Combined with the first dorsal (plantar) metatarsal artery pedicle free bilobed flap with a cell scaffold for the repair of a mid-distal adjacent finger defect: a retrospective study.

PURPOSE: Assessing the clinical effectiveness of combining with the first dorsal (plantar) metatarsal artery pedicle free bilobed flap with a cell scaffold to repair mid-distal defects in adjacent fingers. METHODS: From September 2012 to April 2022, 21 patients with 42 mid-distal defects of adjacent fingers underwent treatment using combined with the first dorsal (plantar) metatarsal artery pedicle free bilobed flap with a cell scaffold. The flaps size ranged from 2.1 cm * 1.6 to 4.9 cm * 3.2 cm. Follow-up evaluations included assessing function, sensation, and appearance, etc. of the injured fingers and donor areas. RESULTS: All 42 flaps survived in 21 patients without any vascular crises, and the wounds healed in phase I. The mean follow-up time was 12.2 months (range 7-22 months). During follow-up, in injured fingers, according to the Michigan Hand Outcomes Questionnaire (MHOQ), the functional recovery and appearance were satisfactory; in Dargan Function Evaluation (DFE), the results were both "excellent" in fourteen patients, "excellent" and "good" in five patients, both "good" in one patient, "good" and "general" in one. In static two-point discrimination (2PD), the variation ranges from 4 to 9 mm in injured fingers and 6-10 mm in donor toes. Cold Intolerance Severity Score (CISS) is mild in all patients. The visual analogue score (VAS) showed no pain in the injured fingers and donor toes. No deformities or other complications were noted at the donor toes. According to Chinese Manchester Foot Pain and Disability Index (C-MFPDI), there was no morbidity on foot function in all donor areas. CONCLUSION: The surgical procedure of combined with the first dorsal (plantar) metatarsal artery pedicle free bilobed flap with a cell scaffold for the repair of mid-distal adjacent fingers defect is highly satisfactory. This approach helps the injured fingers to achieve good function, sensibility and appearance, while also achieving satisfactory results in the donor toes.

The glucose transporter 2 regulates CD8+ T cell function via environment sensing.

T cell activation is associated with a profound and rapid metabolic response to meet increased energy demands for cell division, differentiation and development of effector function. Glucose uptake and engagement of the glycolytic pathway are major checkpoints for this event. Here we show that the low-affinity, concentration-dependent glucose transporter 2 (Glut2) regulates the development of CD8+ T cell effector responses in mice by promoting glucose uptake, glycolysis and glucose storage. Expression of Glut2 is modulated by environmental factors including glucose and oxygen availability and extracellular acidification. Glut2 is highly expressed by circulating, recently primed T cells, allowing efficient glucose uptake and storage. In glucose-deprived inflammatory environments, Glut2 becomes downregulated, thus preventing passive loss of intracellular glucose. Mechanistically, Glut2 expression is regulated by a combination of molecular interactions involving hypoxia-inducible factor-1 alpha, galectin-9 and stomatin. Finally, we show that human T cells also rely on this glucose transporter, thus providing a potential target for therapeutic immunomodulation.

Development of a counterselectable system for rapid and efficient CRISPR-based genome engineering in Zymomonas mobilis.

BACKGROUND: Zymomonas mobilis is an important industrial bacterium ideal for biorefinery and synthetic biology studies. High-throughput CRISPR-based genome editing technologies have been developed to enable targeted engineering of genes and hence metabolic pathways in the model ZM4 strain, expediting the exploitation of this biofuel-producing strain as a cell factory for sustainable chemicals, proteins and biofuels production. As these technologies mainly take plasmid-based strategies, their applications would be impeded due to the fact that curing of the extremely stable plasmids is laborious and inefficient. Whilst counterselection markers have been proven to be efficient for plasmid curing, hitherto only very few counterselection markers have been available for Z. mobilis. RESULTS: We constructed a conditional lethal mutant of the pheS gene of Z. mobilis ZM4, clmPheS, containing T263A and A318G substitutions and coding for a mutated alpha-subunit of phenylalanyl-tRNA synthetase to allow for the incorporation of a toxic analog of phenylalanine, p-chloro-phenylalanine (4-CP), into proteins, and hence leading to inhibition of cell growth. We demonstrated that expression of clmPheS driven by a strong Pgap promoter from a plasmid could render the Z. mobilis ZM4 cells sufficient sensitivity to 4-CP. The clmPheS-expressing cells were assayed to be extremely sensitive to 0.2 mM 4-CP. Subsequently, the clmPheS-assisted counterselection endowed fast curing of genome engineering plasmids immediately after obtaining the desired mutants, shortening the time of every two rounds of multiplex chromosome editing by at least 9 days, and enabled the development of a strategy for scarless modification of the native Z. mobilis ZM4 plasmids. CONCLUSIONS: This study developed a strategy, coupling an endogenous CRISPR-based genome editing toolkit with a counterselection marker created here, for rapid and efficient multi-round multiplex editing of the chromosome, as well as scarless modification of the native plasmids, providing an improved genome engineering toolkit for Z. mobilis and an important reference to develope similar genetic manipulation systems in other non-model organisms.

Comparison between traditional and new obesity measurement index for screening metabolic associated fatty liver disease.

Objectives: Obesity measurement indexes have certain screening value for metabolic diseases. To investigate associations between metabolic associated fatty liver disease (MAFLD) and obesity measurement indexes, including traditional indexes (BMI, WC, WHtR) and new indexes (ABSI, BRI, VAI, LAP), and assess their screening ability. Methods: 12,658 subjects aged 18-75 at the Health Center of a Class III Grade A Hospital were included, who were divided into MAFLD and non-MAFLD groups. Spearman's rank correlation was used to study the correlation between MAFLD and obesity measurement indexes. Receiver operating characteristic (ROC) curves were used to calculate the area under the curve (AUC) to evaluate their screening accuracy. Results: MAFLD had strong correlation with traditional BMI and new index LAP. ROC analysis showed that BMI had the highest AUC (0.89), followed by LAP (0.87). Stratification by BMI, LAP had the highest AUC (0.90) for MAFLD in population without obesity (BMI< 23kg/m2), and its optimal cutoff value was 20.75, with a sensitivity and specificity of 85.9% and 79.0%, respectively. Conclusions: We proposed a two-step screening strategy for MAFLD, combining BMI and LAP, and defined a high-risk population for MAFLD as follows: 1) BMI ≥ 23 kg/m2; and 2) BMI< 23 kg/m2 and LAP ≥ 20.75.

Associations of lipid parameters with non-alcoholic fatty liver disease in type 2 diabetic patients according to obesity status and metabolic goal achievement.

Aims: Non-obese non-alcoholic fatty liver disease (NAFLD) phenotype has sparked interest and frequently occurred in type 2 diabetes mellitus (T2DM). Information on associations between lipid parameters and NAFLD in non-obese patients with diabetes has been lacking. We aimed to investigate the relationships between lipid parameters and NAFLD according to obesity status and metabolic goal achievement in T2DM patients. Methods: A total of 1,913 T2DM patients who were hospitalized between June 2018 and May 2021 were cross-sectionally assessed. We used logistic regression models to estimate the associations of lipid parameters with NAFLD risk according to obesity and metabolic goal achievement status. Results: Higher triglycerides, non-HDL-cholesterol, and all lipid ratios including (total cholesterol/HDL-cholesterol, triglyceride/HDL-cholesterol, LDL-cholesterol/HDL-cholesterol, non-HDL-cholesterol/HDL-cholesterol), and lower HDL-cholesterol were associated with NAFLD risk in both non-obese and obese patients. The associations were stronger in non-obese patients than in obese patients. Further, the inverse associations of total cholesterol and LDL-cholesterol with NAFLD risk were only detected in non-obese patients. Triglycerides, HDL-cholesterol, and all lipid ratios studied were significantly associated with NAFLD risk, irrespective of whether the patients achieved their HbA1c, blood pressure, and LDL-cholesterol goal. The presence of poor lipids and lipid ratios were more strongly associated with NAFLD in patients who attained the HbA1c, blood pressure, and/or LDL-cholesterol goal than in those who did not achieve the goal attainment. Conclusions: The associations of lipids and lipid ratios with NAFLD risk were stronger in T2DM patients who were non-obese and achieved the HbA1c, blood pressure, and/or LDL-cholesterol goal attainment.

Loss of voltage-gated hydrogen channel 1 expression reveals heterogeneous metabolic adaptation to intracellular acidification by T cells.

Voltage-gated hydrogen channel 1 (Hvcn1) is a voltage-gated proton channel, which reduces cytosol acidification and facilitates the production of ROS. The increased expression of this channel in some cancers has led to proposing Hvcn1 antagonists as potential therapeutics. While its role in most leukocytes has been studied in depth, the function of Hvcn1 in T cells remains poorly defined. We show that Hvcn1 plays a nonredundant role in protecting naive T cells from intracellular acidification during priming. Despite sharing overall functional impairment in vivo and in vitro, Hvcn1-deficient CD4+ and CD8+ T cells display profound differences during the transition from naive to primed T cells, including in the preservation of T cell receptor (TCR) signaling, cellular division, and death. These selective features result, at least in part, from a substantially different metabolic response to intracellular acidification associated with priming. While Hvcn1-deficient naive CD4+ T cells reprogram to rescue the glycolytic pathway, naive CD8+ T cells, which express high levels of this channel in the mitochondria, respond by metabolically compensating mitochondrial dysfunction, at least in part via AMPK activation. These observations imply heterogeneity between adaptation of naive CD4+ and CD8+ T cells to intracellular acidification during activation.

Proteomics Analysis of Serum from COVID-19 Patients.

Coronavirus disease 2019 (COVID-19) is a worldwide pandemic. To understand the changes in plasma proteomics upon SARS-CoV-2 infection, we analyzed the protein profiles of plasma samples from 10 COVID-19 patients and 10 healthy volunteers by using the DIA quantitative proteomics technology. We compared and identified differential proteins whose abundance changed upon SARS-CoV-2 infection. Bioinformatic analyses were then conducted for these identified differential proteins. The GO/KEEG database was used for functional annotation and enrichment analysis. The interaction relationship of differential proteins was evaluated with the STRING database, and Cytoscape software was used to conduct network analysis of the obtained data. A total of 323 proteins were detected in all samples. Difference between patients and healthy donors was found in 44 plasma proteins, among which 36 proteins were up-regulated and 8 proteins were down-regulated. GO functional annotation showed that these proteins mostly composed of cellular anatomical entities and proteins involved in biological regulation, cellular processes, transport, and other processes. KEEG functional annotation further showed that these proteins were mainly involved in complement system activation and infectious disease processes. Importantly, a KEEG pathway (natural killer cell-mediated cytotoxicity) was enriched, with three important activators of this pathway, ICAM1/2 and IgG, being up-regulated. Protein-protein interaction (PPI) statistics indicated that, among these 44 proteins, 6 were the most significantly up-regulated (DBH, SHGB, TF, ICAM2, THBS1, and C1RL) while 2 were the most significantly down-regulated (APCS and ORM1). Results from this study showed that a few proteins associated with immune activation were up-regulated in patient plasma. In addition, this study established a method for extraction and quantitative determination of plasma components in convalescent plasma from COVID-19 patients.

Comparative transcriptome profiles of large and small bodied large-scale loaches cultivated in paddy fields.

Fish culture in paddy fields is a traditional aquaculture mode, which has a long history in East Asia. Large-scale loach (Paramisgurnus dabryanus) fast growth is suitable for paddy fields aquaculture in China. The objective of this study was to identify differential expression genes (DEGs) in the brain, liver and muscle tissues between large (LG, top 5% of maximum total length) and small (SG, top 5% of minimum total length) groups using RNA-seq. In total, 150 fish were collected each week and 450 fish were collected at twelfth week from three paddy fields for all the experimental. Histological observation found that the muscle fibre diameter of LG loaches was greater than that of SG loaches. Transcriptome results revealed that the high expression genes (HEGs) in LG loaches (fold change ≥ 2, p < 0.05) were mainly concentrated in metabolic pathways, such as "Thyroid hormone signalling pathway", "Citrate cycle (TCA cycle)", "Carbon metabolism", "Fatty acid metabolism", and "Cholesterol metabolism", and the HEGs in SG loaches were enriched in the pathways related to environmental information processing such as "Cell adhesion molecules (CAMs)", "ECM- receptor interaction" and "Rap1 signalling pathway"; cellular processes such as "Tight junction", "Focal adhesion", "Phagosome" and "Adherens junction". Furthermore, IGFs gene family may play an important role in loach growth for their different expression pattern between the two groups. These findings can enhance our understanding about the molecular mechanism of different growth and development levels of loaches in paddy fields.

Preservation of microvascular barrier function requires CD31 receptor-induced metabolic reprogramming.

Endothelial barrier (EB) breaching is a frequent event during inflammation, and it is followed by the rapid recovery of microvascular integrity. The molecular mechanisms of EB recovery are poorly understood. Triggering of MHC molecules by migrating T-cells is a minimal signal capable of inducing endothelial contraction and transient microvascular leakage. Using this model, we show that EB recovery requires a CD31 receptor-induced, robust glycolytic response sustaining junction re-annealing. Mechanistically, this response involves src-homology phosphatase activation leading to Akt-mediated nuclear exclusion of FoxO1 and concomitant ß-catenin translocation to the nucleus, collectively leading to cMyc transcription. CD31 signals also sustain mitochondrial respiration, however this pathway does not contribute to junction remodeling. We further show that pathologic microvascular leakage in CD31-deficient mice can be corrected by enhancing the glycolytic flux via pharmacological Akt or AMPK activation, thus providing a molecular platform for the therapeutic control of EB response.

miR­296­3p promotes the proliferation of glioblastoma cells by targeting ICAT.

MicroRNAs (miRNA/miRs) serve an important function in the regulation of gene expression, and have been indicated to mediate a number of cellular biological processes, including cell proliferation, the cell cycle, cell apoptosis and cell differentiation. The altered expression of miRNAs has been revealed to result in a variety of human diseases, including glioblastoma multiforme (GBM). The present study indicated an increase in miR­296­3p in glioma tumor types compared with normal brain, particularly in the samples from patients with high grade GBM. Antagonizing miR­296­3p was demonstrated to induce cell growth arrest and cell cycle redistribution in U251 cells. The miR­296­3p antagonist altered the expression of a number of key genes that are involved in cell cycle control, including cyclin D1 and p21. Additionally, the decrease of miR­296­3p increased inhibitor of ß­catenin and T cell factor (ICAT) expression, and increased miR­296­3p­inhibited ICAT expression in U251 cells. Bioinformatics analysis indicated that ICAT is a target gene of miR­296­3p, which was further validated using a dual­luciferase reporter assay. Through the regulation of ICAT, the miR­296­3p antagonist decreased ß­catenin protein expression and increased the expression of its target genes. Silencing ICAT was indicated to reverse the miR­296­3p downregulation­induced inactivation of Wnt signaling and cell growth arrest in glioma cells. The present study also indicated a negative correlation between ICAT mRNA levels and miR­296­3p levels in glioma tumor types. In conclusion, the present study identified an oncogenic function of miR­296­3p in glioblastoma via the direct regulation of ICAT.

Analysis of the laboratory indexes and risk factors in 189 cases of severe fever with thrombocytopenia syndrome.

The current study aimed to analyze the clinical characteristics of severe fever with thrombocytopenia syndrome (SFTS) and to explore the risk factors of critical patients. From 2016 to 2018, we collected the hospitalized diagnosed cases with SFTS in Jinan infectious disease hospital of Shandong University and analyzed by the descriptive epidemiological method. According to the prognosis, they were divided into general group and severe group. The epidemiological characteristics, clinical features, and laboratory indexes of these 2 groups of patients were compared and analyzed at the first visit. The risk factors related to the severity of the disease were analyzed by univariate Logistic regression. In total, 189 cases of SFTS were treated during the period and 33 deaths occurred in the severe group, with the fatality rate of 17.46%. The patients' age (χ = 8.864, P < .01), ALT (Z = -2.304, P = .03), AST (Z = -3.361, P < .01), GLU (t = -4.115, P < .01), CK (Z = -3.964, P < .01), CK-MB (Z = -2.225, P = .03), LDH (Z = -3.655, P < .01), α-HBDH (Z = -2.040, P = .04), APTT (t = -3.355, P < .01), BUN (Z = -2.040, P = .04), Cr (Z = -3.071, P = .01), and D-dimer (Z = -2.026, P = .04) in the severe group were higher than that in the normal group, but the blood platelet (PLT) counts were significantly lower (Z = -2.778, P < .01) than that in the normal group. With the neuropsychiatric symptoms (OR = 24.083, 95% CI = 6.064-95.642), skin bleeding point (OR = 30.000, 95% CI = 6.936-129.764), multiple organ dysfunction (OR = 34.048, 95% CI = 7.740-149.782), past medical history (OR = 3.792, 95% CI = 1.284-11.200), and fasting glucose elevation (OR = 1.359, 95% CI = 1.106-1.668) could predict the severity of the SFTS. In summary, the abnormality of the laboratory index, the special clinical manifestations, and the past medical history of SFTS patients were the important basis for judging the patient's serious condition.

Resistance characteristics of CTX-M type Shigella flexneri in China.

The present study was to identify the drug resistance, resistance mechanism and the extended-spectrum ß-lactamase (ESBLs) genotypes of Shigella flexneri (S. flexneri) in Jinan. Susceptibility tests were performed by MIC-determination. The genotypes of ß-lactamase were identified using PCR and DNA sequencing. The resistance transfer ability of the ESBL-producing strains was examined by conjugation tests. A total of 105 S. flexneri isolates were collected, and 34 (32.4%) were ESBL-producing isolates. All ESBL-producing isolates were susceptible to cefoxitin and imipenem, and 35.3% isolates were resistant to ciprofloxacin. ESBL-producing isolates showed high level resistant to ampicillin (100%), cefotaxime (100%), tetracycline (100%), chloramphenicol (100%), trimethoprim/sulfamethoxazole (100%), ceftazidime (73.5%) and cefepime (73.5%). Three types of ß-lactamase genes (blaTEM, blaOXA and blaCTX-M) were identified in all ESBL-producing isolates, and the genotypes were confirmed as blaTEM-1 (23/34), blaOXA-30 (34/34), blaCTX-M-14 (9/34) and blaCTX-M-15 (25/34) by sequencing. In conclusion, the Shigella strains isolated in Jinan are cross-resistant and multi-drug resistant. The main genotypes of ESBLs are CTX-M-14 and CTX-M-15.

A Subset of CCL25-Induced Gut-Homing T Cells Affects Intestinal Immunity to Infection and Cancer.

Protective immunity relies upon differentiation of T cells into the appropriate subtype required to clear infections and efficient effector T cell localization to antigen-rich tissue. Recent studies have highlighted the role played by subpopulations of tissue-resident memory (TRM) T lymphocytes in the protection from invading pathogens. The intestinal mucosa and associated lymphoid tissue are densely populated by a variety of resident lymphocyte populations, including αß and γδ CD8+ intraepithelial T lymphocytes (IELs) and CD4+ T cells. While the development of intestinal γδ CD8+ IELs has been extensively investigated, the origin and function of intestinal CD4+ T cells have not been clarified. We report that CCR9 signals delivered during naïve T cell priming promote the differentiation of a population of α4ß7+ IFN-γ-producing memory CD4+ T cells, which displays a TRM molecular signature, preferentially localizes to the gastrointestinal (GI) tract and associated lymphoid tissue and cannot be mobilized by remote antigenic challenge. We further show that this population shapes the immune microenvironment of GI tissue, thus affecting effector immunity in infection and cancer.

MELAS and macroangiopathy: A case report and literature review.

RATIONALE: Mitochondrial encephalopathy, lactic acidosis and stroke-like episodes (MELAS) are thought to be rarely accompanied by macroangiopathy. We reported a case of MELAS that presented right distal internal carotid arterial (ICA) stenosis and reviewed 12 similar previously reported cases involving intracranial large blood vessels. PATIENT CONCERNS: A 38-year-old man suffered from recurrent stroke-like episodes (SE) such as alternating hemiparesis (right lesion 3 years ago and current left lesion), cortical blindness and seizure for 3 years, and was previously misdiagnosed as cerebral infarction. Magnetic Resonance Angiography (MRA) and Digital Subtraction Angiography (DSA) revealed right distal ICA stenosis and sparse cortex blood vessels, which were related to the previous SE. DIAGNOSES: He was diagnosed by genetic screening (a mitochondrial DNA A3243G point mutation) and presence of high lactic acidosis (4.03 mmol/L), which rose to 7.8 mmol/L after exercise. INTERVENTION: The patient received Coenzyme Q10, vitamin C, L-arginine for 2 weeks and valproic acid sodium (400 mg bid) to prevent seizures till now. OUTCOMES: He is currently less active and intelligent than his peers, with occasional seizures, and needs family care. LESSONS: Till date, there are 12 reported cases of MELAS combined with major cerebral arteries abnormalities including stenosis, dissection, occlusion, reversible vasoconstriction, aneurysms, and atherosclerosis. Hence, macroangiopathy in MELAS is not very rare. There is correlation between the affected vessels and the lesions in some cases, but not in others, which may increase the misdiagnosis rate. Hence, mitochondrial diseases cannot be excluded due to concurrent macroangiopathic lesions.

Regulatory T Cell Migration Is Dependent on Glucokinase-Mediated Glycolysis.

Migration of activated regulatory T (Treg) cells to inflamed tissue is crucial for their immune-modulatory function. While metabolic reprogramming during Treg cell differentiation has been extensively studied, the bioenergetics of Treg cell trafficking remains undefined. We have investigated the metabolic demands of migrating Treg cells in vitro and in vivo. We show that glycolysis was instrumental for their migration and was initiated by pro-migratory stimuli via a PI3K-mTORC2-mediated pathway culminating in induction of the enzyme glucokinase (GCK). Subsequently, GCK promoted cytoskeletal rearrangements by associating with actin. Treg cells lacking this pathway were functionally suppressive but failed to migrate to skin allografts and inhibit rejection. Similarly, human carriers of a loss-of-function GCK regulatory protein gene-leading to increased GCK activity-had reduced numbers of circulating Treg cells. These cells displayed enhanced migratory activity but similar suppressive function, while conventional T cells were unaffected. Thus, GCK-dependent glycolysis regulates Treg cell migration.

Monitoring Migration of Activated T Cells to Antigen-Rich Non-lymphoid Tissue.

Effective immunity requires appropriate recirculation of naïve T cells through secondary lymphoid organs and migration of antigen-specific T cells to sites of inflammation. Leukocyte migration is a highly regulated process requiring specific interactions between leukocytes and endothelial cells (EC) termed collectively as the leukocyte adhesion cascade. Recruitment and retention of activated T cells to antigen-rich sites of inflammation is a key event in the immune response, which relies in part on local antigen presentation particularly by EC of inflamed vessels. Here we describe methods to assess the contributions of different molecules on antigen-dependent T cell migration, by utilizing IFN-γ to upregulate MHC molecules on EC and local antigen presentation, both in vitro and in vivo.

Obesity-Induced Metabolic Stress Leads to Biased Effector Memory CD4+ T Cell Differentiation via PI3K p110δ-Akt-Mediated Signals.

Low-grade systemic inflammation associated to obesity leads to cardiovascular complications, caused partly by infiltration of adipose and vascular tissue by effector T cells. The signals leading to T cell differentiation and tissue infiltration during obesity are poorly understood. We tested whether saturated fatty acid-induced metabolic stress affects differentiation and trafficking patterns of CD4+ T cells. Memory CD4+ T cells primed in high-fat diet-fed donors preferentially migrated to non-lymphoid, inflammatory sites, independent of the metabolic status of the hosts. This was due to biased CD4+ T cell differentiation into CD44hi-CCR7lo-CD62Llo-CXCR3+-LFA1+ effector memory-like T cells upon priming in high-fat diet-fed animals. Similar phenotype was observed in obese subjects in a cohort of free-living people. This developmental bias was independent of any crosstalk between CD4+ T cells and dendritic cells and was mediated via direct exposure of CD4+ T cells to palmitate, leading to increased activation of a PI3K p110δ-Akt-dependent pathway upon priming.

Mechanisms of T cell organotropism.

Protective immunity relies upon T cell differentiation and subsequent migration to target tissues. Similarly, immune homeostasis requires the localization of regulatory T cells (Tregs) to the sites where immunity takes place. While naïve T lymphocytes recirculate predominantly in secondary lymphoid tissue, primed T cells and activated Tregs must traffic to the antigen rich non-lymphoid tissue to exert effector and regulatory responses, respectively. Following priming in draining lymph nodes, T cells acquire the 'homing receptors' to facilitate their access to specific tissues and organs. An additional level of topographic specificity is provided by T cells receptor recognition of antigen displayed by the endothelium. Furthermore, co-stimulatory signals (such as those induced by CD28) have been shown not only to regulate T cell activation and differentiation, but also to orchestrate the anatomy of the ensuing T cell response. We here review the molecular mechanisms supporting trafficking of both effector and regulatory T cells to specific antigen-rich tissues.

Hepatocyte Growth Factor Receptor c-Met Instructs T Cell Cardiotropism and Promotes T Cell Migration to the Heart via Autocrine Chemokine Release.

Effector-T-cell-mediated immunity depends on the efficient localization of antigen-primed lymphocytes to antigen-rich non-lymphoid tissue, which is facilitated by the expression of a unique set of "homing" receptors acquired by memory T cells. We report that engagement of the hepatocyte growth factor (HGF) receptor c-Met by heart-produced HGF during priming in the lymph nodes instructs T cell cardiotropism, which was associated with a specialized homing "signature" (c-Met(+)CCR4(+)CXCR3(+)). c-Met signals facilitated T cell recruitment to the heart via the chemokine receptor CCR5 by inducing autocrine CCR5 ligand release. c-Met triggering was sufficient to support cardiotropic T cell recirculation, while CCR4 and CXCR3 sustained recruitment during heart inflammation. Transient pharmacological blockade of c-Met during T cell priming led to enhanced survival of heart, but not skin, allografts associated with impaired localization of alloreactive T cells to heart grafts. These findings suggest c-Met as a target for development of organ-selective immunosuppressive therapies.