Artery Grafting for Arterial Anastomoses in Head and Neck Free Tissue Transfer Reconstruction.

BACKGROUND: Vessel grafting is an important technique in head and neck free tissue transfer (FTT) reconstruction when a tension-free anastomosis is not otherwise feasible. To our knowledge, there are limited data regarding interposition artery grafts for arterial anastomoses in head and neck reconstruction. Here, we present a multi-institutional cohort of arterial interposition grafts for FTT reconstruction for head and neck defects. METHODS: A retrospective review was conducted at four tertiary care institutions for patients who underwent FTT reconstruction for head and neck defects which utilized an interposition artery graft for the arterial anastomosis. Charts were reviewed for type and length of artery grafts harvested, surgical indication, indication for artery graft, types of flaps harvested, and various preoperative characteristics (including history of radiation or previous FTT reconstruction surgery). Postoperative complications within postoperative day 30 were measured and reported. RESULTS: Nine patients met inclusion criteria. The lateral circumflex femoral artery (either transverse or descending branches) (n = 3) and facial artery (n = 3) were the most commonly harvested arteries. The scalp (n = 5) was the most common primary defect site. Seven grafts were harvested initially and in a planned fashion, while two were harvested as salvage techniques (either for flap salvage or vein graft failure). In planned grafts, arteries were the preferred interposition grafting method due to either size match preferences (n = 4) or similarities in wall thickness (n = 3) between graft and recipient artery. There were no reported cases of unplanned readmission, postoperative hematoma, fistula formation, wound infection, or donor site morbidities. Two patients required unplanned return to the operating room for flap compromise, both of which ultimately resulted in flap failure secondary to clot formation at both arterial and venous anastomoses. CONCLUSIONS: When arterial pedicle length is insufficient, interposition artery grafting is both a feasible and viable technique to achieve tension-free arterial anastomoses for select cases of highly complex head and neck free tissue reconstruction.

Chatbots as Patient Education Resources for Aesthetic Facial Plastic Surgery: Evaluation of ChatGPT and Google Bard Responses.

Background: ChatGPT and Google Bard™ are popular artificial intelligence chatbots with utility for patients, including those undergoing aesthetic facial plastic surgery. Objective: To compare the accuracy and readability of chatbot-generated responses to patient education questions regarding aesthetic facial plastic surgery using a response accuracy scale and readability testing. Method: ChatGPT and Google Bard™ were asked 28 identical questions using four prompts: none, patient friendly, eighth-grade level, and references. Accuracy was assessed using Global Quality Scale (range: 1-5). Flesch-Kincaid grade level was calculated, and chatbot-provided references were analyzed for veracity. Results: Although 59.8% of responses were good quality (Global Quality Scale ≥4), ChatGPT generated more accurate responses than Google Bard™ on patient-friendly prompting (p < 0.001). Google Bard™ responses were of a significantly lower grade level than ChatGPT for all prompts (p < 0.05). Despite eighth-grade prompting, response grade level for both chatbots was high: ChatGPT (10.5 ± 1.8) and Google Bard™ (9.6 ± 1.3). Prompting for references yielded 108/108 of chatbot-generated references. Forty-one (38.0%) citations were legitimate. Twenty (18.5%) provided accurately reported information from the reference. Conclusion: Although ChatGPT produced more accurate responses and at a higher education level than Google Bard™, both chatbots provided responses above recommended grade levels for patients and failed to provide accurate references.

Evaluating ChatGPT Responses on Thyroid Nodules for Patient Education.

Background: ChatGPT, an artificial intelligence (AI) chatbot, is the fastest growing consumer application in history. Given recent trends identifying increasing patient use of Internet sources for self-education, we seek to evaluate the quality of ChatGPT-generated responses for patient education on thyroid nodules. Methods: ChatGPT was queried 4 times with 30 identical questions. Queries differed by initial chatbot prompting: no prompting, patient-friendly prompting, 8th-grade level prompting, and prompting for references. Answers were scored on a hierarchical score: incorrect, partially correct, correct, or correct with references. Proportions of responses at incremental score thresholds were compared by prompt type using chi-squared analysis. Flesch-Kincaid grade level was calculated for each answer. The relationship between prompt type and grade level was assessed using analysis of variance. References provided within ChatGPT answers were totaled and analyzed for veracity. Results: Across all prompts (n = 120 questions), 83 answers (69.2%) were at least correct. Proportions of responses that were at least partially correct (p = 0.795) and correct (p = 0.402) did not differ by prompt; responses that were correct with references did (p < 0.0001). Responses from 8th-grade level prompting were the lowest mean grade level (13.43 ± 2.86) and were significantly lower than no prompting (14.97 ± 2.01, p = 0.01) and prompting for references (16.43 ± 2.05, p < 0.0001). Prompting for references generated 80/80 (100%) of referenced medical publications within answers. Seventy references (87.5%) were legitimate citations, and 58/80 (72.5%) provided accurately reported information from the referenced publication. Conclusion: ChatGPT overall provides appropriate answers to most questions on thyroid nodules regardless of prompting. Despite targeted prompting strategies, ChatGPT reliably generates responses corresponding to grade levels well-above accepted recommendations for presenting medical information to patients. Significant rates of AI hallucination may preclude clinicians from recommending the current version of ChatGPT as an educational tool for patients at this time.

MDR1-EXPRESSING CD4+ T CELLS WITH TH1.17 FEATURES RESIST TO NEOADJUVANT CHEMOTHERAPY AND ARE ASSOCIATED WITH BREAST CANCER CLINICAL RESPONSE.

BACKGROUND: Multidrug resistance-1 (MDR1) transporter limits the intracellular accumulation of chemotherapies (paclitaxel, anthracyclines) used in breast cancer (BC) treatment. In addition to tumor cells, MDR1 is expressed on immune cell subsets in which it confers chemoresistance. Among human T cells, MDR1 is expressed by most CD8+ T cells, and a subset of CD4+ T helper (Th) cells. Here we explored the expression, function and regulation of MDR1 on CD4+ T cells and investigated the role of this population in response to neoadjuvant chemotherapy (NAC) in BC. METHODS: Phenotypic and functional characteristics of MDR1+ CD4 Th cells were assessed on blood from healthy donors and patients with BC by flow cytometry. These features were extended to CD4+ Th cells from untreated breast tumor by flow cytometry and RNA-sequencing (RNA-seq). We performed in vitro polarization assays to decipher MDR1 regulation on CD4 Th cells. We evaluated in vitro the impact of chemotherapy agents on MDR1+ CD4+ Th cells. We analyzed the impact of NAC treatment on MDR1+ CD4+ Th cells from blood and tumors and their association with treatment efficacy in two independent BC cohorts and in a public RNA-seq data set of BC tumor biopsies before and after NAC. Finally, we performed single cell (sc) RNAseq of blood CD4+ memory T cells from NAC-treated patients and combined them with an scRNAseq public data set. RESULTS: MDR1+ CD4 Th cells were strongly enriched in Th1.17 polyfunctional cells but also in Th17 cells, both in blood and untreated breast tumor tissues. Mechanistically, Tumor growth factor (TGF)-ß1 was required for MDR1 induction during in vitro Th17 or Th1.17 polarization. MDR1 expression conferred a selective advantage to Th1.17 and Th17 cells following paclitaxel treatment in vitro and in vivo in NAC-treated patients. scRNAseq demonstrated MDR1 association with tumor Th1.17 and Th with features of cytotoxic cells. Enrichment in MDR1+ CD4+ Th1.17 and Th17 cells, in blood and tumors positively correlated with pathological response. Absence of early modulation of Th1.17 and Th17 in NAC-resistant patients, argue for its use as a biomarker for chemotherapy regimen adjustment. CONCLUSION: MDR1 favored the enrichment of Th1.17 and Th17 in blood and tumor after NAC that correlated to clinical response.

Differences in Functional and Survival Outcomes Between Patients Receiving Primary Surgery vs Chemoradiation Therapy for Treatment of T1-T2 Oropharyngeal Squamous Cell Carcinoma.

Importance: Due to lack of data from high-powered randomized clinical trials, the differences in functional and survival outcomes for patients with oropharyngeal squamous cell carcinoma (OPSCC) undergoing primary transoral robotic surgery (TORS) vs primary radiation therapy and/or chemoradiation therapy (RT/CRT) are unclear. Objectives: To compare 5-year functional (dysphagia, tracheostomy dependence, and gastrostomy tube dependence) and survivorship outcomes in patients with T1-T2 OPSCC receiving primary TORS vs RT/CRT. Design, Setting, and Population: This national multicenter cohort study used data from a global health network (TriNetX) to identify differences in functional and survival outcomes among patients with OPSCC who underwent primary TORS or RT/CRT in 2002 to 2022. After propensity matching, 726 patients with OPSCC met inclusion criteria. In the TORS group, 363 (50%) patients had undergone primary surgery, and in the RT/CRT group, 363 (50%) patients had received primary RT/CRT. Data analyses were performed from December 2022 to January 2023 using the TriNetX platform. Exposure: Primary surgery with TORS or primary treatment with radiation therapy and/or chemoradiation therapy. Main Outcomes and Measures: Propensity score matching was used to balance the 2 groups. Functional outcomes were measured at 6 months, 1 year, 3 years, 5 years, and more than 5 years posttreatment and included dysphagia, gastrostomy tube dependence, and tracheostomy dependence according to standard medical codes. Five-year overall survivorship was compared between patients undergoing primary TORS vs RT/CRT. Results: Propensity score matching allowed a study sample with 2 cohorts comprising statistically similar parameters with 363 (50%) patients in each. Patients in the TORS cohort had a mean (SD) age of 68.5 (9.9) vs 68.8 (9.7) years in RT/CRT cohort; 86% and 88% were White individuals, respectively; 79% of patients were men in both cohorts. Primary TORS was associated with clinically meaningful increased risk of dysphagia at 6 months (OR, 1.37; 95% CI, 1.01-1.84) and 1 year posttreatment (OR, 1.71; 95% CI, 1.22-2.39) compared with primary RT/CRT. Patients receiving surgery were less likely to be gastrostomy tube dependent at 6 months (OR, 0.46; 95% CI, 0.21-1.00) and 5 years posttreatment (risk difference, -0.05; 95% CI, -0.07 to -0.02). Differences in overall rates of tracheostomy dependence (OR, 0.97; 95% CI, 0.51-1.82) between groups were not clinically meaningful. Patients with OPSCC, unmatched for cancer stage or human papillomavirus status, who received RT/CRT had worse 5-year overall survival than those who underwent primary surgery (70.2% vs 58.4%; hazard ratio, 0.56; 95% CI, 0.40-0.79). Conclusions and Relevance: This national multicenter cohort study of patients undergoing primary TORS vs primary RT/CRT for T1-T2 OPSCC found that primary TORS was associated with a clinically meaningful increased risk of short-term dysphagia. Patients treated with primary RT/CRT had an increased risk of short- and long-term gastrostomy tube dependence and worse 5-year overall survival than those who underwent surgery.

Evaluating ChatGPT responses on obstructive sleep apnea for patient education.

STUDY OBJECTIVES: We evaluated the quality of ChatGPT responses to questions on obstructive sleep apnea for patient education and assessed how prompting the chatbot influences correctness, estimated grade level, and references of answers. METHODS: ChatGPT was queried 4 times with 24 identical questions. Queries differed by initial prompting: no prompting, patient-friendly prompting, physician-level prompting, and prompting for statistics/references. Answers were scored on a hierarchical scale: incorrect, partially correct, correct, correct with either statistic or referenced citation ("correct+"), or correct with both a statistic and citation ("perfect"). Flesch-Kincaid grade level and citation publication years were recorded for answers. Proportions of responses at incremental score thresholds were compared by prompt type using chi-squared analysis. The relationship between prompt type and grade level was assessed using analysis of variance. RESULTS: Across all prompts (n = 96 questions), 69 answers (71.9%) were at least correct. Proportions of responses that were at least partially correct (P = .387) or correct (P = .453) did not differ by prompt; responses that were at least correct+ (P < .001) or perfect (P < .001) did. Statistics/references prompting provided 74/77 (96.1%) references. Responses from patient-friendly prompting had a lower mean grade level (12.45 ± 2.32) than no prompting (14.15 ± 1.59), physician-level prompting (14.27 ± 2.09), and statistics/references prompting (15.00 ± 2.26) (P < .0001). CONCLUSIONS: ChatGPT overall provides appropriate answers to most questions on obstructive sleep apnea regardless of prompting. While prompting decreases response grade level, all responses remained above accepted recommendations for presenting medical information to patients. Given ChatGPT's rapid implementation, sleep experts may seek to further scrutinize its medical literacy and utility for patients. CITATION: Campbell DJ, Estephan LE, Mastrolonardo EV, Amin DR, Huntley CT, Boon MS. Evaluating ChatGPT responses on obstructive sleep apnea for patient education. J Clin Sleep Med. 2023;19(12):1989-1995.

Evaluating YouTube videos on sialendoscopy as an educational resource for patients.

Objectives: Patients are increasingly relying on YouTube for health information. We objectively evaluated the quality and comprehensiveness of sialendoscopy YouTube videos available to patients. We further investigated the relationship between video content and video popularity. Methods: We identified 150 videos using the search term "sialendoscopy." Videos were excluded if they were lectures for medical professionals, operating room (OR) recordings, unrelated, non-English, or non-audio. Video quality and comprehensiveness were evaluated using modified DISCERN criterion (range: 5-25) and novel sialendoscopy criterion (NSC, range: 0-7), respectively. Secondary outcomes included standard video metrics and Video Power Index to measure popularity. Videos were classified binarily by uploader type as from an academic medical center or from other sources. Results: Twenty-two (14.7%) of 150 videos were included for review, with 7 (31.8%) uploaded from academic medical institutions. One hundred-nine (72.7%) videos were excluded as lectures for medical professionals or OR recordings. Overall mean modified DISCERN (13.45 ± 3.42) and NSC (3.05 ± 0.96) scores were low; however, videos uploaded by academic medical institutions were significantly more comprehensive (NSC mean difference = 0.98, 95% CI: 0.16-1.80, p = .02). There were no significant correlations between video popularity and objective measures of quality or comprehensiveness. Conclusions: This study highlights the paucity and low quality of sialendoscopy videos for patients. More popular videos are not higher quality, and most videos are targeted more toward physicians rather than patients. As YouTube becomes increasingly used by patients, there is opportunity for otolaryngologists to produce more informative videos for patients while implementing targeted strategies to increase viewership. Level of Evidence: NA.

Septic Arthritis With Superimposed Acute Gouty Arthritis in a Rheumatoid Arthritis Patient.

Septic arthritis is a rare but serious complication of both rheumatoid and gouty arthritis and can lead to significant morbidity and even mortality. Here, we report a case of septic arthritis with bacteremia, monosodium urate crystals, and hyperuricemia in a 75-year-old male with long-standing rheumatoid arthritis. Arthrocentesis revealed gram-positive cocci representing group B streptococcus (Streptococcus agalactiae) infection and monosodium urate crystals. A diagnosis of septic arthritis with superimposed acute gouty arthritis was made and the patient was treated accordingly. Management included surgical irrigation and debridement, antibiotic therapy, and systemic glucocorticoids which resulted in a significant improvement in the patient's clinical status.

Partial Thrombosis of Inferior Mesenteric Vein With Thrombophlebitis.

Inferior mesenteric vein thrombosis (IMVT) is a rare entity that can lead to a potentially lethal event unless recognized early in the disease. Although its prevalence is low, IMVT presents mainly in certain conditions such as in inflammatory processes like diverticulitis, arrhythmias, hypercoagulable states, connective tissue disorders, malignancy, or hereditary thrombophilias.  Mesenteric venous thrombophlebitis is a condition in which a blood clot in a vein causes inflammation and pain. It can appear in an acute or subacute manner that leads to acute mesenteric ischemia. The case of a 58-year-old male without a significant past medical history who presented with suprapubic abdominal pain secondary to a partial IMVT of unknown etiology with accompanying thrombophlebitis is discussed here.

In Vivo Expansion of Antigen-Specific Regulatory T Cells through Staggered Fc.IL-2 Mutein Dosing and Antigen-Specific Immunotherapy.

In mice, Ag administration in the absence of adjuvant typically elicits tolerogenic immune responses through the deletion or inactivation of conventional CD4 T cells and the formation or expansion of regulatory CD4 T cells (Treg). Although these "Ag-specific immunotherapy" (ASI) approaches are currently under clinical development to treat autoinflammatory conditions, efficacy and safety may be variable and unpredictable because of the diverse activation states of immune cells in subjects with autoimmune and allergic diseases. To reliably induce Ag-specific tolerance in patients, novel methods to control T cell responses during ASI are needed, and strategies that permanently increase Treg frequencies among Ag-specific CD4 T cells may provide long-lasting immunosuppression between treatments. In this study, we present an approach to durably increase the frequency of Ag-specific Treg in mice by administering ASI when Treg numbers are transiently increased with individual doses of a half-life-extended Treg-selective IL-2 mutein. Repeated weekly cycles of IL-2 mutein doses (day 0) followed by ASI (day 3) resulted in a 3- to 5-fold enrichment in Treg among Ag-responsive CD4 T cells. Expanded Ag-specific Treg persisted for more than 3 wk following treatment cessation, as well as through an inflammatory T cell response to an Ag-expressing virus. Combining Treg enrichment with ASI has the potential to durably treat autoimmune disease or allergy by increasing the Treg/conventional CD4 T cell ratio among autoantigen- or allergen-specific T cells.

High-throughput single-cell quantification of hundreds of proteins using conventional flow cytometry and machine learning.

Modern immunologic research increasingly requires high-dimensional analyses to understand the complex milieu of cell types that comprise the tissue microenvironments of disease. To achieve this, we developed Infinity Flow combining hundreds of overlapping flow cytometry panels using machine learning to enable the simultaneous analysis of the coexpression patterns of hundreds of surface-expressed proteins across millions of individual cells. In this study, we demonstrate that this approach allows the comprehensive analysis of the cellular constituency of the steady-state murine lung and the identification of previously unknown cellular heterogeneity in the lungs of melanoma metastasis­bearing mice. We show that by using supervised machine learning, Infinity Flow enhances the accuracy and depth of clustering or dimensionality reduction algorithms. Infinity Flow is a highly scalable, low-cost, and accessible solution to single-cell proteomics in complex tissues.

Designed proteins assemble antibodies into modular nanocages.

Multivalent display of receptor-engaging antibodies or ligands can enhance their activity. Instead of achieving multivalency by attachment to preexisting scaffolds, here we unite form and function by the computational design of nanocages in which one structural component is an antibody or Fc-ligand fusion and the second is a designed antibody-binding homo-oligomer that drives nanocage assembly. Structures of eight nanocages determined by electron microscopy spanning dihedral, tetrahedral, octahedral, and icosahedral architectures with 2, 6, 12, and 30 antibodies per nanocage, respectively, closely match the corresponding computational models. Antibody nanocages targeting cell surface receptors enhance signaling compared with free antibodies or Fc-fusions in death receptor 5 (DR5)-mediated apoptosis, angiopoietin-1 receptor (Tie2)-mediated angiogenesis, CD40 activation, and T cell proliferation. Nanocage assembly also increases severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) pseudovirus neutralization by α-SARS-CoV-2 monoclonal antibodies and Fc-angiotensin-converting enzyme 2 (ACE2) fusion proteins.

Primary Pancreatic Signet Ring Cell Carcinoma: A Case Report and Review of the Literature.

Background: Primary pancreatic signet ring cell carcinoma (PPSRCC) is a rare (<1%) poorly reported histopathological variant of pancreatic cancer with ill-defined treatment guidelines. Herein, we describe a case of nonmetastatic PPSRCC in a 45-year-old female. Presentation: A 45-year-old female presented with 3 weeks of abdominal pain radiating to her back. Other pertinent positives included a 20-pound (9.1-kilogram) weight loss and jaundice, with a known 30-pack-year smoking history. CT scan revealed a 4.6 × 3.6 cm hypoattenuating mass in the head of the pancreas (HOP) with dilatation of the common bile duct. Total bilirubin at presentation was elevated, and a biliary stent was placed endoscopically. Subsequent endoscopic ultrasonography revealed a periampullary ulcerated mass involving the HOP and second portion of the duodenum, with pathology revealing poorly differentiated adenocarcinoma with mucinous background and focal signet ring cells. A classic pancreatoduodenectomy (Whipple procedure) was performed. Final pathology revealed a poorly differentiated (G3) pT3/pN2/pM0 PPSRCC with 11 of 16 positive specimen lymph nodes. The tumor had evidence of both KRAS and TP53 mutations and expressed an MUC1+/MUC2-/MUC5AC+ immunophenotype. Medical oncology recommended a 6-month course of adjuvant modified-dose FOLFIRINOX therapy. Conclusion: This report highlights the need for further research into the pathogenesis of gastrointestinal signet ring cell carcinoma to identify and study therapeutic targets that can eventually be translated to PPSRCC treatment. Given the paucity of PPSRCC, adjuvant therapy candidates follow the current literature on more common pancreatic cancer subtypes to guide treatment.

Rapid Light-Dependent Degradation of Fluorescent Dyes in Formulated Serum-Free Media.

Chemically defined serum-free media are increasingly used as a tool to help standardize experiments by eliminating the potential variability contributed by pooled serum. These media are formulated for the culture and expansion of specific cell types, maintaining cell viability without the need for exogenous animal proteins. Formulated serum-free media could thus help improve viability and reduce variability during sample preparation for flow cytometry, yet a thorough analysis of how such media impact fluorochrome-Ab conjugates has not been performed. In this study, we expose fluorescent Ab-labeled cells or Ab capture beads to white light in the presence of various hematopoietic cell culture media and provide evidence that formulated serum-free media permit rapid light-initiated fluorescent dye degradation in a cell-independent manner. We observed fluorescence signal loss of several dyes, which included fluorescence spillover into adjacent detectors. Finally, photostability of Ab-fluorochrome conjugates in formulated serum-free media is partially restored in the presence of either serum or vitamin C, implicating reactive oxygen species in the observed signal loss. Thus, our data indicate that formulated serum-free media designed to standardize cell culture are not currently optimized for use with fluorochrome-Ab conjugates, and thus, extreme caution should be exercised when using these media in cytometric experiments.

Maintenance of CD4 T cell fitness through regulation of Foxo1.

Foxo transcription factors play an essential role in regulating specialized lymphocyte functions and in maintaining T cell quiescence. Here, we used a system in which Foxo1 transcription-factor activity, which is normally terminated upon cell activation, cannot be silenced, and we show that enforcing Foxo1 activity disrupts homeostasis of CD4 conventional and regulatory T cells. Despite limiting cell metabolism, continued Foxo1 activity is associated with increased activation of the kinase Akt and a cell-intrinsic proliferative advantage; however, survival and cell division are decreased in a competitive setting or growth-factor-limiting conditions. Via control of expression of the transcription factor Myc and the IL-2 receptor ß-chain, termination of Foxo1 signaling couples the increase in cellular cholesterol to biomass accumulation after activation, thereby facilitating immunological synapse formation and mTORC1 activity. These data reveal that Foxo1 regulates the integration of metabolic and mitogenic signals essential for T cell competitive fitness and the coordination of cell growth with cell division.

Control of Regulatory T Cell Migration, Function, and Homeostasis.

Foxp3(+) regulatory T cells (Tregs) are essential for preventing autoimmunity and uncontrolled inflammation, and they modulate immune responses during infection and the development of cancer. Accomplishing these tasks requires the widespread distribution of Tregs in both lymphoid and nonlymphoid tissues, and the selective recruitment of Tregs to different tissue sites has emerged as a key checkpoint that controls tissue inflammation in autoimmunity, infection, and cancer development, as well as in the context of allograft acceptance or rejection. Additionally, Tregs are functionally diverse, and it has become clear that some of this diversity segregates with Treg localization to particular tissue sites. In this article, I review the progress in understanding the mechanisms of Treg trafficking and discuss factors controlling their homeostatic maintenance and function in distinct tissue sites.

Hematopoietic and nonhematopoietic cells promote Type I interferon- and TLR7-dependent monocytosis during low-dose LCMV infection.

Release of inflammatory monocytes from the bone marrow (BM) into the blood is an important physiological response to infection, but the mechanisms regulating this phenomenon during viral infection are not completely defined. Here, we show that low-dose infection with lymphocytic choriomeningitis virus (LCMV) caused rapid, transient inflammatory monocytosis that required type I interferon (IFN) and Toll-like receptor (TLR) 7 signaling. Type I IFN and TLR7 signals were critical for induction of IFN-stimulated gene expression and CCR2 ligand upregulation in the BM microenvironment in response to LCMV infection. Experiments utilizing BM chimeric mice demonstrated that type I IFN and TLR7 signaling on either hematopoietic or nonhematopoietic cells was sufficient to initiate monocytosis in response to LCMV infection. BM plasmacytoid dendritic cells (pDCs) generated type I IFN directly ex vivo, suggesting that pDCs are a hematopoietic contributor of type I IFN in the BM early during LCMV infection. Overall, we describe novel roles for type I IFN and TLR7 signaling in nonhematopoietic cells and BM pDCs in directing IFN-stimulated gene and CCR2 ligand expression in the BM to initiate an increase in blood inflammatory monocytes during viral infection.

Organ-specific and memory treg cells: specificity, development, function, and maintenance.

Foxp3(+) regulatory T cells (Treg cells) are essential for establishing and maintaining self-tolerance, and also inhibit immune responses to innocuous environmental antigens. Imbalances and dysfunction in Treg cells lead to a variety of immune-mediated diseases, as deficits in Treg cell function contribute to the development autoimmune disease and pathological tissue damage, whereas overabundance of Treg cells can promote chronic infection and tumorigenesis. Recent studies have highlighted the fact that Treg cells themselves are a diverse collection of phenotypically and functionally specialized populations, with distinct developmental origins, antigen-specificities, tissue-tropisms, and homeostatic requirements. The signals directing the differentiation of these populations, their specificities and the mechanisms by which they combine to promote organ-specific and systemic tolerance, and how they embody the emerging property of regulatory memory are the focus of this review.

Regulatory T-cell homeostasis: steady-state maintenance and modulation during inflammation.

Regulatory T (Treg) cells play a vital role in the prevention of autoimmunity and the maintenance of self-tolerance, but these cells also have an active role in inhibiting immune responses during viral, bacterial, and parasitic infections. Although excessive Treg activity can lead to immunodeficiency, chronic infection, and cancer, too little Treg activity results in autoimmunity and immunopathology and impairs the quality of pathogen-specific responses. Recent studies have helped define the homeostatic mechanisms that support the diverse pool of peripheral Treg cells under steady-state conditions and delineate how the abundance and function of Treg cells changes during inflammation. These findings are highly relevant for developing effective strategies to manipulate Treg cell activity to promote allograft tolerance and treat autoimmunity, chronic infection, and cancer.