Multi-scale computational investigation of Ag-doped two-dimensional Zn-based MOFs for storage and release of small NO and CO bioactive molecules.

Nitric oxide (NO) and carbon monoxide (CO) are two important gasotransmitters with critical biological roles in the human body. Due to their short lifetime and dangerous side effects at high concentrations, it is essential to find safe storage and slow release methods of these two gases. Herein, we report the multi-scale simulations of two-dimensional (Zn)MOF-470 doped with antimicrobial Ag atoms to evaluate the degree of enhancement of adsorption and dynamics of NO and CO. The results show that NO binds to Ag stronger than CO. In addition, the decoration of the benzene ring with Ag atoms on both sides has led to the effective adsorption of NO and CO with binding energies of -26.34 and -21.71 kcal mol-1, respectively. The GCMC results show that Ag can significantly improve NO and CO storage capacity, especially in low-pressure ranges. The storage capacity of NO in (Zn)MOF-470 and Ag-doped MOFs is 6.12 and 7.21 mol kg-1, respectively. This storage capacity for CO is 4.09 and 5.48 mol kg-1, respectively. The heat of adsorption for NO and CO was obtained to be 31.72 and 25.64 kJ mol-1 for (Zn)MOF-470, and 36.5 and 31.12 kJ mol-1 for Ag-(Zn)MOF-470 at 298 K and 1 bar. Besides, the MD results indicate that when Ag is doped into the structure of MOFs, the dynamics of gases within the pores of MOFs significantly decrease. When Ag atoms are considered mobile, the dynamics of guest molecules increase and it shows that the structural and dynamical behavior of NO and CO strongly depends on the mobility or immobility of doped Ag atoms. The result from the MSD directions (x, y, and z components) indicates that the diffusion of NO and CO within the pores of (Zn)MOF-470 is anisotropic and this may be due to the 2D structural characteristics of the MOF, the dipolar nature of NO and CO molecules, and the very narrow and layered pores of (Zn)MOF-470. These promising results from the simulations suggest that (Zn)MOF-470 and doping Ag atoms into this MOF can improve the storage capacity and slow release of bioactive NO and CO along with utilization of the antimicrobial nature of Ag atoms in medical applications.

Tuning the Selectivity between C2H2 and CO2 in Molecular Porous Materials.

A combined experimental and theoretical study of C2H2 and CO2 adsorption and separation was performed in two isostructural molecular porous materials (MPMs): MPM-1-Cl ([Cu2(adenine)4Cl2]Cl2) and MPM-1-TIFSIX ([Cu2(adenine)4(TiF6)2]). It was revealed that MPM-1-Cl displayed higher low-pressure uptake, isosteric heat of adsorption (Qst), and selectivity for C2H2 than CO2, whereas the opposite was observed for MPM-1-TIFSIX. While MPM-1-Cl contains only one type of accessible channel, which has a greater preference toward C2H2, MPM-1-TIFSIX contains three distinct accessible channels, one of which is a confined region between two large channels that represents the primary binding site for both adsorbates. According to molecular simulations, the initial adsorption site in MPM-1-TIFSIX interacts more strongly with CO2 than C2H2, thus explaining the inversion of adsorbate selectivity relative to MPM-1-Cl.

Peritoneal Dialysis Following Left Ventricular Assist Device Placement and Kidney Recovery: A Case Report.

Acute kidney injury (AKI) complicates up to 50% of left ventricular assist device (LVAD) placements and up to 30% of these patients require dialysis. Despite advances in LVAD technology since the first-generation devices, the risk for AKI remains high. We present a case of a woman in her 50s with previously stable stage C heart failure who developed critical cardiogenic shock and resultant AKI. She required continuous kidney replacement therapy both before and after placement of an LVAD. Following multiple inpatient and outpatient hemodialysis sessions complicated by hypotension, she was transitioned to peritoneal dialysis (PD). She tolerated PD well, and her kidney function continued to improve during the following weeks. After 6 weeks of outpatient PD, she recovered kidney function, allowing for cessation of dialysis. PD is a good option for patients with advanced heart failure who receive an LVAD due to gentler ultrafiltration, decreased risk for bacteremia, and better preservation of kidney function as compared with hemodialysis.

Outcomes Among Patients With Left Ventricular Assist Devices Receiving Maintenance Outpatient Hemodialysis: A Case Series.

RATIONALE & OBJECTIVE: The incidence of left ventricular assist device (LVAD) implantation as destination therapy for heart failure is increasing and kidney failure requiring maintenance hemodialysis is a common complication. Because little is known about the safety or efficacy of outpatient hemodialysis among patients with LVADs, this study sought to describe their clinical course. STUDY DESIGN: Case series of patients with an LVAD undergoing maintenance outpatient hemodialysis whose clinical data were obtained from an electronic medical record. SETTING & PARTICIPANTS: Adults who received an LVAD, survived to hospital discharge, and were subsequently treated with maintenance hemodialysis by a not-for-profit dialysis provider between 2011 and 2019. RESULTS: 11 patients were included. 6 had a known history of chronic kidney disease. Patients underwent outpatient hemodialysis for a mean duration of 165.2 (range, 31-542) days, during which they were treated with 544 total dialysis sessions. 6 of these sessions were stopped early due to dialysis-related adverse events (1.1%). More than 80% of follow-up time was spent out of the hospital; however, 55% of patients were rehospitalized within 1 month of starting outpatient hemodialysis. The most common reason for hospitalization was infection (32%), followed by hypervolemia (14%), and cerebrovascular accident or transient ischemic attack (11%). 4 patients recovered kidney function, 1 underwent combined heart and kidney transplantation, 2 continued treatment, 2 died, and 2 were lost to follow-up. LIMITATIONS: Retrospective design, small number of cases, and lack of complete follow-up data. CONCLUSIONS: Approximately half the patients with complete follow-up either recovered kidney function or underwent combined heart and kidney transplantation. This case series demonstrates that outpatient hemodialysis centers, in partnership with LVAD treatment teams, can successfully provide hemodialysis to patients on LVAD support.

Immobilization of a Polar Sulfone Moiety onto the Pore Surface of a Humid-Stable MOF for Highly Efficient CO2 Separation under Dry and Wet Environments through Direct CO2-Sulfone Interactions.

The stability of microporous metal-organic frameworks (MOFs) in moist environments must be taken into consideration for their practical implementations, which has been largely ignored thus far. Herein, we synthesized a new moisture-stable Zn-MOF, {[Zn2(SDB)2(L)2]·2DMA}n, IITKGP-12, by utilizing a bent organic linker 4,4'-sulfonyldibenzoic acid (H2SDB) containing a polar sulfone group (-SO2) and a N, N-donor spacer (L) with a Brunauer-Emmett-Teller surface area of 216 m2 g-1. This material displays greater CO2 adsorption capacity over N2 and CH4 with high IAST selectivity, which is also validated by breakthrough experiments with longer breakthrough times for CO2. Most importantly, the separation performance is largely unaffected in the presence of moisture of simulated flue gas stream. Temperature-programmed desorption (TPD) analysis shows the ease of the regeneration process, and the performance was verified for multiple cycles. In order to understand the structure-function relationship at the atomistic level, grand canonical Monte Carlo (GCMC) calculation was performed, indicating that the primary binding site for CO2 is between the sulfone moieties in IITKGP-12. CO2 is attracted to the bonded structure (V-shape) of the sulfone moieties in a perpendicular fashion, where CCO2 is aligned with S, and the CO2 axis bisects the SO2 axis. Thus, the strategic approach to immobilize the polar sulfone moiety with a high number of inherent stronger M-N coordination and the absence of coordination unsaturation made this MOF potential toward practical CO2 separation applications.

Ultramicropore Engineering by Dehydration to Enable Molecular Sieving of H2 by Calcium Trimesate.

The high energy footprint of commodity gas purification and increasing demand for gases require new approaches to gas separation. Kinetic separation of gas mixtures through molecular sieving can enable separation by molecular size or shape exclusion. Physisorbents must exhibit the right pore diameter to enable separation, but the 0.3-0.4 nm range relevant to small gas molecules is hard to control. Herein, dehydration of the ultramicroporous metal-organic framework Ca-trimesate, Ca(HBTC)⋅H2 O (H3 BTC=trimesic acid), bnn-1-Ca-H2 O, affords a narrow pore variant, Ca(HBTC), bnn-1-Ca. Whereas bnn-1-Ca-H2 O (pore diameter 0.34 nm) exhibits ultra-high CO2 /N2 , CO2 /CH4 , and C2 H2 /C2 H4 binary selectivity, bnn-1-Ca (pore diameter 0.31 nm) offers ideal selectivity for H2 /CO2 and H2 /N2 under cryogenic conditions. Ca-trimesate, the first physisorbent to exhibit H2 sieving under cryogenic conditions, could be a prototype for a general approach to exert precise control over pore diameter in physisorbents.

Halogen-C2 H2 Binding in Ultramicroporous Metal-Organic Frameworks (MOFs) for Benchmark C2 H2 /CO2 Separation Selectivity.

Acetylene (C2 H2 ) capture is a step in a number of industrial processes, but it comes with a high-energy footprint. Although physisorbents have the potential to reduce this energy footprint, they are handicapped by generally poor selectivity versus other relevant gases, such as CO2 and C2 H4 . In the case of CO2 , the respective physicochemical properties are so similar that traditional physisorbents, such as zeolites, silica, and activated carbons cannot differentiate well between CO2 and C2 H2 . Herein, we report that a family of three isostructural, ultramicroporous (<7 Å) diamondoid metal-organic frameworks, [Cu(TMBP)X] (TMBP=3,3',5,5'-tetramethyl-4,4'-bipyrazole), TCuX (X=Cl, Br, I), offer new benchmark C2 H2 /CO2 separation selectivity at ambient temperature and pressure. We attribute this performance to a new type of strong binding site for C2 H2 . Specifically, halogen⋅⋅⋅HC interactions coupled with other noncovalent in a tight binding site is C2 H2 specific versus CO2 . The binding site is distinct from those found in previous benchmark sorbents, which are based on open metal sites or electrostatic interactions enabled by inorganic fluoro or oxo anions.

Iron Hack - A symposium/hackathon focused on porphyrias, Friedreich's ataxia, and other rare iron-related diseases.

Background: Basic and clinical scientific research at the University of South Florida (USF) have intersected to support a multi-faceted approach around a common focus on rare iron-related diseases. We proposed a modified version of the National Center for Biotechnology Information's (NCBI) Hackathon-model to take full advantage of local expertise in building "Iron Hack", a rare disease-focused hackathon. As the collaborative, problem-solving nature of hackathons tends to attract participants of highly-diverse backgrounds, organizers facilitated a symposium on rare iron-related diseases, specifically porphyrias and Friedreich's ataxia, pitched at general audiences. Methods: The hackathon was structured to begin each day with presentations by expert clinicians, genetic counselors, researchers focused on molecular and cellular biology, public health/global health, genetics/genomics, computational biology, bioinformatics, biomolecular science, bioengineering, and computer science, as well as guest speakers from the American Porphyria Foundation (APF) and Friedreich's Ataxia Research Alliance (FARA) to inform participants as to the human impact of these diseases. Results: As a result of this hackathon, we developed resources that are relevant not only to these specific disease-models, but also to other rare diseases and general bioinformatics problems. Within two and a half days, "Iron Hack" participants successfully built collaborative projects to visualize data, build databases, improve rare disease diagnosis, and study rare-disease inheritance. Conclusions: The purpose of this manuscript is to demonstrate the utility of a hackathon model to generate prototypes of generalizable tools for a given disease and train clinicians and data scientists to interact more effectively.

Trace CO2 capture by an ultramicroporous physisorbent with low water affinity.

CO2 accumulation in confined spaces represents an increasing environmental and health problem. Trace CO2 capture remains an unmet challenge because human health risks can occur at 1000 parts per million (ppm), a level that challenges current generations of chemisorbents (high energy footprint and slow kinetics) and physisorbents (poor selectivity for CO2, especially versus water vapor, and/or poor hydrolytic stability). Here, dynamic breakthrough gas experiments conducted upon the ultramicroporous material SIFSIX-18-Ni-ß reveal trace (1000 to 10,000 ppm) CO2 removal from humid air. We attribute the performance of SIFSIX-18-Ni-ß to two factors that are usually mutually exclusive: a new type of strong CO2 binding site and hydrophobicity similar to ZIF-8. SIFSIX-18-Ni-ß also offers fast sorption kinetics to enable selective capture of CO2 over both N2 (S CN) and H2O (S CW), making it prototypal for a previously unknown class of physisorbents that exhibit effective trace CO2 capture under both dry and humid conditions.

Enhanced Gas Uptake in a Microporous Metal-Organic Framework via a Sorbate Induced-Fit Mechanism.

Physical adsorption of gas molecules in microporous materials is an exothermic process, with desorption entropy driving a decrease in uptake with temperature. Enhanced gas sorption with increasing temperature is rare in porous materials and is indicative of sorbate initiated structural change. Here, sorption of C2H6, C3H6, and C3H8 in a flexible microporous metal-organic framework (MOF) {Cu(FPBDC)]·DMF}n (NKU-FlexMOF-1) (H2FPBDC = 5-(5-fluoropyridin-3-yl)-1,3-benzenedicarboxylic acid) that increases with rising temperature over a practically useful temperature and pressure range is reported along with other small molecule and hydrocarbon sorption isotherms. Single X-ray diffraction studies, temperature-dependent gas sorption isotherms, in situ and variable temperature powder X-ray diffraction experiments, and electronic structure calculations were performed to characterize the conformation-dependent sorption behavior in NKU-FlexMOF-1. In total, the data supports that the atypical sorption behavior is a result of loading-dependent structural changes in the flexible framework of NKU-FlexMOF-1 induced by sorbate-specific guest-framework interactions. The sorbates cause subtle adaptations of the framework distinct to each sorbate providing an induced-fit separation mechanism to resolve chemically similar hydrocarbons through highly specific sorbate-sorbent interactions. The relevant intermolecular contacts are shown to be predominantly repulsion and dispersion interactions. NKU-FlexMOF-1 is also found to be stable in aqueous solutions including toleration of pH changes. These experiments demonstrate the potential of this flexible microporous MOF for cost and energy efficient industrial hydrocarbon separation and purification processes. The efficacy for the separation of C3H6/C3H8 mixtures is explicitly demonstrated using NKU-FlexMOF-1a (i.e., activated NKU-FlexMOF-1) for a particular useful temperature range.

A Microporous Co-MOF for Highly Selective CO2 Sorption in High Loadings Involving Aryl C-H···O═C═O Interactions: Combined Simulation and Breakthrough Studies.

In the context of porous crystalline materials toward CO2 separation and capture, a new 2-fold interpenetrated 3D microporous Co-MOF, IITKGP-11 (IITKGP denotes Indian Institute of Technology Kharagpur), has been synthesized consisting of a 1D channel of ∼3.6 × 5.0 Å2 along the [101] direction with a cavity volume of 35.20%. This microporous framework with a BET surface area of 253 m2g-1 shows higher uptake of CO2 (under 1 bar, 3.35 and 2.70 mmol g-1 at 273 and 295 K, respectively), with high separation selectivities for CO2/N2 and CO2/CH4 gas mixtures under ambient conditions as estimated through IAST calculation. Moreover, real time dynamic breakthrough studies reveal the high adsorption selectivity toward CO2 for these binary mixed gases at 295 K and 1 bar. Besides high gas separation selectivity, capacity considerations in mixed gas phases are also important to check the performance of a given adsorbent. CO2 loading amounts in mixed gas phases are quite high as predicted through IAST calculation and experimentally determined from dynamic breakthrough studies. In order to get insight into the phenomena, GCMC simulation was performed demonstrating that the CO2 molecules are electrostatically trapped via interactions between oxygen on CO2 and hydrogen on pyridyl moieties of the spacers.

Trends in Rates of Lower Extremity Amputation Among Patients With End-stage Renal Disease Who Receive Dialysis.

Importance: Patients with end-stage renal disease (ESRD) who receive dialysis are at high risk of lower extremity amputation. Recent studies indicate decreasing rates of lower extremity amputation in non-ESRD populations, but contemporary data for patients with ESRD who receive dialysis are lacking. Objectives: To assess rates of lower extremity amputation among patients with ESRD who receive dialysis during a recent 15-year period; to analyze whether those rates differed by age, sex, diabetes, or geographic region; and to determine 1-year mortality rates in this population after lower extremity amputation. Design, Setting, and Participants: This retrospective study of 3 700 902 records obtained from a US national registry of patients with ESRD who receive dialysis assessed cross-sectional cohorts for each calendar year from 2000 through 2014. Adult patients with prevalent ESRD treated with hemodialysis or peritoneal dialysis covered by Medicare Part A and B on January 1 of each cohort year were included. Data analysis was conducted from August 2017 to April 2018. Exposures: Age, sex, diabetes, and hospital referral region. Main Outcomes and Measures: Annual rates per 100 person-years of nontraumatic major (above- or below-knee) and minor (below-ankle) amputations. Results: For each annual cohort, there were fewer women (47.5% in 2000, 46.2% in 2005, 44.9% in 2010, and 44.0% in 2014) than men, more than half the patients were white individuals (58.1% in 2000, 56.9% in 2005, 56.9% in 2010, and 56.7% in 2014), and a small proportion were employed (13.9% in 2000, 15.1% in 2005, 16.1% in 2010, and 16.5% in 2014). The rate of lower extremity amputations for patients with ESRD who receive dialysis decreased by 51.0% from 2000 to 2014, driven primarily by a decrease in the rate of major amputations (5.42 [95% CI, 5.28-5.56] in 2000 vs 2.66 [95% CI, 2.59-2.72] per 100 person-years in 2014). Patients with diabetes had amputation rates more than 5 times as high as patients without diabetes. Patients younger than 65 years had higher adjusted amputation rates than older patients, and men had consistently higher adjusted amputation rates than women. Adjusted 1-year mortality rates after lower extremity amputation for patients with ESRD who receive dialysis decreased from 52.2% (95% CI, 50.9%-53.4%) in 2000 to 43.6% (95% CI, 42.5%-44.8%) in 2013. In general, amputation rates decreased among all regions from 2000 to 2014, but regional variability persisted across time despite adjustment for differences in patient demographics and comorbid conditions. Conclusions and Relevance: Although rates of lower extremity amputations among US patients with ESRD who receive dialysis decreased by 51% during a recent 15-year period, mortality rates remained high, with nearly half of patients dying within a year after lower extremity amputation. Our results highlight the need for more research on ways to prevent lower extremity amputation in this extremely high-risk population.

Simulations of hydrogen, carbon dioxide, and small hydrocarbon sorption in a nitrogen-rich rht-metal-organic framework.

Grand canonical Monte Carlo (GCMC) simulations of gas sorption were performed in Cu-TDPAH, also known as rht-MOF-9, hereafter [1], a metal-organic framework (MOF) with rht topology consisting of Cu2+ ions coordinated to 2,5,8-tris(3,5-dicarboxyphenylamino)-1,3,4,6,7,9,9b-heptaazaphenalene (TDPAH) ligands. This MOF is notable for the presence of open-metal copper sites and high nitrogen content on the linkers. [1] Exhibits one of the highest experimental H2 uptakes at 77 K/1 atm within the extant rht-MOF family (ca. 2.72 wt%) and also has strong affinity for CO2 (5.83 mmol g-1 at 298 K/1 atm). Our simulations, which include explicit many-body polarization interactions, accurately modeled macroscopic thermodynamic properties (e.g., sorption isotherms and isosteric heats of adsorption (Qst)) as well as the binding sites for H2, CO2, CH4, C2H2, C2H4, and C2H6 in the MOF. Four different binding sites were observed through analysis of the radial distribution function (g(r)) about the two chemically distinct Cu2+ ions, simulated annealing calculations, and examination of the three-dimensional histogram showing the sites of occupancy: (1) at the Cu2+ ion facing toward the center of the linker (CuL), (2) at the Cu2+ ion facing away from the center of linker (CuC), (3) nestled between three [Cu2(O2CR)4] units in the corner of the truncated tetrahedral (T-Td) cage and (4) straddling the copper nuclei parallel to the axis of the Cu-Cu bond within the T-Td cage. The low-loading (initial) binding site in the MOF is highly sensitive to the partial charges of the Cu2+ ions that were used for parametrization. It was discovered that most sorbates prefer to sorb onto or near the Cu2+ ions that exhibit the greater partial positive charge (i.e., at site 1). The simulated H2 and CO2 sorption results obtained using a polarizable potential for the respective sorbates are in good agreement with the corresponding experimental data, especially near ambient pressure. Simulations of gas sorption were also performed in [1] using nonpolarizable potentials for the individual sorbates; these include potentials from the TraPPE force field for most sorbates.

Predictive models of gas sorption in a metal-organic framework with open-metal sites and small pore sizes.

Simulations of CO2 and H2 sorption were performed in UTSA-20, a metal-organic framework (MOF) having zyg topology and composed of Cu2+ ions coordinated to 3,3',3'',5,5',5''-benzene-1,3,5-triyl-hexabenzoate (BHB) linkers. Previous experimental studies have shown that this MOF displays remarkable CO2 sorption properties and exhibits one of the highest gravimetric H2 uptakes at 77 K/1.0 atm (2.9 wt%) [Z. Guo, et al. Angew. Chem., Int. Ed., 2011, 50, 3178-3181]. For both sorbates, the simulations were executed with the inclusion of explicit many-body polarization interactions, which was necessary to reproduce sorption onto the open-metal sites. Non-polarizable potentials were also utilized for simulations of CO2 sorption as a control. The simulated excess sorption isotherms for both CO2 and H2 are in very good agreement with the corresponding experimental data over a wide range of temperatures and pressures, thus demonstrating the accuracy and predictive power of the polarizable potentials used herein. The theoretical isosteric heat of adsorption (Qst) values are also in good agreement with the newly reported experimental Qst values for the respective sorbates in UTSA-20. Sorption onto the more positively charged Cu2+ ion of the [Cu2(O2CR)4] cluster was observed for both CO2 and H2. However, a binding site with energetics comparable to that for an open-metal site was also discovered for both sorbates. A radial distribution function (g(r)) analysis about the preferential Cu2+ ions for CO2 and H2 revealed that both sorbates display different trends for the relative occupancy about such sites upon increasing/decreasing the pressure in the MOF. Overall, this study provides insights into the CO2 and H2 sorption mechanisms in this MOF containing open-metal sites and small pore sizes for the first time through a classical polarizable force field.

Enhanced removal of aqueous BPA model compounds using Metalloligs.

A model compound, 4-(t-butyl)phenol, was used as a substitute for BPA (bisphenol acetone or Bisphenol A) a material used for the production of a large volume of common plastics. Unfortunately, BPA is suspected to have estrogenic properties, and there is a suspicion that even small amounts can have a deleterious effect against humans, especially female infants. The model compound has some similarities to BPA, but lacks some of the serious properties of BPA dust. Since other workers have demonstrated the capability of removing BPA from plastics by extraction with saline or alcohol, we studied whether Octolig, a polyethylenediimine supported on silica gel, or transition metal derivatives of Octolig could be used to remove concentrations for model compounds from aqueous solution. Octolig gave modest results 20%, the manganese (II) and iron (III) derivatives gave poor results, Cuprilig was an improvement over those two Metalloligs, but the cobalt(II) derivative was able to remove up to 56% of the model compound. Two methods were studied, batch and column chromatography. Under the conditions used in this study, the batch method was superior.

Comparison of anion removal capacities of Octolig and Cuprilig.

Mixtures of sodium salts of phosphate, arsenate, and fluoride were used in chromatography and batch experiments to compare the capacity of two immobilized ligands (IMLIGs) to remove these anions: Octolig and its copper (II)-based metallolig, Cuprilig. The focus of this study was twofold. First, to find out which material, Octolig or Cuprilig, would remove these anions most effectively; and secondly to determine the optimal capacity for removal of representative anions. Removal capacity was evaluated by two methods: by chromatography and by a batch method. The methods gave identical results, but the batch method was more convenient. Cuprilig had a lower capacity for removal of phosphate than Octolig. The capability of Octolig for removing anions was: phosphate > arsenate > fluoride >>> chloride >>>> bromide. Replication of phosphate removal was good for a given batch of Octolig. Of three different samples of Octolig, two seemed to be alike based on the phosphate- removal capacity; the third was different on the basis of a Student's t-test. This distinction indicates the batch procedure could serve as a quality control/assurance technique.

Necroinflammatory liver disease in BALB/c background, TGF-beta 1-deficient mice requires CD4+ T cells.

The etiology of autoimmune liver disease is poorly understood. BALB/c mice deficient in the immunoregulatory cytokine TGF-beta1 spontaneously develop necroinflammatory liver disease, but the immune basis for the development of this pathology has not been demonstrated. Here, we show that BALB/c-TGF-beta1(-/-) mice exhibit abnormal expansion in hepatic mononuclear cells (MNCs) compared with wild-type littermate control mice, particularly in the T cell and macrophage lineages. To test whether lymphocytes of the adaptive immune system are required for the spontaneous development of necroinflammatory liver disease, BALB/c-TGF-beta1(-/-) mice were rendered deficient in B and T cells by crossing them with BALB/c-recombinase-activating gene 1(-/-) mice. BALB/c-TGF-beta1(-/-)/recombinase-activating gene 1(-/-) double-knockout mice showed extended survival and did not develop necroinflammatory liver disease. The cytolytic activity of BALB/c-TGF-beta1(-/-) hepatic lymphocytes was assessed using an in vitro CTL assay. CTL activity was much higher in BALB/c-TGF-beta1(-/-) hepatic MNCs compared with littermate control hepatic MNCs and was particularly pronounced in the CD4(+) T cell subset. Experimental depletion of CD4(+) T cells in young BALB/c-TGF-beta1(-/-) mice prevented the subsequent development of necroinflammatory liver disease, indicating that CD4(+) T cells are essential for disease pathogenesis in vivo. These data definitively establish an immune-mediated etiology for necroinflammatory liver disease in BALB/c-TGF-beta1(-/-) mice and demonstrate the importance of CD4(+) T cells in disease pathogenesis in vivo. Furthermore, TGF-beta1 has a critical role in homeostatic regulation of the hepatic immune system, inhibiting the development or expansion of hepatic cytolytic CD4(+) T cells.