biological actions of alpha/beta interferon (IFN-alpha/beta). Although Tyk2(-/-) mice are phenotypically normal, they exhibit abnormal responses to inflammatory challenges in a variety of cells isolated from Tyk2(-/-) mice. The reported phenotypic alterations in both Tyk2-null cells and mice are consistent with the possibility that the expression of this tyrosine kinase may regulate mitochondrial function. We report here that Tyk2-null pro-B cells are markedly deficient in basal oxygen consumption and exhibit a significant decrease in steady-state cellular ATP levels compared to wild-type cells. Tyk2-null cells also exhibit impaired complex I, III, and IV function of the mitochondrial electron transport chain. Reconstitution of Tyk2-null pro-B cells with either the wild type or a kinase-inactive mutant of Tyk2 restores basal mitochondrial respiration. By contrast, the kinase activity of Tyk2 is required for maintenance of both complex I-dependent mitochondrial respiration as well as induction of apoptosis in cells incubated with IFN-beta. Consistent with the role of Tyk2 in the regulation of tyrosine phosphorylation of Stat3, expression of a constitutively active Stat3 can restore the mitochondrial respiration in Tyk2-null cells treated with IFN-beta. Finally, Tyk2(-/-) mice show decreased exercise tolerance compared to wild-type littermates. Our results implicate a novel role for Tyk2 kinase and Stat3 phosphorylation in mitochondrial respiration.

Growth factor-dependent AKT activation and cell migration requires the function of c-K(B)-Ras versus other cellular ras isoforms

K-Ras-negative fibroblasts are defective in their steady-state expression of MMP-2. This occurs through c-K(B)-Ras dependent regulation of basal levels of AKT activity. In this report, we have extended those studies to demonstrate that in the absence of K-Ras expression, PDGF-BB fails to induce significant AKT activation, although this was not the case in N-Ras-negative cells. This phenotype was directly linked to PDGF-dependent cell migration. All of the independently immortalized K-Ras-negative cells failed to migrate upon the addition of PDGF. Only ectopic expression of c-K(B)-Ras, not c-K(A)-Ras nor oncogenic N-Ras, could restore both PDGF-dependent AKT activation and cell migration. Since most Ras binding partners can interact with all Ras isoforms, the specificity of PDGF-dependent activation of AKT and enhanced cell migration suggests that these outcomes are likely to be regulated through a c-K(B)-Ras-specific binding partner. Others have published that of the four Ras isoforms, only K(B)-Ras can form a stable complex with calmodulin (CaM). Along those lines, we provide evidence that 1) PDGF addition results in increased levels of a complex between c-K(B)-Ras and CaM and 2) the biological outcomes that are strictly dependent on c-K(B)-Ras (AKT activation and cell migration) are blocked by CaM antagonists. The PDGF-dependent activation of ERK is unaffected by the absence of K(B)-Ras and presence of CaM antagonists. This is the first example of a linkage between a specific biological outcome, cell migration, and the activity of a single Ras isoform, c-K(B)-Ras.

Structural and functional consequences of c-N-Ras constitutively associated with intact mitochondria

We demonstrate that both c-N-Ras and c-K(B)-Ras are constitutively associated with purified mitochondria. c-K(B)-Ras is associated with the mitochondrial outer membrane, and c-N-Ras is associated with both the outer membrane and inner mitochondrial compartments. The mitochondrial morphology is abnormal in both c-N-Ras negative and K-Ras negative cells. Normal mitochondrial morphology was restored by targeting N-Ras to both the inner and outer mitochondrial compartments, or by ectopically expressing c-K(B)-Ras. Impaired mitochondrial function can result in increased CHOP and NFkappaB activity, typical for a retrograde signaling response. Both are constitutively elevated in the N-Ras negative cells, but not in the K-Ras negative background, and are restored by c-N-Ras targeted exclusively to the inner mitochondrial compartment. Surprisingly, both targeting and the ability to functionally reduce retrograde transcriptional activity were found to be independent of c-N-Ras farnesylation. Overall, these data demonstrate for the first time a (1) farnesylation independent function for c-N-Ras and (2) that N-Ras within the inner mitochondrial compartment is an essential component of the retrograde signaling system between the mitochondria and nucleus.

beta-Lapachone-induced apoptosis in human prostate cancer cells: involvement of NQO1/xip3

beta-Lapachone (beta-lap) induces apoptosis in various cancer cells, and its intracellular target has recently been elucidated in breast cancer cells. Here we show that NAD(P)H:quinone oxidoreductase (NQO1/xip3) expression in human prostate cancer cells is a key determinant for apoptosis and lethality after beta-lap exposures. beta-Lap-treated, NQO1-deficient LNCaP cells were significantly more resistant to apoptosis than NQO1-expressing DU-145 or PC-3 cells after drug exposures. Formation of an atypical 60-kDa PARP cleavage fragment in DU-145 or PC-3 cells was observed after 10 microM beta-lap treatment and correlated with apoptosis. In contrast, LNCaP cells required 25 microM beta-lap to induce similar responses. Atypical PARP cleavage in beta-lap-treated cells was not affected by 100 microM zVAD-fmk; however, coadministration of dicoumarol, a specific inhibitor of NQO1, reduced beta-lap-mediated cytotoxicity, apoptosis, and atypical PARP cleavage in NQO1-expressing cells. Dicoumarol did not affect the more beta-lap-resistant LNCaP cells. Stable transfection of LNCaP cells with NQO1 increased their sensitivity to beta-lap, enhancing apoptosis compared to parental LNCaP cells or vector-alone transfectants. Dicoumarol increased survival of beta-lap-treated NQO1-expressing LNCaP transfectants. NQO1 activity, therefore, is a key determinant of beta-lap-mediated apoptosis and cytotoxicity in prostate cancer cells.

Activation of a cysteine protease in MCF-7 and T47D breast cancer cells during beta-lapachone-mediated apoptosis

beta-Lapachone (beta-lap) effectively killed MCF-7 and T47D cell lines via apoptosis in a cell-cycle-independent manner. However, the mechanism by which this compound activated downstream proteolytic execution processes were studied. At low concentrations, beta-lap activated the caspase-mediated pathway, similar to the topoisomerase I poison, topotecan; apoptotic reactions caused by both agents at these doses were inhibited by zVAD-fmk. However at higher doses of beta-lap, a novel non-caspase-mediated "atypical" cleavage of PARP (i.e., an approximately 60-kDa cleavage fragment) was observed. Atypical PARP cleavage directly correlated with apoptosis in MCF-7 cells and was inhibited by the global cysteine protease inhibitors iodoacetamide and N-ethylmaleimide. This cleavage was insensitive to inhibitors of caspases, granzyme B, cathepsins B and L, trypsin, and chymotrypsin-like proteases. The protease responsible appears to be calcium-dependent and the concomitant cleavage of PARP and p53 was consistent with a beta-lap-mediated activation of calpain. beta-Lap exposure also stimulated the cleavage of lamin B, a putative caspase 6 substrate. Reexpression of procaspase-3 into caspase-3-null MCF-7 cells did not affect this atypical PARP proteolytic pathway. These findings demonstrate that beta-lap kills cells through the cell-cycle-independent activation of a noncaspase proteolytic pathway.

NAD(P)H:Quinone oxidoreductase activity is the principal determinant of beta-lapachone cytotoxicity

beta-Lapachone activates a novel apoptotic response in a number of cell lines. We demonstrate that the enzyme NAD(P)H:quinone oxidoreductase (NQO1) substantially enhances the toxicity of beta-lapachone. NQO1 expression directly correlated with sensitivity to a 4-h pulse of beta-lapachone in a panel of breast cancer cell lines, and the NQO1 inhibitor, dicoumarol, significantly protected NQO1-expressing cells from all aspects of beta-lapachone toxicity. Stable transfection of the NQO1-deficient cell line, MDA-MB-468, with an NQO1 expression plasmid increased apoptotic responses and lethality after beta-lapachone exposure. Dicoumarol blocked both the apoptotic responses and lethality. Biochemical studies suggest that reduction of beta-lapachone by NQO1 leads to a futile cycling between the quinone and hydroquinone forms, with a concomitant loss of reduced NAD(P)H. In addition, the activation of a cysteine protease, which has characteristics consistent with the neutral calcium-dependent protease, calpain, is observed after beta-lapachone treatment. This is the first definitive elucidation of an intracellular target for beta-lapachone in tumor cells. NQO1 could be exploited for gene therapy, radiotherapy, and/or chemopreventive interventions, since the enzyme is elevated in a number of tumor types (i.e. breast and lung) and during neoplastic transformation.

Coordinate modulation of Sp1, NF-kappa B, and p53 in confluent human malignant melanoma cells after ionizing radiation

Regulation of transcriptional responses in growth-arrested human cells under conditions that promote potentially lethal damage repair after ionizing radiation (IR) is poorly understood. Sp1/retinoblastoma control protein (RCP) DNA binding increased within 30 min and peaked at 2-4 h after IR (450-600 cGy) in confluent radioresistant human malignant melanoma (U1-Mel) cells. Increased phosphorylation of Sp1 directly corresponded to Sp1/RCP binding and immediate-early gene induction, whereas pRb remained hypophosphorylated. Transfection of U1-Mel cells with the human papillomavirus E7 gene abrogated Sp1/RCP induction and G(0)/G(1) cell cycle checkpoint arrest responses, increased apoptosis and radiosensitivity, and augmented genetic instability (i.e., increased polyploidy cells) after IR. Increased NF-kappaB DNA binding in U1-Mel cells after IR treatment lasted much longer (i.e., >20 h). U1-Mel cells overexpressing dominant-negative IkappaBalpha S32/36A mutant protein were significantly more resistant to IR exposure and retained both G(2)/M and G(0)/G(1) cell cycle checkpoint responses without significant genetic instability (i.e., polyploid cell populations were not observed). Nuclear p53 protein levels and DNA binding activity increased only after high doses of IR (>1200 cGy). Disruption of p53 responses in U1-Mel cells by E6 transfection also abrogated G(0)/G(1) cell cycle checkpoint arrest responses and increased polyploidy after IR, but did not alter radiosensitivity. These data suggest that abrogation of individual components of this coordinate IR-activated transcription factor response may lead to divergent alterations in cell cycle checkpoints, genomic instability, apoptosis, and survival. Such coordinate transcription factor activation in human cancer cells is reminiscent of prokaryotic SOS responses, and further elucidation of these events should shed light on the initial molecular events in the chromosome instability phenotype.-Yang, C.-R., Wilson-Van Patten, C., Planchon, S. M., Wuerzberger-Davis, S. M., Davis, T. W., Cuthill, C., Miyamoto, S., Boothman, D. A. Coordinate modulation of Sp1, NF-kappa B, and p53 in confluent human malignant melanoma cells after ionizing radiation.

Bcl-2 protects against beta-lapachone-mediated caspase 3 activation and apoptosis in human myeloid leukemia (HL-60) cells

We previously demonstrated that beta-lapachone (beta-lap) killed cancer cells solely by apoptosis. Beta-Lap induced apoptosis in HL-60 cells in a dose-dependent manner as measured by flow cytometry and DNA ladder formation. Cell cycle changes, such as accumulations in S and G2-phases, were not observed. Apoptosis was accompanied by activation of caspase 3 and concomitant cleavage of poly(ADP-ribose) polymerase (PARP) to an 89 kDa polypeptide. PARP cleavage was blocked by zDEVD-fmk or zVAD-fmk, caspase-specific cleavage site inhibitors. Retrovirally introduced bcl-2 prevented beta-lap-mediated caspase 3 activation and PARP cleavage and increased the viability of Bcl-2-expressing HL-60 cells compared to cells with vector alone. Various beta-lap-related analogs (e.g., dunnione and naphthoquinone derivatives) induced equivalent apoptosis in HL-60 cells, but no compound was more effective than beta-lap. These data provide further evidence that the primary mode of cell killing by beta-lap is by the initiation and execution of apoptosis in human cancer cells.

Induction of apoptosis in MCF-7:WS8 breast cancer cells by beta-lapachone

Beta-lapachone (beta-lap) affects a number of enzymes in vitro, including type I topoisomerase (Topo I); however, its exact intracellular target(s) and mechanism of cell killing remain unknown. We compared the cytotoxic responses of MCF-7:WS8 (MCF-7) human breast cancer cells after 4-h pulses of beta-lap or camptothecin (CPT), a known Topo I poison. A direct correlation between loss of survival and apoptosis was seen after beta-lap treatment (LD50 = 2.5 microM). A concentration-dependent, transient sub-2 N preapoptotic cell population was observed at 4-8 h. Estrogen deprivation-induced synchronization and bromodeoxyuridine-labeling studies revealed an apoptotic exit point near the G1-S border. Apoptosis activated by beta-lap was closely correlated with cleavage of lamin B but not with increases in p53/p21 or decreases in bcl-2. Loss of hyperphosphorylated forms of the retinoblastoma protein was observed within 5 h, but cyclins A, B1, and E levels were unaltered for up to 72 h after 5 microM beta-lap. Topo I and Topo IIalpha levels decreased at > 24 h. Logarithmic-phase MCF-7 cells were not affected by < or = 1 microM beta-lap. In contrast, dramatic and irreversible G2-M arrest with no apoptosis was observed in MCF-7 cells treated with 1 microM CPT, monitored for 6-10 days posttreatment. MCF-7 cells treated with supralethal doses of CPT (5 microM) resulted in only approximately 20% apoptosis. No correlation between apoptosis and loss of survival was observed. MCF-7 cells exposed to > 5 microM CPT arrested at key cell cycle checkpoints (i.e., G1, S, and G2-M), with little or no movement for 6 days. Ten-fold increases in p53/p21 and 2-5-fold decreases in bcl-2, Topo I, Topo IIalpha, and cyclins A and B1, with no change in cyclin E, were observed. Temporal decreases in bcl-2 and cleavage of lamin B corresponded to the minimal apoptotic response observed. Beta-lap activated apoptosis without inducing p53/p21 or cell cycle arrest responses and killed MCF-7 cells solely by apoptosis. In contrast, concentration-dependent increases in nuclear p53/p21 and various cell cycle checkpoint arrests were seen in MCF-7 cells after CPT. Despite dramatic p53/p21 protein induction responses, CPT-treated MCF-7 cells showed low levels of apoptosis, possibly due to protective cell cycle checkpoints or the lack of specific CPT-activated apoptotic pathways in MCF-7 cells.

Damage-sensing mechanisms in human cells after ionizing radiation

Human cells have evolved several mechanisms for responding to damage created by ionizing radiation. Some of these responses involve the activation or suppression of the transcriptional machinery. Other responses involve the downregulation of enzymes, such as topoisomerase I, which appear to be necessary for DNA repair or apoptosis. Over the past five years, many studies have established links between DNA damage, activation of transcription factors that are coupled to DNA repair mechanisms, increased gene transcription and altered cell cycle regulation to allow for repair or cell death via apoptosis or necrosis. Together these factors determine whether a cell will survive with or without carcinogenic consequences. The immediate responses of human cells to ionizing radiation, in terms of sensing and responding to damage, are therefore, critical determinants of cell survival and carcinogenesis.

Beta-lapachone-mediated apoptosis in human promyelocytic leukemia (HL-60) and human prostate cancer cells: a p53-independent response

beta-Lapachone and certain of its derivatives directly bind and inhibit topoisomerase I (Topo I) DNA unwinding activity and form DNA-Topo I complexes, which are not resolvable by SDS-K+ assays. We show that beta-lapachone can induce apoptosis in certain cells, such as in human promyelocytic leukemia (HL-60) and human prostate cancer (DU-145, PC-3, and LNCaP) cells, as also described by Li et al. (Cancer Res., 55: 0000-0000, 1995). Characteristic 180-200-bp oligonucleosome DNA laddering and fragmented DNA-containing apoptotic cells via flow cytometry and morphological examinations were observed in 4 h in HL-60 cells after a 4-h, > or = 0.5 microM beta-lapachone exposure. HL-60 cells treated with camptothecin or topotecan resulted in greater apoptotic DNA laddering and apoptotic cell populations than comparable equitoxic concentrations of beta-lapachone, although beta-lapachone was a more effective Topo I inhibitor. beta-Lapachone treatment (4 h, 1-5 microM) resulted in a block at G0/G1, with decreases in S and G2/M phases and increases in apoptotic cell populations over time in HL-60 and three separate human prostate cancer (DU-145, PC-3, and LNCaP) cells. Similar treatments with topotecan or camptothecin (4 h, 1-5 microM) resulted in blockage of cells in S and apoptosis. Thus, beta-lapachone causes a block in G0/G1 of the cell cycle and induces apoptosis in cells before, or at early times during, DNA synthesis. These events are p53 independent, since PC-3 and HL-60 cells are null cells, LNCaP are wild-type, and DU-145 contain mutant p53, yet all undergo apoptosis after beta-lapachone treatment. Interestingly, beta-lapachone treatment of p53 wild type-containing prostate cancer cells (i.e., LNCaP) did not result in the induction of nuclear levels of p53 protein, as did camptothecin-treated cells. Like other Topo I inhibitors, beta-lapachone may induce apoptosis by locking Topo I onto DNA, blocking replication fork movement, and inducing apoptosis in a p53-independent fashion. beta-Lapachone and its derivatives, as well as other Topo I inhibitors, have potential clinical utility alone against human leukemia and prostate cancers.

Regulation of intestinal epithelial barrier function by TGF-beta 1. Evidence for its role in abrogating the effect of a T cell cytokine

Maintenance of the integrity of the single-cell-thick intestinal epithelium as an in vivo barrier between environmental Ags and mucosal immunocytes is pivotal for health. The T cell cytokine IFN-gamma consistently disrupts this epithelial barrier in vitro, but the substances in mucosa that may be responsible for sustaining or enhancing barrier function have not been clearly identified. Therefore, we characterized the effect on the epithelial barrier of TGF-beta 1 and three prominent neuropeptides (VIP, substance P, somatostatin) by using a model system in which barrier function of a mature polar human colonic epithelial (T84) cell monolayer is reflected in 1) the electrical potential difference across the apical to basolateral surface of each cell, 2) the transmonolayer permeability to macromolecules such as horseradish peroxidase, and 3) lactate dehydrogenase release into the medium indicating epithelial cell cytolysis. Whereas T84 monolayers exposed to TGF-beta 1 alone demonstrated a modest increase in electrical resistance and barrier integrity, TGF-beta 1 showed a striking ability to reduce the capacity of IFN-gamma to disrupt epithelial barrier function. Characterization studies demonstrated that this TGF-beta 1 effect was prolonged (e.g., days) after a single exposure, progressive over the dose range 0.1 to 2.5 ng/ml, reversible with increased concentrations of IFN-gamma, and more pronounced when TGF-beta 1 exposure was to basolateral rather than to apical epithelial membranes. Macromolecular (horseradish peroxidase) penetration of epithelium was not simultaneously altered by TGF-beta 1 and epithelial cellular injury was minimal as gauged by lactate dehydrogenase release. Additional studies using a human pathogen demonstrated that TGF-beta 1 delayed and decreased the barrier disruption caused by exposure to Cryptosporidium parvum. TGF-beta 1 may be the first of a new class of cytokines that maintains and/or enhances barrier function of human enterocytes, in part by countering the effect of a T cell cytokine.

Regulation of intestinal epithelial barrier function by TGF-beta 1. Evidence for its role in abrogating the effect of a T cell cytokine

Maintenance of the integrity of the single-cell-thick intestinal epithelium as an in vivo barrier between environmental Ags and mucosal immunocytes is pivotal for health. The T cell cytokine IFN-gamma consistently disrupts this epithelial barrier in vitro, but the substances in mucosa that may be responsible for sustaining or enhancing barrier function have not been clearly identified. Therefore, we characterized the effect on the epithelial barrier of TGF-beta 1 and three prominent neuropeptides (VIP, substance P, somatostatin) by using a model system in which barrier function of a mature polar human colonic epithelial (T84) cell monolayer is reflected in 1) the electrical potential difference across the apical to basolateral surface of each cell, 2) the transmonolayer permeability to macromolecules such as horseradish peroxidase, and 3) lactate dehydrogenase release into the medium indicating epithelial cell cytolysis. Whereas T84 monolayers exposed to TGF-beta 1 alone demonstrated a modest increase in electrical resistance and barrier integrity, TGF-beta 1 showed a striking ability to reduce the capacity of IFN-gamma to disrupt epithelial barrier function. Characterization studies demonstrated that this TGF-beta 1 effect was prolonged (e.g., days) after a single exposure, progressive over the dose range 0.1 to 2.5 ng/ml, reversible with increased concentrations of IFN-gamma, and more pronounced when TGF-beta 1 exposure was to basolateral rather than to apical epithelial membranes. Macromolecular (horseradish peroxidase) penetration of epithelium was not simultaneously altered by TGF-beta 1 and epithelial cellular injury was minimal as gauged by lactate dehydrogenase release. Additional studies using a human pathogen demonstrated that TGF-beta 1 delayed and decreased the barrier disruption caused by exposure to Cryptosporidium parvum. TGF-beta 1 may be the first of a new class of cytokines that maintains and/or enhances barrier function of human enterocytes, in part by countering the effect of a T cell cytokine.

IFN-gamma modulation of epithelial barrier function. Time course, reversibility, and site of cytokine binding

The single cell-thick intestinal epithelium forms a crucial barrier between the host and environment, and is modeled in vitro by a monolayer of polarized, highly differentiated T84 epithelial cells impermeable to most macromolecules because of functional intercellular tight junctions. Absence of a permeability defect across the monolayer, either transcellular or paracellular, is indicated by development of a transepithelial electrical resistance of &gt; or = 1000 ohm-cm2, reported to be markedly diminished by exposure to a T lymphocyte cytokine, IFN-gamma. We sought to define this phenomenon in four ways by determining its duration and reversibility; the uniqueness of type II (gamma) IFN as opposed to type I (alpha) IFN; the surface of the polarized columnar epithelium likely involved in responding to IFN-gamma; and whether a specific surface membrane receptor on the epithelial cell participates in the response. Using a special apparatus that allows differential cytokine exposure of monolayer surfaces, our data demonstrate 1) only the monolayer's basolateral surface is IFN-gamma responsive, whereas the apical (microvillous) surface is no; 2) the alteration in electrical resistance of epithelium is prolonged (5 days), even after a single (24 h) exposure to IFN-gamma, but nevertheless is reversible; 3) the effect is likely receptor-ligand mediated, because it can be partially blocked by IFN-gamma receptor-specific monoclonal Ig; 4) an alteration in tight junction function (a paracellular pathway) rather than cell necrosis or a transcellular pathway is responsible for IFN-gamma-induced monolayer dysfunction because permeability to a 44,000-Da macromolecule (horseradish peroxidase) did not increase, and intracytoplasmic T84 cell enzymes were not released into the media; and 5) the biologic phenomenon could not be induced by a species (alpha) of class I IFN, making IFN-gamma reasonably unique in this regard. Given the proximity; activation status, and capacity of T lymphocytes for cytokine production in mucosa, we suggest that IFN-gamma-induced changes in epithelial permeability may be a major cause of altered intestinal barrier function in vivo.

IFN-gamma modulation of epithelial barrier function. Time course, reversibility, and site of cytokine binding

The single cell-thick intestinal epithelium forms a crucial barrier between the host and environment, and is modeled in vitro by a monolayer of polarized, highly differentiated T84 epithelial cells impermeable to most macromolecules because of functional intercellular tight junctions. Absence of a permeability defect across the monolayer, either transcellular or paracellular, is indicated by development of a transepithelial electrical resistance of > or = 1000 ohm-cm2, reported to be markedly diminished by exposure to a T lymphocyte cytokine, IFN-gamma. We sought to define this phenomenon in four ways by determining its duration and reversibility; the uniqueness of type II (gamma) IFN as opposed to type I (alpha) IFN; the surface of the polarized columnar epithelium likely involved in responding to IFN-gamma; and whether a specific surface membrane receptor on the epithelial cell participates in the response. Using a special apparatus that allows differential cytokine exposure of monolayer surfaces, our data demonstrate 1) only the monolayer's basolateral surface is IFN-gamma responsive, whereas the apical (microvillous) surface is no; 2) the alteration in electrical resistance of epithelium is prolonged (5 days), even after a single (24 h) exposure to IFN-gamma, but nevertheless is reversible; 3) the effect is likely receptor-ligand mediated, because it can be partially blocked by IFN-gamma receptor-specific monoclonal Ig; 4) an alteration in tight junction function (a paracellular pathway) rather than cell necrosis or a transcellular pathway is responsible for IFN-gamma-induced monolayer dysfunction because permeability to a 44,000-Da macromolecule (horseradish peroxidase) did not increase, and intracytoplasmic T84 cell enzymes were not released into the media; and 5) the biologic phenomenon could not be induced by a species (alpha) of class I IFN, making IFN-gamma reasonably unique in this regard. Given the proximity; activation status, and capacity of T lymphocytes for cytokine production in mucosa, we suggest that IFN-gamma-induced changes in epithelial permeability may be a major cause of altered intestinal barrier function in vivo.