Long-term presence of autoantibodies in plasma of cured leprosy patients.

Autoantibodies have been detected in leprosy patients, indicating that infection with M. leprae may lead to autoimmune disorders. However, whether autoimmune response last until patients are cured is unknown. Knowing the autoimmune response in cured leprosy patients is essential to identify whether symptoms are caused by leprosy itself or by other immune-related diseases. This knowledge is essential for the ongoing health management in cured leprosy patients where autoimmune disorders still exist. In our study, we selected six autoantibodies, including anticardiolipin antibody of IgG (ACA), anti-nuclear antibody (ANA), extractable nuclear antigen antibody (ENA), anti-streptolysin O (ASO), anti-double stranded DNA antibody (dsDNA), and rheumatoid factor (RF), that had been reported in leprosy patients as typical autoantibodies. We tested the six typical autoantibodies combined with LACC1, which encodes a protein associated with autoimmune disease such as Crohn's disease and is also the susceptible gene conferring leprosy risk, in cured leprosy patients through ELISA to assess the cured patient's immune status. We observed high positive rates of autoantibodies in cured leprosy patients, and the average plasma levels of five (ACA, ANA, ENA, ASO, and RF) out of the six autoantibodies were significantly higher in cured leprosy patients than in controls. The positive detection of autoantibodies is independent of the recovery period. Moreover, the level of these autoantibodies showed a strong positive correlation with the level of LACC1 in both controls and cured patients. This study showed that there is long-term autoimmunological activation in leprosy patients, even after decades of recovery. Autoimmune responses may influence the development and prognosis of leprosy. Special care should be given to posttreatment or cured leprosy patients regarding long-term autoimmunological activation.

Clofazimine broadly inhibits coronaviruses including SARS-CoV-2.

The COVID-19 pandemic is the third outbreak this century of a zoonotic disease caused by a coronavirus, following the emergence of severe acute respiratory syndrome (SARS) in 20031 and Middle East respiratory syndrome (MERS) in 20122. Treatment options for coronaviruses are limited. Here we show that clofazimine-an anti-leprosy drug with a favourable safety profile3-possesses inhibitory activity against several coronaviruses, and can antagonize the replication of SARS-CoV-2 and MERS-CoV in a range of in vitro systems. We found that this molecule, which has been approved by the US Food and Drug Administration, inhibits cell fusion mediated by the viral spike glycoprotein, as well as activity of the viral helicase. Prophylactic or therapeutic administration of clofazimine in a hamster model of SARS-CoV-2 pathogenesis led to reduced viral loads in the lung and viral shedding in faeces, and also alleviated the inflammation associated with viral infection. Combinations of clofazimine and remdesivir exhibited antiviral synergy in vitro and in vivo, and restricted viral shedding from the upper respiratory tract. Clofazimine, which is orally bioavailable and comparatively cheap to manufacture, is an attractive clinical candidate for the treatment of outpatients and-when combined with remdesivir-in therapy for hospitalized patients with COVID-19, particularly in contexts in which costs are an important factor or specialized medical facilities are limited. Our data provide evidence that clofazimine may have a role in the control of the current pandemic of COVID-19 and-possibly more importantly-in dealing with coronavirus diseases that may emerge in the future.

Mapping leprosy-associated coding variants of interleukin genes by targeted sequencing.

Previous genotyping-based assays have identified non-coding variants of several interleukins (ILs) being associated with genetic susceptibility to leprosy. However, understanding of the involvement of coding variants within all IL family genes in leprosy was still limited. To obtain the full mutation spectrum of all ILs in leprosy, we performed a targeted deep sequencing of coding regions of 58 ILs genes in 798 leprosy patients (age 56.2 ± 14.4; female 31.5%) and 990 healthy controls (age 38.1 ± 14.0; female 44.3%) from Yunnan, Southwest China. mRNA expression alterations of ILs in leprosy skin lesions or in response to M. leprae treatment were estimated by using publicly available expression datasets. Two coding variants in IL27 (rs17855750, p.S59A, p = 4.02 × 10-8 , odds ratio [OR] = 1.748) and IL1RN (rs45507693, p.A106T, p = 1.45 × 10-5 , OR = 3.629) were significantly associated with leprosy risk. mRNA levels of IL27 and IL1RN were upregulated in whole blood cells after M. leprae stimulation. These data showed that IL27 and IL1RN are leprosy risk genes. Further functional study is required for characterizing the exact role of ILs in leprosy.

Missense Variants in HIF1A and LACC1 Contribute to Leprosy Risk in Han Chinese.

Genome-wide association studies (GWASs) and genome-wide linkage studies (GWLSs) have identified numerous risk genes affecting the susceptibility to leprosy. However, most of the reported GWAS hits are noncoding variants and account for only part of the estimated heritability for this disease. In order to identify additional risk genes and map the potentially functional variants within the GWAS loci, we performed a three-stage study combining whole-exome sequencing (WES; discovery stage), targeted next-generation sequencing (NGS; screening stage), and refined validation of risk missense variants in 1,433 individuals with leprosy and 1,625 healthy control individuals from Yunnan Province, Southwest China. We identified and validated a rare damaging variant, rs142179458 (c.1045G>A [p.Asp349Asn]) in HIF1A, as contributing to leprosy risk (p = 4.95 × 10-9, odds ratio [OR] = 2.266). We were able to show that affected individuals harboring the risk allele presented with multibacillary leprosy at an earlier age (p = 0.025). We also confirmed the association between missense variant rs3764147 (c.760A>G [p.Ile254Val]) in the GWAS hit LACC1 (formerly C13orf31) and leprosy (p = 6.11 × 10-18, OR = 1.605). By using the population attributable fraction, we have shown that HIF1A and LACC1 are the major genes with missense variants contributing to leprosy risk in our study groups. Consistently, mRNA expression levels of both HIF1A and LACC1 were upregulated in the skin lesions of individuals with leprosy and in Mycobacterium leprae-stimulated cells, indicating an active role of HIF1A and LACC1 in leprosy pathogenesis.

The mtDNA replication-related genes TFAM and POLG are associated with leprosy in Han Chinese from Southwest China.

BACKGROUND: The pathogen Mycobacterium leprae of leprosy is heavily dependent on the host energy metabolites and nutritional products for survival. Previously we and others have identified associations of several mitochondrion-related genes and mitochondrial DNA (mtDNA) copy number alterations with leprosy and/or its subtype. We hypothesized that genetic variants of mtDNA replication-related genes would affect leprosy. OBJECTIVE: We aimed to identify genetic associations between the mtDNA replication-related genes TFAM, POLG and leprosy. METHODS: Genetic association study was performed in 2898 individuals from two independent sample sets in Yunnan Province, China. We first screened 7 tag SNPs of TFAM and POLG in 527 leprosy cases and 583 controls (Sample I). Expression quantitative trait loci (eQTL) analysis and differential mRNA expression were analyzed to discern potential effect of risk variants. The entire exon region of TFAM and POLG were further analyzed in 798 leprosy cases and 990 controls (Sample II; 4327 East Asians from the ExAC dataset was included as a reference control) by using targeted gene sequencing for fine mapping potentially causal variants. RESULTS: Two tag SNPs of TFAM (rs1049432, P=0.007) and POLG (rs3176238, P=0.006) were associated with multibacillary leprosy (MB) in Sample I and the significance survived correction for multiple comparisons. SNPs rs1937 of TFAM (which was linked with rs1049432) and rs61756401 of POLG were associated with leprosy, whereas no potentially causative coding variants were identified in Sample II. The eQTL analysis showed that rs1049432 was a significant cis eQTL for TFAM in nerve tissue (P=1.20×10-12), and rs3176238 was a significant cis eQTL for POLG in nerve (P=3.90×10-13) and skin tissues (P=2.50×10-11). Consistently, mRNA level of POLG was differentially expressed in leprotic skin lesions. CONCLUSIONS: Genetic variants of TFAM and POLG were associated with leprosy in Han Chinese, presumably by affecting gene expression.

Common variants in the PARL and PINK1 genes increase the risk to leprosy in Han Chinese from South China.

Leprosy is a chronic infectious and neurological disease caused by Mycobacterium leprae, an unculturable pathogen with massive genomic decay and dependence on host metabolism. We hypothesized that mitochondrial genes PARL and PINK1 would confer risk to leprosy. Thirteen tag SNPs of PARL and PINK1 were analyzed in 3620 individuals with or without leprosy from China. We also sequenced the entire exons of PARL, PINK1 and PARK2 in 80 patients with a family history of leprosy by using the next generation sequencing technology (NGS). We found that PARL SNP rs12631031 conferred a risk to leprosy (Padjusted = 0.019) and multibacillary leprosy (MB, Padjusted = 0.020) at the allelic level. rs12631031 and rs7653061 in PARL were associated with leprosy and MB (dominant model, Padjusted < 0.05) at the genotypic level. PINK1 SNP rs4704 was associated with leprosy at the genotypic level (Padjusted = 0.004). We confirmed that common variants in PARL and PINK1 were associated with leprosy in patients underwent NGS. Furthermore, PARL and PINK1 could physically interact with each other and were involved in the highly connected network formed by reported leprosy susceptibility genes. Together, our results showed that PARL and PINK1 genetic variants are associated with leprosy.

Fine mapping of the GWAS loci identifies SLC35D1 and IL23R as potential risk genes for leprosy.

BACKGROUND: Previous genome-wide association study (GWAS) identified two new leprosy associated loci (1p31.3 [rs3762318] and 6q24.3 [rs2275606]). However, there were insufficient validations in independent populations. OBJECTIVE: To validate the association and to map the potentially causal variants/genes underlying the association between the confirmed GWAS hit and leprosy. METHODS: We genotyped 10 variants in the regions encompassing the two loci in 1110 Han Chinese subjects with and without leprosy, followed by expression quantitative trait loci (eQTL), mRNA expression profiling, and network analysis. We further sequenced the exon region of four genes that were located in the confirmed GWAS hit region in 80 leprosy patients and 99 individuals without leprosy. RESULTS: We validated the positive association of rs3762318 with multibacillary leprosy (P=7.5×10-4), whereas the association of rs2275606 could not be validated. eQTL analysis showed that both the GWAS locus rs3762318 and one surrounding positively associated SNP rs2144658 (P=1.8×10-3) significantly affected the mRNA expression of a nearby gene SLC35D1, which might be involved in metabolism. Moreover, SLC35D1 was differentially expressed in skin tissues of leprosy patients, and the differential expression pattern was consistent among leprosy subtypes. Rare damaging missense variants in IL23R were significantly enriched in leprosy patients. CONCLUSION: Our results supported the positive association between the GWAS reported rs3762318 and leprosy, and SLC35D1 and IL23R might be the causal genes.

Genetic variants of the MAVS, MITA and MFN2 genes are not associated with leprosy in Han Chinese from Southwest China.

Leprosy is a chronic infectious disease caused by Mycobacterium leprae (M. leprae), which has massive genomic decay and dependence on host metabolism. Accumulating evidence showed a crucial role of mitochondria in metabolism and innate immunity. We hypothesized that the mitochondrial-related antimicrobial/antiviral immune genes MAVS (mitochondrial antiviral signaling protein), MITA (mediator of IRF3 activation) and MFN2 (mitofusin 2) would confer a risk to leprosy. In this study, we performed a case-control study to analyze 11 tag and/or non-synonymous SNPs of the MAVS, MITA and MFN2 genes in 527 leprosy patients and 583 healthy individuals, and directly sequenced the three genes in 80 leprosy patients with a family history from Yunnan, Southwest China. We found no association between these SNPs and leprosy (including its subtypes) based on the frequencies of alleles, genotypes and haplotypes between the cases and controls. There was also no enrichment of potential pathogenic variants of the three genes in leprosy patients. Our results suggested that genetic variants of the MAVS, MITA and MFN2 genes might not affect the susceptibility to leprosy.

Integrative analyses of leprosy susceptibility genes indicate a common autoimmune profile.

BACKGROUND: Leprosy is an ancient chronic infection in the skin and peripheral nerves caused by Mycobacterium leprae. The development of leprosy depends on genetic background and the immune status of the host. However, there is no systematic view focusing on the biological pathways, interaction networks and overall expression pattern of leprosy-related immune and genetic factors. OBJECTIVES: To identify the hub genes in the center of leprosy genetic network and to provide an insight into immune and genetic factors contributing to leprosy. METHODS: We retrieved all reported leprosy-related genes and performed integrative analyses covering gene expression profiling, pathway analysis, protein-protein interaction network, and evolutionary analyses. RESULTS: A list of 123 differentially expressed leprosy related genes, which were enriched in activation and regulation of immune response, was obtained in our analyses. Cross-disorder analysis showed that the list of leprosy susceptibility genes was largely shared by typical autoimmune diseases such as lupus erythematosus and arthritis, suggesting that similar pathways might be affected in leprosy and autoimmune diseases. Protein-protein interaction (PPI) and positive selection analyses revealed a co-evolution network of leprosy risk genes. CONCLUSIONS: Our analyses showed that leprosy associated genes constituted a co-evolution network and might undergo positive selection driven by M. leprae. We suggested that leprosy may be a kind of autoimmune disease and the development of leprosy is a matter of defect or over-activation of body immunity.

Common variants of OPA1 conferring genetic susceptibility to leprosy in Han Chinese from Southwest China.

BACKGROUND: Leprosy is an ancient chronic infection caused by Mycobacterium leprae. Onset of leprosy was highly affected by host nutritional condition and energy production, (partially) due to genomic loss and parasitic life style of M. leprae. The optic atrophy 1 (OPA1) gene plays an essential role in mitochondria, which function in cellular energy supply and innate immunity. OBJECTIVE: To investigate the potential involvement of OPA1 in leprosy. METHODS: We analyzed 7 common genetic variants of OPA1 in 1110 Han Chinese subjects with and without leprosy, followed by mRNA expression profiling and protein-protein interaction (PPI) network analysis. RESULTS: We observed positive associations between OPA1 variants rs9838374 (Pgenotypic=0.003) and rs414237 (Pgenotypic=0.002) with lepromatous leprosy. expression quantitative trait loci (eQTL) analysis showed that the leprosy-related risk allele C of rs414237 is correlated with lower OPA1 mRNA expression level. Indeed, we identified a decrease of OPA1 mRNA expression in both with patients and cellular model of leprosy. In addition, the PPI analysis showed that OPA1 protein was actively involved in the interaction network of M. leprae induced differentially expressed genes. CONCLUSION: Our results indicated that OPA1 variants confer risk of leprosy and may affect OPA1 expression, mitochondrial function and antimicrobial pathways.

Genetic variants of complement genes ficolin-2, mannose-binding lectin and complement factor H are associated with leprosy in Han Chinese from Southwest China.

The complement system plays multiple roles in host defense against infection and is supposed to confer genetic susceptibility to leprosy. We aimed to examine whether genetic variants of the Ficolin-2 (FCN2), Mannose-binding lectin (MBL2) and Complement factor H (CFH) genes, which are involved in activation and regulation of the complement system, are associated with leprosy in Han Chinese from Southwest China. 527 leprosy patients and 583 matched controls were recruited from Yunnan Province, China, and were analyzed in this study. We sequenced the promoter region of the FCN2 and MBL2 genes and exon 8 of the FCN2 gene and genotyped three tag SNPs of the CFH gene. Association analysis was performed to discern potential effect of these three genes with leprosy and its subtypes. Luciferase assay was used to characterize the role of different promoter alleles of the FCN2 and MBL2 genes. Genetic variants of FCN2 (rs3811140 and rs7851696), MBL2 (rs11003125, rs7100749, rs11003124 and rs7096206) and CFH (rs1065489 and rs3753395) were significantly associated with leprosy and its subtypes. Haplotypes/genotypes representing low FCN2 and MBL2 transcriptional activity conferred risk to paucibacillary leprosy. Our data confirmed the expected positive association of complement genes with leprosy susceptibility and clinical outcomes in Han Chinese.

Mitochondrial DNA copy number, but not haplogroup, confers a genetic susceptibility to leprosy in Han Chinese from Southwest China.

BACKGROUND: Leprosy is a chronic infectious disease caused by Mycobacterium leprae, an unculturable pathogen with an exceptionally eroded genome. The high level of inactivation of gene function in M. leprae, including many genes in its metabolic pathways, has led to a dependence on host energy production and nutritional products. We hypothesized that host cellular powerhouse--the mitochondria--may affect host susceptibility to M. leprae and the onset of clinical leprosy, and this may be reflected by mitochondrial DNA (mtDNA) background and mtDNA copy number. METHODS: We analyzed the mtDNA sequence variation of 534 leprosy patients and 850 matched controls from Yunnan Province and classified each subject by haplogroup. mtDNA copy number, taken to be proportional to mtDNA content, was measured in a subset of these subjects (296 patients and 231 controls) and 12 leprosy patients upon diagnosis. RESULTS: Comparison of matrilineal components of the case and control populations revealed no significant difference. However, measurement of mtDNA copy number showed that lepromatous leprosy patients had a significantly higher mtDNA content than controls (P = 0.008). Past medical treatments had no effect on the alteration of mtDNA copy number. CONCLUSIONS: Our results suggested that mtDNA content, but not haplogroup, affects leprosy and this influence is limited to the clinical subtype of lepromatous leprosy.

Genetic variants of the MRC1 gene and the IFNG gene are associated with leprosy in Han Chinese from Southwest China.

Leprosy is an ancient infectious disease, with over 200,000 affected people (mainly in Asia and Africa) being registered annually. Genetic factors may confer susceptibility to this disease. In the present study, we genotyped 12 genetic variants of the MRC1 gene and the IFNG gene in 527 Han Chinese with leprosy and 583 healthy individuals from Yunnan, China, to discern potential association of these two genes with leprosy. In particular, we aimed to validate the recently reported association of MRC1 variant rs1926736 (p.G396S) and IFNG variant rs2430561 (+874 T>A) with leprosy, which were initially observed in Vietnamese and Brazilian populations, respectively. Our results failed to confirm the reported association between variants rs1926736 and rs2430561 and leprosy in Han Chinese. However, we found that variants rs692527 (P = 0.022) and rs34856358 (P = 0.022) of the MRC1 gene were associated with paucibacillary leprosy, and rs3138557 of the IFNG gene was significantly associated with multibacillary leprosy. The exact role of the MRC1 gene and the IFNG gene in leprosy awaits future study.

Trends in new leprosy case detection over 57 years (1952-2008) in Yuxi, Yunnan Province of Southwest China.

BACKGROUND: Leprosy control and management in China was maintained via a vertical system. Despite substantial achievements in leprosy control in the past decades, leprosy has not been completely eliminated in several endemic areas of Yunnan Province, China. OBJECTIVES: To report the epidemiological trends and management of leprosy in Yuxi, Yunnan Province from 1952 to 2008. DESIGN: Diagnosis, control, and treatment data for 2223 leprosy cases detected from 1952 to 2008 were analysed. RESULTS: Two large-scale house-to-house surveys were launched in 1957-1958 and 1964-1965, and a remarkable number of new cases were identified during these two surveys. The overall prevalence rate of leprosy in the Yuxi region presented a roughly unimodal distribution between 1952 and 2008, with a peak (9.27 per 10000 population) in 1965. This reflects a combination of case detection and duration of treatment. Overall, the age distribution of the patients changed dramatically over the years, and there were only two childhood cases between 1995 and 2008 (both occurring in 1998). Nearly half of the total cases (49.1%) were classified as multibacillary leprosy type. With the introduction and ubiquitous coverage of the WHO multi-drug therapy (MDT) in this area, leprosy elimination was achieved in 1992. In recent years, the majority of cases (> 80%) were detected by passive approaches, and there is an increasing tendency to find multibacillary leprosy patients. CONCLUSIONS: Our results provide an overall profile of our 57-year effort regarding the leprosy control in the Yuxi region. The trend in detection of new cases in recent years suggested that the transmission of leprosy has stopped in the area or, at least, dramatically declined.