The Association between the History of HIV Diagnosis and Oral Health.

Unmet oral care needs are high among people living with human immunodeficiency virus (HIV)/AIDS (PLWH). Oral health care is of increasing importance as life expectancy is being prolonged extensively among PLWH. The benefit of oral health care in relation to time since HIV diagnosis has not previously been assessed. A retrospective multivariable analysis of the Special Project of National Significance Oral Health Initiative observational cohort study ( N = 2,178) was performed to estimate the odds ratios (ORs) of oral health outcomes comparing historically diagnosed subjects (>1 y since HIV diagnosis) to newly diagnosed subjects (≤1 y since HIV diagnosis). ORs were adjusted for age, study site, language, income, last dental care visit, and dental insurance. Historically diagnosed subjects were more likely to report oral problems than newly HIV-diagnosed subjects (OR, 2.10). Historically diagnosed subjects were more likely to require oral surgery (OR, 1.52), restorative treatment (OR, 1.35), endodontic treatment (OR, 1.63), and more than 10 oral clinic visits over the 24-mo study period (OR, 2.02). The crude cumulative 2-y risk of requiring prosthetic (risk difference [RD], 0.21) and endodontic (RD, 0.11) treatment was higher among historically than newly diagnosed subjects, despite no significance postadjustment. Furthermore, poor oral health outcomes were exacerbated among non-highly active antiretroviral therapy users. Summarizing, the authors found that historically diagnosed subjects were more likely to report oral problems and require dental procedures compared with newly diagnosed subjects, suggesting that oral health among PLWH declines over time since HIV diagnosis. Hence, newly diagnosed PLWH may benefit from the implementation of early oral interventions.

Impact of periodontal intervention on local inflammation, periodontitis, and HIV outcomes.

OBJECTIVE: The aim of this study was to determine active periodontal disease status in HIV and to determine the impact of periodontal disease resolution on HIV status. METHODS: In this longitudinal cohort study, 73 HIV-positive subjects received comprehensive dental care. AAP, CDC/AAP, and BGI case definitions determined periodontal classification. Likelihood and frequency of moderate/severe periodontal disease were assessed based on demographic variables. The influence of periodontal intervention was assessed at baseline, 12, and 24 months. IL-6 was measured in a subset of subjects. RESULTS: Of the periodontal classifications, BGI demonstrated the highest percentage category improvement with the intervention (>50%). Moderate/severe periodontitis was positively associated with HIV regardless of race, smoking status, gender, income level, and age, and was associated with increased IL-6. At baseline, the majority of subjects had severe periodontal disease regardless of ART status. Subjects with suppressed viral load at baseline demonstrated a significant improvement in BGI classification (P = 0.026), increased CD4 counts (P = 0.027), and decreased IL-6 levels (P = 0.03). CONCLUSIONS: Periodontal inflammation was prevalent regardless of ART status. In virologically suppressed subjects, the intervention decreased periodontitis with a concomitant IL-6 decrease and CD4 increase. These findings suggest a relationship between periodontal inflammation, oral microbial translocation, and HIV status.

Hairy leukoplakia; lessons learned: 30-plus years.

Well into the fourth decade of the HIV/AIDS pandemic, we can look back on the early years, the initial discoveries, and the broad sweep of the progress of our understanding of the nature, causes, and significance of the oral lesions seen in those infected with the virus. Prominent among these is oral hairy leukoplakia (HL), a previously unknown lesion of the mouth associated with Epstein-Barr virus (EBV) and initially seen only in people with AIDS, in the then-recognized risk groups, or those shown to be HIV positive. Subsequently, it became clear that the distribution of HL extends well beyond the HIV spectrum. In this brief review, we consider the clinical and histological features of HL, discuss how it was discovered, explore its cause, diagnosis, relationship with AIDS, pathogenesis, significance in EBV biology, options for management, and how it changes with HIV/AIDS therapy.

The Oral HIV/AIDS Research Alliance Program: lessons learned and future directions.

The Oral HIV/AIDS Research Alliance (OHARA) was established in 2006 to provide the capacity to investigate the oral complications associated with HIV/AIDS within the ACTG infrastructure. Its goals were to explore the effects of potent antiretroviral therapy (ART) on the development of opportunistic infections, and variation and resistance of opportunistic pathogens in the context of immune suppression and long-term ART. The objectives of this talk, presented as part of a plenary session at the 7th World Workshop on Oral Health and Disease in AIDS, were to (i) provide an overview of OHARA's most recent research agenda, and how it evolved since OHARA's inception; (ii) describe OHARA's main accomplishments, including examples of research protocols completed and their key findings; and (iii) describe spin-off projects derived from OHARA, lessons learned, and future directions. OHARA has met its central goal and made key contributions to the field in several ways: (i) by developing/updating diagnostic criteria for oral disease endpoints commonly measured in OHARA protocols and in HIV/AIDS research in general and has creating standardized training modules, both for measuring these oral disease endpoints across clinical specialties, and for collecting oral fluid specimens; (ii) by implementing a total of nine protocols, six of which are completed. Three protocols involved domestic research sites, while three involved international research sites (in Africa, India, and South America); (iii) and by developing and validating a number of laboratory assays used in its protocols and in the field of oral HIV/AIDS research.

Innate immunity in HIV-1 infection: epithelial and non-specific host factors of mucosal immunity- a workshop report.

The interplay between HIV-1 and epithelial cells represents a critical aspect in mucosal HIV-1 transmission. Epithelial cells lining the oral cavity cover subepithelial tissues, which contain virus-susceptible host cells including CD4(+) T lymphocytes, monocytes/macrophages, and dendritic cells. Oral epithelia are among the sites of first exposure to both cell-free and cell-associated virus HIV-1 through breast-feeding and oral-genital contact. However, oral mucosa is considered to be naturally resistant to HIV-1 transmission. Oral epithelial cells have been shown to play a crucial role in innate host defense. Nevertheless, it is not clear to what degree these local innate immune factors contribute to HIV-1 resistance of the oral mucosa. This review paper addressed the following issues that were discussed at the 7th World Workshop on Oral Health and Disease in AIDS held in Hyderabad, India, during November 6-9, 2014: (i) What is the fate of HIV-1 after interactions with oral epithelial cells?; (ii) What are the keratinocyte and other anti-HIV effector oral factors, and how do they contribute to mucosal protection?; (iii) How can HIV-1 interactions with oral epithelium affect activation and populations of local immune cells?; (iv) How can HIV-1 interactions alter functions of oral epithelial cells?

Viral infections associated with oral cancers and diseases in the context of HIV: a workshop report.

Human herpesviruses (HHVs) and human papillomavirus (HPV) are common in the general population and, in immunocompetent people, are mostly carried asymptomatically. However, once an individual becomes immunocompromised by age, illness or HIV infection these dormant viruses can manifest and produce disease. In HIV-positive patients, there is an increased risk of disease caused by HHVs and HPV infections and cancers caused by the oncoviruses Epstein-Barr Virus, HHV-8 and HPV. This workshop examined four questions regarding the viruses associated with oral cancers and disease in the HIV-positive and -negative populations, the immune response, and biomarkers useful for accurate diagnostics of these infections and their sequalae. Each presenter identified a number of key areas where further research is required.

Polymicrobial infection and bacterium-mediated epigenetic modification of DNA tumor viruses contribute to pathogenesis.

ABSTRACT The human body plays host to a wide variety of microbes, commensal and pathogenic. In addition to interacting with their host, different microbes, such as bacteria and viruses, interact with each other, sometimes in ways that exacerbate disease. In particular, gene expression of a number of viruses, including Kaposi's sarcoma-associated herpesvirus (KSHV), Epstein-Barr virus (EBV), and human immunodeficiency virus (HIV), is known to be regulated by epigenetic modifications induced by bacteria. These viruses establish latent infection in their host cells and can be reactivated by bacterial products. Viral reactivation has been suggested to contribute to periodontal disease and AIDS. In addition, bacterium-virus interactions may play a role in cancers, such as Kaposi's sarcoma, gastric cancer, and head and neck cancer. It is important to consider the effects of coexisting bacterial infections when studying viral diseases in vivo.

Viruses and salivary gland disease (SGD): lessons from HIV SGD.

Viral infections are often associated with salivary gland pathology. Here we review the pathogenesis of HIV-associated salivary gland disease (HIV-SGD), a hallmark of diffuse infiltrative lymphocytosis syndrome. We investigate the presence and contributions of viral diseases to the pathogenesis of salivary gland diseases, particularly HIV-SGD. We have detected BK viral shedding in the saliva of HIV-SGD patients consistent with viral infection and replication, suggesting a role for oral transmission. For further investigation of BKV pathogenesis in salivary glands, an in vitro model of BKV infection is described. Submandibular (HSG) and parotid (HSY) gland salivary cell lines were capable of permissive BKV infection, as determined by BKV gene expression and replication. Analysis of these data collectively suggests the potential for a BKV oral route of transmission and salivary gland pathogenesis within HIV-SGD.

Mechanisms of viral infections associated with HIV: workshop 2B.

HIV infection is commonly associated with activation and dissemination of several other viral pathogens, including herpes simplex virus 1/2, human cytomegalovirus, human herpesvirus 8, Epstein-Barr virus, Varicella Zoster virus, and human papillomavirus, which behave as opportunistic agents and cause various diseases in immunocompromised hosts. The increased frequency and severity of diseases caused by these viruses in HIV-infected individuals is due mainly to dysfunction of both the adaptive and innate immune responses to viral pathogens. In addition, molecular interactions between HIV and these opportunistic viruses are likely to play critical roles in the progression of disease, including neoplasia. This report reviews the critical aspects of HIV interaction with opportunistic viruses, including Epstein-Barr virus, human cytomegalovirus, herpes simplex virus, Varicella Zoster virus, human herpesvirus 8, and human papillomavirus.

The Oral HIV/AIDS Research Alliance: updated case definitions of oral disease endpoints.

The Oral HIV/AIDS Research Alliance (OHARA) is part of the AIDS Clinical Trials Group (ACTG), the largest HIV clinical trials organization in the world. Its main objective is to investigate oral complications associated with HIV/AIDS as the epidemic is evolving, in particular, the effects of antiretrovirals on oral mucosal lesion development and associated fungal and viral pathogens. The OHARA infrastructure comprises: the Epidemiologic Research Unit (at the University of California San Francisco), the Medical Mycology Unit (at Case Western Reserve University) and the Virology/Specimen Banking Unit (at the University of North Carolina). The team includes dentists, physicians, virologists, mycologists, immunologists, epidemiologists and statisticians. Observational studies and clinical trials are being implemented at ACTG-affiliated sites in the US and resource-poor countries. Many studies have shared end-points, which include oral diseases known to be associated with HIV/AIDS measured by trained and calibrated ACTG study nurses. In preparation for future protocols, we have updated existing diagnostic criteria of the oral manifestations of HIV published in 1992 and 1993. The proposed case definitions are designed to be used in large-scale epidemiologic studies and clinical trials, in both US and resource-poor settings, where diagnoses may be made by non-dental healthcare providers. The objective of this article is to present updated case definitions for HIV-related oral diseases that will be used to measure standardized clinical end-points in OHARA studies, and that can be used by any investigator outside of OHARA/ACTG conducting clinical research that pertains to these end-points.

Signaling cascades triggered by bacterial metabolic end products during reactivation of Kaposi's sarcoma-associated herpesvirus.

The present studies explore the role of polymicrobial infection in the reactivation of Kaposi's sarcoma-associated herpesvirus (KSHV) and analyze signaling pathways activated upon this induction. We hypothesized that activation of the cellular stress-activated mitogen-activated protein kinase (MAPK) p38 pathway would play a key role in the bacterium-mediated disruption of viral latency similar to that of previously reported results obtained with other inducers of gammaherpesvirus lytic replication. KSHV within infected BCBL-1 cells was induced to replicate following exposure to metabolic end products from gram-negative or -positive bacteria that were then simultaneously exposed to specific inhibitors of signal transduction pathways. We have determined that bacterium-mediated induction of lytic KSHV infection is significantly reduced by the inhibition of the p38 MAPK pathway. In contrast, inhibition of the phosphatidylinositol 3-kinase pathway did not impair induction of lytic replication or p38 phosphorylation. Protein kinase C, though activated, was not the major pathway used for bacterium-induced viral reactivation. Furthermore, hyperacetylation of histones 3 and 4 was detected. Collectively, our results show that metabolic end products from these pathogens induce lytic replication of KSHV in BCBL-1 cells primarily via the activation of a stress-activated MAPK pathway. Importantly, we demonstrate for the first time a mechanism by which polymicrobial bacterial infections result in KSHV reactivation and pathogenesis.

A dynamic model for induced reactivation of latent virus.

We develop a deterministic mathematical model to describe reactivation of latent virus by chemical inducers. This model is applied to the reactivation of latent KSHV in BCBL-1 cell cultures with butyrate as the inducing agent. Parameters for the model are first estimated from known properties of the exponentially growing, uninduced cell cultures. Additional parameters that are necessary to describe induction are determined from fits to experimental data from the literature. Our initial model provides good agreement with two independent sets of experimental data, but also points to the need for a new class of experiments which are required for further understanding of the underlying mechanisms.

Stability and release of antiviral drugs from ethylene vinyl acetate (EVA) copolymer.

The use of polymer based drug delivery systems in dentistry is a relatively new area of research with the exception of the inhibition of secondary caries by the release of fluoride ions from polyalkenoate cements and their predecessors silicate cements. The present study was to test on orally biocompatible material, ethylene vinyl acetate copolymer (EVA), for release of antiviral drugs at oral therapeutic levels over extended periods of time. We also determined their stability during film casting and release. Materials studied include gancyclovir (GCY), acyclovir (ACY), dichloromethane (DCM), and ethylene vinyl acetate (EVA). The square films (3 x 3 x 0.1 cm) were prepared from the dry sheet obtained by solvent evaporation of polymer casting solutions. These solutions were made of EVA and the drug (40:1) in 70 ml of dichloromethane at 38 degrees C. Then drug release characteristics from the drug loaded films were examined at 37 degrees C for a minimum of 14 days in 10 ml medium (ddwater) replaced daily. Kinetics of drug release were followed by spectral measurements using previously determined lambda(max) values (GCY = 250 nm; ACY = 253 nm). A minimum of three samples was tested and reproducible results were obtained. Drug stability (ACY) during film casting and its release was determined using 1H NMR spectrometer (Bruker DRX-500 and 400). Rate of drug release was determined from the part of the curve (rate vs. time) after the onset of the "burst." Although GCY has a larger molecular weight (255) than ACY (225), GCY exhibited about three times higher rate of release than ACY. This difference in rate values may be explained due to its relatively greater solubility in EVA, facilitating faster diffusion of the molecules through the channels present in EVA. This is consistent with the observation that the rate at which drug molecules diffuse through the channels of the polymer, can be increased by decreasing the molecular weight. In the case of ACY, the molecules may be undergoing molecular associations, perhaps dimerization or trimerization in addition to its lower solubility in EVA. The diffusion of ACY tends to be slower under these circumstances compared to GCY resulting in lower rate value than in the case of GCY. Biological studies revealed that ACY exhibited a remarkable decrease in a number of viral organisms present in virus infected cell culture system using real-time polymerase chain reaction (RT-PCR). NMR analysis indicates that the chemical structure of the drug remains stable during film casting process and release.

Oral EBV and KSHV infection in HIV.

The gamma herpesviruses, Kaposi's-sarcoma-associated herpesvirus (KSHV) and Epstein-Barr virus (EBV), are tightly associated with the development of AIDS-associated oral disease and malignancy during immune suppression. The objective of this investigation was to characterize oral infection and pathogenesis in healthy and immune-suppressed individuals. To characterize oral EBV and KSHV infection, we examined throat washings and oral epithelial cells from HIV-positive and HIV-negative individuals. Quantitative/real-time polymerase-chain-reaction (PCR) assays, transmission electronmicroscopy, immunostaining, and sequence analysis were used to identify viral infection. Virus was isolated from throat-wash samples and was used to infect epithelial and lymphoid cell lines. We detected EBV and KSHV in the oral cavity in healthy and immune-suppressed individuals. Viral strain analysis of KSHV K1 in multiple clones from the oral cavities of healthy persons and immunosuppressed patients detected several strains previously detected in KS lesions, with minor strain variation within individuals. Immunoelectron microscopy for multiple viral antigens detected consistent expression of viral proteins and oral epithelial specimens. In oral epithelial cells infected with wild-type KSHV in vitro, the K8.1 glycoprotein associated with lytic KSHV infection was detected in both primary and telomerase immortalized oral epithelial cultures by 24 hours post-infection. Virions were detected, subsequent to infection, by scanning electron microscopy. Oral epithelial cells were also infected in vitro with wild-type EBV originating from throat washes. Analysis of these data suggests that, like EBV, KSHV infection is present in the oropharynx of healthy individuals, is transmissible in vitro, and may be transmitted by saliva.

Mechanisms of expression of HHV8, EBV and HPV in selected HIV-associated oral lesions.

Opportunistic DNA viruses, particularly members of the herpesvirus family, are frequently the aetiological agents of HIV-associated oral lesions. Oral lesions common to the early phase of the AIDS epidemic, including Kaposi's sarcoma (KS), oral aphthous ulceration, AIDS-associated oral lymphoma, and oral hairy leukoplakia (OHL), have been tested for the prevalence of Epstein-Barr virus (EBV) and Kaposi's sarcoma-associated herpesvirus (KSHV). While EBV DNA is detected by PCR in all of these lesions, abundant viral replication can only be detected in OHL. In OHL, a novel state of EBV infection has been discovered with concurrent expression of replicative and transforming proteins, with all of these proteins contributing to the development of the lesion. Activation of signalling pathways and up-regulation of the viral receptor, proliferative and antiapoptotic genes by these proteins induce several of the histological features common to OHL, such as acanthosis and hyperproliferation. In contrast to other permissive herpesvirus infections, expression of EBV transforming proteins within the permissively infected OHL tissue enables epithelial cell survival and may enhance viral replication. Detection of KSHV in these HIV-infected individuals has been localized only to their saliva. Replicative and latent KSHV gene products have been detected in association with the development of oral KS lesions. EBV, but not human cytomegalovirus (HCMV), has been detected by PCR in minor salivary gland biopsies of HIV-associated salivary gland disease. Human papillomaviruses (HPV) are associated with oral warts in HIV-positive individuals; a diagnosis that appears to be increasing in frequency in the era of highly active antiretroviral therapy. To date, there appears to be little increase in the incidence of HPV-associated oral cancer. The mechanisms of interaction between HIV and HPV are not fully understood. Expression of viral gene products is clearly important and necessary for the development of multiple AIDS-associated oral lesions.

Hairy leukoplakia: an unusual combination of transforming and permissive Epstein-Barr virus infections.

Human herpesviruses are characterized by distinct states of infection. Typically in permissive herpesvirus infection, abundant virus production results in cell lysis. In latent transforming Epstein-Barr virus (EBV) infection, viral proteins that induce cell growth are expressed. The immunodeficiency-associated hairy leukoplakia (HLP) lesion is the only pathologic manifestation of permissive EBV infection; however, within HLP, viral proteins characteristic of latent infection have also been detected. In this study, we further analyzed expression of EBV latent genes and investigated their contribution to the unique histologic phenotype of HLP. Coexpression of lytic and transforming viral proteins was detected simultaneously within individual HLP keratinocytes. LMP1 has now been shown to be uniformly expressed in the affected tissue, and it is associated and colocalizes with tumor necrosis factor receptor-associated factor (TRAF) signaling molecules. Effects induced by activated TRAF signaling that were detected in HLP included activation of NF-kappaB and c-Jun terminal kinase 1 (JNK1) and upregulated expression of epidermal growth factor receptor (EGFR), CD40, A20, and TRAFs. This study identifies a novel state of EBV infection with concurrent expression of replicative and transforming proteins. It is probable that both replicative and latent proteins contribute to HLP development and induce many of the histologic features of HLP, such as acanthosis and hyperproliferation. In contrast to other permissive herpesvirus infections, expression of EBV transforming proteins within the permissively infected HLP tissue enables epithelial cell survival and may enhance viral replication.

The molecular epidemiology and evolution of Epstein-Barr virus: sequence variation and genetic recombination in the latent membrane protein-1 gene.

The phylogeny and evolution of Epstein-Barr virus (EBV) genetic variation are poorly understood. EBV latent membrane protein-1 (LMP-1) gene sequences are especially heterogeneous and may be useful as a tool for EBV genotype identification. Therefore, LMP-1 sequences obtained directly from EBV-infected human tissues were examined by PCR amplification and cloning. EBV genotypes were defined as "strains" from among 22 identified LMP-1 sequence patterns. Three molecular mechanisms were identified by which genetic diversity arises in the LMP-1 gene: point mutation, sequence deletion or duplication, and homologous recombination. The rate of LMP-1 gene evolution was found to be accelerated by coinfection with multiple EBV strains. The results of this study refine our understanding of LMP-1 sequence variation and enable accurate discrimination between independent EBV infection events and the consequence of intrahost EBV evolution. Thus, this LMP-1 sequence-based approach to EBV molecular epidemiology will facilitate the study of intrahost EBV infection, coinfection, and persistence.

Transcription of Epstein-Barr virus latent cycle genes in oral hairy leukoplakia.

The hairy leukoplakia lesion (HLP) is a unique example of a permissive infection with Epstein-Barr virus (EBV) in the tongue epithelium. HLP contains abundant replicating viral DNA and may be coinfected with multiple EBV strains. In this study, characterization of viral gene transcription within HLP biopsy specimens revealed that several genes, usually expressed in latently infected lymphocytes, are also transcribed in the HLP lesion. The BamHI W and C promoters, (Wp and Cp) are consistently active in the HLP lesion, resulting in transcription and processing of mRNAs that encode the Epstein-Barr nuclear antigens (EBNAs) EBNA-LP, EBNA1, EBNA2, EBNA3B, and EBNA3C. The EBNA2 protein has been shown to activate expression of the EBV receptor, CD21. In HLP, CD21 transcription is also detected, usually in samples that contain transcripts for EBNA2. Transcripts encoding the LMP1 gene, the LMP2 gene, and rightward transcripts from the BamHI A fragment of the EBV genome are also detected in HLP. These gene products are invariably expressed in latently infected lymphocytes. This pattern of transcription suggests that genes characteristic of latent infection are also expressed in HLP. The activation of Wp and expression of EBNA2 and CD21 may contribute to the unique ability of the HLP lesion to permit superinfection and viral replication of multiple EBV strains.

Epstein-Barr virus and human herpesvirus 8 prevalence in human immunodeficiency virus-associated oral mucosal lesions.

The prevalence of Epstein-Barr virus (EBV) and the recently identified Kaposi's sarcoma (KS)-associated herpesvirus (also designated human herpesvirus 8 [HHV-8]) was determined in oral lesions and oral neoplasms common to persons with human immunodeficiency virus (HIV) infection. Oral lesions were examined by polymerase chain reaction (PCR) for EBV and HHV-8 DNA and by Southern blot analysis for EBV clonality. EBV was detected by Southern blot in hairy leukoplakia lesions, in a subset of AIDS-related lymphomas, and in saliva from HIV-positive persons but not in pseudohairy leukoplakia lesions, oral aphthous ulcers, or oral KS lesions. EBV was detected, however, by PCR in most of the lesions, while HHV-8 was detected only in oral KSs. The absence of HHV-8 DNA in both the EBV-associated hairy leukoplakia lesions and in the EBV-associated AIDS-related lymphomas strengthens the etiologic relationship of EBV to these pathologies and the etiologic role of HHV-8 in KS.

Epstein-Barr virus infection and expression in oral lesions.

OBJECTIVE: The prevalence of Epstein-Barr virus (EBV) and the recently discovered Kaposi's sarcoma associated herpes virus, human herpesvirus 8 (KSHV or HHV8), was determined within oral lesions common to HIV infection including OHL, pseudoOHL (PHL), oral lymphoma, oral aphthous ulcers, and an oral Kaposi's sarcoma. METHODS: DNA and RNA were extracted from oral lesions. EBV and HHV8 genomes were detected by Southern blot and polymerase chain reaction (PCR), and viral expression was analyzed using PCR amplification of cDNA. RESULTS: Multiple EBV strains were detected within OHL with recombination across repeat sequences generating new viral variants. EBV expression in OHL included expression of some viral genes, usually expressed in latent infections, that induce the EBV receptor. EBV replication was detected only within OHL lesions but not within adjacent Kaposi's tissue or oral aphthous ulcers while HHV8 was only detected within the Kaposi's lesions. CONCLUSIONS: These findings indicate that the OHL lesion is unique with viral replication and superinfection with additional EBV strains. Expression of the EBV receptor within the OHL lesion may promote superinfection which then activates EBV replication. The consistent detection of EBV replication only within OHL lesions and the detection of HHV8 only within Kaposi's sarcoma, strengthens the etiologic link between EBV and HHV8 infection to these specific pathologies.