Relevance of pharmacogenetic aspects of mercaptopurine metabolism in the treatment of interstitial lung disease:

Identification of Immune-Related Genes and Small-Molecule Drugs in Interstitial Cystitis/Bladder Pain Syndrome Based on the Integrative Machine Learning Algorithms and Molecular Docking

Background

Interstitial cystitis/bladder pain syndrome (IC/BPS) is a chronic, severely distressing clinical syndrome characterized by bladder pain and pressure perceptions. The origin and pathophysiology of IC/BPS are currently unclear, making it difficult to diagnose and formulate successful treatments. Our study is aimed at investigating the role of immune-related genes in the diagnosis, progression, and therapy of IC/BPS.

Method

The gene expression datasets GSE11783, GSE11839, GSE28242, and GSE57560 were retrieved from the GEO database for further analysis. Immune-related IC/BPS differentially expressed genes (DEGs) were identified by limma. Three distinct machine learning approaches, least absolute shrinkage and selection operator (LASSO), support vector machine-recursive feature elimination (SVM-RFE), and random forest (RF), were used to find the immune-related IC characteristic genes. Nomogram and receiving operator curves (ROC) were plotted to measure characteristic effectiveness. Using the CMap database and the molecular docking approach, potential small-molecule medicines were found and verified. Consensus cluster analysis was also performed to separate the IC/BPS samples into immunological subtypes.

Results

A total of 24 immune-related IC/BPS-DEGs were identified. When compared to the normal control group, the IC/BPS cohort had significantly more immune cell infiltration. Integrative machine learning methods discovered 5 IC/BPS characteristic genes (RASGRP1, PPBP, RBP4, CR2, and PROS2) that may predict IC/BPS diagnosis and immune cell infiltration. Furthermore, two immunological subgroups with substantial variations in immune cell infiltration across IC/BPS samples were identified, which were named cluster1 and cluster2, with the hallmark genes having greater expression in cluster2. Finally, bumetanide was shown to have the potential to be a medication for the treatment of IC/BPS, and it performed well in terms of its molecular binding with RASGRP1.

Conclusion

We found and validated 5 immune-related IC/BPS genes (RASGRP1, PPBP, RBP4, CR2, and PROS2) and 2 IC/BPS immune subtypes. In addition, bumetanide was discovered to be a potential drug for treating IC/BPS, which may provide new insight into the diagnosis and immune therapy of IC/BPS patients.

Comorbidities of sarcoidosis

Sarcoidosis is a heterogeneous disease, which can affect virtually every body organ, even though lungs and intra thoracic lymph nodes are almost universally affected. The presence of noncaseating granulomas is the histopathological hallmark of the disease, and clinical picture depends on the organs affected. Data about interaction between sarcoidosis and comorbidities, such as cardiovascular and pulmonary diseases, autoimmune disorders, malignancy and drug-related adverse events are limited. Several lung conditions can be associated with sarcoidosis, such as pulmonary hypertension and fibrosis, making it difficult sometimes the differentiation between complications and distinctive pathologies. Their coexistence may complicate the diagnosis of sarcoidosis and contribute to the highly variable and unpredictable natural history, particularly if several diseases are recognised. A thorough assessment of specific disorders that can be associated with sarcoidosis should always be carried out, and future studies will need to evaluate sarcoidosis not only as a single disorder, but also in the light of possible concomitant conditions.Key messagesComorbidities in sarcoidosis are common, especially cardiovascular and pulmonary diseases.In the diagnostic workup, a distinction must be made between sarcoidosis-related complaints and complaints caused by other separate disorders. It can be very difficult to distinguish between complications of sarcoidosis and other concomitant conditions.The coexistence of multiple conditions may complicate the diagnosis of sarcoidosis, affect its natural course and response to treatment.

Drug-induced comorbidities in patients with sarcoidosis

PURPOSE OF REVIEW

Sarcoidosis is a chronic multisystemic inflammatory disease of unknown aetiology with a wide range of highly variable clinical manifestations and unpredictable disease course. Sarcoidosis patients may present with specific organ-related symptoms involving functional impairments, and less specific symptoms. The decision whether and when to treat a sarcoidosis patient with pharmacotherapy depends on two major factors: risk of organ failure and/or death and impairment of quality of life. This decision is complex and not standardized.

RECENT FINDINGS

Glucocorticoids (GCs) are recommended as initial treatment, when needed. Subsequent GC-sparing alternatives frequently follow. Comorbidities or adverse drug reactions (ADRs) from drugs used in sarcoidosis treatment are sometimes very hard to differentiate from symptoms associated with the disease itself, which may cause diagnostic dilemmas. An ideal approach to minimalize ADRs would involve genetic screening prior to prescribing certain 'high-risk drugs' and therapeutic drug monitoring during treatment. Pharmacogenomic testing aims to guide appropriate selection of medicines, with the potential of reducing unnecessary polypharmacy while improving clinical outcomes.

SUMMARY

A multidisciplinary approach to the management of sarcoidosis may avoid unnecessary ADRs. It is important to consider the possibility of drug-induced damage in sarcoidosis, especially if the clinical situation deteriorates after the introduction of a particular drug.

Personalized medicine in interstitial lung diseases

PURPOSE OF REVIEW

A number of recent studies have explored the possibility to apply personalized medicine to interstitial lung diseases (ILDs), particularly idiopathic pulmonary fibrosis (IPF), the most common and deadly of the idiopathic interstitial pneumonias. In our review, we summarize and discuss the most recent literature on personalized medicine in IPF as well as hypersensitivity pneumonitis and sarcoidosis, with emphasis on patient subgroups for which a personalized approach to disease prognostication and management may become a reality in the near future.

RECENT FINDINGS

Most of the studies that have explored the applicability of personalized medicine to ILDs have been conducted in patients with IPF. Such studies have suggested the existence of several distinct disease subgroups defined by similar genetic profiles, molecular pathways, exposures and individual lifestyles. Personalized medicine in hypersensitivity pneumonitis is in its infancy. The development and applicability of personalized medicine to sarcoidosis, on the other hand, remains problematic for several reasons, including the lack of a diagnostic gold standard, the highly variable and unpredictable disease course, particularly across patients of different ethnicities, the poor correlation between disease activity and disease severity and the lack of a validated management algorithm.

SUMMARY

A number of distinct patient subgroups have been identified in ILDs. Although available data need to be validated longitudinally, the possibility to study homogeneous groups of patients may allow prediction of disease behavior and response to treatment with dramatic clinical implications.

Cytotoxic agents in sarcoidosis: which one should we choose?

PURPOSE OF REVIEW

Sarcoidosis is a granulomatous disease which affects multiple organs. Its therapeutic management is very challenging due to the heterogeneity in disease manifestation and clinical course, as well as the potential side effects of the immunosuppressive therapy. An overview of presently available second-line and third-line systemic agents is provided.

RECENT FINDINGS

Because curative treatment is currently not available for sarcoidosis, nonspecific immunosuppression with prednisone remains the first-choice therapy. However, as chronic use of corticosteroids is accompanied with severe adverse events, timely implementation of appropriate steroid-sparing cytotoxic agents is important. Commonly prescribed second-line agents in sarcoidosis are methotrexate, azathioprine, leflunomide and hydroxychloroquine. Nevertheless, the evidence supporting their use is limited. Third-line treatment options, including tumor necrosis factor-alpha inhibitors infliximab and adalimumab and the experimental therapeutic rituximab, are currently reserved for patients refractory to standard therapy.

SUMMARY

A better insight into the advantages and disadvantages of second-line and third-line treatment is important. The long-term effects of immunosuppressive agents, the optimal starting and maintenance dosages, and the best interval and discontinuation regimens should be elucidated. Identified associations of polymorphisms with treatment response suggest a step towards personalized medicine. Future research should focus on the role for pharmacogenetic and phenotypic predictors of treatment response and toxicity.

Novel pharmacotherapy of sarcoidosis

Sarcoidosis is a multisystem granulomatous disease of unknown etiology that most commonly affects the lungs. Treatment of sarcoidosis can be challenging as it is often difficult to measure disease activity and distinguish active inflammation from fibrosis. Identifying the inflammatory mediators in sarcoidosis has led to the development and use of novel therapeutic agents. The goal of pharmacotherapy is to decrease granuloma accumulation, ameliorate symptoms and improve organ function. Systemic corticosteroids remain the first line treatment. Other immunosuppressive agents may be considered for the patients who respond poorly to corticosteroids or who experience significant adverse effects. An overview of pharmacotherapy of sarcoidosis is provided here.

Erythrocyte inosine triphosphatase activity is decreased in HIV-seropositive individuals

Background

Inosine triphosphatase (ITPase) is encoded by the polymorphic gene ITPA and maintains low intracellular levels of the inosine nucleotides ITP and dITP. The most frequently reported polymorphisms are ITPA c.94C>A (rs 1127354) and ITPA c. 124+21 A>C (rs7270101). Some nucleoside-analogues used in the treatment of HIV-seropositive (HIV+) patients are potential substrates for ITPase. Therefore, the frequency of ITPA SNPs and ITPase activity were studied in a population of HIV+-patients.

Methods

The study population consisted of 222 patients, predominantly Caucasian males, >95% using HAART. Erythrocyte ITPase activity was determined by measuring the formation of IMP from ITP. ITPA genotype was determined by sequencing genomic DNA. Distribution of ITPase activity, genotype-phenotype correlation and allele frequencies were compared to 198 control subjects. The effect of nucleoside analogues on ITPase activity was studied using lymphoblastic T-cell cultures and human recombinant ITPase. Enzyme kinetic experiments were performed on erythrocyte ITPase from HIV+ patients and controls.

Results

No difference was observed in the allele frequencies between the HIV+-cohort (± HAART) and the control population. HIV+ carriers of the wild type and ITPA c.94C>A had significantly lower ITPase activities than control subjects with the same genotype (p<0.005). This was not observed in ITPA c. 124+21 A>C carriers. Nucleoside analogues did not affect ITPase activity in cell culture and human recombinant ITPase. Conclusion: ITPA population genetics were identical in HIV+ and control populations. However, the majority of HIV+-patients had decreased erythrocyte ITPase activity compared to controls, probably due to decreased amounts of ITPase protein. It seems unlikely that ITPase activity is decreased due to nucleoside analogues (HAART). Long-term effects of HIV-infection altering ITPase protein expression or stability may explain the phenomenon observed.

Pharmacogenetic significance of inosine triphosphatase

Inosine triphosphatase (ITPase) is the enzyme that catalyzes the conversion of inosine triphosphate (ITP) and deoxy-inosine triphosphate (dITP) to inosine monophosphate and deoxy-inosine monophosphate, respectively, thereby maintaining low intracellular concentrations of ITP and dITP. Individuals deficient in ITPase activity were first recognized over 30 years ago. For decades, no clinical significance could be attributed to this inborn error of metabolism whatsoever. In recent years, evidence has started to accumulate that polymorphisms in the gene encoding ITPase are associated with potentially severe adverse drug reactions towards the thiopurine drugs azathioprine and 6-mercaptopurine. The pharmacogenetic significance is presently being debated in the literature. However, the present state of knowledge is still insufficient to definitively determine the pharmacogenetic significance of ITPase. This article aims to review the current knowledge on the role of ITPase in thiopurine metabolism.