ABSTRACT Introduction: Intralesional infiltration of epidermal growth factor (EGF) has emerged as a therapeutic alternative for diabetic foot ulcer (DFU) healing. The objectives of this research were: to determine the molecular profile of patients with DFU and to characterize the systemic effects of EGF intralesional treatment in such patients, taking into account redox balance markers, components of the advanced glycation end-product (AGE) pathway, factors related to the extracellular matrix (ECM) stability and pro-inflammatory markers. Methods: Thirteen patients with DFU were characterized in comparison with diabetic patients without ulcers (compensated and non-compensated) and non-diabetic subjects, attending to redox balance markers, components of the AGE pathway, and elements related to the stability of the ECM. The systemic response of patients with DFU to the intralesional treatment with EGF was evaluated according to the same parameters, in addition to other pro-inflammatory markers. Results: Patients with DFU exhibited the most disheveled biochemical profile, with elevated oxidative stress, low antioxidant reserves, increased glycoxidation products and matrix metalloproteases (MMP), with respect to non-ulcerated diabetic patients and to non-diabetic subjects. The intralesional administration of EGF was associated with a significant recovery of the parameters studied and with the systemic attenuation of several pro-inflammatory markers. Conclusions: These results indicate that intralesional infiltration of EGF translates into systemic antioxidant, anti-inflammatory, anti-degradative and anti-AGE effects, which contribute to restoring homeostasis in the diabetic patient.

RESUMEN Introducción: La infiltración intralesional con factor de crecimiento epidérmico (EGF) ha emergido como alternativa terapéutica para la cicatrización de las úlceras de pie diabético (UPD). Los objetivos de esta investigación fueron: determinar el perfil molecular de los pacientes con UPD y caracterizar los efectos sistémicos del tratamiento intralesional con EGF en tales pacientes atendiendo a marcadores de balance redox, componentes de la vía de los productos avanzados de glicación (AGE), factores relacionados con la estabilidad de la matriz extracelular (MEC) y marcadores pro-inflamatorios. Métodos: Se caracterizaron 13 pacientes con UPD en comparación con diabéticos sin úlceras (compensados y no compensados) e individuos no diabéticos, atendiendo a marcadores de balance redox, componentes de la vía de los AGE y elementos relacionados con la estabilidad de la MEC. La respuesta sistémica de los pacientes con UPD al tratamiento intralesional con EGF se evaluó atendiendo a los mismos parámetros, además de otros marcadores pro-inflamatorios. Resultados: Los pacientes con UPD exhibieron un perfil bioquímico muy alterado, con elevado estrés oxidativo, bajas reservas antioxidantes, aumento de los productos de glicoxidación y de las metaloproteasas de la matriz (MMP), con respecto a los diabéticos sin úlceras y a los no diabéticos. La administración intralesional de EGF estuvo asociada a una recuperación significativa de los parámetros estudiados y a la atenuación sistémica de varios marcadores pro-inflamatorios. Conclusiones: Los resultados indican que la infiltración intralesional con EGF se traduce en efectos sistémicos antioxidantes, anti-inflamatorios, anti-degradativos y anti-AGE, que contribuyen a restaurar la homeostasia del paciente diabético.

Abstract BACKGROUND Diabetic foot ulcers are a common diabetic complication leading to alarming figures of amputation, disability, and early mortality. The diabetic glucooxidative environment impairs the healing response, promoting the onset of a ‘wound chronicity phenotype’. In 50% of ulcers, these non-healing wounds act as an open door for developing infections, a process facilitated by diabetic patients’ dysimmunity. Infection can elicit biofilm formation that worsens wound prognosis. How this microorganism community is able to take advantage of underlying diabetic conditions and thrive both within the wound and the diabetic host is an expanding research field. OBJECTIVES 1) Offer an overview of the major cellular and molecular derangements of the diabetic healing process versus physiological cascades in a non-diabetic host. 2) Describe the main immunopathological aspects of diabetics’ immune response and explore how these contribute to wound infection susceptibility. 3) Conceptualize infection and biofilim in diabetic foot ulcers and analyze their dynamic interactions with wound bed cells and matrices, and their systemic effects at the organism level. 4) Offer an integrative conceptual framework of wound–dysimmunity–infection–organism damage. EVIDENCE AQUISITION We retrieved 683 articles indexed in Medline/PubMed, SciELO, Bioline International and Google Scholar. 280 articles were selected for discussion under four major subheadings: 1) normal healing processes, 2) impaired healing processes in the diabetic population, 3) diabetic dysimmunity and 4) diabetic foot infection and its interaction with the host. DEVELOPMENT The diabetic healing response is heterogeneous, torpid and asynchronous, leading to wound chronicity. The accumulation of senescent cells and a protracted inflammatory profile with a pro-catabolic balance hinder the proliferative response and delay re-epithelialization. Diabetes reduces the immune system’s abilities to orchestrate an appropriate antimicrobial response and offers ideal conditions for microbiota establishment and biofilm formation. Biofilm–microbial entrenchment hinders antimicrobial therapy effectiveness, amplifies the host's pre-existing immunodepression, arrests the wound’s proliferative phase, increases localized catabolism, prolongs pathogenic inflammation and perpetuates wound chronicity. In such circumstances the infected wound may act as a proinflammatory and pro-oxidant organ superimposed onto the host, which eventually intensifies peripheral insulin resistance and disrupts homeostasis. CONCLUSIONS The number of lower-limb amputations remains high worldwide despite continued research efforts on diabetic foot ulcers. Identifying and manipulating the molecular drivers underlying diabetic wound healing failure, and dysimmunity-driven susceptibility to infection will offer more effective therapeutic tools for the diabetic population.

Abstract Lower-extremity diabetic ulcers are responsible for 80% of annual worldwide nontraumatic amputations. Epidermal growth factor (EGF) reduction is one of the molecular pillars of diabetic ulcer chronicity, thus EGF administration may be considered a type of replacement therapy. Topical EGF administration to improve and speed wound healing began in 1989 on burn patients as part of an acute-healing therapy. Further clinical studies based on topically administering EGF to different chronic wounds resulted in disappointing outcomes. An analysis of the literature on unsuccessful clinical trials identified a lack of knowledge concerning: (I) molecular and cellular foundations of wound chronicity and (II) the pharmacodynamic requisites governing EGF interaction with its receptor to promote cell response. Yet, EGF intra- and perilesional infiltration were shown to circumvent the pharmacodynamic limitations of topical application. Since the first studies, the following decades of basic and clinical research on EGF therapy for problem wounds have shed light on potential uses of growth factors in regenerative medicine. EGF’s molecular and biochemical effects at both local and systemic levels are diverse: (1) downregulation of genes encoding inflammation mediators and increased expression of genes involved in cell proliferation, angiogenesis and matrix secretion; (2) EGF intervention positively impacts both mesenchymal and epithelial cells, reducing inflammation and stimulating the recruitment of precursor circulating cells that promote the formation of new blood vessels; (3) at the subcellular level, upregulation of the EGF receptor with subsequent intracellular trafficking, including mitochondrial allocation along with restored morphology of multiple organelles; and (4) local EGF infiltration resulting in a systemic, organismal repercussion, thus contributing to attenuation of circulating inflammatory and catabolic reactants, restored reduction-oxidation balance, and decreased toxic glycation products and soluble apoptogenic effectors. It is likely that EGF treatment may rearrange critical epigenetic drivers of diabetic metabolic memory.

Type 2 diabetes mellitus comprises a group of non-communicable metabolic diseases with an expanding pandemic magnitude. Diabetes predisposes to lower extremities ulceration and impairs the healing process leading to wounds chronification. Diabetes also dismantles innate immunity favoring wound infection. Amputation is therefore acknowledged as one of the disease's complications. Hyperglycemia appears as the proximal detonator of toxic effectors including pro-inflammation, spillover of reactive oxygen and nitrogen species. The systemic accumulation of advanced glycation end-products irreversibly impairs the entire physiology from cells-to-organs. Insulin axis deficiency weakens wounds' anabolism and predisposes to inflammation. These factors converge to hamper fibroblasts and endothelial cells proliferation, migration, homing, secretion and organization of a productive granulation tissue. Diabetic wound bed may turn chronically inflamed, pro-catabolic and a superimposed source of circulating pro-inflammatory cytokines, establishing a self-perpetuating loop. Diabetic toxicity breadth includes mitochondrial damages in fibroblasts and endothelial cells becoming prone to apoptosis thus hindering granulation. Endothelial progenitor cells recruitment and tubulogenesis are also impaired. Failure of wound re-epithelialization remains as a clinical challenge while it appears to be biologically multifactorial. Novel medical interventions as the local intra-ulcer infiltration of epidermal growth factor have emerged to hopefully reduce the current worldwide amputation rates.

La diabetes mellitus tipo 2 implica desórdenes metabólicos no transmisibles, cuya incidencia va en aumento, con una extensión casi pandémica. Predispone a padecer úlceras en las extremidades inferiores y a su cronicidad, al afectar el proceso de cicatrización. También interfiere la inmunidad innata, lo que favorece la infección de posibles lesiones, y puede conducir a la amputación. La hiperglucemia desencadena los efectores tóxicos que incluyen la inflamación y la producción en exceso de especies reactivas de oxígeno y nitrógeno. Los productos finales altamente glicosilados, que se acumulan sistemáticamente, desarticulan la estructura de células y órganos. La deficiencia en el eje insulínico debilita el anabolismo en las lesiones y predispone a la inflamación. Estos factores convergen y debilitan la proliferación, la migración, el direccionamiento, la secreción y la organización de los fibroblastos y células endoteliales, lo que interfiere en la formación de tejido de granulación útil. El lecho de las heridas puede convertirse en una fuente inflamatoria y procatabólica de citocinas, y constituir un ciclo de perpetuación. La toxicidad diabética provoca daños mitocondriales en los fibroblastos y las células endoteliales, que los hace susceptibles de apoptosis y dificulta la granulación del tejido. También afecta el reclutamiento de las células progenitoras endoteliales, e impide la tubulogénesis. La regeneración del tejido epitelial en las lesiones sigue siendo un desafío clínico que depende de múltiples factores biológicos. Nuevas intervenciones médicas, como la infiltración local intralesional del factor de crecimiento epidérmico recombinante, prometen la reducción de las tasas mundiales de amputación.