T cell suppression in the bone marrow of visceral leishmaniasis patients: impact of parasite load

Visceral leishmaniasis (VL) is a disseminated and lethal disease of reticulo-endothelial system caused by protozoan parasites Leishmania donovani and L. infantum, which are known to induce host T cell suppression. To understand the impact of parasite load on T cell function, the present was focused on parasite load with T cell function in bone marrow of 26 VL patients. We observed significant enrichment of forkhead box protein 3 (FoxP3)⁺ (P = 0·0003) and interleukin (IL)-10⁺ FoxP3⁺ regulatory T cells (T_reg ) (P = 0·004) in the bone marrow (BM) of patients with high parasite load (HPL) compared with low parasite load (LPL). Concordantly, T effector cells producing interferon (IFN)-γ (P = 0·005) and IL-17A (P = 0·002) were reduced in the BM of HPL. Blocking of T_reg -cell derived suppressive cytokines [(IL-10 and transforming growth factor (TGF)-β] rescued the effector T cells and their functions. However, it was observed that TGF-β levels were dominant, favouring T_reg cell differentiation. Furthermore, the low ratio of IL-6/TGF-β favours the suppressive milieu in HPL patients. Here we show the change in levels of various cytokines with the parasitic load during active VL, which could be helpful in devising newer immunotherapeutic strategies against this disease.

Genetic variability of begomoviruses associated with cotton leaf curl disease originating from India

Cotton leaf curl disease (CLCuD) causing viruses belong to the Begomovirus genus of the family Geminiviridae. Most begomoviruses are bipartite with two molecules of circular single stranded DNA (A and B) encapsidated in icosahedral geminate particles. However, the begomoviruses associated with CLCuD have DNA-beta instead of DNA-B. In this communication we report the complete genomic sequence of DNA-A component of two CLCuD-causing begomoviruses, cotton leaf curl Kokhran virus-Dabawali (CLCuKV-Dab), tomato leaf curl Bangalore virus-Cotton [Fatehabad] (ToLCBV-Cotton [Fat]) and partial sequences of two other isolates cotton leaf curl Rajasthan virus-Bangalore (CLCuRV-Ban) and cotton leaf curl Kokhran virus-Ganganagar (CLCuKV-Gang). A phylogenetic analysis of these isolates along with other related begomoviruses showed that ToLCBV-Cotton [Fat] isolate was closest to the tomato leaf curl Bangalore virus-5 (ToLCBV-Ban5) where as CLCuKV-Dab isolate was close to the cotton leaf curl Kokhran virus-Faisalabad1 (CLCuKV-Fai1), cotton leaf curl Kokhran virus-72b (CLCuKV-72b) and cotton leaf curl Kokhran virus-806b (CLCuKV-806b) isolates from Pakistan. The phylogenetic analysis further showed that the ToLCBV-Cotton [Fat] and CLCuKV-Dab isolates along with CLCuKV-Fai1, CLCuKV-72b and CLCuKV-806b are closer to the ToLCBV, tomato leaf curl Gujarat virus (ToLCGV), tomato leaf curl Gujarat virus-Varanasi (ToLCGV-Var) and tomato leaf curl Sri Lanka virus (ToLCSLV) isolates, where as cotton leaf curl Alabad virus-804a (CLCuAV-804a), cotton leaf curl Multhan virus (CLCuMV) cluster with the isolates from cotton leaf curl Rajasthan virus (CLCuRV) and okra yellow vein mosaic virus (OYVMV). These results demonstrate the extensive variability observed in this group of viruses. The AC4 ORF is the least conserved among these viruses. In order to further asses the variability in the CLCuD-causing begomoviruses, the region showing minimum similarity in the DNA-A sequence was first determined by a comparison of segments of different lengths of the aligned sequences. The results indicated that region 2411-424 (771 nt) was the least conserved. A phylogenetic tree constructed using the sequences of all the CLCuD causing begomoviruses, corresponding to the least conserved region showed that they form two distinct clusters.

Conversion to neoral for neurotoxicity after primary adult liver transplantation under tacrolimus

BACKGROUND

Neurological complications after orthotopic liver transplantation (OLTX) have remained a major concern in a small proportion of patients. The etiology of these complications is often thought to be multifactorial: the influence of calcineurin inhibitors is occasionally thought to play an important role. When neurotoxicity occurs after OLTX under tacrolimus, it is usually a minor complication and responds readily to a reduction in the dosage of or a temporary withdrawal of tacrolimus. However, neurotoxic complications occasionally do not respond to this conventional process. Neoral is a microemulsion formulation of cyclosporine. It has more consistent pharmacokinetic parameters and improved bioavailability when compared with conventional cyclosporine. The aim of the present report was to evaluate the role of Neoral in OLTX recipients with neurotoxic complication who failed to respond to a reduction in the dosage of tacrolimus.

METHOD

Between August 1995 and November 1997, 330 adults (age >18 years) received primary OLTX under tacrolimus-based immunosuppression (mean age 52.6+/-11.4 years). There were 190 men and 140 women. Twenty-three (7%) patients (mean age 53.2+/-11.8 years; 17 men, 6 women) were converted to Neoral (mean 35+/-41 days after OLTX). These patients were followed until June 1998 (mean follow-up 22.7+/-7.8 months).

RESULTS

Four (17.4%) patients died during the follow-up period, and two patients underwent retransplantation. Neurological symptoms improved in all patients who survived. Adequate trough concentrations were achieved in all patients with p.o. Neoral. Nine (39%) patients experienced rejection episodes after conversion. Six (26.1%) patients were converted back to tacrolimus because of ongoing rejection (n=3), retransplantation (n=2), or persistent nausea and vomiting (n=1) without recurrence of the original neurological complication.

CONCLUSION

Neurological complications after OLTX disorders that occur under tacrolimus and that fail to respond to a reduction in the dosage can be treated safely by conversion to Neoral. However, the rate of rejection is up to 39%, and patients can often be converted back to tacrolimus without recurrence of the original neurological complication.

Immunosuppressive therapy

Although several new immunosuppressive medications have been developed in the past decade, many possible avenues are yet to be explored. Although the newer agents have not reflected any clear benefit in patient or graft survival over CsA or tacrolimus, they have been useful in reducing the incidence and severity of rejection, reducing the concomitant use of steroids, and decreasing the doses of CsA or tacrolimus to minimize their toxicity profile. The appearance of these new agents has given more options to clinicians, who can select the one with the least toxicity and most efficacy for individual patients. In the future, combinations of these agents, in conjunction with a strategy to induce tolerance of the donor organ without drug toxicity, will be the goal.