Rahat Ali Khan

Histamine, Histamine Receptors, and their Role in Immunomodulation: An Updated Systematic Review

Histamine, a biological amine, is considered as a principle mediator of many pathological processes regulating several essential events in allergies and autoimmune diseases. It stimulates different biological activities through differen- tial expression of four types of histamine receptors (H1R, H2R, H3R and H4R) on secretion by effector cells (mast cells and basophils) through various immunological or non-immunological stimuli. Since H4R has been discovered very re- cently and there is paucity of comprehensive literature covering new histamine receptors, their antagonists/agonists, and role in immune regulation and immunomodulation, we tried to update the current aspects and fill the gap in existing litera- ture. This review will highlight the biological and pharmacological characterization of histamine, histamine receptors, their antagonists/agonists, and implications in immune regulation and immunomodulation.

Effect of Nigella sativa oil on various clinical and biochemical parameters of insulin resistance syndrome

AIM: The seeds of the Nigella sativa plant have been used to promote health and fight disease for centuries, especially in the Middle East and in Southeast Asia. This plant has been a focus of much research. This clinical study was undertaken to know the adjuvant effect of N. sativa oil on various clinical and biochemical parameters of the insulin resistance syndrome. MATERIALS AND METHODS: This prospective study was conducted at a tertiary health care center in North India. After confirmation of diagnosis, 60 patients who fulfilled the inclusion and exclusion criteria were enrolled in this study. Written informed consent was taken from all the patients enrolled. Approval from the institutional ethical committee was also obtained. The patients were divided into two groups of 30 each. In group I (the standard group), patients were advised tablet atorvastatin 10 mg once a day and tablet metformin 500 mg twice a day for a period of 6 weeks. In group II (the N. sativa group), the patients were advised tablet atorvastatin 10 mg once a day, tablet metformin 500 mg twice a day, and N. sativa oil 2.5 ml twice daily for a period of 6 weeks. Fasting and postprandial blood glucose, fasting lipid profile, and waist circumference were recorded before therapy and after completion of therapy. RESULT: The treatment group showed significant (P < 0.05) improvement with reference to total cholesterol, low density lipoprotein cholesterol (LDL-C), and fasting blood glucose (P < 0.05). CONCLUSION: N. sativa oil was found to be effective as an add-on therapy in patients of insulin resistance syndrome. N. sativa oil has a significant activity in diabetic and dyslipidemic patients.

Statin induced diabetes and its clinical implications

Statins are one of the most commonly used drugs in the world based on their potential to prevent adverse cardiovascular events. These cholesterol-lowering drugs received a US Food and Drug Administration warning, in February 2012, regarding increased risk of incident diabetes and impaired glycemic control in patients who already have diabetes. The possible association of diabetes with statin therapy has started a wave of discussion in the medical community. A number of meta-analyses conducted in recent years have demonstrated that the association is real although causality has not been proved yet. Individual statins differ with respect to their diabetogenic property; women and elderly persons appear to be at increased risk. Various aspects of statins adverse effect on glycemic control remain to be explored. As further research in this area continues, physicians might still take some precautions to make risk benefit ratio more favorable for the patients.

Dose-dependent effect of histamine on antibody generation in vivo

Objective: To delineate immunomodulatory role of histamine on antibody generation profile in rabbit in the present dose-dependent histamine study. Methods: The cohort comprised of three groups (Ⅲ. Ⅳ and Ⅴ), containing six rabbits each, and received subcutaneous histamine 50μg/kg×b. i. s in die (b. i. d.), 100μg/kg×b. i. d. and 200μg/kg×b. i. d., respectively for 10 days (starting from the 1st day). They were subsequently immunized on the 3rd day with intravenous injection of sheep blood cell (SRBC) (1×10^9 cells/mL). Group Ⅱ (positive control) (n=6) received vehicle (sterile distilled water) and immunized at day 3 similarly while group Ⅰ (negative control) (n=6) remained non-immunized and received only vehicle. All experimentations were performed in triplicate. Blood samples were collected on pre-immunization (pre-Ⅰ) (day 0). as well as on days 7-, 14-, 21-. 28- and 58-post-immunization (post-Ⅰ). Immunological parameters [total immunoglobulins (Igs). IgM and IgG] were analyzed by enzyme linked immunosorbent assay (ELISA) technique. Results: Histamine could influence a detectable antibody response to SRBC as early as day 7-post-Ⅰ. which lasted until day 58-post-Ⅰ. The results were found statistically significant (P＜0.05). Conclusions: Our results provide evidence that histamine has a short-term effect on antibody generation (until its presence in the body), and the antibody generation titer in vivo were affected by the concentration of histamine.

Modulation of in vivo immunoglobulin production by endogenous histamine and H1R and H2R agonists and antagonists

The present study was designed to delineate the immunomodulatory role of histamine receptors (H1R and H2R) and their antibody generation in a rabbit model. Six groups containing 18 rabbits each received either vehicle (sterile distilled water, 1 ml/kg x b.i.d), histamine (100 μg/kg x b.i.d.), H1R agonist (HTMT, 10 μg/kg x b.i.d.), H2R agonist (amthamine, 10 μg/kg x b.i.d.), H1R antagonist (pheniramine, 10 mg/kg x b.i.d.) or H2R antagonist (ranitidine, 10 mg/kg x b.i.d.). All animals were subsequently immunized with an intravenous injection of sheep red blood cells (SRBC). Estimations of total serum immunoglobulins (Igs), immunoglobulin M (IgM) and immunoglobulin G (IgG) were performed by ELISA and hemagglutination assay (HA) at days 0 (pre-immunization), 7, 14, 21, 28 and 58 (post-immunization). Both the ELISA and the HA showed similar production of Igs, IgM and IgG but the results were found comparatively more significant by ELISA as opposed to HA. Results showed that histamine could influence a detectable antibody response to SRBC early (i.e., at day 7), which lasted until day 58. Immunomodulatory processes showed suppression of an Ig generation in the H1R-antagonist group with enhancement in the H2R-antagonist group. The H1R-agonist group showed an increased Ig production in comparison to the H2R-agonist group. The IgM production was inhibited in the H1R-antagonist group as compared to the H2R-antagonist group, and it was also suppressed in H1R-agonist group as compared to H2R-agonist group. IgG production was inhibited in the H1R-antagonist group as opposed to the H2R-antagonist group. In contrast, the H1R-agonist group increased IgG production as compared to the H2R-agonist group. All the results were found to be statistically significant (p < 0.05 or p < 0.01). In conclusion, histamine and its receptor (H1R and H2R) agonists enhance antibody production by triggering the histamine receptors (H1R and H2R), and both the H1R antagonist and the H2R antagonist positively or negatively regulate the antibody production. The findings of this study may have clinical significance.

Evaluation of the anti-inflammatory activity of the aqueous and ethanolic extracts of the leaves of Albizzia lebbeck in rats.

Albizzia lebbeck Benth. (Mimosaceae) is a medicinal tree used to treat several inflammatory ailments in the Indian traditional Ayurvedic system of medicine. The aim of the present study was to evaluate the possible anti-inflammatory activity of the aqueous (AE) and ethanolic (EE) extracts of the leaves of A. lebbeck to support the ethnopharmacological claims. The study was carried out using Wistar rats (100–150 g). The AE and EE were prepared using the Soxhlet extraction process. The anti-inflammatory activity of the AE and EE of the leaves of A. lebbeck were studied using carrageenan-induced paw edema and cotton pellet-induced granuloma models. The AE and EE of the leaves of A. lebbeck at doses of 50, 100, and 200 mg/kg p.o. (oral administration) showed a dose-dependent and significant (p < 0.05) inhibition of carrageenan-induced hind paw edema with maximum percentage inhibition (PI) values of 22.34, 30.85, 39.36 and 22.53, 32.98, 42.55, respectively. The AE and EE at doses of 50, 100, 200 mg/kg p.o. significantly (p < 0.05) inhibited granuloma formation with PI values of 19.07, 27.57, 38.55 and 23.93, 32.23, 42.33, respectively. The AE and EE of the leaves of A. lebbeck showed significant (p < 0.05) anti-inflammatory activity.

Evaluation of Rhubarb Supplementation in Stages 3 and 4 of Chronic Kidney Disease: A Randomized Clinical Trial.

Objective. To evaluate the efficacy and safety of Rhubarb supplementation in patients of chronic kidney disease. Material and Methods. This study was a prospective comparative study conducted in patients of chronic kidney disease (stages 3 & 4) attending Renal Clinic of Department of Medicine, JN Medical College & Hospital, AMU, Aligarh. Patients were randomly divided into two interventional groups. Group I (Control) was given conservative management while Group II (Rhubarb) received conservative management along with Rhubarb capsule (350 mg, thrice daily) for 12 weeks. Haemogram and renal function tests were measured at 0, 4, 8, and 12 weeks of treatment. Results. There was progressive improvement in clinical features in both the groups after 12 weeks of treatment but Rhubarb group showed more marked improvement as compared to control group. Both groups showed gradual improvement in the biochemical parameters as compared to their pretreated values which was more marked in Rhubarb supplemented group. There was reduction in blood glucose, blood urea, serum creatinine, and 24 hour total urine protein (TUP). There was increase in haemoglobin, 24 hour total urine volume (TUV), and glomerular filtration rate (GFR). There was no statistical difference in two groups with respect to side effects (P > 0.05). Conclusion. Rhubarb supplementation improved the therapeutic effect of conservative management in stage 3 and stage 4 patients of chronic kidney disease.

Immunological, biochemical and histopathological evaluation of histamine receptors (H1R, H2R, H3R and H4R)-antagonist in rabbit experimental model: A short term study

The present study was designed to delineate the immuno- and hepatotoxicological roles of HRs-antagonists in vivo which is elementary in existing literature. The cohort comprised of two experimental studies. Experimental study 1 was designed for immunological investigations and consisted of seven groups and immunized with intravenous injection of SRBC at day 3 containing six rabbits each. Experimental study 2 was designed to assess the functional status of liver and comprised of seven groups containing five rabbits each. In both experimental studies group-I received sterile distilled water intramuscularly, and group II-VI received subcutaneous histamine, pheniramine (H1R-antagonist), ranitidine (H2R-antagonist), iodophenpropit (H3R-antagonist) and JNJ7777120 (H4R-antagonist), respectively while group-VII received DMSO intramuscularly. ELISA was used to assess the immunological investigations. The SRBC-specific immunoglobulins (Igs), IgM and IgG were significantly increased (p<0.05). Hepatotoxicity due to same histamine and HRs-antagonists were demonstrated by biochemical and histopathological methods. Rabbits in group II-VI had significantly (p<0.05) elevated levels of serum enzymes (ALT, AST, ALP) and bilirubin. Histopathological examination showed maintained hepatic lobular architecture in histamine and DMSO-treated groups a kin to control. Notable findings in other groups included increased binuclearity in H1R, trinuclearity in H2R, oxyphilic clusters of hepatocytes in H3R and moderate centrilobular necrosis in H3R and H4R-antagonist-treated groups without obvious inflammatory cell infiltration and Kupffer cell prominence. It is concluded that HRs-antagonist play immune suppressive role through H1R, H2R and H4R while immune enhancing role through H3R. In addition, HRs-antagonists appear moderately hepatotoxic in terms of altered serum enzyme levels and non-inflammatory hepatocellular damage.

Dose-dependent effect of histamine on liver function markers in immunized rabbits

OBJECTIVE The present study was designed to delineate the hepatotoxicological roles of histamine dose-dependently in immunized rabbits. METHODS The cohort comprised of three groups (II, III and IV), containing 18 rabbits each, and received subcutaneous histamine 50 μg/kg, 100 μg/kg and 200 μg/kg, respectively for 10 days (b.i.d., starting from 3 days prior to immunization until 7 days after immunization). Group I (control, n=18) received subcutaneous sterile distilled water for 10 days. They were subsequently immunized at day 3 with intravenous injection of SRBC (1×10(9) cells/ml). Blood samples were collected on pre-immunization (pre-I) day 0, as well as on days 7-, 14-, 21-, 28- and 58-post-immunization (post-I). Biochemical parameters aspartate aminotransferase (AST), alanine aminotransferase (ALT), alkaline phosphatase (ALP) and bilirubin [total bilirubin (TB), direct bilirubin (DB) and indirect bilirubin (IB)] were determined. RESULTS Groups II and IV revealed a significant decrease (on day 0-pre-I) and a significant increase (on days 7-, 14-, 21-, 28- and 58-post-I) in ALT and AST levels, when compared with the corresponding values of groups I and III while group II showed a significant increase in ALT and AST levels as compared to group IV. ALP levels in groups II, III and IV showed a significant enhancement when compared with group I. Moreover, results of TB, DB and IB demonstrated increased levels in group III when compared with groups I, II and IV. The results were found statistically significant (p<0.05). CONCLUSION Short-term treatment of histamine produces dose-dependent differential patterns of hepatic dysfunctions suggestive mild liver degeneration warranting further long-term studies.

Biochemical and histopathological evaluation of histamine receptors (H1R, H2R, H3R and H4R)-agonist in rabbits

The present study was designed to investigate the biochemical and histopathological changes in the livers of rabbits treated with histamine and histamine receptors (H1R-H4R)-agonist. The cohort comprised of six groups containing five rabbits each. Control group received sterile distilled water (1 mL/kg × b.i.d.) and treated groups received subcutaneous histamine (100 μg/kg × b.i.d.) and H1R-H4R-agonist (histamine trifluoro-methyl toluidide, amthamine, R-[-]-α-methylhistamine, clobenpropit, respectively) each in a dose of 10 μg/kg × b.i.d. (12 h [8 am and 8 pm]) for 30 days. Hepatotoxicity due to these agonists was analyzed using biochemical and histopathological methods. Histamine and H1R-H3R-agonist were found to be hepatotoxic as shown by statistically significant (p < 0.05) elevated levels of alanine aminotransferase (ALT) and aspartate aminotransferase (AST), most marked in the H3R-agonist group. However, their levels in H4R-agonist group remained very similar to the control group. The entire drug treated groups as compared to control showed significant elevated levels of alkaline phosphatase (ALP). Histopathological examination revealed obvious changes in histamine, H2R- and H3R-agonist groups in terms of alteration of hepatic microstructure, congestion, focal necrosis and increased incidence of multinucleate hepatocytes while H1R and H4R groups showed minimal changes. From the findings of the present study it may be concluded that on repeated administration, histamine and HR-agonists-induced hepatotoxicity which is most pronounced with H3R-agonist though not severe enough to jeopardize the vital functions of liver and warrants further long-term studies.