Claudin-2 suppresses GEF-H1, RHOA, and MRTF, thereby impacting proliferation and profibrotic phenotype of tubular cells.

The tight junctional pore-forming protein claudin-2 (CLDN-2) mediates paracellular Na+ and water transport in leaky epithelia and alters cancer cell proliferation. Previously, we reported that tumor necrosis factor-α time-dependently alters CLDN-2 expression in tubular epithelial cells. Here, we found a similar expression pattern in a mouse kidney injury model (unilateral ureteral obstruction), consisting of an initial increase followed by a drop in CLDN-2 protein expression. CLDN-2 silencing in LLC-PK1 tubular cells induced activation and phosphorylation of guanine nucleotide exchange factor H1 (GEF-H1), leading to Ras homolog family member A (RHOA) activation. Silencing of other claudins had no such effects, and re-expression of an siRNA-resistant CLDN-2 prevented RHOA activation, indicating specific effects of CLDN-2 on RHOA. Moreover, kidneys from CLDN-2 knockout mice had elevated levels of active RHOA. Of note, CLDN-2 silencing reduced LLC-PK1 cell proliferation and elevated expression of cyclin-dependent kinase inhibitor P27 (P27KIP1) in a GEF-H1/RHOA-dependent manner. P27KIP1 silencing abrogated the effects of CLDN-2 depletion on proliferation. CLDN-2 loss also activated myocardin-related transcription factor (MRTF), a fibrogenic RHOA effector, and elevated expression of connective tissue growth factor and smooth muscle actin. Finally, CLDN-2 down-regulation contributed to RHOA activation and smooth muscle actin expression induced by prolonged tumor necrosis factor-α treatment, because they were mitigated by re-expression of CLDN-2. Our results indicate that CLDN-2 suppresses GEF-H1/RHOA. CLDN-2 down-regulation, for example, by inflammation, can reduce proliferation and promote MRTF activation through RHOA. These findings suggest that the initial CLDN-2 elevation might aid epithelial regeneration, and CLDN-2 loss could contribute to fibrotic reprogramming.

Tumor necrosis factor-α induces a biphasic change in claudin-2 expression in tubular epithelial cells: role in barrier functions.

The inflammatory cytokine tumor necrosis factor-α (TNF-α) is a pathogenic factor in acute and chronic kidney disease. TNF-α is known to alter expression of epithelial tight junction (TJ) proteins; however, the underlying mechanisms and the impact of this effect on epithelial functions remain poorly defined. Here we describe a novel biphasic effect of TNF-α on TJ protein expression. In LLC-PK1 tubular cells, short-term (1-6 h) TNF-α treatment selectively elevated the expression of the channel-forming TJ protein claudin-2. In contrast, prolonged (>8 h) TNF-α treatment caused a marked downregulation in claudin-2 and an increase in claudin-1, -4, and -7. The early increase and the late decrease in claudin-2 expression involved distinct mechanisms. TNF-α slowed claudin-2 degradation through ERK, causing the early increase. This increase was also mediated by the EGF receptor and RhoA and Rho kinase. In contrast, prolonged TNF-α treatment reduced claudin-2 mRNA levels and promoter activity independent from these signaling pathways. Electric Cell-substrate Impedance Sensing measurements revealed that TNF-α also exerted a biphasic effect on transepithelial resistance (TER) with an initial decrease and a late increase. Thus there was a good temporal correlation between TNF-α-induced claudin-2 protein and TER changes. Indeed, silencing experiments showed that the late TER increase was at least in part caused by reduced claudin-2 expression. Surprisingly, however, claudin-2 silencing did not prevent the early TER drop. Taken together, the TNF-α-induced changes in claudin-2 levels might contribute to TER changes and could also play a role in newly described functions of claudin-2 such as proliferation regulation.

Construction of a random circular permutation library using an engineered transposon.

Circular permutation is an important protein engineering tool used to create sequence diversity of a protein by changing its linear order of amino acid sequence. Circular permutation has proven to be effective in the evolution of proteins for desired properties while maintaining similar three-dimensional structures. Due to the lack of a robust design principle guiding the selection of new termini, construction of a combinatorial library is much preferred for comprehensive evaluation of circular permutation. Unfortunately, the conventional methods used to create random circular permutation libraries cause significant sequence modification at new termini of circular permutants. In addition, these methods impose additional limitations by requiring either relatively inefficient blunt-end ligation during library construction or redesign of transposons for tailored expression of circular permutants. In this study, we present the development of an engineered transposon for facile construction of random circular permutation libraries. We provide evidence that minimal modification at the new termini of the random circular permutants is possible with our engineered transposon. In addition, our method enables the use of sticky-end ligation during library construction and provides external tunability for expression of random circular permutants.

Consumer Trends Reflected in the Contents of the Pediatric Esophagus: A 20-Year Review.

OBJECTIVES: To evaluate epidemiological trends of pediatric esophageal foreign body (EFB) ingestion over two decades. METHODS: A retrospective analysis was performed using data from the National Electronic Injury Surveillance System (NEISS) database for children <18 years who presented to a United States Emergency Department (ED) with EFB between 2003 and 2022. Number of cases and type of EFB were recorded. Rates of EFBs over time were analyzed via linear regression. RESULTS: A total of 52,315 EFB cases were identified over the 20-year period, with a national estimate of 1,589,325 cases. The most frequently ingested objects were coins (37.6%), toys (13.5%), and batteries (6.8%). Overall incidence of EFB ingestion increased from 7.3 to 14.2/10,000 children from 2003 to 2022 (R2 = 0.8, p < 0.0001). Incidence of coin ingestion increased from 3 to 4.5/10,000 children (R2 = 0.06, p = 0.335) but represented a smaller proportion of all EFB over time (66% in 2003 versus 43% in 2022). Incidence of magnet, battery, and toy ingestion have increased from 0.3 to 1.0/10,000 (R2 = 0.9, p < 0.0001), 0.3 to 1/10,000 (R2 = 0.7, p < 0.0001), and 0.6 to 2.3/10,000 (R2 = 0.8, p < 0.0001) children, respectively, between 2003 and 2022. The proportion of magnet, battery, and toy ingestion have increased over time (3.2%, 6.5%, and 11.8%, respectively, in 2003 to 11.4%, 11.7%, and 22.2%, respectively, in 2022). CONCLUSION: Magnet, battery, and toy ingestion have increased significantly in the past two decades, while the proportion of coin ingestion has decreased. This trend may reflect shifts within the consumer market and increased availability of electronics concurrent with the adoption of digital currency. LEVEL OF EVIDENCE: 4 Laryngoscope, 2024.

Therapist-Driven Telephone Call Outreach to Improve Depression Remission in a Federally Qualified Health Center.

The authors examined the feasibility and impact of a therapist-driven outreach program on depression outcomes in a primary care clinic. Patients with a diagnosis of depression but missing a 1-year follow-up Patient Health Questionnaire-9 (PHQ-9) screening were rescreened via telephone. Eligible patients (N=241) were contacted, and implementation rates and outcomes, along with feasibility, were assessed. Of the patients contacted, 47% indicated a depression response (reduction in PHQ-9 score of ≥50%), and 33% met remission criteria (PHQ-9 score <5). PHQ-9 scores decreased by approximately 7 points (p<0.001). This project may have helped to improve depression symptoms and remission rates for patients of the clinic and to facilitate patient reengagement with treatment.

Ultra-deep sequencing validates safety of CRISPR/Cas9 genome editing in human hematopoietic stem and progenitor cells.

As CRISPR-based therapies enter the clinic, evaluation of safety remains a critical and active area of study. Here, we employ a clinical next generation sequencing (NGS) workflow to achieve high sequencing depth and detect ultra-low frequency variants across exons of genes associated with cancer, all exons, and genome wide. In three separate primary human hematopoietic stem and progenitor cell (HSPC) donors assessed in technical triplicates, we electroporated high-fidelity Cas9 protein targeted to three loci (AAVS1, HBB, and ZFPM2) and harvested genomic DNA at days 4 and 10. Our results demonstrate that clinically relevant delivery of high-fidelity Cas9 to primary HSPCs and ex vivo culture up to 10 days does not introduce or enrich for tumorigenic variants and that even a single SNP in a gRNA spacer sequence is sufficient to eliminate Cas9 off-target activity in primary, repair-competent human HSPCs.

Lymphocytic Esophagitis With Predominance of CD4 T Cells and Expansion of Th1 Cells Is Associated With Achalasia.

OBJECTIVES: Although histologic features in biopsies suggesting a possibility of achalasia would be helpful diagnostically, such features remain unknown. The goal of this study was to explore the prevalence, histologic features, and immunophenotype of lymphocytic esophagitis (LyE) in achalasia biopsies. METHODS: The study group consisted of 57 patients with achalasia. Controls comprised 52 patients with severe gastroesophageal reflux disease (GERD) and normal esophageal motility. CD4/CD8 immunophenotype of lymphocytes was analyzed by immunohistochemistry. RESULTS: LyE was identified in 30% (17/57) of patients with achalasia and 6% (3/52) of patients with GERD, indicating a strong association with achalasia (odds ratio, 6.94; 95% confidence interval, 1.90-25.38). LyE was focal in 59% (10/17) of the cases and diffuse in 41% (7/17). CD4 T-cell predominance over CD8 T cells was observed in 88% of patients with achalasia and LyE. T helper 1 (Th1) cells, but not T helper 2 cells, were expanded in CD4 T cells; in the absence of evident infection, this was compatible with the role of Th1 cells in organ-specific autoimmunity. CONCLUSIONS: Achalasia should be considered in the differential diagnosis of clinical entities associated with CD4-predominant LyE. Additional studies to explore the significance of Th1 cells in achalasia-associated LyE are warranted.

CD16+CD163+ monocytes traffic to sites of inflammation during necrotizing enterocolitis in premature infants.

Necrotizing enterocolitis (NEC) is a severe gastrointestinal complication of prematurity. Using suspension and imaging mass cytometry coupled with single-cell RNA sequencing, we demonstrate severe inflammation in patients with NEC. NEC mucosa could be subtyped by an influx of three distinct neutrophil phenotypes (immature, newly emigrated, and aged). Furthermore, CD16+CD163+ monocytes/Mϕ, correlated with newly emigrated neutrophils, were specifically enriched in NEC mucosa, found adjacent to the blood vessels, and increased in circulation of infants with surgical NEC, suggesting trafficking from the periphery to areas of inflammation. NEC-specific monocytes/Mϕ transcribed inflammatory genes, including TREM1, IL1A, IL1B, and calprotectin, and neutrophil recruitment genes IL8, CXCL1, CXCL2, CXCL5 and had enrichment of gene sets in pathways involved in chemotaxis, migration, phagocytosis, and reactive oxygen species generation. In summary, we identify a novel subtype of inflammatory monocytes/Mϕ associated with NEC that should be further evaluated as a potential biomarker of surgical NEC and a target for the development of NEC-specific therapeutics.

Generation of T-cell-redirecting bispecific antibodies with differentiated profiles of cytokine release and biodistribution by CD3 affinity tuning.

T-cell-redirecting bispecific antibodies have emerged as a new class of therapeutic agents designed to simultaneously bind to T cells via CD3 and to tumor cells via tumor-cell-specific antigens (TSA), inducing T-cell-mediated killing of tumor cells. The promising preclinical and clinical efficacy of TSAxCD3 antibodies is often accompanied by toxicities such as cytokine release syndrome due to T-cell activation. How the efficacy and toxicity profile of the TSAxCD3 bispecific antibodies depends on the binding affinity to CD3 remains unclear. Here, we evaluate bispecific antibodies that were engineered to have a range of CD3 affinities, while retaining the same binding affinity for the selected tumor antigen. These agents were tested for their ability to kill tumor cells in vitro, and their biodistribution, serum half-life, and anti-tumor activity in vivo. Remarkably, by altering the binding affinity for CD3 alone, we can generate bispecific antibodies that maintain potent killing of TSA + tumor cells but display differential patterns of cytokine release, pharmacokinetics, and biodistribution. Therefore, tuning CD3 affinity is a promising method to improve the therapeutic index of T-cell-engaging bispecific antibodies.

Human immunodeficiency virus type 1 escapes from interleukin-2-producing CD4+ T-cell responses without high-frequency fixation of mutations.

The presence of interleukin-2 (IL-2)-producing human immunodeficiency virus type 1 (HIV-1)-specific CD4(+) T-cell responses has been associated with the immunological control of HIV-1 replication; however, the causal relationship between these factors remains unclear. Here we show that IL-2-producing HIV-1-specific CD4(+) T cells can be cloned from acutely HIV-1-infected individuals. Despite the early presence of these cells, each of the individuals in the present study exhibited progressive disease, with one individual showing rapid progression. In this rapid progressor, three IL-2-producing HIV-1 Gag-specific CD4(+) T-cell responses were identified and mapped to the following optimal epitopes: HIVWASRELER, REPRGSDIAGT, and FRDYVDRFYKT. Responses to these epitopes in peripheral blood mononuclear cells were monitored longitudinally to >1 year postinfection, and contemporaneous circulating plasma viruses were sequenced. A variant of the FRDYVDRFYKT epitope sequence, FRDYVDQFYKT, was observed in 1/21 plasma viruses sequenced at 5 months postinfection and 1/10 viruses at 7 months postinfection. This variant failed to stimulate the corresponding CD4(+) T-cell clone and thus constitutes an escape mutant. Responses to each of the three Gag epitopes were rapidly lost, and this loss was accompanied by a loss of antigen-specific cells in the periphery as measured by using an FRDYVDRFYKT-presenting major histocompatibility complex class II tetramer. Highly active antiretroviral therapy was associated with the reemergence of FRDYVDRFYKT-specific cells by tetramer. Thus, our data support that IL-2-producing HIV-1-specific CD4(+) T-cell responses can exert immune pressure during early HIV-1 infection but that the inability of these responses to enforce enduring control of viral replication is related to the deletion and/or dysfunction of HIV-1-specific CD4(+) T cells rather than to the fixation of escape mutations at high frequencies.

Tumor-targeted CD28 bispecific antibodies enhance the antitumor efficacy of PD-1 immunotherapy.

Monoclonal antibodies that block the programmed cell death 1 (PD-1) checkpoint have revolutionized cancer immunotherapy. However, many major tumor types remain unresponsive to anti-PD-1 therapy, and even among responsive tumor types, most of the patients do not develop durable antitumor immunity. It has been shown that bispecific antibodies activate T cells by cross-linking the TCR/CD3 complex with a tumor-specific antigen (TSA). The class of TSAxCD3 bispecific antibodies have generated exciting results in early clinical trials. We have recently described another class of "costimulatory bispecifics" that cross-link a TSA to CD28 (TSAxCD28) and cooperate with TSAxCD3 bispecifics. Here, we demonstrate that these TSAxCD28 bispecifics (one specific for prostate cancer and the other for epithelial tumors) can also synergize with the broader anti-PD-1 approach and endow responsiveness-as well as long-term immune memory-against tumors that otherwise do not respond to anti-PD-1 alone. Unlike CD28 superagonists, which broadly activate T cells and induce cytokine storm, TSAxCD28 bispecifics display little or no toxicity when used alone or in combination with a PD-1 blocker in genetically humanized immunocompetent mouse models or in primates and thus may provide a well-tolerated and "off the shelf" combination approach with PD-1 immunotherapy that can markedly enhance antitumor efficacy.

DNA variability of human genes.

We have investigated the level of DNA-based variation (both SNPs and haplotypes) for several thousand human genes. In addition, we have characterized how this variation is distributed in a number of biologically and clinically important ways. First, we have determined how SNPs are distributed within human genes: where they occur relative to various functional regions; levels of variability of human SNPs; pattern of the molecular sequence of SNPs; and how these compare with the corresponding sequence of a chimpanzee. Second, we have determined how these aspects of SNP distribution vary among four human population samples. All genes were sequenced on DNA obtained from 82 unrelated individuals: 20 African-Americans, 20 East Asians, 21 European-Americans, 18 Hispanic-Latinos and three Native Americans. In particular, we looked at patterns of SNP and haplotype sharing among the four larger population samples. Third, we have determined the patterns of linkage disequilibrium among SNPs, which also determines the haplotype variability of each gene. These characteristics also vary substantially among populations. A deeper understanding of these aspects of human genetic variation will be of vital importance when trying to identify the genetic contribution to complex phenotypes such as aging.

SNP and haplotype variation in the human genome.

We have surveyed and summarized several aspects of DNA variability among humans. The variation described is the result of mutation followed by a combination of drift, migration and selection bringing the frequencies high enough to be observed. This paper describes what we have learned about how DNA variability differs among genes and populations. We sequenced functional regions of a set of 3950 genes. DNA was sampled from 82 unrelated humans: 20 African-Americans, 20 East Asians, 21 Caucasians, 18 Hispanic-Latinos and 3 Native Americans. Different aspects of variability showed a great deal of concordance. In particular, we studied patterns of single nucleotide polymorphism (SNP) allele and haplotype sharing among the four, large sample populations. We also examined how linkage disequilibrium (LD) between SNPs relates to physical distance in the different populations. It is clear from our findings that while many variants are common to all populations, many others have a more restricted distribution. Research that attempts to find genetic variants that explain phenotypic variants must be careful in their choice of study population.

The role of cytokines which signal through the common gamma chain cytokine receptor in the reversal of HIV specific CD4(+) and CD8(+) T cell anergy.

BACKGROUND: HIV specific T cells are putatively anergic in vivo. IL-2, a member of a class of cytokines that binds to receptors containing the common gamma chain (gammac) has been shown to reverse anergy. We examined the role of gammac cytokines in reversing HIV specific T cell anergy. METHODS: PBMC from untreated HIV-infected individuals were briefly exposed to a panel of gammac cytokines, and frequencies of gag specific T cells were enumerated by intracellular IFN-gamma flow cytometry. RESULTS: Of the gammac cytokines, brief exposure to IL-2, IL-15, or combined IL-15/IL-7 significantly enhanced (range 2-7 fold) the CD4(+) and CD8(+) T cell IFN-gamma responses to HIV gag, with IL-15 giving the greatest enhancement. The effects of cytokines were not due to enhanced proliferation of pre-existing antigen specific cells, but were due to a combination of enhanced cytokine production from antigen specific T cells plus activation of non-epitope specific T cells. CONCLUSIONS: These observations support the notion that a significant number of HIV specific T cells are circulating in an anergic state. IL-2, IL-7 and particularly IL-15 as an immune modulator to reverse HIV-1 specific T cell anergy should be investigated, with the caveat that non-specific activation of T cells may also be induced.

Preferential apoptosis of HIV-1-specific CD4+ T cells.

In contrast to other viral infections such as CMV, circulating frequencies of HIV-1-specific CD4+ T cells in peripheral blood are quantitatively diminished in the majority of HIV-1-infected individuals. One mechanism for this quantitative defect is preferential infection of HIV-1-specific CD4+ T cells, although <10% of HIV-1-specific CD4+ T cells are infected. Apoptosis has been proposed as an important contributor to the pathogenesis of CD4+ T cell depletion in HIV/AIDS. We show here that, within HIV-1-infected individuals, a greater proportion of ex vivo HIV-1-specific CD4+ T cells undergo apoptosis compared with CMV-specific CD4+ T cells (45 vs 7.4%, respectively, p < 0.05, in chronic progressors). The degree of apoptosis within HIV-1-specific CD4+ T cells correlates with viral load and disease progression, and highly active antiretroviral therapy abrogates these differences. The data support a mechanism for apoptosis in these cells similar to that found in activation-induced apoptosis through the TCR, resulting in oxygen-free radical production, mitochondrial damage, and caspase-9 activation. That HIV-1 proteins can also directly enhance activation-induced apoptosis supports a mechanism for a preferential induction of apoptosis of HIV-1-specific CD4+ T cells, which contributes to a loss of immunological control of HIV-1 replication.