Vitamin D receptor expression levels determine the severity and complexity of disease progression among leprosy reaction patients

Iron and vitamin D intake on a diet are able to modify the in vitro immune response to Mycobacterium leprae

BACKGROUND

The impact of nutrient availability on the survival of Mycobacterium leprae and the development of leprosy remains largely unknown. Iron is essential for the survival and replication of pathogens, while vitamin D has been involved with pathogen elimination and immunoregulation.

OBJECTIVES

We evaluated the influence of dietary iron and vitamin D supplementation and restriction on the inflammatory response of mouse immune cells in vitro.

METHODS

After 30 days of standard or modified diets, peritoneal cells and splenocytes were stimulated with the alive microorganisms and sonicated antigens of M. leprae, respectively. The production of inflammatory cytokines, reactive oxygen species, and cell proliferation were evaluated.

FINDINGS

In peritoneal cells, vitamin D supplementation and iron restriction reduced the production of IL-6 and TNF in response to M. leprae, while splenocytes presented a reduction in TNF production under the same conditions. Lower levels of IFN-γ and TNF were observed in both iron-supplemented and iron-deficient splenocytes. Besides, iron supplementation also reduced the production of IL-6 and IL-10. No changes in the production of reactive oxygen species or in cell proliferation were observed related to different diets.

MAIN CONCLUSIONS

Taken together, these data point to an interference of the status of these nutrients on the interaction between the host and M. leprae, with the potential to interfere with the progression of leprosy. Our results highlight the impact of nutritional aspects on this neglected disease, which is significantly associated with unfavourable social conditions.

Association between serum level of vitamin D (25-hydroxyvitamin D) and plasma level of vitamin D receptor with bacteriological index in leprosy patients

Macrophages respond against Mycobacterium leprae infection through interacting with vitamin D and vitamin D receptor (VDR). There has been no study analyzing the association between vitamin D and VDR with bacteriological index (BI) in leprosy patients in Indonesia. To analyze the serum level of 25- hydroxyvitamin D (25(OH)D) and plasma level of VDR as well as their association with BI in leprosy patients in Indonesia. This is a cross-sectional study. Serum level of 25(OH)D was assessed with in vitro chemiluminescent immunoassay. Plasma level of VDR was assessed with enzyme linked immunosorbent assay method. Median serum level of 25(OH)D was 12.68 ng/mL. There was no correlation between serum level of 25(OH)D and BI (r=0.033; p=0.869). Median plasma level of VDR was 1.36 ng/mL. There was no correlation between plasma level of VDR and BI (r=- 0.063; p=0.749) and no significant association between BI and serum level of 25(OH) and plasma level of VDR (R2=0.055). There was no association between serum level of 25(OH)D and plasma level of VDR with BI in leprosy patients.

A Rare Case of Hansen's Disease Complicated by G6PD Deficiency

We present the case of a 37-year-old Haitian male who presented with a seven-month history of skin lesions on his face and extremities, weight loss, intermittent chills, difficulty in breathing, and bilateral paresthesias in his feet. The lesions were most prominent on the pinnae of the ears. Biopsy of the lesions revealed large, rounded granulomatous infiltrates and histiocytes. Acid fast (Ziehl-Neelsen technique) and Kinyoun stains were positive for numerous acid-fast mycobacteria within the histiocytes. A polymerase chain reaction (PCR) was positive for Mycobacterium leprae, which confirmed a diagnosis of lepromatous leprosy. Further analysis revealed positive purified protein derivatives (PPD) and QuantiFERON-TB™ test (QIAGEN, Hilden, Germany) with negative chest x-ray and sputum cultures. Labs also revealed vitamin D and G6PD (glucose-6-phosphate-dehydrogenasedeficiency. The patient was started on a combined therapy regimen of rifampin, moxifloxacin, and minocycline. In addition, he was started on vitamin D supplementation. After undergoing treatment for one year, there was notable regression of the patient's cutaneous lesions. Treatment is planned to continue for a total of 24 months. This case exemplifies the successful treatment of Hansen's disease in a patient with a G6PD deficiency. The patient's G6PD deficiency required avoidance of dapsone, which is typically used in the treatment of Hansen's disease. Furthermore, the patient's positive PPD and QuantiFERON-TB tests led to a delay in the treatment in order to rule out active tuberculosis. Left untreated, Hansen's disease has a high morbidity risk. Treatment regimens require careful consideration of coexisting comorbidities.

Host-Related Laboratory Parameters for Leprosy Reactions

Leprosy reactions are acute inflammatory episodes that complicate the course of a Mycobacterium leprae infection and are the major cause of leprosy-associated pathology. Two types of leprosy reactions with relatively distinct pathogenesis and clinical features can occur: type 1 reaction, also known as reversal reaction, and type 2 reaction, also known as erythema nodosum leprosum. These acute nerve-destructive immune exacerbations often cause irreversible disabilities and deformities, especially when diagnosis is delayed. However, there is no diagnostic test to detect or predict leprosy reactions before the onset of clinical symptoms. Identification of biomarkers for leprosy reactions, which impede the development of symptoms or correlate with early-onset, will allow precise diagnosis and timely interventions to greatly improve the patients' quality of life. Here, we review the progress of research aimed at identifying biomarkers for leprosy reactions, including its correlation with not only immunity but also genetics, transcripts, and metabolites, providing an understanding of the immune dysfunction and inflammation that underly the pathogenesis of leprosy reactions. Nevertheless, no biomarkers that can reliably predict the subsequent occurrence of leprosy reactions from non-reactional patients and distinguish type I reaction from type II have yet been found.

Undernutrition, food insecurity, and leprosy in North Gondar Zone, Ethiopia: A case-control study to identify infection risk factors associated with poverty

BACKGROUND

Ethiopia has over 3,200 new cases of leprosy diagnosed every year. Prevention remains a challenge as transmission pathways are poorly understood. Susceptibility and disease manifestations are highly dependent on individual host-immune response. Nutritional deficiencies, such as protein-energy malnutrition, have been linked to reduced cell-mediated immunity, which in the case of leprosy, could lead to a higher chance of active leprosy and thus an increased reservoir of transmissible infection.

METHODOLOGY/PRINCIPAL FINDINGS

Between June and August 2018, recently diagnosed patients with leprosy and individuals without known contact with cases were enrolled as controls in North Gondar regional health centers. Participants answered survey questions on biometric data, demographics, socioeconomic situation, and dietary habits. Descriptive statistics, univariate, and multivariate logisitic regression examined associations between undernutrition, specifically body mass index (BMI), middle upper arm circumference (MUAC), and leprosy. Eighty-one participants (40 cases of leprosy, 41 controls) were enrolled (75% male) with an average age of 38.6 years (SD 18.3). The majority of cases were multibacillary (MB) (90%). There was a high prevalence of undernutrition with 24 (29.6%) participants underweight (BMI <18.5) and 17 (21%) having a low MUAC. On multivariate analysis, underweight was significantly associated with leprosy (aOR = 9.25, 95% CI 2.77, 30.81). Also found to be associated with leprosy was cutting the size of meals/skipping meals (OR = 2.9, 95% CI 1.0, 8.32) or not having enough money for food (OR = 10, 95% CI 3.44 29.06).

CONCLUSIONS/SIGNIFICANCE

The results suggest a strong association between leprosy and undernutrition, while also supporting the framework that food insecurity may lead to undernutrition that then could increase susceptibility to leprosy. In conclusion, this study highlights the need to study the interplay of undernutrition, food insecurity, and the manifestations of leprosy.

Hypovitaminosis D and reduced cathelicidin are strongly correlated during the multidrug therapy against leprosy

Mycobacterium leprae infection depends on the competence of the host immune defense to induce effective protection against this intracellular pathogen. The present study investigated the serum levels of vitamin D and the antimicrobial peptide cathelicidin, to determine the statistical correlation between them in leprosy patients before and post-six months of multidrug therapy (MDT), household contacts, and healthy individuals. Previous studies associated these molecules with high risks to develop mycobacterial diseases, such as tuberculosis and leprosy. A total of 34 leprosy patients [paucibacillary (n = 14), multibacillary (n = 20)], and 25 household contacts were recruited. Eighteen healthy adults were selected as a control group. Serum concentrations of vitamin D (25(OH)VD₃) and cathelicidin were measured using high-performance liquid chromatography (HPLC), and an enzyme-linked immunosorbent assay (ELISA) kit, respectively. There were no significant differences in serum levels of 25(OH)VD₃ between all groups, and the overall prevalence rate of vitamin D deficiency was 67.1%. Cathelicidin levels were significantly lower in both untreated and treated patients when compared to controls and household contacts (p < 0.05). Strong correlations between hypovitaminosis D and reduced cathelicidin in untreated (r = 0.86) and post-six months of MDT (r = 0.79) leprosy patients were observed. These results suggest that vitamin D status and cathelicidin levels are strongly correlated during multidrug therapy for leprosy and nutritional supplementation from the beginning of treatment could strengthen the immune response against leprosy.

The Burden of Helminth Coinfections and Micronutrient Deficiencies in Patients with and without Leprosy Reactions: A Pilot Study in Minas Gerais, Brazil

Leprosy reactions are immune-mediated complications occurring in up to 50% of patients. The immune consequences of helminth infections and micronutrient deficiencies suggest a potential role in type 1 reactions (T1R) or type 2 reactions (T2R). We conducted a case-control study in Minas Gerais, Brazil, to evaluate whether comorbidities and other factors are associated with reactions in patients with multibacillary leprosy. Stool and serum were tested for helminth infections. Deficiencies of vitamin A, D, and iron were measured using serum retinol, 25-hydroxyvitamin D, and ferritin, respectively. Logistic regression models identified associations between reactions and helminth infections, micronutrient deficiencies, and other variables. Seventy-three patients were enrolled, 24 (33%) with T1R, 21 (29%) with T2R, 8 (15%) with mixed T1R/T2R, and 20 (27%) without reactions. Evidence of helminth infections were found in 11 participants (15%) and included IgG4 reactivity against Schistosoma mansoni, Strongyloides, and Ascaris antigens. Thirty-eight (52%) had vitamin D deficiency, eight (11%) had vitamin A insufficiency, 21 (29%) had anemia, and one (1.4%) had iron deficiency. Multivariable logistic regression showed no statistically significant associations between helminth coinfections and total reactions (adjusted odds ratios [aOR]: 1.36, 95% CI: 0.22, 8.33), T1R (aOR: 0.85, 95% CI: 0.17, 4.17), or T2R (aOR: 2.41, 95% CI: 0.29, 20.0). Vitamin D deficiency and vitamin A insufficiency were also not statistically associated with reactions. However, vitamin deficiencies and helminth infections were prevalent in these patients, suggesting a potential role for additional treatment interventions. Studying reactions prospectively may further clarify the role of comorbidities in the clinical presentation of leprosy.

Serum 25-hydroxyvitamin D level and vitamin D receptor (VDR) polymorphisms in patients infected with Leishmania tropica: a case control study

Leishmania, an obligate intracellular parasite is eliminated by a strong Th-1 host response. As Vitamin D metabolism and its receptor activity are important factors in human native immune system against some microorganisms, we hypothesized that VDR gene polymorphisms and concentration of Vitamin D might have effect on incidence of cutaneous leishmaniasis. The aim of this study was to investigate the association between VDR gene polymorphism and/or the serum vitamin D level and leishmaniasis in the infected patients in comparison to the healthy individuals. In this case-control study, the BsmI, FokI and Taq1 polymorphisms in the VDR gene and serum levels of vitamin D were studied in Iranian infected with Leishmania tropica (n = 50) and healthy controls using polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) and Electrochemiluminescence methods respectively. Data were statistically analyzed using SPSS software, Chi square and ANOVA tests. The results of this study showed that despite the relatively higher frequency of BsmI-BB, FokI-FF and TaqI-Tt than Non BsmI-BB, Non FokI-FF and Non TaqI-Tt in the patients compared with the healthy individuals, the differences were not statistically significant (P > 0.05). Based on our findings, the relationship between the VDR polymorphism, the serum concentration of 25-hydroxyvitamin D and the susceptibility to Leishmania tropica infection, remains unclear requiring further in-depth studies. However, for better interpretation, it is necessary to consider factors such as the size of the sample examined and the other alleles of VDR, including ApaI.

Association of Fok1 VDR polymorphism with Vitamin D and its associated molecules in pulmonary tuberculosis patients and their household contacts

Status of Fok I VDR polymorphism along with vitamin D, Vitamin D receptor (VDR), and cathelicidin levels in Tuberculosis (TB) patients compared to household contacts and implication of these findings in susceptibility to TB is not known. 150 active TB patients, 150 household contacts and 150 healthy controls were recruited from North Indian population. Fok1 VDR polymorphism was studied by polymerase chain reaction- restriction fragment length polymorphism (PCR-RFLP).VDR mRNA and protein levels were studied using quantitative real time PCR (q rt PCR) and enzyme linked immunosorbent assay (ELISA) respectively. Cathelicidin and Vitamin D levels were measured using ELISA and chemiluminescence immunoassay (CLIA) respectively. Significant association was found between Fok1 polymorphism and susceptibility to TB (P < 0.0005). VDR mRNA, VDR protein and vitamin D levels were significantly lower in active TB group when compared to household contacts and healthy controls (P < 0.0001, 0.0001 and 0.0005 respectively). Cathelicidin levels were higher in active TB patients compared to other groups (P < 0.0001). Expression of VDR and cathelicidin was significantly higher among 'FF' genotypes of VDR (more active form of VDR) compared to 'ff' genotype (less active form of VDR). 'f' allele was associated with increased susceptibility to TB. Higher frequency of 'F' allele, increased VDR expression along with increased vitamin D levels in household contacts compared to active TB group might be responsible for protection against active TB.

Vitamin D Receptor Gene Polymorphisms Are Associated With Leprosy in Southern Brazil

Vitamin D, together with its nuclear receptor (VDR), plays an important role in modulating the immune response, decreasing the inflammatory process. Some polymorphisms of the VDR gene, such as BsmI (G>A rs1544410), ApaI (G>T rs7975232), and TaqI (T>C rs731236) could affect its stability and mRNA transcription activity, while FokI T>C (rs2228570) gives a truncated protein with three fewer amino acids and more efficiency in binding vitamin D. This study evaluated these four polymorphisms in the immunopathogenesis of leprosy in 404 patients and 432 control individuals without chronic or infectious disease in southern Brazil. When analyzing differences in the allele and genotype frequency of polymorphisms between patients (leprosy per se, multibacillary, and paucibacillary clinical forms) and controls, we found no statistically significant association. Regarding haplotype analysis, the bAt haplotype was associated with protection from leprosy per se (P = 0.004, OR = 0.34, CI = 0.16–0.71) and from the multibacillary clinical form (P = 0.005, OR = 0.30, CI = 0.13–0.70). In individuals aged 40 or more years, this haplotype has also showed protection against leprosy per se and multibacillary (OR = 0.26, CI = 0.09–0.76; OR = 0.26, CI = 0.07–0.78, respectively), while the BAt haplotype was a risk factor for leprosy per se in the same age group (OR = 1.34, CI = 1.04–1.73). In conclusion, despite having found no associations between the VDR gene polymorphisms with the development of leprosy, the haplotypes formed by the BsmI, ApaI, and TaqI polymorphisms were associated with leprosy per se and the multibacillary clinical form.

Status of vitamin D and the associated host factors in pulmonary tuberculosis patients and their household contacts: A cross sectional study

Innate immunity plays an important role in pathophysiology of tuberculosis which is influenced by various host factors. One such factor is vitamin D which, along with its associated molecule, can alter the host defense against Mycobacterium Tuberculosis (M.Tb.) via altered production of cathelicidin and nitric oxide, both having bactericidal effect. Therefore, assessment of vitamin D and its associated molecules in tuberculosis patients and household contacts as compared to healthy controls were done and the implication of these findings in susceptibility to tuberculosis (TB) was studied. 80 active TB patients, 75 household contacts and 70 healthy controls were included. Vitamin D receptor (VDR), vitamin D binding protein (VDBP) and inducible nitric oxide synthase (iNOS) mRNA levels were studied using quantitative PCR. Serum VDR, cathelicidin, and iNOS levels were measured using ELISA. Vitamin D and NO levels were measured in serum using chemiluminescence based immunoassay and greiss reaction based colorimetry kit respectively. Decreased serum levels of vitamin D were observed in active TB patients as compared to healthy controls (p < 0.001). VDR and iNOS mRNA levels were found to be significantly lower in active TB patients compared to household contacts and healthy controls (p < 0.0001 and 0.005 respectively). VDBP mRNA expression was found to be lower in active TB group as compared to household contacts and healthy controls however the difference was not found to be significant (p > 0.21). Although, mRNA expression of VDR, VDR protein and iNOS along with vitamin D levels were significantly (p < 0.05) higher in household contacts compared to active TB group. However, levels of iNOS, NO and cathelicidin were found to be higher in TB patients as compared to household contacts and healthy controls (p < 0.01, 0.05 and 0.01 respectively). Higher levels of Vitamin D along with VDR and iNOS expression in household contacts as compared to active TB patients suggest vitamin D might have a protective role against TB plausibly decreasing disease susceptibility. Low vitamin D levels in active TB patients warrants further studies to determine the role of vitamin D supplementation in prevention and treatment of TB.

VDR polymorphism, gene expression and vitamin D levels in leprosy patients from North Indian population

Background

Leprosy is a chronic infectious disease caused by Mycobacterium leprae and mainly affects skin, peripheral nerves. Vitamin D receptor (VDR) gene polymorphism has been found to be associated with leprosy. Vitamin D has been shown to control several host immunomodulating properties through VDR gene. Vitamin D deficiency was also found to be linked to an increased risk for several infections and metabolic diseases.

Objective

In the present study, we investigated the association of VDR gene polymorphism, mRNA gene expression of VDR and the vitamin D levels with leprosy and its reactional states.

Methodology

A total of 305 leprosy patients consisting of tuberculoid (TT), borderline tuberculoid (BT), borderline lepromatous (BL), lepromatous leprosy (LL), as well as 200 healthy controls were enrolled in the study. We identified single nucleotide polymorphisms (SNPs) of VDR Taq1, Fok1 and Apa1, as well as the expression of VDR mRNA gene using PCR-based restriction fragment length polymorphism (RFLP) analysis and real-time PCR respectively. We also performed ELISA to measure vitamin D levels.

Result

We observed that SNP of VDR gene (Fok1 and Taq1) are associated with the leprosy disease. The allelic frequency distribution of T and t allele (p = 0.0037), F and f allele (p = 0.0024) was significantly higher in leprosy patients and healthy controls. ff genotype of Fok1 was found to be associated with leprosy patients [p = 0.0004; OR (95% CI) 3.148 (1.662–5.965)]. The recessive model of Fok1 genotype was also found to be significantly associated in leprosy patients in comparison to healthy controls [p = 0.00004; OR (95% CI) 2.85 (1.56–5.22)]. Leprosy patients are significantly associated with t-F-a haplotype. Further, VDR gene expression was found to be lower in non-reaction group compared to that of reaction group of leprosy and healthy controls. Paradoxically, we noted no difference in the levels of vitamin D between leprosy patients and healthy controls.

Conclusion

Blood levels of vitamin D do not play any role in clinical manifestations of any forms of leprosy. ff genotype of Fok1 and tt genotype of Taq1 was found to be associated with leprosy per se. Association of t-F-a haplotype with leprosy was found to be significant and could be used as a genetic marker to identify individuals at high risk for developing leprosy. VDR gene expression was lower in TT/BT and BL/LL groups of leprosy in comparison to that of healthy controls.

Present study was carried out to find out the association of vitamin D receptor (VDR) gene polymorphism, mRNA gene expression of VDR gene and level of vitamin D with leprosy reactions and leprosy patients. Surprisingly, level of vitamin D in leprosy patients was not found to be associated with the disease and its manifestations. VDR genotypes (Fok1 and Taq1) were found to be associated with leprosy patients. t-F-a haplotype was significantly associated with leprosy patients. Gene expression of vitamin D receptor was lower in leprosy patients in comparison to healthy controls.

Intrinsic activation of the vitamin D antimicrobial pathway by M. leprae infection is inhibited by type I IFN

Following infection, virulent mycobacteria persist and grow within the macrophage, suggesting that the intrinsic activation of an innate antimicrobial response is subverted by the intracellular pathogen. For Mycobacterium leprae, the intracellular bacterium that causes leprosy, the addition of exogenous innate or adaptive immune ligands to the infected monocytes/macrophages was required to detect a vitamin D-dependent antimicrobial activity. We investigated whether there is an intrinsic immune response to M. leprae in macrophages that is inhibited by the pathogen. Upon infection of monocytes with M. leprae, there was no upregulation of CYP27B1 nor its enzymatic activity converting the inactive prohormone form of vitamin D (25-hydroxyvitamin D) to the bioactive form (1,25α-dihydroxyvitamin D). Given that M. leprae-induced type I interferon (IFN) inhibited monocyte activation, we blocked the type I IFN receptor (IFNAR), revealing the intrinsic capacity of monocytes to recognize M. leprae and upregulate CYP27B1. Consistent with these in vitro studies, an inverse relationship between expression of CYP27B1 vs. type I IFN downstream gene OAS1 was detected in leprosy patient lesions, leading us to study cytokine-derived macrophages (MΦ) to model cellular responses at the site of disease. Infection of IL-15-derived MΦ, similar to MΦ in lesions from the self-limited form of leprosy, with M. leprae did not inhibit induction of the vitamin D antimicrobial pathway. In contrast, infection of IL-10-derived MΦ, similar to MΦ in lesions from patients with the progressive form of leprosy, resulted in induction of type I IFN and suppression of the vitamin D directed pathway. Importantly, blockade of the type I IFN response in infected IL-10 MΦ decreased M. leprae viability. These results indicate that M. leprae evades the intrinsic capacity of human monocytes/MΦ to activate the vitamin D-mediated antimicrobial pathway via the induction of type I IFN.

Our macrophages are equipped with the ability to detect and kill invading pathogens, and yet, these cells of the innate immune system are still subject to infection by intracellular bacterium. In particular, mycobacterium, the type of intracellular bacteria responsible for diseases such as tuberculosis and leprosy, are very successful at establishing infection within macrophages. By studying Mycobacterium leprae, the etiological agent of leprosy, we describe an immune evasion mechanism whereby this bacterial pathogen utilizes our own antiviral immune response against the macrophage. Type I interferons (IFN) are a major part of our immune response to viral infections; however, this response will also suppress our ability to fight opportunistic bacterial infection. During infection of our macrophages, M. leprae induces an aberrant type I IFN response that subsequently suppresses our macrophage’s ability to activate the vitamin D-mediated antimicrobial pathway, a critical antimicrobial response for containment of mycobacterium. Thus, understanding how these pathogens can evade our immune response will be important for the development of new therapies against these chronic infections.

Vitamin D receptor expression and hepcidin levels in the protection or severity of leprosy: a systematic review

Leprosy is a chronic infectious disease whose disequilibrium in the host's genetic, immunological and clinical mechanisms leads to distinct manifestations defining the type of immunological response. This review focuses its attention on the influence of the Vitamin D Receptor and hepcidin expressions that can suggest the protection or severity of leprosy.

A Systematic Review of Immunological Studies of Erythema Nodosum Leprosum

Erythema nodosum leprosum (ENL) is a painful inflammatory complication of leprosy occurring in 50% of lepromatous leprosy patients and 5-10% of borderline lepromatous patients. It is a significant cause of economic hardship, morbidity and mortality in leprosy patients. Our understanding of the causes of ENL is limited. We performed a systematic review of the published literature and critically evaluated the evidence for the role of neutrophils, immune complexes (ICs), T-cells, cytokines, and other immunological factors that could contribute to the development of ENL. Searches of the literature were performed in PubMed. Studies, independent of published date, using samples from patients with ENL were included. The search revealed more than 20,000 articles of which 146 eligible studies were included in this systematic review. The studies demonstrate that ENL may be associated with a neutrophilic infiltrate, but it is not clear whether it is an IC-mediated process or that the presence of ICs is an epiphenomenon. Increased levels of tumor necrosis factor-α and other pro-inflammatory cytokines support the role of this cytokine in the inflammatory phase of ENL but not necessarily the initiation. T-cell subsets appear to be important in ENL since multiple studies report an increased CD4⁺/CD8⁺ ratio in both skin and peripheral blood of patients with ENL. Microarray data have identified new molecules and whole pathophysiological pathways associated with ENL and provides new insights into the pathogenesis of ENL. Studies of ENL are often difficult to compare due to a lack of case definitions, treatment status, and timing of sampling as well as the use of different laboratory techniques. A standardized approach to some of these issues would be useful. ENL appears to be a complex interaction of various aspects of the immune system. Rigorous clinical descriptions of well-defined cohorts of patients and a systems biology approach using available technologies such as genomics, epigenomics, transcriptomics, and proteomics could yield greater understanding of the condition.