Biomedical subjects

Mahmoud A Pouladi

Publications and source records attributed to Mahmoud A Pouladi.

8 recordsLinked to original sources

PubMed2026

High-affinity, structure-validated and selective macrocyclic peptide tools for chemical biology studies of Huntingtin.

Huntington's disease (HD) is a fatal neurodegenerative disorder caused by a Cytosine-Adenosine-Guanine (CAG) repeat expansion in the Huntingtin (HTT) gene, with no disease-modifying therapies currently available. The precise molecular function of the HTT protein is unclear, and the lack of selective chemical tools has limited functional studies. We have identified and characterized macrocyclic peptide binders targeting HTT. These binders exhibit low-nanomolar affinity in vitro and engage distinct HTT and HTT-HAP40 interfaces, as revealed by hydrogen-deuterium exchange mass spectrometry and cryoelectron microscopy. Chemoproteomics confirmed selective binding in cell extracts from wildtype but not HTT-null cell lines. HAP40 consistently and stoichiometrically copurified with HTT across cell lines, including with HTT variants containing different CAG repeat lengths, highlighting the broad presence of the HTT-HAP40 complex.

Huntingtin Protein↗

PubMed2025

High-Affinity, Structure-Validated and Selective Macrocyclic Peptide Tools for Chemical Biology Studies of Huntingtin.

Huntington's disease (HD) is a fatal neurodegenerative disorder caused by a CAG repeat expansion in the Huntingtin (HTT) gene, with no disease-modifying therapies currently available. The precise molecular function of the HTT protein is unclear, and the lack of selective chemical tools has limited functional studies. We have identified and characterized macrocyclic peptide binders targeting HTT. These binders exhibit low-nanomolar affinity in vitro and engage distinct HTT and HTT-HAP40 interfaces, as revealed by hydrogen-deuterium exchange mass spectrometry and cryo-electron microscopy. Chemoproteomics confirmed selective binding in cell extracts from wildtype but not HTT-null cell lines. HAP40 consistently and stoichiometrically co-purified with HTT across cell lines, including with HTT variants containing different CAG repeat lengths, highlighting the broad presence of the HTT-HAP40 complex.

HAP40↗

PubMed2005

Mainstream cigarette smoke exposure attenuates airway immune inflammatory responses to surrogate and common environmental allergens in mice, despite evidence of increased systemic sensitization.

The purpose of this study was to investigate the impact of mainstream cigarette smoke exposure (MTS) on allergic sensitization and the development of allergic inflammatory processes. Using two different experimental murine models of allergic airways inflammation, we present evidence that MTS increased cytokine production by splenocytes in response to OVA and ragweed challenge. Paradoxically, MTS exposure resulted in an overall attenuation of the immune inflammatory response, including a dramatic reduction in the number of eosinophils and activated (CD69+) and Th2-associated (T1ST2+) CD4 T lymphocytes in the lung. Although MTS did not impact circulating levels of OVA-specific IgE and IgG1, we observed a striking reduction in OVA-specific IgG2a production and significantly diminished airway hyperresponsiveness. MTS, therefore, plays a disparate role in the development of allergic responses, inducing a heightened state of allergen-specific sensitization, but dampening local immune inflammatory processes in the lung.

Allergens↗

PubMed2005

House dust mite facilitates ovalbumin-specific allergic sensitization and airway inflammation.

RATIONALE: Mouse models of allergic airway disease have greatly contributed to our understanding of disease induction and pathogenesis. Although these models typically investigate responses to a single antigen or allergen, humans are frequently exposed to a myriad of allergens, each with distinct antigenic potential. OBJECTIVES: Given that airway exposure to ovalbumin (OVA), a prototypic innocuous antigen, induces inhalation tolerance, we wished to investigate how this response would be altered if OVA were encountered concurrently with a house dust mite extract (HDM), which we have recently shown is capable of eliciting a robust allergic airway inflammatory response that is mediated, at least in part, by granulocyte-macrophage colony-stimulating factor. METHODS: Balb/c mice were exposed daily to HDM (intranasally) followed immediately by exposure to aerosolized OVA for 5 weeks. To allow the inflammatory response elicited by HDM to subside fully, mice were then allowed to rest, unexposed, for 8 weeks, at which time they were rechallenged with aerosolized OVA for 3 consecutive days. MEASUREMENTS AND MAIN RESULTS: At this time, we observed a robust eosinophilic inflammatory response in the lung that was associated with an increase in bronchial hyperreactivity. Moreover, we documented significantly elevated serum levels of OVA-specific IgE and IgG(1) and increased production of the Th2 cytokines interleukin 4 (IL-4), IL-5, and IL-13 by splenocytes stimulated in vitro with OVA. CONCLUSION: Our data demonstrate the potential of a potent allergen such as HDM to establish a lung microenvironment that fosters the development of allergic sensitization to otherwise weak or innocuous antigens, such as OVA.

Animals↗

PubMed2004

Impact of cigarette smoke on clearance and inflammation after Pseudomonas aeruginosa infection.

The object of this study was to investigate the impact of cigarette smoke on bacterial clearance and immune inflammatory parameters after infection with Pseudomonas aeruginosa in mice. We observed a delayed rate of bacterial clearance in smoke-exposed compared with sham-exposed mice. This was associated with increased inflammation characterized by greater numbers of neutrophils and mononuclear cells in the bronchoalveolar lavage. After infection, we observed increased levels of proinflammatory cytokines (tumor necrosis factor-alpha, interleukin-1beta, and interleukin-6) and chemokines (monocyte chemoattractant protein-1 [MCP-1] and macrophage inflammatory protein-2 [MIP-2]) as well as myeloperoxidase and proteolytic activity in the lungs of smoke-exposed compared with sham-exposed animals. Delayed clearance was associated with increased morbidity and greater weight loss of smoke-exposed mice. After delivery of inactivated bacteria, we observed a similar inflammatory response, clinical score, and tumor necrosis factor-alpha expression in smoke- and sham-exposed animals, suggesting that increased inflammation and altered clinical presentation are due to the delayed rate of bacterial clearance. Our findings suggest that cigarette smoke affects respiratory immune-inflammatory responses elicited by bacteria. We postulate that altered respiratory host defense may be implicated in smoking-related diseases such as chronic obstructive pulmonary disease.

Animals↗

PubMed2004

Concomitant airway expression of granulocyte-macrophage colony-stimulating factor and decorin, a natural inhibitor of transforming growth factor-beta, breaks established inhalation tolerance.

We previously showed that granulocyte-macrophage colony-stimulating factor (GM-CSF) breaks tolerance induction. The objective of this study was to determine whether GM-CSF breaks established inhalation tolerance. To induce tolerance, BALB/c mice were exposed to aerosolized ovalbumin (OVA) for 10 consecutive days. A control group was exposed to saline. Subsequently, tolerant and control animals were exposed to OVA in a GM-CSF-enriched airway microenvironment. Tolerant animals, unlike control animals, did not develop airway and peripheral blood eosinophilia, had diminished levels of OVA-specific IgE, and reduced airway hyper-responsiveness. While tolerant animals did not express IL-4, IL-5 and IL-13, levels of the regulatory cytokines IL-10, IFN-gamma and transfoming growth factor (TGF)-beta were similar between tolerant and non-tolerant animals. Lung CD4+ T cells were activated according to CD69, CD25 and T1/ST2 expression, but systemic responses characterized by splenocyte proliferation and Th2 effector function were dramatically reduced. Concurrent expression of GM-CSF and decorin, a natural inhibitor of TGF-beta, reversed eosinophilic unresponsiveness. Our study suggests that the breakdown of tolerance and, by extension, the emergence of eosinophilic inflammation, requires two signals: one that triggers sensitization and one that interferes with negative regulation. Moreover, our study shows that dysregulated expression of an extracellular matrix protein may break established tolerance and lead to eosinophilic airway inflammation.

Administration, Inhalation↗

PubMed2003

Cigarette smoke decreases pulmonary dendritic cells and impacts antiviral immune responsiveness.

We investigated the impact of cigarette smoke exposure on respiratory immune defense mechanisms. Mice were exposed to two cigarettes daily, 5 d/wk, for 2-4 mo. Tobacco smoke decreased the number of dendritic cells (DCs) in the lung tissue. Furthermore, smoke exposure dramatically reduced the percentage of B7.1-expressing DCs. Because DCs are believed to be indispensable to the initiation of adaptive immune responses, we investigated the impact of cigarette smoke on immune responsiveness toward adenovirus. Mice were exposed to two cigarettes for 2-4 mo and inoculated with 2 x 10(8) pfu of a replication-deficient adenovirus on three occasions, 2 wk apart, during the last month of tobacco smoke exposure. Smoke exposure specifically prevented the expansion and maximal activation of CD4 T cells and reduced the number of both activated CD4 and CD8 T cells. Consequently, smoke exposure shifted the activated CD4:CD8 T cell ratio from 3 to 1.5 when compared with sham exposure. Significant decreases were also observed in serum adenovirus-specific pan IgG, IgG1, and IgG2a immunoglobulin levels, which was associated with diminished viral neutralization capacity. We demonstrate that chronic tobacco smoke exposure impairs the immune response against adenovirus. This may, in part, explain the increased prevalence of viral infections in chronic obstructive pulmonary disease.

Adenoviridae↗

PubMed2003

Interleukin-13-dependent expression of matrix metalloproteinase-12 is required for the development of airway eosinophilia in mice.

We investigated the expression and function of matrix metalloproteinase-12 (MMP-12) in a model of allergic airway inflammation. Mice were sensitized mucosally by exposure to aerosolized ovalbumin (OVA) daily over a period of 10 d in the context of adenovirus-mediated granulocyte macrophage colony-stimulating factor (GM-CSF) expression. The ensuing inflammatory response is characterized by a Th2 cytokine profile, OVA-specific IgE, and airway eosinophilia. Using real-time, quantitative reverse transcriptase-polymerase chain reaction we assessed MMP-12 mRNA expression in whole lung tissue. We observed a 12- and 70-fold increase in expression at Days 7 and 11, respectively, in OVA-exposed mice when compared with naive controls. Immunoblot analysis revealed an increase in MMP-12 protein in the bronchoalveolar lavage fluid of mice exposed to OVA in the context of GM-CSF. No such elevation was observed in mice exposed to saline only in the context of GM-CSF. To assess functional role of MMP-12, MMP-12 knockout (KO) mice were subjected to the aforementioned protocol. We observed an 80% reduction in eosinophils in the bronchoalveolar lavage fluid of KO mice compared with their wild-type littermates. Using interleukin-13 KO mice, we demonstrated that expression of MMP-12 is interleukin-13-dependent. Collectively, our data indicate a novel function for MMP-12 in the process of airway eosinophil accumulation.

Animals↗