Search Results (1,832)

Background: Inflammatory bowel disease (IBD), including Crohn’s disease (CD) and ulcerative colitis (UC), is a group of chronic gastrointestinal (GI) diseases with complex and multifactorial pathophysiology. The global prevalence of IBD is increasing, highlighting the need to develop new therapeutic approaches. Plant-derived extracts have recently gained prominence due to their anti-inflammatory properties. Methods: This study investigated: apricot leaves (ALE), peach leaves (PLE), black chokeberry fruit (BCHE), rosehip seeds (RSE), passion fruit seeds (PSE), and linden blossom (LBE) (all at the concentration 10–200 µg/mL) in RAW 264.7 mouse macrophages. Cytotoxicity was assessed using the neutral red uptake (NRU) assay, and anti-inflammatory activity was assessed using Griess assay in the lipopolysaccharide (LPS)-induced inflammation. Additionally, the mRNA expression levels of key inflammatory genes (interferon-γ (Ifn-γ), interleukin-6 (Il-6), nitric oxide synthase (Nos2), and tumor necrosis factor-α (Tnf-α)) were analyzed. Results: ALE and PLE exhibited minimal cytotoxicity and strong anti-inflammatory activity, reducing the expression of all analyzed genes. PSE demonstrated anti-inflammatory activity in the Griess assay, but did not alter mRNA expression. Conclusions: ALE and PLE exhibit promising anti-inflammatory properties and warrant further preclinical investigation. Comprehensive in vitro and in vivo studies are necessary to confirm these results. Full article

Skin wound healing is a complex and highly coordinated biological process involving inflammation, cell migration and proliferation, angiogenesis, extracellular matrix remodeling and tissue regeneration. While the zebrafish-derived antimicrobial peptide AP10W exhibits broad-spectrum antimicrobial properties, its potential in tissue repair remains unexplored. Herein, we demonstrate that AP10W possesses intrinsic wound-healing capabilities, providing a preliminary investigation into its underlying mechanisms. In this study, using a full-thickness murine wound model and in vitro cell-based assays to evaluate the effects of AP10W on fibroblasts, keratinocytes, endothelial cells, and macrophages, we found that AP10W significantly promoted fibroblast and keratinocyte migration and proliferation. Furthermore, it enhanced endothelial cell motility, survival, and tube formation, while upregulating key pro-angiogenic factors, including Vascular endothelial growth factor A (VEGFA), Platelet-derived growth factor (PDGF), and Fibroblast growth factor 2 (FGF2). Concurrently, AP10W drove macrophage reprogramming from a pro-inflammatory M1 phenotype toward a pro-healing M2 state, as evidenced by upregulated Arginase-1 (Arg-1) and Interleukin-10 (Il-10) expression, alongside attenuated Tumor necrosis factor-alpha (Tnf-α), Interleukin-1 beta (Il-1β), Interleukin-6 (Il-6), and Inducible nitric oxide synthase (iNOS) levels. In vivo, the topical application of AP10W accelerated wound closure, markedly improving re-epithelialization, collagen deposition, vascularization, tissue perfusion, and skin appendage regeneration. Preliminary mechanistic studies revealed that AP10W increased YAP expression and nuclear translocation; conversely, the pharmacological inhibition of YAP significantly abrogated these pro-healing effects. Collectively, our findings identify AP10W as a multifunctional peptide with potent wound-healing properties, positioning it as a promising candidate for wound therapy. Full article

Background: Hemolysis and eryptosis of red blood cells (RBCs) contribute to chemotherapy-induced anemia, a marker of poor prognosis. Geraniol (GER) is an anticancer acyclic monoterpene alcohol found in several plant extracts, but a dearth of evidence exists regarding the potential toxicity of GER in RBCs. Methods: Hemolysis and eryptosis were evaluated using colorimetric and fluorescence-assisted cell-sorting methods, respectively. Phosphatidylserine (PS) exposure, loss of volume, and intracellular Ca²⁺ were measured by annexin-V-FITC, forward scatter (FSC), and Fluo4/AM staining. Cells were also examined by electron microscopy to identify membrane blebbing and by the Westergren method to assess erythrocyte sedimentation rate (ESR). Results: In a concentration-responsive fashion, GER induced hemolysis and PS exposure in addition to elevated ESR. GER-induced cell death was characterized by reduced FSC, membrane blebs, and increased Fluo4 fluorescence. Ca²⁺ deprivation prevented eryptosis, whereas concurrent Ca²⁺ deprivation and membrane depolarization prevented hemolysis, eryptosis, and cell shrinkage. Furthermore, whereas inhibition of cyclooxygenase (COX), casein kinase 1α (CK1α), or Rac1 GTPase ameliorated eryptosis and hemolysis, the latter was only prevented by caspase, nitric oxide synthase, or serine palmitoyltransferase inhibition. Exclusive reversal of eryptosis was rather only achieved in the presence of either caffeine or adenine. Conclusions: GER is a novel stimulator of hemolysis and eryptosis, an activity mediated through membrane hyperpolarization following Ca²⁺ elevation. In parallel, GER seems to involve the COX/CK1α/Rac1 GTPase axis to trigger its cytotoxic effects. Targeting the identified mechanisms in combination therapy may attenuate the off-target toxicity of GER and enhance its specificity to cancer cells. Full article

Background/Objectives: Clinical application of Doxorubicin (Doxo) is limited by cardiotoxicity, a process strongly associated with an interplay between oxidative stress and inflammatory signaling, particularly Nuclear Factor kappa-light-chain-enhancer of activated B cells (NF-κB) activation and Nucleotide oligomerization domain-like receptor family, pyrin domain containing 3 (NLRP3) inflammasome engagement. Identifying strategies capable of mitigating these interconnected pathways is of critical importance in cardio-oncology. Simvastatin (SIM) is a promising option since it modulates oxidative stress, inflammation, and cell death through its pleiotropic effects, so this study aimed to evaluate whether SIM attenuates Doxo-induced inflammatory responses. Methods: Human Cardiomyocyte (HCM) cells were pre-treated with SIM (10 µM) for 4 h and then co-exposed to SIM and Doxo (1 µM) for 20 h. Cytofluorimetric analysis was used to evaluate inducible nitric oxide synthase (iNOS), Connexin 43 (Cx43), and Cx43 phosphorylated at Serine 368 (p^S368Cx43) levels. Real-time qPCR was performed to evaluate iNOS gene expression, while Nitric oxide (NO) release was evaluated by spectrophotometric analysis. Interleukin (IL)-1β, IL-18, IL-6, tumor necrosis factor alpha (TNF-α) production, and NLRP3 levels were evaluated by means of ELISA assay. Expression levels of inhibitor of nuclear factor kappa B alpha (IκB-α), Caspase-1, and Gasdermin D (GSDMD) were evaluated by Western Blot analysis. Nuclear translocation of NF-κB was evaluated by immunofluorescence assay. Results: In our experimental model, SIM significantly (p < 0.01) reduced Doxo-induced nitrite release, as well as iNOS gene expression (p < 0.05) and protein levels (p < 0.01). SIM also markedly attenuated Doxo-induced NF-κB signaling, pro-inflammatory cytokines production (TNF-α and IL-6, p < 0.01), and inflammosome-related responses (cleaved caspase-1, IL-1β, N-terminal domain of GSDMD), and NLRP3 expression p < 0.05). Additionally, SIM significantly attenuated the overexpression of Cx43 and its phosphorylated form (p^S368Cx43), which are responsible for impairing intercellular communication and electrical coupling in cardiomyocytes and contribute to arrhythmias and conduction abnormalities characteristic of acute Doxo-induced cardiotoxicity. Conclusions: Overall, these findings demonstrate that SIM exerts a multifaceted cardioprotective effect against Doxo-induced injury, thereby targeting interconnected inflammatory and pro-arrhythmic pathways implicated in Doxo cardiotoxicity. Full article

Phosphatidylinositol-3-kinases (PI3Ks) are heterodimers of catalytic and regulatory subunits that regulate cell metabolism, activation, and survival. PI3K, particularly the p110α catalytic isoform, is frequently mutated in cancer, and highly specific inhibitors such as alpelisib are currently used in oncology and in PIK3CA-related overgrowth disorders. Given the relevance of macrophages in anti-tumor immunity, we examined the impact of alpelisib on murine monocytes’ intracellular signaling and on in vitro differentiation, polarization, and effector functions of macrophages. Real-time qPCR (RT-qPCR) showed comparable relative expression of PI3K isoforms (p110α, p110β, p110δ, p110γ and p85) in bone marrow monocytes and in macrophages differentiated with macrophage colony-stimulating factor (M-CSF) or granulocyte-macrophage colony-stimulating factor (GM-CSF). However, alpelisib increased p110α, p110β, and p85 relative gene expression (2–3-fold) during M-CSF-dependent differentiation. Functionally, alpelisib-treated M-CSF macrophages displayed enhanced interleukin (IL)-6 and tumor necrosis factor alpha (TNF-α) secretion and reduced IL-10 production after lipopolysaccharide (LPS) plus interferon gamma (IFN-γ) or LPS stimulation. In contrast, GM-CSF macrophages differentiated with alpelisib secreted lower levels of IL-6 and TNF-α and reduced inducible nitric oxide synthase (iNOS) and arginase-1 (Arg-1) gene expression. Additionally, cytokine profiles (IL-2, IL-6, IFN-γ and IL-10) were altered when alpelisib-treated macrophages were cocultured with CD4⁺ T cells under either antigen-specific or polyclonal activation conditions, indicating that the inhibitor modifies both differentiation and subsequent effector interactions of the macrophages. Thus, alpelisib induces lasting effects on macrophage differentiation and function, with potential implications in tumor-associated macrophages that develop under M-CSF or GM-CSF-rich cancer microenvironments. Full article

Background/Objectives: The ACE2/Ang-(1–7)/Mas receptor axis is a protective, counter-regulatory component of the RAAS that opposes Ang II/AT₁R-mediated vasoconstriction. The present study evaluated the pharmacological effects of Ang-(1–7) in the rat inferior vena cava (IVC), a venous capacitance vessel involved in the regulation of venous return and cardiac preload. We hypothesized that Ang-(1–7) exerts anti-contractile effects in the rat inferior vena cava through activation of potassium channel-dependent mechanisms in venous smooth muscle. Methods: Isolated IVC rings from Wistar rats were studied using organ bath assays. Ang-(1–7) effects were assessed on pre-constriction induced by angiotensin II (Ang II), phenylephrine (PE), endothelin-1 (ET-1), and thromboxane A₂ analog (U46619). Responses were recorded and quantified. Mechanistic involvement of nitric oxide (NO), prostaglandins, soluble guanylate cyclase (sGC), and K⁺ channels was evaluated using specific pharmacological inhibitors. Results: Ang-(1–7) attenuated Ang II-induced contraction. The effect was markedly reduced by tetraethylammonium (TEA), indicating a predominant role of potassium channel-dependent mechanisms in venous smooth muscle. In contrast, inhibition of nitric oxide synthase, soluble guanylate cyclase, or cyclooxygenase had minimal influence. Ang-(1–7) also produced concentration-dependent relaxation in PE-, ET-1-, and U46619-precontracted vessels, demonstrating agonist-dependent anti-contractile activity. Conclusions: Ang-(1–7) exerts significant anti-contractile effects in the rat inferior vena cava primarily through activation of TEA-sensitive K⁺ channels in venous smooth muscle. These findings demonstrate functional activity of the ACE2/Ang-(1–7)/Mas axis in a major venous capacitance vessel and provide mechanistic insight into Ang-(1–7)-mediated modulation of venous tone, supporting further investigation in in vivo models. Full article

Plant polysaccharides can exert immunomodulatory activities. In this study we provided chemical characterization of wheat cell culture-derived polysaccharides (WCCPS) and assessed their capacity to modulate inflammatory responses in mouse macrophages. The total sample (T-010) contained arabinogalactans, arabinans, glucans and xyloglucans. Fractionation by anion-exchange chromatography rendered a bound acidic fraction (B-010) and an unbound neutral fraction (UB-010). The B-010 fraction was enriched in arabinogalactans and arabinans, with some galactans, homogalacturonans, and arabinoxylans. The neutral UB-010 fraction was composed of glucans and xyloglucans. None of the WCCPS preparations triggered cytokine production on their own, but each potentiated different macrophage responses to bacterial lipopolysaccharide (LPS). The total WCCPS in T-010 increased LPS-induced tumor necrosis factor-alpha (TNF-α) and interleukin (IL)-6 secretion, whereas the acidic arabinogalactan-rich fraction B-010 boosted IL-6 release and selectively upregulated nitric oxide synthase 2 (Nos2) and cholesterol 25-hydroxylase (Ch25h) expression in response to LPS. In contrast, the neutral UB-010 fraction enhanced IL-6 levels and induced Nos2 expression without altering Ch25h expression. These results suggest that WCCPS can modulate distinct aspects of the inflammatory response, with their effects shaped by their composition and structural features. Future research will focus on elucidating the molecular mechanisms underlying the immunomodulatory activity of WCCPS. Full article

Background/Objectives: Body Protection Compound-157 (BPC 157) is a stable gastric pentadecapeptide with cytoprotective, pro-angiogenic, and nitric oxide (NO)-modulating properties that has gained increasing attention for its therapeutic potential. Although vasodilatory effects have been demonstrated in animal models, functional evidence in human arterial tissue remains limited. This study investigated the effects of BPC 157 on vascular tone in human internal mammary artery (IMA) rings and evaluated the contribution of endothelial NO signaling. Methods: Residual IMA segments obtained from elective coronary artery bypass graft surgeries (n = 12) were dissected into endothelium-intact and endothelium-denuded rings. Following equilibration, the rings were challenged by phenylephrine (PheE; 3 × 10⁻⁶ M) to induce contraction. Cumulative concentration–response curves of BPC 157 (0.01–1 mg/mL) for five consecutive doses were constructed. The involvement of NO was assessed by BPC 157 dose–response curves in the nitric oxide synthase (NOS) inhibitor Nω-nitro-L-arginine methyl ester (L-NAME; 10⁻⁶ M) pre-incubated rings. Maximum force of contraction, area under the curve, maximum response (Emax), and negative logarithm of the half-maximal effective concentration (pEC50) values were analyzed. Results: BPC 157 produced a concentration-dependent reduction in PheE-induced contraction in both groups, with significantly greater relaxation in endothelium-intact rings (p < 0.05). L-NAME increased contractile responsiveness in intact rings and attenuated BPC 157-induced relaxation. Under NOS inhibition, differences between groups progressively diminished and concentration–response curves converged at higher concentrations. Emax analysis demonstrated that endothelial integrity markedly enhanced maximal vasorelaxation, whereas this advantage was largely abolished after NOS inhibition. Conclusions: BPC 157 induces concentration-dependent vasorelaxation in human arterial tissue, predominantly mediated via an endothelium-dependent NO pathway. Endothelial integrity primarily enhances maximal efficacy, while residual effects indicate additional mechanisms. These findings provide early mechanistic evidence for the vascular activity of BPC 157, although further molecular and in vivo studies are required to clarify its clinical relevance. Full article

Nitric oxide (NO) plays an important role in neuronal communication, synaptic plasticity and vascular regulation. Due to its important function in neuronal homeostasis, NO imbalance is associated with neurodegeneration. Specifically, in Alzheimer’s disease (AD), amyotrophic lateral sclerosis (ALS), Parkinson’s disease (PD) and frontotemporal lobar degeneration (FTLD), an excessive amount of NO, mostly produced by inducible NO synthase (iNOS), reacts with superoxide to form peroxynitrite, driving oxidative/nitrosative stress, mitochondrial dysfunction, and aberrant protein modifications. In AD, NO dysregulation promotes amyloid-β (Aβ) accumulation, tau hyperphosphorylation and synaptic loss, creating a self-perpetuating cycle of neuronal damage. NO’s dual role, protective at physiological levels but harmful if overproduced, underscores the therapeutic potential of antioxidant compounds that restore the balance of NO/NOS (especially iNOS) while preserving physiological functions. However, despite the emerging role of antioxidant-based therapeutic approaches, clinical translation is limited by the complexity of NO signaling and the absence of safe, specific NOS inhibitors. By targeting the molecular switch from protective to toxic, NO activity may offer new personalized treatment avenues for neurodegenerative diseases. Full article

Arachidonic acid (AA) is an emerging regulator of fibroblast activity in pulmonary fibrosis; however, the underlying intracellular mechanisms remain unclear. This study investigated the effects of AA on the free intracellular calcium concentration ([Ca²⁺]_i), nitric oxide (NO), and reactive oxygen species (ROS) in human WI-38 lung fibroblasts. Using fluorescent imaging and pharmacological tools, we demonstrate that AA evokes a robust, concentration-dependent increase in [Ca²⁺]_i. This response is initiated by G protein-coupled receptor 40 (GPR40), which leads to endoplasmic reticulum Ca²⁺ release through inositol 1,4,5-trisphosphate receptors (IP₃Rs) and lysosomal Ca²⁺ mobilisation through two-pore channels (TPCs). Sustained Ca²⁺ elevation is primarily mediated by influx through transient receptor potential vanilloid 4 (TRPV4) channels, with a minor contribution from store-operated Ca²⁺ entry. The AA-induced Ca²⁺ signal stimulates endothelial NO synthase-dependent NO production, which in turn triggers ROS generation, revealing a tightly coupled Ca²⁺–NO–ROS signalling network. Our findings identify AA as a potent modulator of Ca²⁺ and redox signalling in lung fibroblasts, and highlight GPR40, TRPV4, IP₃Rs and lysosomal TPCs as potential therapeutic targets for intervening in pulmonary fibrosis. Full article

Heart inflammation and oxidative stress are pivotal pathological drivers in the pathophysiology of various cardiovascular diseases. The present study aims to investigate the beneficial effects induced by extracts derived from edible plants, such as Olea europaea, and sugar cane on heart health. In particular, we investigated the effects of a novel combination constituting Olea europaea, Scutellaria baicalensis, and policosanol extracts on heart, in in vitro and ex vivo models. Olea europaea, S. baicalensis, policosanol extracts and their combination prevented H₂O₂-induced reduction in H9c2 cell (immortalized myoblasts, isolated from rat heart tissue) viability. Moreover, pre-incubation with the combination significantly reduced H₂O₂-induced ROS levels in the same cells. Our present findings also showed that Olea europaea, S. baicalensis and policosanol extracts, as well as their combination, increased lipopolysaccharide (LPS)-induced catalase gene expression at all concentrations tested, in mouse heart specimens. In addition, we also observed that Olea europaea, S. baicalensis and policosanol extracts, as well as their combination, significantly inhibited LPS-induced inducible nitric oxide synthase, cyclooxygenase-2, nuclear factor-kB, and tumor necrosis factor-α gene expression, in the same experimental model. Interestingly, the combination was more effective at decreasing the mRNA levels of all pro-inflammatory markers investigated. Finally, the combination was also able to suppress LPS-induced B-type natriuretic peptide and cardiac troponin I gene expression ex vivo. In conclusion, these findings suggest that this plant-based combination could offer potential benefits for cardiovascular health and support overall heart function in humans. Full article

Background: Intracerebral hemorrhage (ICH) is a devastating subtype of stroke, in which neuroinflammation and blood–brain barrier (BBB) disruption are secondary pathophysiological events that drive progressive brain injury. Histone lysine demethylase JMJD3 (Jumonji C domain-containing protein 3) is a master epigenetic switch governing inflammatory signaling; however, its participation in ICH-induced vascular disruption and its possible mechanism remain elusive. Objective: To examine the expression patterns of JMJD3 in the context of ICH and to evaluate the therapeutic potential of its specific inhibitor, GSK-J4, in attenuating neuroinflammation and BBB disruption in a murine ICH model. Methods: Hemin treatment of a mouse C8-D1A astrocytic cell line was used to develop an in vitro ICH model. The transcript level of the Jmjd3 gene and its correlation with pro-inflammatory signaling were analyzed with or without GSK-J4 pretreatment. ICH in vivo was created experimentally in adult male C57BL/6 mice through stereotactic striatal injection of collagenase IV, and the mice were randomly assigned to sham, ICH + vehicle, and ICH + GSK-J4 (30 mg/kg intraperitoneally (i.p.), every other day starting three days before ICH) groups. At three days post-ICH, ipsilateral brain tissues were collected to detect JMJD3 cellular localization, pro-inflammatory mediator levels, tight junction protein expression, BBB ultrastructure, and hematoma volume. White matter integrity and neuronal recovery were assessed on day 7, and sensorimotor function was assessed longitudinally on days 1, 3, 5, 7, and 14. Results: Jmjd3 gene transcription was upregulated in hemin-treated astrocytes and correlated positively with IL-6 pro-inflammatory signaling activation. In vivo, the co-localization of JMJD3 with the astrocytic identifier glial fibrillary acidic protein (GFAP) was markedly increased in the area adjacent to the hematoma at three days post-ICH. GSK-J4 administration significantly suppressed the pro-inflammatory signaling cascade by decreasing the levels of inducible nitric oxide synthase (iNOS), tumor necrosis factor-α (TNF-α), and matrix metalloproteinase-9 (MMP-9), enhanced brain vascular structural and functional integrity by upregulating tight junction proteins zonula occludens protein-1 (ZO-1) and claudin-5, improved BBB ultrastructural integrity, and decreased hematoma volume at three days post-ICH. Furthermore, GSK-J4 administration promoted white matter integrity (increased myelin basic protein [MBP] expression) and neuronal recovery (increased neuron-specific nuclear protein [NeuN] expression) at seven days post-ICH and significantly improved the performance of ICH mice in sensorimotor behavioral tests. Conclusions: Astrocytic JMJD3 is upregulated following ICH and promotes neuroinflammation, which in turn mediates BBB disruption. Pharmacological inhibition of JMJD3 by GSK-J4 attenuates neuroinflammation and subsequent BBB damage, accelerates hematoma resolution, and promotes histological and functional recovery after ICH, likely by downregulating MMP-9 expression. These findings identify astrocytic JMJD3 as a novel epigenetic therapeutic target for acute ICH. Full article

Background: Liver inflammation and fibrosis are directly associated with non-alcoholic fatty liver disease (NAFLD). Dysregulation of the potent pro-inflammatory cytokine interleukin-1 beta (IL-1β), inducible nitric oxide synthase (iNOS), and tissue leukocyte infiltration (CD45 +ve) are connected with multiorgan injury and fibrosis. We investigated whether the induction of NAFLD can cause dysregulation in the hepatic IL-1β/iNOS and IL-1β/CD45 axes of inflammation and fibrosis, as well as in endogenous metabolites (lipids, glucose, and insulin) and apoptosis, in the presence and absence of the flavonoid quercetin. Methods: The model group of rats was fed with a high-fat and high-carbohydrate diet (HFCD) for 4 weeks. The protective group of rats was given both quercetin (50 mg/kg) and HFCD for 4 weeks. All rats were sacrificed on day 29. Results: NAFLD was induced in rats as demonstrated by dyslipidemia, hyperglycemia, insulin resistance, liver inflammation, and elevation of liver injury enzymes. NAFLD was also associated with the upregulation of hepatic IL-1β, iNOS, CD45, and apoptosis (p53). Biomarkers of fibrosis (TIMP-1 and α-SMA) were also elevated, and fibrosis was confirmed in the model group by increased collagen deposition and elevated stages of fibrosis score (Stage 1 to 2 of Brunt’s NASH classification). All these parameters were significantly (p < 0.01) modulated by quercetin treatment. Additionally, a significant (p < 0.001) correlation between IL-1β and hepatic injury parameters was observed. Conclusions: These findings suggest a potential association between NAFLD and the IL-1β/iNOS and IL-1β/CD45 axes of liver injury and fibrosis, as well as dyslipidemia, glycemia, and apoptosis, with quercetin exhibiting beneficial hepatic pleiotropic effects. Full article

Extracellular vesicles (EVs) are promising biomarkers for liquid biopsy, but their clinical application is limited by intrinsic heterogeneity and the lack of methods capable of resolving functionally distinct EV subpopulations at the single-vesicle level. Conventional bulk analyses obscure rare but clinically relevant EV subsets, while most single-EV approaches focus on physical properties or surface markers, with limited access to intravesicular functional information. Here, we report a fusion-enabled EV detection strategy at the single-particle level for functional profiling of macrophage-derived EVs. Liposomal probes encapsulating L-arginine, NADPH, and a nitric oxide (NO)-responsive fluorescent dye are engineered to fuse with EV membranes, delivering substrates into the vesicle lumen. In macrophage-derived EVs, inducible nitric oxide synthase (iNOS) catalyzes NO production, activating the fluorescent probe and generating a localized signal within individual vesicles. Signal generation is confined to vesicle-restricted reactions, ensuring specificity and minimizing background. The formation of hybrid vesicles further facilitates optical detection using conventional fluorescence microscopy. Full article

The canine transmissible venereal tumor (TVT) is a neoplasm of the external genitalia of dogs, considered one of four reported contagious tumors in animals. These tumors have different presentations, with steady, progressive, or regressive stages. In some areas of Mexico, where the prevalence of TVT is high (5.15%), two morphological types are usually observed: one steady, pedunculated, strawberry-like (Type A) and one progressive, multilobulated, cauliflower-like (Type B). This study aimed to characterize the histopathological and inflammatory infiltrate patterns in eight stray dogs showing both morphological types of natural TVT (n = 4 each), to identify potential differences between tumor morphologies. Histopathological and immunohistochemical techniques were applied to tumor samples to evaluate the interaction between pathological morphology and the following cell markers: ionized calcium-binding adaptor molecule 1 (IBA1) for activated macrophages (including resident macrophages), inducible nitric oxide synthase (iNOS) for M1 macrophages, CD163 for M2 macrophages, CD3 for T lymphocytes, CD20 for B lymphocytes, and lambda light chain for plasma cells. The results showed a greater inflammatory infiltrate in Type A tumors than in Type B ones, with a parallel increase in activated macrophages and B lymphocytes. The presence of M1 and M2 macrophages was scarce in both types of tumors, and T lymphocytes were almost absent. This study reveals a stronger and more balanced local immune response in dogs with Type A TVTs compared with Type B tumors, which may underlie differences in tumor characteristics, although individual tumor heterogeneity should be considered. Full article