Assessment of serum level of interleukin-1b and interleukin-12 in leprosy: impact of previous Bacillus Calmitte Guerin vaccination

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.

Serum Th1/Th2 and macrophage lineage cytokines in leprosy; correlation with circulating CD4(+) CD25(high) FoxP3(+) T-regs cells

Not only macrophages, T-helper (Th)1 and Th2, but also CD4(+) CD25(high) FoxP3(+) regulatory T cells (T-regs) are involved in immune response to Mycobacterium leprae. We aimed to evaluate serum interleukin (IL)-1β and IL-12p70 (macrophage cytokines), interferon-γ (IFN-γ) (Th1 cytokine), IL-4 (Th2 cytokine) and circulating CD4(+) CD25(high) FoxP3(+) T-regs, in untreated leprosy patients. Forty three patients and 40 controls were assessed for the mentioned cytokines using ELISA. Patients were assessed for circulating T-regs using flow cytometry. Patients were subgrouped into tuberculoid (TT), pure neural leprosy (PNL), borderline cases, lepromatous (LL), type 1 reactional leprosy (RL1) and erythema nodosum leprosum (ENL). Serum IL-12p70, IFN-γ and IL-4 were significantly higher in patients versus controls (P < 0.05). Serum IL-4 was highest in LL and lowest in RL1 (P = 0.003). Serum IL-1β levels was significantly higher in multibacillary versus paucibacillary patients (P = 0.006). Significantly higher T-regs levels was detected in TT, RL1 and PNL, while the lowest levels in ENL(P < 0.001), with significant differences versus controls (P < 0.05). FoxP3 expression% was significantly lower in PNL than other patients and controls (P < 0.05). T-regs/T-effs was lowest in ENL(P < 0.05). IFN-γ correlated positively with T-regs but negatively with IL-1β (P = 0.041&0.046 respectively), which correlated positively with T-effs%( P = 0.05). IL-4 correlated positively with T-regs FoxP3 expression% (P = 0.009). We concluded that: Circulating T-regs were increased in TT, RL1 and PNL patients, known of relatively high cell-mediated immunity. This finding was supported by low FoxP3 expression (in PNL) and correlation between T-regs count and IFN-γ level. Overproduction of IL-4 in LL may infer liability to develop ENL, with disease progression and immune hyperactivation, marked by deficient T-regs and increased T-regs FoxP3 expression%. IL-1β probably has a pro-inflammatory role in multibacillary patients as correlated with T-effs%.

Clinical manifestations of leprosy after BCG vaccination: an observational study in Bangladesh

BACKGROUND

Although BCG is used as a vaccine against tuberculosis, it also protects against leprosy. Previous evaluation over 18 years of an intervention of two doses BCG for 3536 household contacts of leprosy patients showed that 28 (23%) out of 122 contacts diagnosed with leprosy, developed symptoms 2-10 months after vaccination. This study describes contacts of leprosy patients in Bangladesh who developed leprosy within 12 weeks after receiving a single BCG dose.

METHODS

A cluster RCT in Bangladesh aims to study the effectiveness of the BCG vaccine versus BCG in combination with single dose rifampicin (SDR) given 2 to 3 months after BCG, in the prevention of leprosy among contacts of newly diagnosed leprosy patients. During the first 1,5 years of this ongoing trial we identified contacts who developed leprosy within the first 12 weeks after receiving BCG vaccination, the timeframe before SDR is given.

RESULTS

We identified 21 contacts who developed leprosy within 12 weeks after BCG vaccination among 5196 vaccinated contacts (0.40%). All 21 cases presented with paucibacillary (PB) leprosy, including children and adults. About half of these cases had previously received BCG vaccination as indicated by the presence of a BCG scar; 43% presented with signs of nerve function impairment and/or Type 1 (reversal) reaction, and 56% of the index patients had multibacillary (MB) leprosy.

CONCLUSION

An unexpectedly high proportion of healthy contacts of leprosy patients presented with PB leprosy within 12 weeks after receiving BCG vaccination, possibly as a result of boosted cell-mediated immunity by homologues of Mycobacterium leprae antigens in BCG. Various immunological mechanisms could underlie this phenomenon, including an immune reconstitution inflammatory syndrome (IRIS). Further studies are required to determine whether BCG vaccination merely altered the incubation period or actually changed the course of the infection from self-limiting, subclinical infection to manifest disease.