Single-Cell Profiling Unveils the Inflammatory Heterogeneity within Cutaneous Lesions of Bullous Pemphigoid.

Bullous pemphigoid (BP) is a subepidermal blistering skin disease with a complex pathogenesis involving various immune cells. However, the transcriptional features of these cells remain poorly defined. In this study, we constructed a comprehensive and single-cell resolution atlas of various immune cells within BP skin lesions through integrative single-cell analysis, flow cytometry, and multiplex immunohistochemistry. We observed prominent expansion and transcriptional changes in mast cells, macrophages, basophils, and neutrophils within BP lesions. Mast cells within the lesions adopted an active state and exhibited an elevated capacity for producing proinflammatory mediators. We observed an imbalance of macrophages/dendritic cells within BP lesions. Two macrophage subpopulations (NLRP3+ and C1q+) with distinct transcriptional profiles were identified and upregulated effector programs. T-peripheral helper-like T helper 2 cells were expanded in skin lesions and peripheral blood of patients with BP and were capable of promoting B-cell responses. In addition, we observed clonally expanded granzyme B-positive CD8+ T cells within BP lesions. Chemokine receptor mapping revealed the potential roles of macrophages and mast cells in recruiting pathogenic immune cells and underlying mechanisms within BP lesions. Thus, this study reveals key immune pathogenic features of BP lesions, thereby providing valuable insights for potential therapeutic interventions in this disease.

Integrative single-cell analysis reveals distinct adaptive immune signatures in the cutaneous lesions of pemphigus.

Pemphigus, an autoimmune bullous disease affecting the skin and mucosal membranes, is primarily driven by anti-desmoglein (Dsg) autoantibodies. However, the underlying immune mechanisms of this disease remain largely elusive. Here, we compile an unbiased atlas of immune cells in pemphigus cutaneous lesions at single-cell resolution. We reveal clonally expanded antibody-secreting cells (ASCs) that exhibit variable hypermutation and accumulation of IgG4 class-switching in their immunoglobulin genes. Importantly, pathogenic Dsg-specific ASCs are localized within pemphigus lesions and can evolve from both Dsg-autoreactive and non-binding precursors. We observe an altered distribution of CD4+ T cell subsets within pemphigus lesions, including an imbalance of Th17/Th2 cells. Significantly, we identify a distinct subpopulation of Th17 cells expressing CXCL13 and IL-21 within pemphigus lesions, implying its pivotal role in B cell recruitment and local production of autoantibodies. Furthermore, we characterize multiple clonally expanded CD8+ subpopulations, including effector GMZB+ and GMZK+ subsets with augmented cytotoxic activities, within pemphigus lesions. Chemokine-receptor mapping uncovers cell-type-specific signaling programs involved in the recruitment of T/B cells within pemphigus lesions. Our findings significantly contribute to advancing the understanding of the heterogeneous immune microenvironment and the pathogenesis of pemphigus cutaneous lesions, thereby providing valuable insights for potential therapeutic interventions in this disease.

Risk factors for macro vascular disease in type 2 diabetes mellitus patients with non-alcoholic fatty liver disease.

This study investigates the connection between abnormal liver enzymes and macro vascular disease in type 2 diabetes mellitus (T2DM) patients with non-alcoholic fatty liver disease (NAFLD). Clinical data from 276 T2DM patients with NAFLD were retrospectively examined and divided into two groups based on the presence or absence of macro vascular disease. Various biochemical markers were tested, including fasting C-peptide, total bilirubin (TBil), total protein (TP), albumin (Alb), C-reactive protein (CRP) and the insulin resistance index (HOMA-IR). The study found no significant differences in demographic variables between the two groups. However, patients with macro vascular disease had significantly higher levels of fasting C-peptide, CRP, HOMA-IR, TBil, TP, Alb and certain blood lipid markers. The study concludes that in T2DM patients with NAFLD, increased blood lipids, liver function and inflammatory factors are risk factors for macro vascular disease, suggesting the importance of clinical management to lower macro vascular disease prevalence.

A pilot study of lymphodepletion intensity for peripheral blood mononuclear cell-derived neoantigen-specific CD8 + T cell therapy in patients with advanced solid tumors.

Currently, the optimal lymphodepletion intensity for peripheral blood mononuclear cell-derived neoantigen-specific CD8 + T cell (Neo-T) therapy has yet to be determined. We report a single-arm, open-label and non-randomized phase 1 study (NCT02959905) of Neo-T therapy with lymphodepletion at various dose intensity in patients with locally advanced or metastatic solid tumors that are refractory to standard therapies. The primary end point is safety and the secondary end points are disease control rate (DCR), progression-free survival (PFS), overall survival (OS). Results show that the treatment is well tolerated with lymphopenia being the most common adverse event in the highest-intensity lymphodepletion groups. Neo-T infusion-related adverse events are only grade 1-2 in the no lymphodepletion group. The median PFS is 7.1 months (95% CI:3.7-9.8), the median OS is 16.8 months (95% CI: 11.9-31.7), and the DCR is 66.7% (6/9) among all groups. Three patients achieve partial response, two of them are in the no lymphodepletion group. In the group without lymphodepletion pretreatment, one patient refractory to prior anti-PD1 therapy shows partial response to Neo-T therapy. Neoantigen specific TCRs are examined in two patients and show delayed expansion after lymphodepletion treatment. In summary, Neo-T therapy without lymphodepletion could be a safe and promising regimen for advanced solid tumors.

Luman regulates the activity of the LHCGR promoter.

Testosterone in male mammals is mainly secreted by testicular Leydig cells, and its secretion process is regulated by the hypothalamic-pituitary-gonadal axis. After receiving the luteinizing hormone (LH) stimulus signal, the lutropin/choriogonadotropin receptor (LHCGR) on the Leydig cell membrane transfers the signal into the cell and finally increases the secretion of testosterone by upregulating the expression of steroid hormone synthase. In previous experiments, we found that interfering with the expression of the Luman protein can significantly increase testosterone secretion in MLTC-1 cells. In this experiment, we found that knockdown of Luman in MLTC-1 cells significantly increased the concentration of cAMP and upregulated the expression of AC and LHCGR. Moreover, an analysis of the activity of the LHCGR promoter by a dual luciferase reporter system showed that knockdown of Luman increased the activity of the LHCGR promoter. Therefore, we believe that knockdown of Luman increased the activity of the LHCGR promoter and upregulated the expression of LHCGR, thereby increasing the concentration of intracellular cAMP and ultimately leading to an increase of testosterone secretion by MLTC-1 cells.

Griseofulvin Radiosensitizes Non-Small Cell Lung Cancer Cells and Activates cGAS.

Extra copies of centrosomes are frequently observed in cancer cells. To survive and proliferate, cancer cells have developed strategies to cluster extra-centrosomes to form bipolar mitotic spindles. The aim of this study was to investigate whether centrosome clustering (CC) inhibition (CCi) would preferentially radiosensitize non-small cell lung cancer (NSCLC). Griseofulvin (GF; FDA-approved treatment) inhibits CC, and combined with radiation treatment (RT), resulted in a significant increase in the number of NSCLC cells with multipolar spindles, and decreased cell viability and colony formation ability in vitro. In vivo, GF treatment was well tolerated by mice, and the combined therapy of GF and radiation treatment resulted in a significant tumor growth delay. Both GF and radiation treatment also induced the generation of micronuclei (MN) in vitro and in vivo and activated cyclic GMP-AMP synthase (cGAS) in NSCLC cells. A significant increase in downstream cGAS-STING pathway activation was seen after combination treatment in A549 radioresistant cells that was dependent on cGAS. In conclusion, GF increased radiation treatment efficacy in lung cancer preclinical models in vitro and in vivo. This effect may be associated with the generation of MN and the activation of cGAS. These data suggest that the combination therapy of CCi, radiation treatment, and immunotherapy could be a promising strategy to treat NSCLC.

Toxoplasma gondii induces MLTC-1 apoptosis via ERS pathway.

Toxoplasma gondii (T. gondii) is a serious intracellular parasite and mammalian infection can damage the reproductive system and lead to apoptosis of Murine Leydig tumor cells (MLTC-1); however, the mechanism is unclear. The testis Leydig cell is the main testosterone synthesis cell in male mammals. We studied the mechanism of T. gondii infection on Leydig cell apoptosis in vitro. MLTC-1 were divided into control and experimental groups. Experiment group cells and tachyzoites were co-cultured, in a 1:20 ratio, for 3, 6, 9, and 12 h. T. gondii entered the cells and caused lesions at 12 h. Flow cytometry showed that the apoptosis rate of the experiment group increased with time and was significantly higher (P < 0.05) than the control group. RT-qPCR and western blot demonstrated that the expression of P53, Caspase-3, and Bax were significantly increased at 12 h (P < 0.05). Bcl-2 expression was significantly increased at 12 h (P < 0.05). The ER stress (ERS) pathway was important in cell apoptosis. RT-qPCR and western blot showed that the expression of CHOP was significantly increased at 12 h (P < 0.05). These data indicate that T. gondii induced MLTC-1 cell apoptosis may occur via the ERS pathway.

CYP4 subfamily V member 2 (CYP4V2) polymorphisms were associated with ischemic stroke in Chinese Han population.

BACKGROUND: CYP4 subfamily V member 2 (CYP4V2) polymorphisms are related to venous thromboembolism. However, the influence of CYP4V2 polymorphisms on the susceptibility to ischemic stroke (IS) remains undetermined. METHODS: We selected and genotyped five polymorphisms of CYP4V2 in 575 cases and 575 controls to test whether CYP4V2 variants were associated with the risk for IS in a Chinese Han population. Genotyping of CYP4V2 polymorphisms was performed using the Agena MassARRAY platform. Logistic regression analysis was used to assess the association between CYP4V2 polymorphisms and IS risk by calculating odds ratios (ORs) and 95% confidence interval (CI). False-positive report probability analysis was applied to assess the noteworthy relationship of the significant findings. RESULTS: CYP4V2 rs1398007 might be a risk factor for IS (OR = 1.34, 95% CI 1.05-1.71, p = 0.009). Specially, confounding factors (age, gender, smoking and drinking status) might affect the relationship between rs1398007 and IS susceptibility. Moreover, rs1053094 and rs56413992 were associated with IS risk in males. Multifactor dimensionality reduction analysis showed the combination of rs13146272 and rs3736455 had the strongest interaction effect (information gain value of 0.40%). Furthermore, genotypes of rs1398007 (p = 0.006) and rs1053094 (p = 0.044) were associated with the levels of high-density lipoprotein cholesterol (HDL-C) among healthy controls. CONCLUSION: Our results first provided evidence that CYP4V2 rs1398007 might be a risk factor for IS, which provides instructive clues for studying the mechanisms of CYP4V2 to the pathogenesis of IS.

Nanoengineered, magnetically guided drug delivery for tumors: A developmental study.

Fighting against tumors is an ongoing challenge in both medicinal and clinical applications. In recent years, chemotherapy, along with surgery, has significantly improved the situation to prolong life expectancy. Theoretically, and regardless of dosage, we now have drugs that are strong enough to eliminate most tumors. However, due to uncontrollable drug distribution in the body, it is difficult to increase treatment efficiency by simply increasing dosages. For this reason, the need for a drug delivery system that can release "bombs" at the target organ or tissue as precisely as possible has elicited the interest of researchers. In our work, we design and construct a silica-based nanocomposite to meet the above demand. The novel nanocomposite drug carrier can be guided to target tumors or tissue by a magnetic field, since it is constructed with superparamagnetic Fe3O4 as the core. The Fe3O4 core is clad in a mesoporous silica molecular sieve MCM-41 (represented as MS, in this article), since this MS has enormous ordered hexagonal caves providing sufficient space to hold the drug molecules. To modify the magnetically guided carriers so that they become both magnetically guided and light-responsive, benzophenone hydrazone is coupled into the molecular sieve tunnel. When a certain wavelength of light is imposed on the gating molecules, C=N double bonds vibrate and swing, causing the cavity that holds the drug molecules to change size and open the tunnels. Hence, the nanocomposite has the ability to release loaded drugs with light irradiation. The structure, loading abilities, and the size of the nanocomposite are inspected with a scanning electron microscope, a transmission electron microscope, thermogravimetry analysis, N2 adsorption/desorption, and dynamic light scattering The biocompatibility and in vitro drug molecule controlled release are tested with an SMMC-7721 cell line.

Automatic whole blood cell analysis from blood smear using label-free multi-modal imaging with deep neural networks.

Whole blood cell analysis is widely used in medical applications since its results are indicators for diagnosing a series of diseases. In this work, we report automatic whole blood cell analysis from blood smear using label-free multi-modal imaging with deep neural networks. First, a commercial microscope equipped with our developed Phase Real-time Microscope Camera (PhaseRMiC) obtains both bright-field and quantitative phase images. Then, these images are automatically processed by our designed blood smear recognition networks (BSRNet) that recognize erythrocytes, leukocytes and platelets. Finally, blood cell parameters such as counts, shapes and volumes can be extracted according to both quantitative phase images and automatic recognition results. The proposed whole blood cell analysis technique provides high-quality blood cell images and supports accurate blood cell recognition and analysis. Moreover, this approach requires rather simple and cost-effective setups as well as easy and rapid sample preparations. Therefore, this proposed method has great potential application in blood testing aiming at disease diagnostics.

[Preparation and characterization of near-infrared responsive sinomenine hydrochloride reservoir microneedles].

The present study designed and prepared near-infrared responsive sinomenine hydrochloride(SIN) reservoir microneedles and evaluated the feasibility of this type of microneedles in increasing the drug loading and transdermal absorption by characterizing their mechanical properties and in vitro release characteristics.SIN was selected as the model drug, and methoxy poly(ethylene glycol) poly(caprolactone)(mPEG-PCL) copolymers and indocyanine green(ICG) were employed as amphiphilic block copolymers and light inductor to prepare near-infrared responsive nanoparticles.Based on the preparation principle of bubble microneedles, near-infrared responsive SIN reservoir microneedles were designed and prepared.The features of the near-infrared responsive SIN reservoir microneedles were characterized by measuring the morphology, length, mechanical properties, and skin penetration of microneedles.Meanwhile, the drug release performance of reservoir microneedles was evaluated by in vitro release assay.The results showed that the prepared SIN microneedles were conical, with an exposed tip height of about 650 µm.Each needle could load about 0.5 mg of drugs per square centi-meter, and this type of microneedle showed good mechanical properties and performance in skin penetration.The results of the in vitro release assay showed that the 24 h cumulative release per unit area and release rate of the microneedle were 825.61 µg·cm~(-2) and 74.3%, respectively, which indicated that its release kinetics was in line with the first-order kinetic model.This study preliminarily proved that the reservoir microneedle could effectively increase the drug loading with good mechanical properties and release perfor-mance.

Long-Term Outcomes and Genetic Predictors of Response to Metastasis-Directed Therapy Versus Observation in Oligometastatic Prostate Cancer: Analysis of STOMP and ORIOLE Trials.

Clinical trials frequently include multiple end points that mature at different times. The initial report, typically based on the primary end point, may be published when key planned co-primary or secondary analyses are not yet available. Clinical Trial Updates provide an opportunity to disseminate additional results from studies, published in JCO or elsewhere, for which the primary end point has already been reported.The initial STOMP and ORIOLE trial reports suggested that metastasis-directed therapy (MDT) in oligometastatic castration-sensitive prostate cancer (omCSPC) was associated with improved treatment outcomes. Here, we present long-term outcomes of MDT in omCSPC by pooling STOMP and ORIOLE and assess the ability of a high-risk mutational signature to risk stratify outcomes after MDT. The primary end point was progression-free survival (PFS) calculated using the Kaplan-Meier method. High-risk mutations were defined as pathogenic somatic mutations within ATM, BRCA1/2, Rb1, or TP53. The median follow-up for the whole group was 52.5 months. Median PFS was prolonged with MDT compared with observation (pooled hazard ratio [HR], 0.44; 95% CI, 0.29 to 0.66; P value < .001), with the largest benefit of MDT in patients with a high-risk mutation (HR high-risk, 0.05; HR no high-risk, 0.42; P value for interaction: .12). Within the MDT cohort, the PFS was 13.4 months in those without a high-risk mutation, compared with 7.5 months in those with a high-risk mutation (HR, 0.53; 95% CI, 0.25 to 1.11; P = .09). Long-term outcomes from the only two randomized trials in omCSPC suggest a sustained clinical benefit to MDT over observation. A high-risk mutational signature may help risk stratify treatment outcomes after MDT.

Durable complete response to neoantigen-loaded dendritic-cell vaccine following anti-PD-1 therapy in metastatic gastric cancer.

ABSRACT: Neoantigens are ideal targets for dendritic cell (DC) vaccines. So far, only a few neoantigen-based DC vaccines have been investigated in clinical trials. Here, we reported a case of a patient with metastatic gastric cancer who received personalized neoantigen-loaded monocyte-derived dendritic cell (Neo-MoDC) vaccines followed by combination therapy of the Neo-MoDC and immune checkpoint inhibitor (ICI). The patient developed T cell responses against neoantigens after receiving the Neo-MoDC vaccine alone. The following combination therapy triggered a stronger immune response and mediated complete regression of all tumors for over 25 months till October, 2021. Peripheral blood mononuclear cells recognized seven of the eight vaccine neoantigens. And the frequency of neoantigen-specific T cell clones increased obviously after vaccination. Overall, this report describing a complete tumor regression in a gastric cancer patient mediated by Neo-MoDC vaccine in combination with ICI, and suggesting a promising treatment for patients with metastatic gastric cancer.

Target animal safety evaluation of a novel topical combination of esafoxolaner, eprinomectin and praziquantel for cats.

The safety profile of NexGard® Combo, a novel topical product for cats combining esafoxolaner, eprinomectin and praziquantel, for the treatment and prevention of internal and external parasites, was evaluated in kittens, in two margin-of-safety studies (Studies #1 and #2), and in an oral tolerance study (Study #3). In the margin of safety studies, kittens were dosed several times topically with multiples of the maximum exposure dose (1×): in Study #1, 3× and 5× doses four times at 2-week intervals; in Study #2, 1×, 3× and 5× doses six times at 4-week intervals. In Study #3, kittens were dosed orally once with a 1× dose. Furthermore, in Study #1, another group of kittens was dosed topically twice at a 4-week interval with a formulation of esafoxolaner as the sole active ingredient dosed at 23×. Physical examinations and clinical pathology analyses were performed throughout the studies, followed by necropsy and detailed histopathological evaluation in Studies #1 and #2. No significant treatment related effects were observed in the three studies, except for one occurrence of reversible neurological signs attributed to eprinomectin in one cat after the third 5× dose in Study #2, with clinical signs observed nine hours after dosing, pronounced for a few hours, significantly improved the next day, and absent 2 days after dosing. In conclusion, NexGard® Combo was demonstrated safe in kittens following repeated topical administrations and following oral ingestion, and very high topical doses of esafoxolaner were well tolerated.

TITLE: Évaluation de la sécurité des animaux cibles d'une nouvelle combinaison topique d'esafoxolaner, d'éprinomectine et de praziquantel pour les chats. ABSTRACT: Le profil de sécurité de NexGard® Combo, un nouveau produit topique destiné aux chats associant l'esafoxolaner, l'éprinomectine et le praziquantel, pour le traitement et la prévention des parasites internes et externes, a été évalué chez les chatons, dans deux études de marge de sécurité (études n° 1 et n° 2) et dans une étude de tolérance orale (étude n° 3). Dans les études de marge de sécurité, les chatons ont reçu plusieurs doses topiques avec des multiples de la dose maximale d'exposition (1×) : dans l'étude n° 1, des doses 3× et 5×, quatre fois, à des intervalles de 2 semaines ; dans l'étude n° 2, des doses 1×, 3× et 5×, six fois, à des intervalles de 4 semaines. Dans l'étude n° 3, les chatons ont reçu une dose orale une fois avec une dose 1×. De plus, dans l'étude n° 1, un autre groupe de chatons a reçu une dose topique deux fois à 4 semaines d'intervalle avec une formulation d'esafoxolaner comme seul ingrédient actif dosé à 23×. Des examens physiques et des analyses de pathologie clinique ont été effectués tout au long des études, suivis d'une autopsie et d'une évaluation histopathologique détaillée dans les études n° 1 et n° 2. Aucun effet significatif lié au traitement n'a été observé dans les trois études, à l'exception d'une occurrence de signes neurologiques réversibles attribués à l'éprinomectine chez un chat après la troisième dose 5× dans l'étude n° 2, avec des signes cliniques observés neuf heures après l'administration, prononcés pour quelques heures, considérablement améliorée le lendemain et absent 2 jours après l'administration. En conclusion, NexGard® Combo s'est avéré sûr chez les chatons après des administrations topiques répétées et après une ingestion orale, et des doses topiques très élevées d'esafoxolaner ont été bien tolérées.

The hexosamine biosynthetic pathway and cancer: Current knowledge and future therapeutic strategies.

The hexosamine biosynthetic pathway (HBP) is a glucose metabolism pathway that results in the synthesis of a nucleotide sugar UDP-GlcNAc, which is subsequently used for the post-translational modification (O-GlcNAcylation) of intracellular proteins that regulate nutrient sensing and stress response. The HBP is carried out by a series of enzymes, many of which have been extensively implicated in cancer pathophysiology. Increasing evidence suggests that elevated activation of the HBP may act as a cancer biomarker. Inhibition of HBP enzymes could suppress tumor cell growth, modulate the immune response, reduce resistance, and sensitize tumor cells to conventional cancer therapy. Therefore, targeting the HBP may serve as a novel strategy for treating cancer patients. Here, we review the current findings on the significance of HBP enzymes in various cancers and discuss future approaches for exploiting HBP inhibition for cancer treatment.

Time-course single-cell RNA sequencing reveals transcriptional dynamics and heterogeneity of limbal stem cells derived from human pluripotent stem cells.

BACKGROUND: Human pluripotent stem cell-derived limbal stem cells (hPSC-derived LSCs) provide a promising cell source for corneal transplants and ocular surface reconstruction. Although recent efforts in the identification of LSC markers have increased our understanding of the biology of LSCs, much more remains to be characterized in the developmental origin, cell fate determination, and identity of human LSCs. The lack of knowledge hindered the establishment of efficient differentiation protocols for generating hPSC-derived LSCs and held back their clinical application. RESULTS: Here, we performed a time-course single-cell RNA-seq to investigate transcriptional heterogeneity and expression changes of LSCs derived from human embryonic stem cells (hESCs). Based on current protocol, expression heterogeneity of reported LSC markers were identified in subpopulations of differentiated cells. EMT has been shown to occur during differentiation process, which could possibly result in generation of untargeted cells. Pseudotime trajectory analysis revealed transcriptional changes and signatures of commitment of hESCs-derived LSCs and their progeny-the transit amplifying cells. CONCLUSION: Single-cell RNA-seq revealed time-course expression changes and significant transcriptional heterogeneity during hESC-derived LSC differentiation in vitro. Our results demonstrated candidate developmental trajectory and several new candidate markers for LSCs, which could facilitate elucidating the identity and developmental origin of human LSCs in vivo.

Longitudinal Changes in Skin Microbiome Associated with Change in Skin Status in Patients with Psoriasis.

The aim of this study was to identify key microbes associated with change in skin status (lesional vs normal). Longitudinal changes in the skin microbiome between patients with psoriasis and healthy family controls living in the same household were studied using whole genome metagenomic shotgun sequencing at 4 time-points. There were significant changes in abundance of the pathogen Campylobacter jejuni and its higher taxonomic levels when the skin status of patients with psoriasis changed. There were significant longitudinal variations in alpha diveristy (p < 0.001) and beta diversity (p < 0.05) of the skin microbiome in patients with psoriasis, but not in the healthy control group, which indicated composition of skin microbiome in patients with psoriasis was different from healthy control and was dynamically less stable. This study will serve as the basis for future temporal studies of the skin microbiome and probiotic therapeutics.

Mapping disparities in homicide trends across Brazil: 2000-2014.

BACKGROUND: Homicides are a major problem in Brazil. Drugs and arms trafficking, and land conflicts are three of the many factors driving homicide rates in Brazil. Understanding long-term spatiotemporal trends and social structural factors associated with homicides in Brazil would be useful for designing policies aimed at reducing homicide rates. METHODS: We obtained data from 2000 to 2014 from the Brazil Ministry of Health (MOH) Mortality Information System and sociodemographic data from the Brazil Institute of Geography and Statistics (IBGE). First, we quantified the rate of change in homicides at the municipality and state levels. Second, we used principal component regression and k-medoids clustering to examine differences in temporal trends across municipalities. Lastly, we used Bayesian hierarchical space-time models to describe spatio-temporal patterns and to assess the contribution of structural factors. RESULTS: There were significant variations in homicide rates across states and municipalities. We noted the largest decrease in homicide rates in the western and southeastern states of Sao Paulo, Rio de Janeiro and Espirito Santo, which coincided with an increase in homicide rates in the northeastern states of Ceará, Alagoas, Paraiba, Rio Grande Norte, Sergipe and Bahia during the fifteen-year period. The decrease in homicides in municipalities with populations of at least 250,000 coincided with an increase in municipalities with 25,000 people or less. Structural factors that predicted municipality-level homicide rates included crude domestic product, urbanization, border with neighboring countries and proportion of population aged fifteen to twenty-nine. CONCLUSIONS: Our findings support both a dissemination hypothesis and an interiorization hypothesis. These findings should be considered when designing interventions to curb homicide rates.